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Use buffer of EVP_MAX_MD_SIZE bytes for digests

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OpenSSL doesn't actually guarantee to only write to digest_size worth of
bytes in the output buffer. The examples and docs claim this constant is
the max.
This commit is contained in:
Alex Stapleton 2014-02-28 19:53:18 +00:00
parent bf12413077
commit 53ecc9837e
1 changed files with 4 additions and 4 deletions
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8
cryptography/hazmat/backends/openssl/backend.py
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@ -534,14 +534,14 @@ class _HashContext(object):
def finalize(self):
buf = self._backend._ffi.new("unsigned char[]",
self.algorithm.digest_size)
self._backend._lib.EVP_MAX_MD_SIZE)
outlen = self._backend._ffi.new("unsigned int *")
res = self._backend._lib.EVP_DigestFinal_ex(self._ctx, buf, outlen)
assert res != 0
assert outlen[0] == self.algorithm.digest_size
res = self._backend._lib.EVP_MD_CTX_cleanup(self._ctx)
assert res == 1
return self._backend._ffi.buffer(buf)[:]
return self._backend._ffi.buffer(buf)[:outlen[0]]
@utils.register_interface(interfaces.HashContext)
@ -593,7 +593,7 @@ class _HMACContext(object):
def finalize(self):
buf = self._backend._ffi.new("unsigned char[]",
self.algorithm.digest_size)
self._backend._lib.EVP_MAX_MD_SIZE)
outlen = self._backend._ffi.new("unsigned int *")
res = self._backend._lib.Cryptography_HMAC_Final(
self._ctx, buf, outlen
@ -601,7 +601,7 @@ class _HMACContext(object):
assert res != 0
assert outlen[0] == self.algorithm.digest_size
self._backend._lib.HMAC_CTX_cleanup(self._ctx)
return self._backend._ffi.buffer(buf)[:]
return self._backend._ffi.buffer(buf)[:outlen[0]]
@utils.register_interface(interfaces.AsymmetricSignatureContext)