内容表

ssl — 套接字对象的 TLS/SSL 包裹器

上一话题

socket — 低级网络接口

下一话题

就业培训下载中心 Wiki 联络

登录注册

首页
Python 3.12.4
索引
模块
下一
上一
Python 标准库
网络和进程间通信
ssl — 套接字对象的 TLS/SSL 包裹器

`ssl` — 套接字对象的 TLS/SSL 包裹器 ¶

源代码： Lib/ssl.py

This module provides access to Transport Layer Security (often known as “Secure Sockets Layer”) encryption and peer authentication facilities for network sockets, both client-side and server-side. This module uses the OpenSSL library. It is available on all modern Unix systems, Windows, macOS, and probably additional platforms, as long as OpenSSL is installed on that platform.

注意

Some behavior may be platform dependent, since calls are made to the operating system socket APIs. The installed version of OpenSSL may also cause variations in behavior. For example, TLSv1.3 comes with OpenSSL version 1.1.1.

警告

不要使用此模块当未阅读安全注意事项 . Doing so may lead to a false sense of security, as the default settings of the ssl module are not necessarily appropriate for your application.

可用性：非 Emscripten，非 WASI。

本模块不工作 (或不可用) 于 WebAssembly 平台 wasm32-emscripten and wasm32-wasi 。见 WebAssembly 平台了解更多信息。

This section documents the objects and functions in the ssl module; for more general information about TLS, SSL, and certificates, the reader is referred to the documents in the “See Also” section at the bottom.

此模块提供类 ssl.SSLSocket ，派生自 socket.socket type, and provides a socket-like wrapper that also encrypts and decrypts the data going over the socket with SSL. It supports additional methods such as getpeercert() , which retrieves the certificate of the other side of the connection, and cipher() , which retrieves the cipher being used for the secure connection.

For more sophisticated applications, the ssl.SSLContext class helps manage settings and certificates, which can then be inherited by SSL sockets created through the SSLContext.wrap_socket() 方法。

3.5.3 版改变：更新 OpenSSL 1.1.0 链接支持

3.6 版改变： OpenSSL 0.9.8, 1.0.0 and 1.0.1 are deprecated and no longer supported. In the future the ssl module will require at least OpenSSL 1.0.2 or 1.1.0.

3.10 版改变： PEP 644 has been implemented. The ssl module requires OpenSSL 1.1.1 or newer.

Use of deprecated constants and functions result in deprecation warnings.

函数、常量和异常 ¶

套接字创建 ¶

实例化的 SSLSocket must be created using the SSLContext.wrap_socket() method. The helper function create_default_context() returns a new context with secure default settings.

Client socket example with default context and IPv4/IPv6 dual stack:

import socket
import ssl
hostname = 'www.python.org'
context = ssl.create_default_context()
with socket.create_connection((hostname, 443)) as sock:
    with context.wrap_socket(sock, server_hostname=hostname) as ssock:
        print(ssock.version())

Client socket example with custom context and IPv4:

hostname = 'www.python.org'
# PROTOCOL_TLS_CLIENT requires valid cert chain and hostname
context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
context.load_verify_locations('path/to/cabundle.pem')
with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as sock:
    with context.wrap_socket(sock, server_hostname=hostname) as ssock:
        print(ssock.version())

Server socket example listening on localhost IPv4:

context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
context.load_cert_chain('/path/to/certchain.pem', '/path/to/private.key')
with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as sock:
    sock.bind(('127.0.0.1', 8443))
    sock.listen(5)
    with context.wrap_socket(sock, server_side=True) as ssock:
        conn, addr = ssock.accept()
        ...

上下文创建 ¶

方便函数帮助创建 SSLContext 对象对于常见目的。

ssl. create_default_context ( purpose = Purpose.SERVER_AUTH , cafile = None , capath = None , cadata = None ) ¶

返回新的 SSLContext 对象采用默认设置为给定 purpose 。设置的选取是通过 ssl 模块，和通常表示更高安全级别相比当调用 SSLContext 构造函数直接。

cafile , capath , cadata represent optional CA certificates to trust for certificate verification, as in SSLContext.load_verify_locations() . If all three are None , this function can choose to trust the system’s default CA certificates instead.

The settings are: PROTOCOL_TLS_CLIENT or PROTOCOL_TLS_SERVER , OP_NO_SSLv2 ，和 OP_NO_SSLv3 with high encryption cipher suites without RC4 and without unauthenticated cipher suites. Passing SERVER_AUTH as purpose sets verify_mode to CERT_REQUIRED and either loads CA certificates (when at least one of cafile , capath or cadata is given) or uses SSLContext.load_default_certs() to load default CA certificates.

当 keylog_filename is supported and the environment variable SSLKEYLOGFILE 有设置， create_default_context() enables key logging.

注意

The protocol, options, cipher and other settings may change to more restrictive values anytime without prior deprecation. The values represent a fair balance between compatibility and security.

If your application needs specific settings, you should create a SSLContext and apply the settings yourself.

注意

If you find that when certain older clients or servers attempt to connect with a SSLContext created by this function that they get an error stating “Protocol or cipher suite mismatch”, it may be that they only support SSL3.0 which this function excludes using the OP_NO_SSLv3 . SSL3.0 is widely considered to be completely broken . If you still wish to continue to use this function but still allow SSL 3.0 connections you can re-enable them using:

ctx = ssl.create_default_context(Purpose.CLIENT_AUTH)
ctx.options &= ~ssl.OP_NO_SSLv3

Added in version 3.4.

3.4.4 版改变： RC4 was dropped from the default cipher string.

3.6 版改变： ChaCha20/Poly1305 was added to the default cipher string.

3DES was dropped from the default cipher string.

3.8 版改变： Support for key logging to SSLKEYLOGFILE 被添加。

3.10 版改变： The context now uses PROTOCOL_TLS_CLIENT or PROTOCOL_TLS_SERVER protocol instead of generic PROTOCOL_TLS .

异常 ¶

exception ssl. SSLError ¶

Raised to signal an error from the underlying SSL implementation (currently provided by the OpenSSL library). This signifies some problem in the higher-level encryption and authentication layer that’s superimposed on the underlying network connection. This error is a subtype of OSError . The error code and message of SSLError instances are provided by the OpenSSL library.

3.3 版改变： SSLError used to be a subtype of socket.error .

library ¶

A string mnemonic designating the OpenSSL submodule in which the error occurred, such as SSL , PEM or X509 . The range of possible values depends on the OpenSSL version.

Added in version 3.3.

reason ¶

A string mnemonic designating the reason this error occurred, for example CERTIFICATE_VERIFY_FAILED . The range of possible values depends on the OpenSSL version.

Added in version 3.3.

exception ssl. SSLZeroReturnError ¶

子类化的 SSLError raised when trying to read or write and the SSL connection has been closed cleanly. Note that this doesn’t mean that the underlying transport (read TCP) has been closed.

Added in version 3.3.

exception ssl. SSLWantReadError ¶

子类化的 SSLError raised by a non-blocking SSL socket when trying to read or write data, but more data needs to be received on the underlying TCP transport before the request can be fulfilled.

Added in version 3.3.

exception ssl. SSLWantWriteError ¶

子类化的 SSLError raised by a non-blocking SSL socket when trying to read or write data, but more data needs to be sent on the underlying TCP transport before the request can be fulfilled.

Added in version 3.3.

exception ssl. SSLSyscallError ¶

子类化的 SSLError raised when a system error was encountered while trying to fulfill an operation on a SSL socket. Unfortunately, there is no easy way to inspect the original errno number.

Added in version 3.3.

exception ssl. SSLEOFError ¶

子类化的 SSLError raised when the SSL connection has been terminated abruptly. Generally, you shouldn’t try to reuse the underlying transport when this error is encountered.

Added in version 3.3.

exception ssl. SSLCertVerificationError ¶

子类化的 SSLError raised when certificate validation has failed.

Added in version 3.7.

verify_code ¶: A numeric error number that denotes the verification error.

verify_message ¶: A human readable string of the verification error.

exception ssl. CertificateError ¶

别名化的 SSLCertVerificationError .

3.7 版改变： The exception is now an alias for SSLCertVerificationError .

随机生成 ¶

ssl. RAND_bytes ( num ) ¶

返回 num cryptographically strong pseudo-random bytes. Raises an SSLError if the PRNG has not been seeded with enough data or if the operation is not supported by the current RAND method. RAND_status() can be used to check the status of the PRNG and RAND_add() can be used to seed the PRNG.

For almost all applications os.urandom() is preferable.

Read the Wikipedia article, Cryptographically secure pseudorandom number generator (CSPRNG) , to get the requirements of a cryptographically strong generator.

Added in version 3.3.

ssl. RAND_status ( ) ¶: 返回 True if the SSL pseudo-random number generator has been seeded with ‘enough’ randomness, and False otherwise. You can use ssl.RAND_egd() and ssl.RAND_add() to increase the randomness of the pseudo-random number generator.

ssl. RAND_add ( bytes , entropy ) ¶

Mix the given bytes into the SSL pseudo-random number generator. The parameter entropy (a float) is a lower bound on the entropy contained in string (so you can always use 0.0 )。见 RFC 1750 for more information on sources of entropy.

