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Diffstat (limited to 'docs/hazmat/primitives/asymmetric/utils.rst')
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/utils.rst | 70 |
1 files changed, 65 insertions, 5 deletions
diff --git a/docs/hazmat/primitives/asymmetric/utils.rst b/docs/hazmat/primitives/asymmetric/utils.rst index 7380f0b5..f46acb2e 100644 --- a/docs/hazmat/primitives/asymmetric/utils.rst +++ b/docs/hazmat/primitives/asymmetric/utils.rst @@ -6,10 +6,11 @@ Asymmetric Utilities .. currentmodule:: cryptography.hazmat.primitives.asymmetric.utils -.. function:: decode_rfc6979_signature(signature) +.. function:: decode_dss_signature(signature) - Takes in :rfc:`6979` signatures generated by the DSA/ECDSA signers and - returns a tuple ``(r, s)``. + Takes in signatures generated by the DSA/ECDSA signers and returns a + tuple ``(r, s)``. These signatures are ASN.1 encoded ``Dss-Sig-Value`` + sequences (as defined in :rfc:`3279`) :param bytes signature: The signature to decode. @@ -17,12 +18,71 @@ Asymmetric Utilities :raises ValueError: Raised if the signature is malformed. -.. function:: encode_rfc6979_signature(r, s) +.. function:: encode_dss_signature(r, s) - Creates an :rfc:`6979` byte string from raw signature values. + Creates an ASN.1 encoded ``Dss-Sig-Value`` (as defined in :rfc:`3279`) from + raw ``r`` and ``s`` values. :param int r: The raw signature value ``r``. :param int s: The raw signature value ``s``. :return bytes: The encoded signature. + +.. class:: Prehashed(algorithm) + + .. versionadded:: 1.6 + + ``Prehashed`` can be passed as the ``algorithm`` in the RSA + :meth:`~cryptography.hazmat.primitives.asymmetric.rsa.RSAPrivateKey.sign` + and + :meth:`~cryptography.hazmat.primitives.asymmetric.rsa.RSAPublicKey.verify` + as well as DSA + :meth:`~cryptography.hazmat.primitives.asymmetric.dsa.DSAPrivateKey.sign` + and + :meth:`~cryptography.hazmat.primitives.asymmetric.dsa.DSAPublicKey.verify` + methods. + + For elliptic curves it can be passed as the ``algorithm`` in + :class:`~cryptography.hazmat.primitives.asymmetric.ec.ECDSA` and then used + with + :meth:`~cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePrivateKey.sign` + and + :meth:`~cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePublicKey.verify` + . + + :param algorithm: An instance of + :class:`~cryptography.hazmat.primitives.hashes.HashAlgorithm`. + + .. doctest:: + + >>> import hashlib + >>> from cryptography.hazmat.backends import default_backend + >>> from cryptography.hazmat.primitives import hashes + >>> from cryptography.hazmat.primitives.asymmetric import ( + ... padding, rsa, utils + ... ) + >>> private_key = rsa.generate_private_key( + ... public_exponent=65537, + ... key_size=2048, + ... backend=default_backend() + ... ) + >>> prehashed_msg = hashlib.sha256(b"A message I want to sign").digest() + >>> signature = private_key.sign( + ... prehashed_msg, + ... padding.PSS( + ... mgf=padding.MGF1(hashes.SHA256()), + ... salt_length=padding.PSS.MAX_LENGTH + ... ), + ... utils.Prehashed(hashes.SHA256()) + ... ) + >>> public_key = private_key.public_key() + >>> public_key.verify( + ... signature, + ... prehashed_msg, + ... padding.PSS( + ... mgf=padding.MGF1(hashes.SHA256()), + ... salt_length=padding.PSS.MAX_LENGTH + ... ), + ... utils.Prehashed(hashes.SHA256()) + ... ) |