| 0,0 → 1,94 |
|---|
| from blockcipher import * |
| from pypresent import Present |
| |
| def new(key,mode=MODE_ECB,IV=None,counter=None,segment_size=None,rounds=32): |
| """Create a new cipher object |
| |
| Wrapper for pure python implementation rijndael.py |
| |
| key = raw string containing the key, AES-128..256 will be selected according to the key length |
| mode = python_PRESENT.MODE_ECB/CBC/CFB/OFB/CTR/CMAC, default is ECB |
| -> for every mode, except ECB and CTR, it is important to construct a seperate cipher for encryption and decryption |
| IV = IV as a raw string, default is "all zero" IV |
| -> needed for CBC, CFB and OFB mode |
| counter = counter object (CryptoPlus.Util.util.Counter) |
| -> only needed for CTR mode |
| -> use a seperate counter object for the cipher and decipher: the counter is updated directly, not a copy |
| see CTR example further on in the docstring |
| rounds = amount of rounds |
| segment_size = amount of bits to use from the keystream in each chain part |
| -> supported values: multiple of 8 between 8 and the blocksize |
| of the cipher (only per byte access possible), default is 8 |
| -> only needed for CFB mode |
| rounds = amount of rounds, default = 32 |
| |
| Notes: |
| - Always construct a seperate cipher object for encryption and decryption. Once a cipher object has been used for encryption, |
| it can't be used for decryption because it keeps a state (if necessary) for the IV. |
| |
| EXAMPLES: |
| ********** |
| IMPORTING: |
| ----------- |
| >>> from CryptoPlus.Cipher import python_PRESENT |
| |
| ECB Test Vectors: |
| ------------------ |
| >>> key = "00000000000000000000".decode('hex') |
| >>> plain = "0000000000000000".decode('hex') |
| >>> cipher = python_PRESENT.new(key,python_PRESENT.MODE_ECB) |
| >>> cipher.encrypt(plain).encode('hex') |
| '5579c1387b228445' |
| |
| >>> key = "00000000000000000000000000000000".decode('hex') |
| >>> plain = "0000000000000000".decode('hex') |
| >>> cipher = python_PRESENT.new(key,python_PRESENT.MODE_ECB,rounds=64) |
| >>> cipher.encrypt(plain).encode('hex') |
| '59a27d01607ebf05' |
| |
| >>> key = "00000000000000000000".decode('hex') |
| >>> plain = "0000000000000000".decode('hex') |
| >>> cipher = python_PRESENT.new(key,python_PRESENT.MODE_ECB,rounds=64) |
| >>> cipher.encrypt(plain).encode('hex') |
| '13991dd588bc1288' |
| |
| Test Vectors for maximum rounds supported by PRESENT reference C code: |
| ----------------------------------------------------------------------- |
| >>> key = "0123456789abcdef0123".decode('hex') |
| >>> plain = "0123456789abcdef".decode('hex') |
| >>> cipher = python_PRESENT.new(key,python_PRESENT.MODE_ECB,rounds=65534) |
| >>> ciphertext = cipher.encrypt(plain) |
| >>> ciphertext.encode('hex') |
| 'a140dc5d7175ca20' |
| >>> cipher.decrypt(ciphertext).encode('hex') |
| '0123456789abcdef' |
| |
| >>> key = "0123456789abcdef0123456789abcdef".decode('hex') |
| >>> plain = "0123456789abcdef".decode('hex') |
| >>> cipher = python_PRESENT.new(key,python_PRESENT.MODE_ECB,rounds=65534) |
| >>> ciphertext = cipher.encrypt(plain) |
| >>> ciphertext.encode('hex') |
| '21007772e5d4ef14' |
| >>> cipher.decrypt(ciphertext).encode('hex') |
| '0123456789abcdef' |
| """ |
| return python_PRESENT(key,mode,IV,counter,rounds,segment_size) |
| |
| class python_PRESENT(BlockCipher): |
| key_error_message = "Key should be 80 or 128 bits" |
| |
| def __init__(self,key,mode,IV,counter,rounds,segment_size): |
| cipher_module = Present |
| args = {'rounds':rounds} |
| self.blocksize = 8 |
| BlockCipher.__init__(self,key,mode,IV,counter,cipher_module,segment_size,args) |
| |
| def keylen_valid(self,key): |
| return len(key) in (10,16) |
| |
| def _test(): |
| import doctest |
| doctest.testmod() |
| |
| if __name__ == "__main__": |
| _test() |