3.5 版改变：可写像字节对象现接受。

证书处理 ¶

ssl. cert_time_to_seconds ( cert_time ) ¶

Return the time in seconds since the Epoch, given the cert_time string representing the “notBefore” or “notAfter” date from a certificate in "%b %d %H:%M:%S %Y %Z" strptime format (C locale).

这里是范例：

>>> import ssl
>>> timestamp = ssl.cert_time_to_seconds("Jan  5 09:34:43 2018 GMT")
>>> timestamp
1515144883
>>> from datetime import datetime
>>> print(datetime.utcfromtimestamp(timestamp))
2018-01-05 09:34:43

“notBefore” or “notAfter” dates must use GMT ( RFC 5280 ).

3.5 版改变： Interpret the input time as a time in UTC as specified by ‘GMT’ timezone in the input string. Local timezone was used previously. Return an integer (no fractions of a second in the input format)

ssl. get_server_certificate ( addr , ssl_version=PROTOCOL_TLS_CLIENT , ca_certs=None [ , timeout ] ) ¶

Given the address addr of an SSL-protected server, as a ( hostname , port-number ) pair, fetches the server’s certificate, and returns it as a PEM-encoded string. If ssl_version is specified, uses that version of the SSL protocol to attempt to connect to the server. If ca_certs is specified, it should be a file containing a list of root certificates, the same format as used for the cafile parameter in SSLContext.load_verify_locations() . The call will attempt to validate the server certificate against that set of root certificates, and will fail if the validation attempt fails. A timeout can be specified with the timeout 参数。

3.3 版改变： This function is now IPv6-compatible.

3.5 版改变：默认 ssl_version is changed from PROTOCOL_SSLv3 to PROTOCOL_TLS for maximum compatibility with modern servers.

3.10 版改变： The timeout 参数被添加。

ssl. DER_cert_to_PEM_cert ( DER_cert_bytes ) ¶: Given a certificate as a DER-encoded blob of bytes, returns a PEM-encoded string version of the same certificate.

ssl. PEM_cert_to_DER_cert ( PEM_cert_string ) ¶: Given a certificate as an ASCII PEM string, returns a DER-encoded sequence of bytes for that same certificate.

ssl. get_default_verify_paths ( ) ¶

Returns a named tuple with paths to OpenSSL’s default cafile and capath. The paths are the same as used by SSLContext.set_default_verify_paths() . The return value is a 命名元组 DefaultVerifyPaths :

cafile - resolved path to cafile or None if the file doesn’t exist,
capath - resolved path to capath or None if the directory doesn’t exist,
openssl_cafile_env - OpenSSL’s environment key that points to a cafile,
openssl_cafile - hard coded path to a cafile,
openssl_capath_env - OpenSSL’s environment key that points to a capath,
openssl_capath - hard coded path to a capath directory

Added in version 3.4.

ssl. enum_certificates ( store_name ) ¶

Retrieve certificates from Windows’ system cert store. store_name may be one of CA , ROOT or MY . Windows may provide additional cert stores, too.

The function returns a list of (cert_bytes, encoding_type, trust) tuples. The encoding_type specifies the encoding of cert_bytes. It is either x509_asn for X.509 ASN.1 data or pkcs_7_asn for PKCS#7 ASN.1 data. Trust specifies the purpose of the certificate as a set of OIDS or exactly True if the certificate is trustworthy for all purposes.

范例：

>>> ssl.enum_certificates("CA")
[(b'data...', 'x509_asn', {'1.3.6.1.5.5.7.3.1', '1.3.6.1.5.5.7.3.2'}),
 (b'data...', 'x509_asn', True)]

可用性：Windows。

Added in version 3.4.

ssl. enum_crls ( store_name ) ¶

Retrieve CRLs from Windows’ system cert store. store_name may be one of CA , ROOT or MY . Windows may provide additional cert stores, too.

可用性：Windows。

Added in version 3.4.

常量 ¶

All constants are now enum.IntEnum or enum.IntFlag 集合。

Added in version 3.6.

ssl. CERT_NONE ¶

ssl. CERT_OPTIONAL ¶

ssl. CERT_REQUIRED ¶

class ssl. VerifyMode ¶

ssl. VERIFY_DEFAULT ¶

ssl. VERIFY_CRL_CHECK_LEAF ¶

ssl. VERIFY_CRL_CHECK_CHAIN ¶

ssl. VERIFY_X509_STRICT ¶

ssl. VERIFY_ALLOW_PROXY_CERTS ¶

ssl. VERIFY_X509_TRUSTED_FIRST ¶

ssl. VERIFY_X509_PARTIAL_CHAIN ¶

class ssl. VerifyFlags ¶

ssl. PROTOCOL_TLS ¶

从 3.10 版起弃用： TLS clients and servers require different default settings for secure communication. The generic TLS protocol constant is deprecated in favor of PROTOCOL_TLS_CLIENT and PROTOCOL_TLS_SERVER .

ssl. PROTOCOL_TLS_CLIENT ¶

ssl. PROTOCOL_TLS_SERVER ¶

ssl. PROTOCOL_SSLv23 ¶

ssl. PROTOCOL_SSLv3 ¶

从 3.6 版起弃用： OpenSSL has deprecated all version specific protocols. Use the default protocol PROTOCOL_TLS_SERVER or PROTOCOL_TLS_CLIENT with SSLContext.minimum_version and SSLContext.maximum_version 代替。

ssl. PROTOCOL_TLSv1 ¶: Selects TLS version 1.0 as the channel encryption protocol.

从 3.6 版起弃用： OpenSSL has deprecated all version specific protocols.

ssl. PROTOCOL_TLSv1_1 ¶

从 3.6 版起弃用： OpenSSL has deprecated all version specific protocols.

ssl. PROTOCOL_TLSv1_2 ¶

Selects TLS version 1.2 as the channel encryption protocol. Available only with openssl version 1.0.1+.

Added in version 3.4.

从 3.6 版起弃用： OpenSSL has deprecated all version specific protocols.

ssl. OP_ALL ¶

Enables workarounds for various bugs present in other SSL implementations. This option is set by default. It does not necessarily set the same flags as OpenSSL’s SSL_OP_ALL 常量。

Added in version 3.2.

ssl. OP_NO_SSLv2 ¶

Prevents an SSLv2 connection. This option is only applicable in conjunction with PROTOCOL_TLS . It prevents the peers from choosing SSLv2 as the protocol version.

Added in version 3.2.

从 3.6 版起弃用： SSLv2 is deprecated

ssl. OP_NO_SSLv3 ¶

Prevents an SSLv3 connection. This option is only applicable in conjunction with PROTOCOL_TLS . It prevents the peers from choosing SSLv3 as the protocol version.

Added in version 3.2.

从 3.6 版起弃用： SSLv3 is deprecated

ssl. OP_NO_TLSv1 ¶

Prevents a TLSv1 connection. This option is only applicable in conjunction with PROTOCOL_TLS . It prevents the peers from choosing TLSv1 as the protocol version.

Added in version 3.2.

从 3.7 版起弃用： The option is deprecated since OpenSSL 1.1.0, use the new SSLContext.minimum_version and SSLContext.maximum_version 代替。

ssl. OP_NO_TLSv1_1 ¶

Prevents a TLSv1.1 connection. This option is only applicable in conjunction with PROTOCOL_TLS . It prevents the peers from choosing TLSv1.1 as the protocol version. Available only with openssl version 1.0.1+.

Added in version 3.4.

从 3.7 版起弃用： The option is deprecated since OpenSSL 1.1.0.

ssl. OP_NO_TLSv1_2 ¶

Prevents a TLSv1.2 connection. This option is only applicable in conjunction with PROTOCOL_TLS . It prevents the peers from choosing TLSv1.2 as the protocol version. Available only with openssl version 1.0.1+.

Added in version 3.4.

从 3.7 版起弃用： The option is deprecated since OpenSSL 1.1.0.

ssl. OP_NO_TLSv1_3 ¶

Prevents a TLSv1.3 connection. This option is only applicable in conjunction with PROTOCOL_TLS . It prevents the peers from choosing TLSv1.3 as the protocol version. TLS 1.3 is available with OpenSSL 1.1.1 or later. When Python has been compiled against an older version of OpenSSL, the flag defaults to 0 .

Added in version 3.6.3.

从 3.7 版起弃用： The option is deprecated since OpenSSL 1.1.0. It was added to 2.7.15 and 3.6.3 for backwards compatibility with OpenSSL 1.0.2.

ssl. OP_NO_RENEGOTIATION ¶

Disable all renegotiation in TLSv1.2 and earlier. Do not send HelloRequest messages, and ignore renegotiation requests via ClientHello.

This option is only available with OpenSSL 1.1.0h and later.

Added in version 3.7.

ssl. OP_CIPHER_SERVER_PREFERENCE ¶

Use the server’s cipher ordering preference, rather than the client’s. This option has no effect on client sockets and SSLv2 server sockets.

