diff options
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/dsa.rst | 3 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/ec.rst | 4 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/index.rst | 1 | ||||
| -rw-r--r-- | docs/hazmat/primitives/asymmetric/utils.rst | 16 | ||||
| -rw-r--r-- | src/cryptography/hazmat/primitives/asymmetric/utils.py | 22 |
5 files changed, 44 insertions, 2 deletions
diff --git a/docs/hazmat/primitives/asymmetric/dsa.rst b/docs/hazmat/primitives/asymmetric/dsa.rst index 43741ede..df3c99fc 100644 --- a/docs/hazmat/primitives/asymmetric/dsa.rst +++ b/docs/hazmat/primitives/asymmetric/dsa.rst @@ -80,7 +80,8 @@ provider. >>> signature = signer.finalize() The ``signature`` is a ``bytes`` object, whose contents is DER encoded as -described in :rfc:`6979`. +described in :rfc:`6979`. This can be decoded using +:func:`~cryptography.hazmat.primitives.asymmetric.utils.decode_rfc6979_signature`. Verification ~~~~~~~~~~~~ diff --git a/docs/hazmat/primitives/asymmetric/ec.rst b/docs/hazmat/primitives/asymmetric/ec.rst index fd20cbb2..13ab7c11 100644 --- a/docs/hazmat/primitives/asymmetric/ec.rst +++ b/docs/hazmat/primitives/asymmetric/ec.rst @@ -53,7 +53,9 @@ Elliptic Curve Signature Algorithms >>> signature = signer.finalize() The ``signature`` is a ``bytes`` object, whose contents is DER encoded as - described in :rfc:`6979`. + described in :rfc:`6979`. This can be decoded using + :func:`~cryptography.hazmat.primitives.asymmetric.utils.decode_rfc6979_signature`. + .. class:: EllipticCurvePrivateNumbers(private_value, public_numbers) diff --git a/docs/hazmat/primitives/asymmetric/index.rst b/docs/hazmat/primitives/asymmetric/index.rst index 6a5228ba..24f0f5b1 100644 --- a/docs/hazmat/primitives/asymmetric/index.rst +++ b/docs/hazmat/primitives/asymmetric/index.rst @@ -11,3 +11,4 @@ Asymmetric algorithms rsa padding serialization + utils diff --git a/docs/hazmat/primitives/asymmetric/utils.rst b/docs/hazmat/primitives/asymmetric/utils.rst new file mode 100644 index 00000000..9749b6d1 --- /dev/null +++ b/docs/hazmat/primitives/asymmetric/utils.rst @@ -0,0 +1,16 @@ +.. hazmat:: + +Asymmetric Utilities +==================== + +.. currentmodule:: cryptography.hazmat.primitives.asymmetric.utils + + +.. function:: decode_rfc6979_signature(signature) + + Takes in :rfc:`6979` signatures generated by the DSA/ECDSA signers and + returns a tuple ``(r, s)``. + + :param bytes signature: The signature to decode. + + :returns: The decoded tuple ``(r, s)``. diff --git a/src/cryptography/hazmat/primitives/asymmetric/utils.py b/src/cryptography/hazmat/primitives/asymmetric/utils.py new file mode 100644 index 00000000..5e35b3f6 --- /dev/null +++ b/src/cryptography/hazmat/primitives/asymmetric/utils.py @@ -0,0 +1,22 @@ +# This file is dual licensed under the terms of the Apache License, Version +# 2.0, and the BSD License. See the LICENSE file in the root of this repository +# for complete details. + +from __future__ import absolute_import, division, print_function + +from pyasn1.codec.der import decoder +from pyasn1.type import namedtype, univ + + +class _DSSSigValue(univ.Sequence): + componentType = namedtype.NamedTypes( + namedtype.NamedType('r', univ.Integer()), + namedtype.NamedType('s', univ.Integer()) + ) + + +def decode_rfc6979_signature(signature): + data = decoder.decode(signature, asn1Spec=_DSSSigValue()) + r = int(data[0].getComponentByName('r')) + s = int(data[0].getComponentByName('s')) + return (r, s) |