Added full aes-256-ige with tests
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Sammy Pfeiffer
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5a39d105fa
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64
encrypt_decrypt_ige_test.py
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64
encrypt_decrypt_ige_test.py
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__author__ = 'sam'
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from ige import ige
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# AES 256 IGE is using AES ECB internally, it implies (extract from PyCrypto.cipher.AES):
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# key : byte string
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# The secret key to use in the symmetric cipher.
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# It must be 16 (*AES-128*), 24 (*AES-192*), or 32 (*AES-256*) bytes long.
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# IV : byte string
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# The initialization vector to use for encryption or decryption.
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#
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# It is ignored for `MODE_ECB` and `MODE_CTR`.
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#
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# For all other modes, it must be `block_size` bytes longs.
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# message must be a multiple of 16 in size
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msg_to_encrypt = "This is a secret message"
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padding_needed = 16 - len(msg_to_encrypt) % 16
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msg_to_encrypt_padded = msg_to_encrypt + b'0' * padding_needed
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print("Encrypting: '" + str(msg_to_encrypt) + "'")
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print("With padding: '" + str(msg_to_encrypt_padded) + "'")
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# 32 bytes long key
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aes_key = b'12345678901234567890123456789012'
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print("With key for AES 256 ECB: '" + str(aes_key) + "'")
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# Initialization Vector must be 32 bytes
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aes_iv = b'01234567890123456789012345678901'
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print("And initialization vector: '" + str(aes_iv) + "'")
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encrypted_msg = ige(msg_to_encrypt_padded, aes_key, aes_iv, operation="encrypt")
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print("\nEncrypted msg: '" + str(encrypted_msg) + "'")
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print("In hex: " + encrypted_msg.__repr__())
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decrypted_msg = ige(encrypted_msg, aes_key, aes_iv, operation="decrypt")
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print("\nDecrypted msg: '" + str(decrypted_msg) + "'")
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print("In hex: " + decrypted_msg.__repr__())
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if msg_to_encrypt_padded == decrypted_msg:
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print("Encrypt + Decrypt process, completed succesfully.")
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# Let's test incorrect inputs
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print("\n\nTesting incorrect inputs:")
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# Message with length not multiple of 16
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msg_not_multiple_of_16 = "6bytes"
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print("Trying to encrypt: '" + msg_not_multiple_of_16 +
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"' of size: " + str(len(msg_not_multiple_of_16)))
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try:
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encrypted_msg = ige(msg_not_multiple_of_16, aes_key, aes_iv, operation="encrypt")
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except ValueError as ve:
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print(" Correctly got ValueError: '" + str(ve) + "'")
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# key not being 32 bytes
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aes_key_not_32_bytes = b'0123456789'
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print("Trying to use key: '" + str(aes_key_not_32_bytes) + "'")
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try:
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encrypted_msg = ige(msg_to_encrypt_padded, aes_key_not_32_bytes, aes_iv, operation="encrypt")
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except ValueError as ve:
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print(" Correctly got ValueError: '" + str(ve) + "'")
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# iv not being 32 bytes
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iv_key_not_32_bytes = b'0123456789'
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print("Trying to use iv: '" + str(iv_key_not_32_bytes) + "'")
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try:
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encrypted_msg = ige(msg_to_encrypt_padded, aes_key, iv_key_not_32_bytes, operation="encrypt")
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except ValueError as ve:
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print(" Correctly got ValueError: '" + str(ve) + "'")
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67
ige.py
67
ige.py
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@ -51,10 +51,15 @@ def xor_strings(a, b): # xor two strings of different lengths
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else:
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return bytes(x ^ y for x, y in zip(a, b))
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def ige(message, key, iv):
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"""given a key, given an iv, and message, decrypt it."""
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def ige(message, key, iv, operation="decrypt"):
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"""Given a key, given an iv, and message
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do whatever operation asked in the operation field.
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Operation will be checked for: "decrypt" and "encrypt" strings.
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Returns the message encrypted/decrypted.
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message must be a multiple by 16 bytes (for division in 16 byte blocks)
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key must be 32 byte
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iv must be 32 byte (it's not internally used in AES 256 ECB, but it's
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needed for IGE)"""
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if type(message) == long:
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message = number.long_to_bytes(message)
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if type(key) == long:
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@ -62,33 +67,49 @@ def ige(message, key, iv):
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if type(iv) == long:
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iv = number.long_to_bytes(iv)
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if len(key) != 32:
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raise ValueError("key must be 32 bytes long (was " +
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str(len(key)) + " bytes)")
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if len(iv) != 32:
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raise ValueError("iv must be 32 bytes long (was " +
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str(len(iv)) + " bytes)")
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cipher = AES.new(key, AES.MODE_ECB, iv)
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blocksize = cipher.block_size
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if len(message) % blocksize != 0:
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raise ValueError("message must be a multiple of 16 bytes (try adding " +
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str(16 - len(message) % 16) + " bytes of padding)")
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prev_x = iv[0:blocksize]
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prev_y = iv[blocksize:] # len should be > 0
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ivp = iv[0:blocksize]
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ivp2 = iv[blocksize:]
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decrypted = None
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ciphered = None
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for i in range(0, len(message), blocksize):
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x = message[i:i+blocksize]
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y = xor_strings(cipher.decrypt(xor_strings(x, prev_y)), prev_x)
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prev_x = x
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prev_y = y
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# decrypted = sumBytes(decrypted, y);
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if decrypted is None:
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decrypted = y
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indata = message[i:i+blocksize]
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if operation == "decrypt":
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outdata = xor_strings(cipher.decrypt(xor_strings(indata, ivp2)), ivp)
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ivp = indata
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ivp2 = outdata
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elif operation == "encrypt":
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outdata = xor_strings(cipher.encrypt(xor_strings(indata, ivp)), ivp2)
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ivp = outdata
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ivp2 = indata
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else:
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decrypted_ba = bytearray(decrypted)
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decrypted_ba.extend(y)
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if version_info >= (3, 4, 0):
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decrypted = bytes(decrypted_ba)
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else:
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decrypted = str(decrypted_ba)
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raise ValueError("operation must be either 'decrypt' or 'encrypt'")
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if ciphered is None:
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ciphered = outdata
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else:
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ciphered_ba = bytearray(ciphered)
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ciphered_ba.extend(outdata)
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if version_info >= (3, 4, 0):
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ciphered = bytes(ciphered_ba)
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else:
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ciphered = str(ciphered_ba)
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return ciphered
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return decrypted
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if __name__ == "__main__":
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encrypted_answer_str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