Added in version 3.3.

ssl. OP_SINGLE_DH_USE ¶

Prevents reuse of the same DH key for distinct SSL sessions. This improves forward secrecy but requires more computational resources. This option only applies to server sockets.

Added in version 3.3.

ssl. OP_SINGLE_ECDH_USE ¶

Prevents reuse of the same ECDH key for distinct SSL sessions. This improves forward secrecy but requires more computational resources. This option only applies to server sockets.

Added in version 3.3.

ssl. OP_ENABLE_MIDDLEBOX_COMPAT ¶

Send dummy Change Cipher Spec (CCS) messages in TLS 1.3 handshake to make a TLS 1.3 connection look more like a TLS 1.2 connection.

This option is only available with OpenSSL 1.1.1 and later.

Added in version 3.8.

ssl. OP_NO_COMPRESSION ¶

Disable compression on the SSL channel. This is useful if the application protocol supports its own compression scheme.

Added in version 3.3.

class ssl. Options ¶: enum.IntFlag collection of OP_* constants.

ssl. OP_NO_TICKET ¶

Prevent client side from requesting a session ticket.

Added in version 3.6.

ssl. OP_IGNORE_UNEXPECTED_EOF ¶

Ignore unexpected shutdown of TLS connections.

This option is only available with OpenSSL 3.0.0 and later.

Added in version 3.10.

ssl. OP_ENABLE_KTLS ¶

Enable the use of the kernel TLS. To benefit from the feature, OpenSSL must have been compiled with support for it, and the negotiated cipher suites and extensions must be supported by it (a list of supported ones may vary by platform and kernel version).

Note that with enabled kernel TLS some cryptographic operations are performed by the kernel directly and not via any available OpenSSL Providers. This might be undesirable if, for example, the application requires all cryptographic operations to be performed by the FIPS provider.

This option is only available with OpenSSL 3.0.0 and later.

3.12 版添加。

ssl. OP_LEGACY_SERVER_CONNECT ¶

Allow legacy insecure renegotiation between OpenSSL and unpatched servers only.

3.12 版添加。

ssl. HAS_ALPN ¶

Whether the OpenSSL library has built-in support for the Application-Layer Protocol Negotiation TLS extension as described in RFC 7301 .

Added in version 3.5.

ssl. HAS_NEVER_CHECK_COMMON_NAME ¶

Whether the OpenSSL library has built-in support not checking subject common name and SSLContext.hostname_checks_common_name is writeable.

Added in version 3.7.

ssl. HAS_ECDH ¶

Whether the OpenSSL library has built-in support for the Elliptic Curve-based Diffie-Hellman key exchange. This should be true unless the feature was explicitly disabled by the distributor.

Added in version 3.3.

ssl. HAS_SNI ¶

Whether the OpenSSL library has built-in support for the SNI (服务器名称指示) 扩展 (作为定义在 RFC 6066 ).

Added in version 3.2.

ssl. HAS_NPN ¶

Whether the OpenSSL library has built-in support for the Next Protocol Negotiation as described in the Application Layer Protocol Negotiation . When true, you can use the SSLContext.set_npn_protocols() method to advertise which protocols you want to support.

Added in version 3.3.

ssl. HAS_SSLv2 ¶

Whether the OpenSSL library has built-in support for the SSL 2.0 protocol.

Added in version 3.7.

ssl. HAS_SSLv3 ¶

Whether the OpenSSL library has built-in support for the SSL 3.0 protocol.

Added in version 3.7.

ssl. HAS_TLSv1 ¶

Whether the OpenSSL library has built-in support for the TLS 1.0 protocol.

Added in version 3.7.

ssl. HAS_TLSv1_1 ¶

Whether the OpenSSL library has built-in support for the TLS 1.1 protocol.

Added in version 3.7.

ssl. HAS_TLSv1_2 ¶

Whether the OpenSSL library has built-in support for the TLS 1.2 protocol.

Added in version 3.7.

ssl. HAS_TLSv1_3 ¶

Whether the OpenSSL library has built-in support for the TLS 1.3 protocol.

Added in version 3.7.

ssl. CHANNEL_BINDING_TYPES ¶

List of supported TLS channel binding types. Strings in this list can be used as arguments to SSLSocket.get_channel_binding() .

Added in version 3.3.

ssl. OPENSSL_VERSION ¶

The version string of the OpenSSL library loaded by the interpreter:

>>> ssl.OPENSSL_VERSION
'OpenSSL 1.0.2k  26 Jan 2017'

Added in version 3.2.

ssl. OPENSSL_VERSION_INFO ¶

A tuple of five integers representing version information about the OpenSSL library:

>>> ssl.OPENSSL_VERSION_INFO
(1, 0, 2, 11, 15)

Added in version 3.2.

ssl. OPENSSL_VERSION_NUMBER ¶

The raw version number of the OpenSSL library, as a single integer:

>>> ssl.OPENSSL_VERSION_NUMBER
268443839
>>> hex(ssl.OPENSSL_VERSION_NUMBER)
'0x100020bf'

Added in version 3.2.

ssl. ALERT_DESCRIPTION_HANDSHAKE_FAILURE ¶

ssl. ALERT_DESCRIPTION_INTERNAL_ERROR ¶

ALERT_DESCRIPTION_*

Alert Descriptions from RFC 5246 and others. The IANA TLS Alert Registry contains this list and references to the RFCs where their meaning is defined.

Used as the return value of the callback function in SSLContext.set_servername_callback() .

Added in version 3.4.

class ssl. AlertDescription ¶

enum.IntEnum collection of ALERT_DESCRIPTION_* constants.

Added in version 3.6.

Purpose. SERVER_AUTH ¶

Option for create_default_context() and SSLContext.load_default_certs() . This value indicates that the context may be used to authenticate web servers (therefore, it will be used to create client-side sockets).

Added in version 3.4.

Purpose. CLIENT_AUTH ¶

Option for create_default_context() and SSLContext.load_default_certs() . This value indicates that the context may be used to authenticate web clients (therefore, it will be used to create server-side sockets).

Added in version 3.4.

class ssl. SSLErrorNumber ¶

enum.IntEnum collection of SSL_ERROR_* constants.

Added in version 3.6.

class ssl. TLSVersion ¶

enum.IntEnum collection of SSL and TLS versions for SSLContext.maximum_version and SSLContext.minimum_version .

Added in version 3.7.

TLSVersion. MINIMUM_SUPPORTED ¶

TLSVersion. MAXIMUM_SUPPORTED ¶: The minimum or maximum supported SSL or TLS version. These are magic constants. Their values don’t reflect the lowest and highest available TLS/SSL versions.

TLSVersion. SSLv3 ¶

TLSVersion. TLSv1 ¶

TLSVersion. TLSv1_1 ¶

TLSVersion. TLSv1_2 ¶

TLSVersion. TLSv1_3 ¶: SSL 3.0 to TLS 1.3.

从 3.10 版起弃用：所有 TLSVersion members except TLSVersion.TLSv1_2 and TLSVersion.TLSv1_3 被弃用。

SSL 套接字 ¶

class ssl. SSLSocket ( socket.socket ) ¶

从 3.6 版起弃用： It is deprecated to create a SSLSocket instance directly, use SSLContext.wrap_socket() to wrap a socket.

3.7 版改变： SSLSocket instances must to created with wrap_socket() . In earlier versions, it was possible to create instances directly. This was never documented or officially supported.

3.10 版改变： Python now uses SSL_read_ex and SSL_write_ex internally. The functions support reading and writing of data larger than 2 GB. Writing zero-length data no longer fails with a protocol violation error.

SSL sockets also have the following additional methods and attributes:

SSLSocket. read ( len = 1024 , buffer = None ) ¶

从 3.6 版起弃用：使用 recv() 而不是 read() .

SSLSocket. write ( buf ) ¶

写入 buf to the SSL socket and return the number of bytes written. The buf argument must be an object supporting the buffer interface.

引发 SSLWantReadError or SSLWantWriteError if the socket is non-blocking and the write would block.

As at any time a re-negotiation is possible, a call to write() can also cause read operations.

3.5 版改变： The socket timeout is no longer reset each time bytes are received or sent. The socket timeout is now the maximum total duration to write buf .

从 3.6 版起弃用：使用 send() 而不是 write() .

注意

The read() and write() methods are the low-level methods that read and write unencrypted, application-level data and decrypt/encrypt it to encrypted, wire-level data. These methods require an active SSL connection, i.e. the handshake was completed and SSLSocket.unwrap() was not called.

Normally you should use the socket API methods like recv() and send() instead of these methods.

SSLSocket. do_handshake ( ) ¶

Perform the SSL setup handshake.

3.4 版改变： The handshake method also performs match_hostname() 当 check_hostname attribute of the socket’s context 为 True。

3.5 版改变： The socket timeout is no longer reset each time bytes are received or sent. The socket timeout is now the maximum total duration of the handshake.

3.7 版改变： Hostname or IP address is matched by OpenSSL during handshake. The function match_hostname() is no longer used. In case OpenSSL refuses a hostname or IP address, the handshake is aborted early and a TLS alert message is sent to the peer.

