69 lines
2.1 KiB
Python
69 lines
2.1 KiB
Python
"""Pure-Python AES implementation."""
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from cryptomath import *
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from AES import *
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from rijndael import rijndael
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def new(key, mode, IV):
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return Python_AES(key, mode, IV)
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class Python_AES(AES):
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def __init__(self, key, mode, IV):
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AES.__init__(self, key, mode, IV, "python")
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self.rijndael = rijndael(key, 16)
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self.IV = IV
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def encrypt(self, plaintext):
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AES.encrypt(self, plaintext)
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plaintextBytes = stringToBytes(plaintext)
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chainBytes = stringToBytes(self.IV)
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#CBC Mode: For each block...
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for x in range(len(plaintextBytes)/16):
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#XOR with the chaining block
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blockBytes = plaintextBytes[x*16 : (x*16)+16]
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for y in range(16):
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blockBytes[y] ^= chainBytes[y]
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blockString = bytesToString(blockBytes)
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#Encrypt it
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encryptedBytes = stringToBytes(self.rijndael.encrypt(blockString))
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#Overwrite the input with the output
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for y in range(16):
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plaintextBytes[(x*16)+y] = encryptedBytes[y]
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#Set the next chaining block
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chainBytes = encryptedBytes
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self.IV = bytesToString(chainBytes)
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return bytesToString(plaintextBytes)
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def decrypt(self, ciphertext):
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AES.decrypt(self, ciphertext)
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ciphertextBytes = stringToBytes(ciphertext)
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chainBytes = stringToBytes(self.IV)
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#CBC Mode: For each block...
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for x in range(len(ciphertextBytes)/16):
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#Decrypt it
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blockBytes = ciphertextBytes[x*16 : (x*16)+16]
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blockString = bytesToString(blockBytes)
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decryptedBytes = stringToBytes(self.rijndael.decrypt(blockString))
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#XOR with the chaining block and overwrite the input with output
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for y in range(16):
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decryptedBytes[y] ^= chainBytes[y]
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ciphertextBytes[(x*16)+y] = decryptedBytes[y]
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#Set the next chaining block
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chainBytes = blockBytes
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self.IV = bytesToString(chainBytes)
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return bytesToString(ciphertextBytes)
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