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Merge pull request #241 from strayge/master

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added resync IV during decrypt Symmetrically Encrypted Data Packet
This commit is contained in:
Michael Greene
2019-06-07 14:53:57 -07:00
committed by GitHub
parent e6b62a5cc0 7dcdcf5898
commit 9caf462794
1 changed files with 11 additions and 5 deletions
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16
pgpy/packet/packets.py
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@@ -1055,17 +1055,23 @@ class SKEData(Packet):
del packet[:self.header.length]
def decrypt(self, key, alg): # pragma: no cover
pt = _decrypt(bytes(self.ct), bytes(key), alg)
block_size_bytes = alg.block_size // 8
pt_prefix = _decrypt(bytes(self.ct[:block_size_bytes + 2]), bytes(key), alg)
iv = bytes(pt[:alg.block_size // 8])
del pt[:alg.block_size // 8]
# old Symmetrically Encrypted Data Packet required
# to change iv after decrypting prefix
iv_resync = bytes(self.ct[2:block_size_bytes + 2])
ivl2 = bytes(pt[:2])
del pt[:2]
iv = bytes(pt_prefix[:block_size_bytes])
del pt_prefix[:block_size_bytes]
ivl2 = bytes(pt_prefix[:2])
if not constant_time.bytes_eq(iv[-2:], ivl2):
raise PGPDecryptionError("Decryption failed")
pt = _decrypt(bytes(self.ct[block_size_bytes + 2:]), bytes(key), alg, iv=iv_resync)
return pt