SSLSocket. getpeercert ( binary_form = False ) ¶

If there is no certificate for the peer on the other end of the connection, return None . If the SSL handshake hasn’t been done yet, raise ValueError .

若 binary_form 参数为 False , and a certificate was received from the peer, this method returns a dict instance. If the certificate was not validated, the dict is empty. If the certificate was validated, it returns a dict with several keys, amongst them subject (the principal for which the certificate was issued) and issuer (the principal issuing the certificate). If a certificate contains an instance of the Subject Alternative Name 扩展 (见 RFC 3280 ), there will also be a subjectAltName key in the dictionary.

The subject and issuer fields are tuples containing the sequence of relative distinguished names (RDNs) given in the certificate’s data structure for the respective fields, and each RDN is a sequence of name-value pairs. Here is a real-world example:

{'issuer': ((('countryName', 'IL'),),
            (('organizationName', 'StartCom Ltd.'),),
            (('organizationalUnitName',
              'Secure Digital Certificate Signing'),),
            (('commonName',
              'StartCom Class 2 Primary Intermediate Server CA'),)),
 'notAfter': 'Nov 22 08:15:19 2013 GMT',
 'notBefore': 'Nov 21 03:09:52 2011 GMT',
 'serialNumber': '95F0',
 'subject': ((('description', '571208-SLe257oHY9fVQ07Z'),),
             (('countryName', 'US'),),
             (('stateOrProvinceName', 'California'),),
             (('localityName', 'San Francisco'),),
             (('organizationName', 'Electronic Frontier Foundation, Inc.'),),
             (('commonName', '*.eff.org'),),
             (('emailAddress', 'hostmaster@eff.org'),)),
 'subjectAltName': (('DNS', '*.eff.org'), ('DNS', 'eff.org')),
 'version': 3}

若 binary_form 参数为 True , and a certificate was provided, this method returns the DER-encoded form of the entire certificate as a sequence of bytes, or None if the peer did not provide a certificate. Whether the peer provides a certificate depends on the SSL socket’s role:

for a client SSL socket, the server will always provide a certificate, regardless of whether validation was required;
for a server SSL socket, the client will only provide a certificate when requested by the server; therefore getpeercert() 将返回 None if you used CERT_NONE (rather than CERT_OPTIONAL or CERT_REQUIRED ).

另请参阅 SSLContext.check_hostname .

3.2 版改变： The returned dictionary includes additional items such as issuer and notBefore .

3.4 版改变： ValueError is raised when the handshake isn’t done. The returned dictionary includes additional X509v3 extension items such as crlDistributionPoints , caIssuers and OCSP URIs.

3.9 版改变： IPv6 address strings no longer have a trailing new line.

SSLSocket. cipher ( ) ¶: Returns a three-value tuple containing the name of the cipher being used, the version of the SSL protocol that defines its use, and the number of secret bits being used. If no connection has been established, returns None .

SSLSocket. shared_ciphers ( ) ¶

Return the list of ciphers available in both the client and server. Each entry of the returned list is a three-value tuple containing the name of the cipher, the version of the SSL protocol that defines its use, and the number of secret bits the cipher uses. shared_ciphers() 返回 None if no connection has been established or the socket is a client socket.

Added in version 3.5.

SSLSocket. compression ( ) ¶

Return the compression algorithm being used as a string, or None if the connection isn’t compressed.

If the higher-level protocol supports its own compression mechanism, you can use OP_NO_COMPRESSION to disable SSL-level compression.

Added in version 3.3.

SSLSocket. get_channel_binding ( cb_type = 'tls-unique' ) ¶

Get channel binding data for current connection, as a bytes object. Returns None if not connected or the handshake has not been completed.

The cb_type parameter allow selection of the desired channel binding type. Valid channel binding types are listed in the CHANNEL_BINDING_TYPES list. Currently only the ‘tls-unique’ channel binding, defined by RFC 5929 , is supported. ValueError will be raised if an unsupported channel binding type is requested.

Added in version 3.3.

SSLSocket. selected_alpn_protocol ( ) ¶

Return the protocol that was selected during the TLS handshake. If SSLContext.set_alpn_protocols() was not called, if the other party does not support ALPN, if this socket does not support any of the client’s proposed protocols, or if the handshake has not happened yet, None 被返回。

Added in version 3.5.

SSLSocket. selected_npn_protocol ( ) ¶

Return the higher-level protocol that was selected during the TLS/SSL handshake. If SSLContext.set_npn_protocols() was not called, or if the other party does not support NPN, or if the handshake has not yet happened, this will return None .

Added in version 3.3.

从 3.10 版起弃用： NPN has been superseded by ALPN

SSLSocket. unwrap ( ) ¶: Performs the SSL shutdown handshake, which removes the TLS layer from the underlying socket, and returns the underlying socket object. This can be used to go from encrypted operation over a connection to unencrypted. The returned socket should always be used for further communication with the other side of the connection, rather than the original socket.

SSLSocket. verify_client_post_handshake ( ) ¶

Requests post-handshake authentication (PHA) from a TLS 1.3 client. PHA can only be initiated for a TLS 1.3 connection from a server-side socket, after the initial TLS handshake and with PHA enabled on both sides, see SSLContext.post_handshake_auth .

The method does not perform a cert exchange immediately. The server-side sends a CertificateRequest during the next write event and expects the client to respond with a certificate on the next read event.

If any precondition isn’t met (e.g. not TLS 1.3, PHA not enabled), an SSLError 被引发。

注意

Only available with OpenSSL 1.1.1 and TLS 1.3 enabled. Without TLS 1.3 support, the method raises NotImplementedError .

Added in version 3.8.

SSLSocket. version ( ) ¶

Return the actual SSL protocol version negotiated by the connection as a string, or None if no secure connection is established. As of this writing, possible return values include "SSLv2" , "SSLv3" , "TLSv1" , "TLSv1.1" and "TLSv1.2" . Recent OpenSSL versions may define more return values.

Added in version 3.5.

SSLSocket. pending ( ) ¶: Returns the number of already decrypted bytes available for read, pending on the connection.

SSLSocket. context ¶

The SSLContext object this SSL socket is tied to.

Added in version 3.2.

SSLSocket. server_side ¶

A boolean which is True for server-side sockets and False for client-side sockets.

Added in version 3.2.

SSLSocket. server_hostname ¶

Hostname of the server: str type, or None for server-side socket or if the hostname was not specified in the constructor.

Added in version 3.2.

3.7 版改变： The attribute is now always ASCII text. When server_hostname is an internationalized domain name (IDN), this attribute now stores the A-label form ( "xn--pythn-mua.org" ), rather than the U-label form ( "pythön.org" ).

SSLSocket. session ¶

The SSLSession for this SSL connection. The session is available for client and server side sockets after the TLS handshake has been performed. For client sockets the session can be set before do_handshake() has been called to reuse a session.

Added in version 3.6.

SSLSocket. session_reused ¶: Added in version 3.6.

SSL 上下文 ¶

Added in version 3.2.

An SSL context holds various data longer-lived than single SSL connections, such as SSL configuration options, certificate(s) and private key(s). It also manages a cache of SSL sessions for server-side sockets, in order to speed up repeated connections from the same clients.

class ssl. SSLContext ( protocol = None ) ¶

创建新的 SSL (安全套接字层) 上下文。可以传递 protocol which must be one of the PROTOCOL_* constants defined in this module. The parameter specifies which version of the SSL protocol to use. Typically, the server chooses a particular protocol version, and the client must adapt to the server’s choice. Most of the versions are not interoperable with the other versions. If not specified, the default is PROTOCOL_TLS ; it provides the most compatibility with other versions.

Here’s a table showing which versions in a client (down the side) can connect to which versions in a server (along the top):

client / server	SSLv2	SSLv3	TLS [ 3 ]	TLSv1	TLSv1.1	TLSv1.2
SSLv2	yes	no	no [ 1 ]	no	no	no
SSLv3	no	yes	no [ 2 ]	no	no	no
TLS ( SSLv23 ) [ 3 ]	no [ 1 ]	no [ 2 ]	yes	yes	yes	yes
TLSv1	no	no	yes	yes	no	no
TLSv1.1	no	no	yes	no	yes	no
TLSv1.2	no	no	yes	no	no	yes

脚注

[ 1 ] ( 1 , 2 )

SSLContext 禁用 SSLv2 采用 OP_NO_SSLv2 在默认情况下。

[ 2 ] ( 1 , 2 )

SSLContext 禁用 SSLv3 采用 OP_NO_SSLv3 在默认情况下。

[ 3 ] ( 1 , 2 )

TLS 1.3 protocol will be available with PROTOCOL_TLS in OpenSSL >= 1.1.1. There is no dedicated PROTOCOL constant for just TLS 1.3.

另请参阅

create_default_context() lets the ssl module choose security settings for a given purpose.

