refactor dsa sign/verify as prep for prehash (#3262)
diff --git a/src/cryptography/hazmat/backends/openssl/dsa.py b/src/cryptography/hazmat/backends/openssl/dsa.py
index 4370286..07d2c3b 100644
--- a/src/cryptography/hazmat/backends/openssl/dsa.py
+++ b/src/cryptography/hazmat/backends/openssl/dsa.py
@@ -31,6 +31,34 @@
return _truncate_digest(digest, order_bits)
+def _dsa_sig_sign(backend, private_key, data):
+ sig_buf_len = backend._lib.DSA_size(private_key._dsa_cdata)
+ sig_buf = backend._ffi.new("unsigned char[]", sig_buf_len)
+ buflen = backend._ffi.new("unsigned int *")
+
+ # The first parameter passed to DSA_sign is unused by OpenSSL but
+ # must be an integer.
+ res = backend._lib.DSA_sign(
+ 0, data, len(data), sig_buf, buflen, private_key._dsa_cdata
+ )
+ backend.openssl_assert(res == 1)
+ backend.openssl_assert(buflen[0])
+
+ return backend._ffi.buffer(sig_buf)[:buflen[0]]
+
+
+def _dsa_sig_verify(backend, public_key, signature, data):
+ # The first parameter passed to DSA_verify is unused by OpenSSL but
+ # must be an integer.
+ res = backend._lib.DSA_verify(
+ 0, data, len(data), signature, len(signature), public_key._dsa_cdata
+ )
+
+ if res != 1:
+ backend._consume_errors()
+ raise InvalidSignature
+
+
@utils.register_interface(AsymmetricVerificationContext)
class _DSAVerificationContext(object):
def __init__(self, backend, public_key, signature, algorithm):
@@ -50,16 +78,9 @@
data_to_verify = _truncate_digest_for_dsa(
self._public_key._dsa_cdata, data_to_verify, self._backend
)
-
- # The first parameter passed to DSA_verify is unused by OpenSSL but
- # must be an integer.
- res = self._backend._lib.DSA_verify(
- 0, data_to_verify, len(data_to_verify), self._signature,
- len(self._signature), self._public_key._dsa_cdata)
-
- if res != 1:
- self._backend._consume_errors()
- raise InvalidSignature
+ _dsa_sig_verify(
+ self._backend, self._public_key, self._signature, data_to_verify
+ )
@utils.register_interface(AsymmetricSignatureContext)
@@ -78,19 +99,7 @@
data_to_sign = _truncate_digest_for_dsa(
self._private_key._dsa_cdata, data_to_sign, self._backend
)
- sig_buf_len = self._backend._lib.DSA_size(self._private_key._dsa_cdata)
- sig_buf = self._backend._ffi.new("unsigned char[]", sig_buf_len)
- buflen = self._backend._ffi.new("unsigned int *")
-
- # The first parameter passed to DSA_sign is unused by OpenSSL but
- # must be an integer.
- res = self._backend._lib.DSA_sign(
- 0, data_to_sign, len(data_to_sign), sig_buf,
- buflen, self._private_key._dsa_cdata)
- self._backend.openssl_assert(res == 1)
- self._backend.openssl_assert(buflen[0])
-
- return self._backend._ffi.buffer(sig_buf)[:buflen[0]]
+ return _dsa_sig_sign(self._backend, self._private_key, data_to_sign)
@utils.register_interface(dsa.DSAParametersWithNumbers)