hashlib
— 安全哈希和消息摘要
¶
源代码： Lib/hashlib.py
此模块实现了很多不同安全哈希和消息摘要算法的公共接口。包括 FIPS (联邦信息处理标准) 安全哈希算法 SHA1、SHA224、SHA256、SHA384、SHA512 （定义在 FIPS 180-2）及 RSA 的 MD5 算法 (定义在 Internet RFC 1321 )。术语 "安全哈希" 和 "消息摘要" 可互换。旧算法称为消息摘要。现代术语是安全哈希。
注意
若想要 adler32 (或 crc32) 哈希函数，可找到它们在
zlib
模块。
警告
某些算法有已知的哈希冲突弱点，参考结尾的 "另请参阅" 章节。
有一命名构造函数方法对于每种类型的
hash
。全部返回具有相同简单接口的哈希对象。例如：使用
sha1()
to create a SHA1 hash object. You can now feed this object with
像字节对象
(通常
bytes
) 使用
update()
方法。在任何时候都可以向它请求
digest
为喂给它的串联数据，到目前为止是使用
digest()
or
hexdigest()
方法。
注意
为获得更好的多线程性能，Python GIL 被释放，对于大于 2047 字节的数据，当创建 (或更新) 对象时。
注意
将字符串对象喂给
update()
不被支持，因为哈希工作于字节，但不工作于字符。
此模块中始终存在的哈希算法构造函数包括
md5()
,
sha1()
,
sha224()
,
sha256()
,
sha384()
，和
sha512()
. Additional algorithms may also be available depending upon the OpenSSL library that Python uses on your platform.
例如，要获得摘要对于字节字符串
b'Nobody inspects the
spammish repetition'
:
>>> import hashlib >>> m = hashlib.md5() >>> m.update(b"Nobody inspects") >>> m.update(b" the spammish repetition") >>> m.digest() b'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9' >>> m.digest_size 16 >>> m.block_size 64
更浓缩：
>>> hashlib.sha224(b"Nobody inspects the spammish repetition").hexdigest() 'a4337bc45a8fc544c03f52dc550cd6e1e87021bc896588bd79e901e2'
hashlib.
new
(
name
[
,
data
]
)
¶
Is a generic constructor that takes the string name of the desired algorithm as its first parameter. It also exists to allow access to the above listed hashes as well as any other algorithms that your OpenSSL library may offer. The named constructors are much faster than
new()
且应该是首选的。
使用
new()
采用由 OpenSSL 提供的算法：
>>> h = hashlib.new('ripemd160') >>> h.update(b"Nobody inspects the spammish repetition") >>> h.hexdigest() 'cc4a5ce1b3df48aec5d22d1f16b894a0b894eccc'
Hashlib 提供下列常量属性：
hashlib.
algorithms_guaranteed
¶
A set containing the names of the hash algorithms guaranteed to be supported by this module on all platforms.
3.2 版新增。
hashlib.
algorithms_available
¶
A set containing the names of the hash algorithms that are available in the running Python interpreter. These names will be recognized when passed to
new()
.
algorithms_guaranteed
will always be a subset. The same algorithm may appear multiple times in this set under different names (thanks to OpenSSL).
3.2 版新增。
The following values are provided as constant attributes of the hash objects returned by the constructors:
hash.
digest_size
¶
哈希结果的大小 (以字节为单位)。
hash.
block_size
¶
The internal block size of the hash algorithm in bytes.
哈希对象拥有下列属性：
hash.
名称
¶
The canonical name of this hash, always lowercase and always suitable as a parameter to
new()
to create another hash of this type.
3.4 版改变： The name attribute has been present in CPython since its inception, but until Python 3.4 was not formally specified, so may not exist on some platforms.
A hash object has the following methods:
hash.
update
(
arg
)
¶
Update the hash object with the object
arg
, which must be interpretable as a buffer of bytes. Repeated calls are equivalent to a single call with the concatenation of all the arguments:
m.update(a); m.update(b)
相当于
m.update(a+b)
.
3.1 版改变： The Python GIL is released to allow other threads to run while hash updates on data larger than 2047 bytes is taking place when using hash algorithms supplied by OpenSSL.
hash.
digest
(
)
¶
Return the digest of the data passed to the
update()
method so far. This is a bytes object of size
digest_size
which may contain bytes in the whole range from 0 to 255.
hash.
hexdigest
(
)
¶
像
digest()
except the digest is returned as a string object of double length, containing only hexadecimal digits. This may be used to exchange the value safely in email or other non-binary environments.
hash.
copy
(
)
¶
Return a copy (“clone”) of the hash object. This can be used to efficiently compute the digests of data sharing a common initial substring.
Key derivation and key stretching algorithms are designed for secure password hashing. Naive algorithms such as
sha1(password)
are not resistant against brute-force attacks. A good password hashing function must be tunable, slow, and include a
salt
.
hashlib.
pbkdf2_hmac
(
hash_name
,
password
,
salt
,
iterations
,
dklen=None
)
¶
The function provides PKCS#5 password-based key derivation function 2. It uses HMAC as pseudorandom function.
字符串
hash_name
is the desired name of the hash digest algorithm for HMAC, e.g. ‘sha1’ or ‘sha256’.
password
and
salt
are interpreted as buffers of bytes. Applications and libraries should limit
password
to a sensible length (e.g. 1024).
salt
should be about 16 or more bytes from a proper source, e.g.
os.urandom()
.
The number of iterations should be chosen based on the hash algorithm and computing power. As of 2013, at least 100,000 iterations of SHA-256 are suggested.
dklen
is the length of the derived key. If
dklen
is
None
then the digest size of the hash algorithm
hash_name
is used, e.g. 64 for SHA-512.
>>> import hashlib, binascii >>> dk = hashlib.pbkdf2_hmac('sha256', b'password', b'salt', 100000) >>> binascii.hexlify(dk) b'0394a2ede332c9a13eb82e9b24631604c31df978b4e2f0fbd2c549944f9d79a5'
3.4 版新增。
注意
A fast implementation of
pbkdf2_hmac
is available with OpenSSL. The Python implementation uses an inline version of
hmac
. It is about three times slower and doesn’t release the GIL.
另请参阅
hmac
base64