3.6 版改变： The context is created with secure default values. The options OP_NO_COMPRESSION , OP_CIPHER_SERVER_PREFERENCE , OP_SINGLE_DH_USE , OP_SINGLE_ECDH_USE , OP_NO_SSLv2 ，和 OP_NO_SSLv3 (except for PROTOCOL_SSLv3 ) are set by default. The initial cipher suite list contains only HIGH ciphers, no NULL ciphers and no MD5 ciphers.

从 3.10 版起弃用： SSLContext without protocol argument is deprecated. The context class will either require PROTOCOL_TLS_CLIENT or PROTOCOL_TLS_SERVER protocol in the future.

3.10 版改变： The default cipher suites now include only secure AES and ChaCha20 ciphers with forward secrecy and security level 2. RSA and DH keys with less than 2048 bits and ECC keys with less than 224 bits are prohibited. PROTOCOL_TLS , PROTOCOL_TLS_CLIENT ，和 PROTOCOL_TLS_SERVER use TLS 1.2 as minimum TLS version.

SSLContext objects have the following methods and attributes:

SSLContext. cert_store_stats ( ) ¶

Get statistics about quantities of loaded X.509 certificates, count of X.509 certificates flagged as CA certificates and certificate revocation lists as dictionary.

Example for a context with one CA cert and one other cert:

>>> context.cert_store_stats()
{'crl': 0, 'x509_ca': 1, 'x509': 2}

Added in version 3.4.

SSLContext. load_cert_chain ( certfile , keyfile = None , password = None ) ¶

Load a private key and the corresponding certificate. The certfile string must be the path to a single file in PEM format containing the certificate as well as any number of CA certificates needed to establish the certificate’s authenticity. The keyfile string, if present, must point to a file containing the private key. Otherwise the private key will be taken from certfile as well. See the discussion of 证书 for more information on how the certificate is stored in the certfile .

The password argument may be a function to call to get the password for decrypting the private key. It will only be called if the private key is encrypted and a password is necessary. It will be called with no arguments, and it should return a string, bytes, or bytearray. If the return value is a string it will be encoded as UTF-8 before using it to decrypt the key. Alternatively a string, bytes, or bytearray value may be supplied directly as the password argument. It will be ignored if the private key is not encrypted and no password is needed.

若 password argument is not specified and a password is required, OpenSSL’s built-in password prompting mechanism will be used to interactively prompt the user for a password.

An SSLError is raised if the private key doesn’t match with the certificate.

3.3 版改变：新增可选自变量 password .

SSLContext. load_default_certs ( purpose = Purpose.SERVER_AUTH ) ¶

Load a set of default “certification authority” (CA) certificates from default locations. On Windows it loads CA certs from the CA and ROOT system stores. On all systems it calls SSLContext.set_default_verify_paths() . In the future the method may load CA certificates from other locations, too.

The purpose flag specifies what kind of CA certificates are loaded. The default settings Purpose.SERVER_AUTH loads certificates, that are flagged and trusted for TLS web server authentication (client side sockets). Purpose.CLIENT_AUTH loads CA certificates for client certificate verification on the server side.

Added in version 3.4.

SSLContext. load_verify_locations ( cafile = None , capath = None , cadata = None ) ¶

加载一组 CA (证书颁发机构) 证书，用于验证其它对等方证书当 verify_mode 除了 CERT_NONE 。至少某一 cafile or capath 必须指定。

This method can also load certification revocation lists (CRLs) in PEM or DER format. In order to make use of CRLs, SSLContext.verify_flags must be configured properly.

The cafile string, if present, is the path to a file of concatenated CA certificates in PEM format. See the discussion of 证书 for more information about how to arrange the certificates in this file.

The capath string, if present, is the path to a directory containing several CA certificates in PEM format, following an OpenSSL specific layout .

The cadata object, if present, is either an ASCII string of one or more PEM-encoded certificates or a 像字节对象 of DER-encoded certificates. Like with capath extra lines around PEM-encoded certificates are ignored but at least one certificate must be present.

3.4 版改变：新增可选自变量 cadata

SSLContext. get_ca_certs ( binary_form = False ) ¶

Get a list of loaded “certification authority” (CA) certificates. If the binary_form 参数为 False each list entry is a dict like the output of SSLSocket.getpeercert() . Otherwise the method returns a list of DER-encoded certificates. The returned list does not contain certificates from capath unless a certificate was requested and loaded by a SSL connection.

注意

Certificates in a capath directory aren’t loaded unless they have been used at least once.

Added in version 3.4.

SSLContext. get_ciphers ( ) ¶

Get a list of enabled ciphers. The list is in order of cipher priority. See SSLContext.set_ciphers() .

范例：

>>> ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
>>> ctx.set_ciphers('ECDHE+AESGCM:!ECDSA')
>>> ctx.get_ciphers()
[{'aead': True,
  'alg_bits': 256,
  'auth': 'auth-rsa',
  'description': 'ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH     Au=RSA  '
                 'Enc=AESGCM(256) Mac=AEAD',
  'digest': None,
  'id': 50380848,
  'kea': 'kx-ecdhe',
  'name': 'ECDHE-RSA-AES256-GCM-SHA384',
  'protocol': 'TLSv1.2',
  'strength_bits': 256,
  'symmetric': 'aes-256-gcm'},
 {'aead': True,
  'alg_bits': 128,
  'auth': 'auth-rsa',
  'description': 'ECDHE-RSA-AES128-GCM-SHA256 TLSv1.2 Kx=ECDH     Au=RSA  '
                 'Enc=AESGCM(128) Mac=AEAD',
  'digest': None,
  'id': 50380847,
  'kea': 'kx-ecdhe',
  'name': 'ECDHE-RSA-AES128-GCM-SHA256',
  'protocol': 'TLSv1.2',
  'strength_bits': 128,
  'symmetric': 'aes-128-gcm'}]

Added in version 3.6.

SSLContext. set_default_verify_paths ( ) ¶: Load a set of default “certification authority” (CA) certificates from a filesystem path defined when building the OpenSSL library. Unfortunately, there’s no easy way to know whether this method succeeds: no error is returned if no certificates are to be found. When the OpenSSL library is provided as part of the operating system, though, it is likely to be configured properly.

SSLContext. set_ciphers ( ciphers ) ¶

Set the available ciphers for sockets created with this context. It should be a string in the OpenSSL cipher list format . If no cipher can be selected (because compile-time options or other configuration forbids use of all the specified ciphers), an SSLError 会被引发。

注意

when connected, the SSLSocket.cipher() method of SSL sockets will give the currently selected cipher.

TLS 1.3 cipher suites cannot be disabled with set_ciphers() .

SSLContext. set_alpn_protocols ( protocols ) ¶

Specify which protocols the socket should advertise during the SSL/TLS handshake. It should be a list of ASCII strings, like ['http/1.1', 'spdy/2'] , ordered by preference. The selection of a protocol will happen during the handshake, and will play out according to RFC 7301 . After a successful handshake, the SSLSocket.selected_alpn_protocol() method will return the agreed-upon protocol.

This method will raise NotImplementedError if HAS_ALPN is False .

Added in version 3.5.

SSLContext. set_npn_protocols ( protocols ) ¶

Specify which protocols the socket should advertise during the SSL/TLS handshake. It should be a list of strings, like ['http/1.1', 'spdy/2'] , ordered by preference. The selection of a protocol will happen during the handshake, and will play out according to the Application Layer Protocol Negotiation . After a successful handshake, the SSLSocket.selected_npn_protocol() method will return the agreed-upon protocol.

This method will raise NotImplementedError if HAS_NPN is False .

Added in version 3.3.

从 3.10 版起弃用： NPN has been superseded by ALPN

SSLContext. sni_callback ¶

Register a callback function that will be called after the TLS Client Hello handshake message has been received by the SSL/TLS server when the TLS client specifies a server name indication. The server name indication mechanism is specified in RFC 6066 section 3 - Server Name Indication.

Only one callback can be set per SSLContext 。若 sni_callback 被设为 None then the callback is disabled. Calling this function a subsequent time will disable the previously registered callback.

The callback function will be called with three arguments; the first being the ssl.SSLSocket , the second is a string that represents the server name that the client is intending to communicate (or None if the TLS Client Hello does not contain a server name) and the third argument is the original SSLContext . The server name argument is text. For internationalized domain name, the server name is an IDN A-label ( "xn--pythn-mua.org" ).

A typical use of this callback is to change the ssl.SSLSocket ’s SSLSocket.context attribute to a new object of type SSLContext representing a certificate chain that matches the server name.

Due to the early negotiation phase of the TLS connection, only limited methods and attributes are usable like SSLSocket.selected_alpn_protocol() and SSLSocket.context 。 SSLSocket.getpeercert() , SSLSocket.cipher() and SSLSocket.compression() methods require that the TLS connection has progressed beyond the TLS Client Hello and therefore will not return meaningful values nor can they be called safely.

The sni_callback function must return None to allow the TLS negotiation to continue. If a TLS failure is required, a constant ALERT_DESCRIPTION_* can be returned. Other return values will result in a TLS fatal error with ALERT_DESCRIPTION_INTERNAL_ERROR .

