SHAKE256¶
SHAKE256 is an extendable-output function (XOF) in the SHA-3 family, as specified in FIPS 202.
As a XOF, SHAKE256 is a generalization of a cryptographic hash function. Instead of creating a fixed-length digest (e.g. 32 bytes like SHA-2/256), it can produce outputs of any desidered length.
Output bits do not depend of the output length.
The 256 in its name indicates its maximum security level (in bits), as described in Sections A.1 and A.2 of FIPS 202.
In the following example, the output is 26 bytes (208 bits) long:
>>> from Crypto.Hash import SHAKE256
>>> from binascii import hexlify
>>>
>>> shake = SHAKE256.new()
>>> shake.update(b'Some data')
>>> print hexlify(shake.read(26))
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class
Crypto.Hash.SHAKE256.SHAKE256_XOF(data=None)¶ A SHAKE256 hash object. Do not instantiate directly. Use the
new()function.Variables: oid (string) – ASN.1 Object ID -
read(length)¶ Compute the next piece of XOF output.
Parameters: length (integer) – the amount of bytes this method must return Returns: the next piece of XOF output (of the given length) Return type: byte string
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update(data)¶ Continue hashing of a message by consuming the next chunk of data.
Parameters: data (byte string/byte array/memoryview) – The next chunk of the message being hashed.
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Crypto.Hash.SHAKE256.new(data=None)¶ Return a fresh instance of a SHAKE256 object.
Parameters: data (byte string/byte array/memoryview) – The very first chunk of the message to hash. It is equivalent to an early call to update(). Optional.Return: A SHAKE256_XOFobject