If an exception is raised from the sni_callback function the TLS connection will terminate with a fatal TLS alert message ALERT_DESCRIPTION_HANDSHAKE_FAILURE .

This method will raise NotImplementedError if the OpenSSL library had OPENSSL_NO_TLSEXT defined when it was built.

Added in version 3.7.

SSLContext. set_servername_callback ( server_name_callback ) ¶

This is a legacy API retained for backwards compatibility. When possible, you should use sni_callback instead. The given server_name_callback 类似于 sni_callback , except that when the server hostname is an IDN-encoded internationalized domain name, the server_name_callback receives a decoded U-label ( "pythön.org" ).

If there is an decoding error on the server name, the TLS connection will terminate with an ALERT_DESCRIPTION_INTERNAL_ERROR fatal TLS alert message to the client.

Added in version 3.4.

SSLContext. load_dh_params ( dhfile ) ¶

Load the key generation parameters for Diffie-Hellman (DH) key exchange. Using DH key exchange improves forward secrecy at the expense of computational resources (both on the server and on the client). The dhfile parameter should be the path to a file containing DH parameters in PEM format.

This setting doesn’t apply to client sockets. You can also use the OP_SINGLE_DH_USE option to further improve security.

Added in version 3.3.

SSLContext. set_ecdh_curve ( curve_name ) ¶

Set the curve name for Elliptic Curve-based Diffie-Hellman (ECDH) key exchange. ECDH is significantly faster than regular DH while arguably as secure. The curve_name parameter should be a string describing a well-known elliptic curve, for example prime256v1 for a widely supported curve.

This setting doesn’t apply to client sockets. You can also use the OP_SINGLE_ECDH_USE option to further improve security.

This method is not available if HAS_ECDH is False .

Added in version 3.3.

另请参阅

SSL/TLS & Perfect Forward Secrecy

SSLContext. wrap_socket ( sock , server_side = False , do_handshake_on_connect = True , suppress_ragged_eofs = True , server_hostname = None , session = None ) ¶

Wrap an existing Python socket sock 并返回实例化的 SSLContext.sslsocket_class (默认 SSLSocket ). The returned SSL socket is tied to the context, its settings and certificates. sock 必须为 SOCK_STREAM socket; other socket types are unsupported.

参数 server_side is a boolean which identifies whether server-side or client-side behavior is desired from this socket.

For client-side sockets, the context construction is lazy; if the underlying socket isn’t connected yet, the context construction will be performed after connect() is called on the socket. For server-side sockets, if the socket has no remote peer, it is assumed to be a listening socket, and the server-side SSL wrapping is automatically performed on client connections accepted via the accept() method. The method may raise SSLError .

On client connections, the optional parameter server_hostname specifies the hostname of the service which we are connecting to. This allows a single server to host multiple SSL-based services with distinct certificates, quite similarly to HTTP virtual hosts. Specifying server_hostname 将引发 ValueError if server_side 为 True。

参数 do_handshake_on_connect specifies whether to do the SSL handshake automatically after doing a socket.connect() , or whether the application program will call it explicitly, by invoking the SSLSocket.do_handshake() method. Calling SSLSocket.do_handshake() explicitly gives the program control over the blocking behavior of the socket I/O involved in the handshake.

参数 suppress_ragged_eofs specifies how the SSLSocket.recv() method should signal unexpected EOF from the other end of the connection. If specified as True (the default), it returns a normal EOF (an empty bytes object) in response to unexpected EOF errors raised from the underlying socket; if False , it will raise the exceptions back to the caller.

session ，见 session .

To wrap an SSLSocket in another SSLSocket ，使用 SSLContext.wrap_bio() .

3.5 版改变： Always allow a server_hostname to be passed, even if OpenSSL does not have SNI.

3.6 版改变： session 自变量被添加。

3.7 版改变： The method returns an instance of SSLContext.sslsocket_class instead of hard-coded SSLSocket .

SSLContext. sslsocket_class ¶

The return type of SSLContext.wrap_socket() , defaults to SSLSocket . The attribute can be overridden on instance of class in order to return a custom subclass of SSLSocket .

Added in version 3.7.

SSLContext. wrap_bio ( incoming , outgoing , server_side = False , server_hostname = None , session = None ) ¶

Wrap the BIO objects incoming and outgoing 并返回实例化的 SSLContext.sslobject_class (默认 SSLObject ). The SSL routines will read input data from the incoming BIO and write data to the outgoing BIO.

The server_side , server_hostname and session parameters have the same meaning as in SSLContext.wrap_socket() .

3.6 版改变： session 自变量被添加。

3.7 版改变： The method returns an instance of SSLContext.sslobject_class instead of hard-coded SSLObject .

SSLContext. sslobject_class ¶

The return type of SSLContext.wrap_bio() , defaults to SSLObject . The attribute can be overridden on instance of class in order to return a custom subclass of SSLObject .

Added in version 3.7.

SSLContext. session_stats ( ) ¶

Get statistics about the SSL sessions created or managed by this context. A dictionary is returned which maps the names of each piece of information to their numeric values. For example, here is the total number of hits and misses in the session cache since the context was created:

>>> stats = context.session_stats()
>>> stats['hits'], stats['misses']
(0, 0)

SSLContext. check_hostname ¶

SSLContext. keylog_filename ¶

Write TLS keys to a keylog file, whenever key material is generated or received. The keylog file is designed for debugging purposes only. The file format is specified by NSS and used by many traffic analyzers such as Wireshark. The log file is opened in append-only mode. Writes are synchronized between threads, but not between processes.

Added in version 3.8.

SSLContext. maximum_version ¶

A TLSVersion enum member representing the highest supported TLS version. The value defaults to TLSVersion.MAXIMUM_SUPPORTED . The attribute is read-only for protocols other than PROTOCOL_TLS , PROTOCOL_TLS_CLIENT ，和 PROTOCOL_TLS_SERVER .

属性 maximum_version , minimum_version and SSLContext.options all affect the supported SSL and TLS versions of the context. The implementation does not prevent invalid combination. For example a context with OP_NO_TLSv1_2 in options and maximum_version 设为 TLSVersion.TLSv1_2 will not be able to establish a TLS 1.2 connection.

Added in version 3.7.

SSLContext. minimum_version ¶

像 SSLContext.maximum_version except it is the lowest supported version or TLSVersion.MINIMUM_SUPPORTED .

Added in version 3.7.

SSLContext. num_tickets ¶

Control the number of TLS 1.3 session tickets of a PROTOCOL_TLS_SERVER context. The setting has no impact on TLS 1.0 to 1.2 connections.

Added in version 3.8.

SSLContext. 选项 ¶

An integer representing the set of SSL options enabled on this context. The default value is OP_ALL , but you can specify other options such as OP_NO_SSLv2 by ORing them together.

3.6 版改变： SSLContext.options 返回 Options flags:

>>> ssl.create_default_context().options
<Options.OP_ALL|OP_NO_SSLv3|OP_NO_SSLv2|OP_NO_COMPRESSION: 2197947391>

从 3.7 版起弃用：所有 OP_NO_SSL* and OP_NO_TLS* options have been deprecated since Python 3.7. Use SSLContext.minimum_version and SSLContext.maximum_version 代替。

SSLContext. post_handshake_auth ¶

SSLContext. protocol ¶: The protocol version chosen when constructing the context. This attribute is read-only.

SSLContext. hostname_checks_common_name ¶

Whether check_hostname falls back to verify the cert’s subject common name in the absence of a subject alternative name extension (default: true).

Added in version 3.7.

3.10 版改变： The flag had no effect with OpenSSL before version 1.1.1l. Python 3.8.9, 3.9.3, and 3.10 include workarounds for previous versions.

SSLContext. security_level ¶

An integer representing the security level for the context. This attribute is read-only.

Added in version 3.10.

SSLContext. verify_flags ¶

The flags for certificate verification operations. You can set flags like VERIFY_CRL_CHECK_LEAF by ORing them together. By default OpenSSL does neither require nor verify certificate revocation lists (CRLs).

Added in version 3.4.

3.6 版改变： SSLContext.verify_flags 返回 VerifyFlags flags:

>>> ssl.create_default_context().verify_flags
<VerifyFlags.VERIFY_X509_TRUSTED_FIRST: 32768>

SSLContext. verify_mode ¶

证书 ¶

Certificates in general are part of a public-key / private-key system. In this system, each principal , (which may be a machine, or a person, or an organization) is assigned a unique two-part encryption key. One part of the key is public, and is called the public key ; the other part is kept secret, and is called the private key . The two parts are related, in that if you encrypt a message with one of the parts, you can decrypt it with the other part, and only with the other part.

A certificate contains information about two principals. It contains the name of a subject , and the subject’s public key. It also contains a statement by a second principal, the issuer , that the subject is who they claim to be, and that this is indeed the subject’s public key. The issuer’s statement is signed with the issuer’s private key, which only the issuer knows. However, anyone can verify the issuer’s statement by finding the issuer’s public key, decrypting the statement with it, and comparing it to the other information in the certificate. The certificate also contains information about the time period over which it is valid. This is expressed as two fields, called “notBefore” and “notAfter”.

In the Python use of certificates, a client or server can use a certificate to prove who they are. The other side of a network connection can also be required to produce a certificate, and that certificate can be validated to the satisfaction of the client or server that requires such validation. The connection attempt can be set to raise an exception if the validation fails. Validation is done automatically, by the underlying OpenSSL framework; the application need not concern itself with its mechanics. But the application does usually need to provide sets of certificates to allow this process to take place.

Python uses files to contain certificates. They should be formatted as “PEM” (see RFC 1422 ), which is a base-64 encoded form wrapped with a header line and a footer line:

-----BEGIN CERTIFICATE-----
... (certificate in base64 PEM encoding) ...
-----END CERTIFICATE-----

证书链 ¶

The Python files which contain certificates can contain a sequence of certificates, sometimes called a certificate chain . This chain should start with the specific certificate for the principal who “is” the client or server, and then the certificate for the issuer of that certificate, and then the certificate for the issuer of that certificate, and so on up the chain till you get to a certificate which is self-signed , that is, a certificate which has the same subject and issuer, sometimes called a root certificate . The certificates should just be concatenated together in the certificate file. For example, suppose we had a three certificate chain, from our server certificate to the certificate of the certification authority that signed our server certificate, to the root certificate of the agency which issued the certification authority’s certificate:

-----BEGIN CERTIFICATE-----
... (certificate for your server)...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
... (the certificate for the CA)...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
... (the root certificate for the CA's issuer)...
-----END CERTIFICATE-----

CA 证书 ¶

If you are going to require validation of the other side of the connection’s certificate, you need to provide a “CA certs” file, filled with the certificate chains for each issuer you are willing to trust. Again, this file just contains these chains concatenated together. For validation, Python will use the first chain it finds in the file which matches. The platform’s certificates file can be used by calling SSLContext.load_default_certs() , this is done automatically with create_default_context() .

组合密钥和证书 ¶

Often the private key is stored in the same file as the certificate; in this case, only the certfile 参数用于 SSLContext.load_cert_chain() needs to be passed. If the private key is stored with the certificate, it should come before the first certificate in the certificate chain:

-----BEGIN RSA PRIVATE KEY-----
... (private key in base64 encoding) ...
-----END RSA PRIVATE KEY-----
-----BEGIN CERTIFICATE-----
... (certificate in base64 PEM encoding) ...
-----END CERTIFICATE-----

自签名证书 ¶

If you are going to create a server that provides SSL-encrypted connection services, you will need to acquire a certificate for that service. There are many ways of acquiring appropriate certificates, such as buying one from a certification authority. Another common practice is to generate a self-signed certificate. The simplest way to do this is with the OpenSSL package, using something like the following:

% openssl req -new -x509 -days 365 -nodes -out cert.pem -keyout cert.pem
Generating a 1024 bit RSA private key
.......++++++
.............................++++++
writing new private key to 'cert.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:US
State or Province Name (full name) [Some-State]:MyState
Locality Name (eg, city) []:Some City
Organization Name (eg, company) [Internet Widgits Pty Ltd]:My Organization, Inc.
Organizational Unit Name (eg, section) []:My Group
Common Name (eg, YOUR name) []:myserver.mygroup.myorganization.com
Email Address []:ops@myserver.mygroup.myorganization.com
%

The disadvantage of a self-signed certificate is that it is its own root certificate, and no one else will have it in their cache of known (and trusted) root certificates.

范例 ¶

测试 SSL (安全套接字层) 支持 ¶

To test for the presence of SSL support in a Python installation, user code should use the following idiom:

try:
    import ssl
except ImportError:
    pass
else:
    ...  # do something that requires SSL support

客户端侧操作 ¶

This example creates a SSL context with the recommended security settings for client sockets, including automatic certificate verification:

>>> context = ssl.create_default_context()

If you prefer to tune security settings yourself, you might create a context from scratch (but beware that you might not get the settings right):

>>> context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
>>> context.load_verify_locations("/etc/ssl/certs/ca-bundle.crt")

(this snippet assumes your operating system places a bundle of all CA certificates in /etc/ssl/certs/ca-bundle.crt ; if not, you’ll get an error and have to adjust the location)

The PROTOCOL_TLS_CLIENT protocol configures the context for cert validation and hostname verification. verify_mode 被设为 CERT_REQUIRED and check_hostname 被设为 True . All other protocols create SSL contexts with insecure defaults.

When you use the context to connect to a server, CERT_REQUIRED and check_hostname validate the server certificate: it ensures that the server certificate was signed with one of the CA certificates, checks the signature for correctness, and verifies other properties like validity and identity of the hostname:

>>> conn = context.wrap_socket(socket.socket(socket.AF_INET),
...                            server_hostname="www.python.org")
>>> conn.connect(("www.python.org", 443))

You may then fetch the certificate:

>>> cert = conn.getpeercert()

Visual inspection shows that the certificate does identify the desired service (that is, the HTTPS host www.python.org ):

>>> pprint.pprint(cert)
{'OCSP': ('http://ocsp.digicert.com',),
 'caIssuers': ('http://cacerts.digicert.com/DigiCertSHA2ExtendedValidationServerCA.crt',),
 'crlDistributionPoints': ('http://crl3.digicert.com/sha2-ev-server-g1.crl',
                           'http://crl4.digicert.com/sha2-ev-server-g1.crl'),
 'issuer': ((('countryName', 'US'),),
            (('organizationName', 'DigiCert Inc'),),
            (('organizationalUnitName', 'www.digicert.com'),),
            (('commonName', 'DigiCert SHA2 Extended Validation Server CA'),)),
 'notAfter': 'Sep  9 12:00:00 2016 GMT',
 'notBefore': 'Sep  5 00:00:00 2014 GMT',
 'serialNumber': '01BB6F00122B177F36CAB49CEA8B6B26',
 'subject': ((('businessCategory', 'Private Organization'),),
             (('1.3.6.1.4.1.311.60.2.1.3', 'US'),),
             (('1.3.6.1.4.1.311.60.2.1.2', 'Delaware'),),
             (('serialNumber', '3359300'),),
             (('streetAddress', '16 Allen Rd'),),
             (('postalCode', '03894-4801'),),
             (('countryName', 'US'),),
             (('stateOrProvinceName', 'NH'),),
             (('localityName', 'Wolfeboro'),),
             (('organizationName', 'Python Software Foundation'),),
             (('commonName', 'www.python.org'),)),
 'subjectAltName': (('DNS', 'www.python.org'),
                    ('DNS', 'python.org'),
                    ('DNS', 'pypi.org'),
                    ('DNS', 'docs.python.org'),
                    ('DNS', 'testpypi.org'),
                    ('DNS', 'bugs.python.org'),
                    ('DNS', 'wiki.python.org'),
                    ('DNS', 'hg.python.org'),
                    ('DNS', 'mail.python.org'),
                    ('DNS', 'packaging.python.org'),
                    ('DNS', 'pythonhosted.org'),
                    ('DNS', 'www.pythonhosted.org'),
                    ('DNS', 'test.pythonhosted.org'),
                    ('DNS', 'us.pycon.org'),
                    ('DNS', 'id.python.org')),
 'version': 3}

Now the SSL channel is established and the certificate verified, you can proceed to talk with the server:

>>> conn.sendall(b"HEAD / HTTP/1.0\r\nHost: linuxfr.org\r\n\r\n")
>>> pprint.pprint(conn.recv(1024).split(b"\r\n"))
[b'HTTP/1.1 200 OK',
 b'Date: Sat, 18 Oct 2014 18:27:20 GMT',
 b'Server: nginx',
 b'Content-Type: text/html; charset=utf-8',
 b'X-Frame-Options: SAMEORIGIN',
 b'Content-Length: 45679',
 b'Accept-Ranges: bytes',
 b'Via: 1.1 varnish',
 b'Age: 2188',
 b'X-Served-By: cache-lcy1134-LCY',
 b'X-Cache: HIT',
 b'X-Cache-Hits: 11',
 b'Vary: Cookie',
 b'Strict-Transport-Security: max-age=63072000; includeSubDomains',
 b'Connection: close',
 b'',
 b'']

See the discussion of 安全注意事项下文。

服务器侧操作 ¶

For server operation, typically you’ll need to have a server certificate, and private key, each in a file. You’ll first create a context holding the key and the certificate, so that clients can check your authenticity. Then you’ll open a socket, bind it to a port, call listen() on it, and start waiting for clients to connect:

import socket, ssl
context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
context.load_cert_chain(certfile="mycertfile", keyfile="mykeyfile")
bindsocket = socket.socket()
bindsocket.bind(('myaddr.example.com', 10023))
bindsocket.listen(5)

When a client connects, you’ll call accept() on the socket to get the new socket from the other end, and use the context’s SSLContext.wrap_socket() method to create a server-side SSL socket for the connection:

while True:
    newsocket, fromaddr = bindsocket.accept()
    connstream = context.wrap_socket(newsocket, server_side=True)
    try:
        deal_with_client(connstream)
    finally:
        connstream.shutdown(socket.SHUT_RDWR)
        connstream.close()

Then you’ll read data from the connstream and do something with it till you are finished with the client (or the client is finished with you):

def deal_with_client(connstream):
    data = connstream.recv(1024)
    # empty data means the client is finished with us
    while data:
        if not do_something(connstream, data):
            # we'll assume do_something returns False
            # when we're finished with client
            break
        data = connstream.recv(1024)
    # finished with client

And go back to listening for new client connections (of course, a real server would probably handle each client connection in a separate thread, or put the sockets in 非阻塞模式 and use an event loop).

关于非阻塞套接字的注意事项 ¶

SSL sockets behave slightly different than regular sockets in non-blocking mode. When working with non-blocking sockets, there are thus several things you need to be aware of:

Most SSLSocket methods will raise either SSLWantWriteError or SSLWantReadError 而不是 BlockingIOError if an I/O operation would block. SSLWantReadError will be raised if a read operation on the underlying socket is necessary, and SSLWantWriteError for a write operation on the underlying socket. Note that attempts to write to an SSL socket may require reading from the underlying socket first, and attempts to read from the SSL socket may require a prior write to the underlying socket.

3.5 版改变： In earlier Python versions, the SSLSocket.send() method returned zero instead of raising SSLWantWriteError or SSLWantReadError .
调用 select() tells you that the OS-level socket can be read from (or written to), but it does not imply that there is sufficient data at the upper SSL layer. For example, only part of an SSL frame might have arrived. Therefore, you must be ready to handle SSLSocket.recv() and SSLSocket.send() failures, and retry after another call to select() .
Conversely, since the SSL layer has its own framing, a SSL socket may still have data available for reading without select() being aware of it. Therefore, you should first call SSLSocket.recv() to drain any potentially available data, and then only block on a select() call if still necessary.

(of course, similar provisions apply when using other primitives such as poll() , or those in the selectors 模块)

The SSL handshake itself will be non-blocking: the SSLSocket.do_handshake() method has to be retried until it returns successfully. Here is a synopsis using select() to wait for the socket’s readiness:

while True:
    try:
        sock.do_handshake()
        break
    except ssl.SSLWantReadError:
        select.select([sock], [], [])
    except ssl.SSLWantWriteError:
        select.select([], [sock], [])

另请参阅

The asyncio module supports non-blocking SSL sockets and provides a higher level API. It polls for events using the selectors module and handles SSLWantWriteError , SSLWantReadError and BlockingIOError exceptions. It runs the SSL handshake asynchronously as well.

内存 BIO 支持 ¶

Added in version 3.5.

Ever since the SSL module was introduced in Python 2.6, the SSLSocket class has provided two related but distinct areas of functionality:

SSL protocol handling
Network IO

The network IO API is identical to that provided by socket.socket , from which SSLSocket also inherits. This allows an SSL socket to be used as a drop-in replacement for a regular socket, making it very easy to add SSL support to an existing application.

Combining SSL protocol handling and network IO usually works well, but there are some cases where it doesn’t. An example is async IO frameworks that want to use a different IO multiplexing model than the “select/poll on a file descriptor” (readiness based) model that is assumed by socket.socket and by the internal OpenSSL socket IO routines. This is mostly relevant for platforms like Windows where this model is not efficient. For this purpose, a reduced scope variant of SSLSocket called SSLObject 被提供。

class ssl. SSLObject ¶

An SSLObject communicates with the outside world using memory buffers. The class MemoryBIO provides a memory buffer that can be used for this purpose. It wraps an OpenSSL memory BIO (Basic IO) object:

class ssl. MemoryBIO ¶

SSL (安全套接字层) 会话 ¶

Added in version 3.6.

class ssl. SSLSession ¶

Session object used by session .

id ¶

time ¶

timeout ¶

ticket_lifetime_hint ¶

has_ticket ¶

安全注意事项 ¶

最好默认 ¶

For 客户端使用 ，若对安全策略没有任何特殊要求，强烈推荐使用 create_default_context() function to create your SSL context. It will load the system’s trusted CA certificates, enable certificate validation and hostname checking, and try to choose reasonably secure protocol and cipher settings.

例如，这里是将如何使用 smtplib.SMTP 类创建到 SMTP 服务器的可信、安全连接：

>>> import ssl, smtplib
>>> smtp = smtplib.SMTP("mail.python.org", port=587)
>>> context = ssl.create_default_context()
>>> smtp.starttls(context=context)
(220, b'2.0.0 Ready to start TLS')

If a client certificate is needed for the connection, it can be added with SSLContext.load_cert_chain() .

By contrast, if you create the SSL context by calling the SSLContext constructor yourself, it will not have certificate validation nor hostname checking enabled by default. If you do so, please read the paragraphs below to achieve a good security level.

手动设置 ¶

验证证书 ¶

When calling the SSLContext constructor directly, CERT_NONE is the default. Since it does not authenticate the other peer, it can be insecure, especially in client mode where most of time you would like to ensure the authenticity of the server you’re talking to. Therefore, when in client mode, it is highly recommended to use CERT_REQUIRED . However, it is in itself not sufficient; you also have to check that the server certificate, which can be obtained by calling SSLSocket.getpeercert() , matches the desired service. For many protocols and applications, the service can be identified by the hostname. This common check is automatically performed when SSLContext.check_hostname 被启用。

3.7 版改变： Hostname matchings is now performed by OpenSSL. Python no longer uses match_hostname() .

In server mode, if you want to authenticate your clients using the SSL layer (rather than using a higher-level authentication mechanism), you’ll also have to specify CERT_REQUIRED and similarly check the client certificate.

协议版本 ¶

SSL versions 2 and 3 are considered insecure and are therefore dangerous to use. If you want maximum compatibility between clients and servers, it is recommended to use PROTOCOL_TLS_CLIENT or PROTOCOL_TLS_SERVER as the protocol version. SSLv2 and SSLv3 are disabled by default.

>>> client_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
>>> client_context.minimum_version = ssl.TLSVersion.TLSv1_3
>>> client_context.maximum_version = ssl.TLSVersion.TLSv1_3

The SSL context created above will only allow TLSv1.3 and later (if supported by your system) connections to a server. PROTOCOL_TLS_CLIENT implies certificate validation and hostname checks by default. You have to load certificates into the context.

密码选定 ¶

If you have advanced security requirements, fine-tuning of the ciphers enabled when negotiating a SSL session is possible through the SSLContext.set_ciphers() method. Starting from Python 3.2.3, the ssl module disables certain weak ciphers by default, but you may want to further restrict the cipher choice. Be sure to read OpenSSL’s documentation about the cipher list format . If you want to check which ciphers are enabled by a given cipher list, use SSLContext.get_ciphers() 或 openssl ciphers command on your system.

多进程 ¶

If using this module as part of a multi-processed application (using, for example the multiprocessing or concurrent.futures modules), be aware that OpenSSL’s internal random number generator does not properly handle forked processes. Applications must change the PRNG state of the parent process if they use any SSL feature with os.fork() . Any successful call of RAND_add() or RAND_bytes() is sufficient.

TLS 1.3 ¶

Added in version 3.7.

The TLS 1.3 protocol behaves slightly differently than previous version of TLS/SSL. Some new TLS 1.3 features are not yet available.

TLS 1.3 uses a disjunct set of cipher suites. All AES-GCM and ChaCha20 cipher suites are enabled by default. The method SSLContext.set_ciphers() cannot enable or disable any TLS 1.3 ciphers yet, but SSLContext.get_ciphers() returns them.
Session tickets are no longer sent as part of the initial handshake and are handled differently. SSLSocket.session and SSLSession are not compatible with TLS 1.3.
Client-side certificates are also no longer verified during the initial handshake. A server can request a certificate at any time. Clients process certificate requests while they send or receive application data from the server.
TLS 1.3 features like early data, deferred TLS client cert request, signature algorithm configuration, and rekeying are not supported yet.

另请参阅

类 socket.socket: Documentation of underlying socket class
SSL/TLS Strong Encryption: An Introduction: Intro from the Apache HTTP Server documentation
RFC 1422: Privacy Enhancement for Internet Electronic Mail: Part II: Certificate-Based Key Management: Steve Kent
RFC 4086: Randomness Requirements for Security: Donald E., Jeffrey I. Schiller
RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile: D. Cooper
RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2: T. Dierks et. al.
RFC 6066: Transport Layer Security (TLS) Extensions: D. Eastlake
IANA TLS: Transport Layer Security (TLS) Parameters: IANA
RFC 7525: Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS): IETF
Mozilla’s Server Side TLS recommendations: Mozilla

内容表

ssl — 套接字对象的 TLS/SSL 包裹器

上一话题

socket — 低级网络接口

下一话题

select — 等待 I/O 完成

本页

报告 Bug
展示源

快速搜索

键入搜索术语或模块、类、函数名称。

首页
Python 3.12.4
索引
模块
下一
上一
Python 标准库
网络和进程间通信
ssl — 套接字对象的 TLS/SSL 包裹器