diff options
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/ocb.js | 9 | ||||
| -rw-r--r-- | crypto/ocb.py | 89 |
2 files changed, 72 insertions, 26 deletions
diff --git a/crypto/ocb.js b/crypto/ocb.js index d7d53aa..2e91f60 100644 --- a/crypto/ocb.js +++ b/crypto/ocb.js @@ -1,8 +1,7 @@ -load('sjcl.js') +load('../webclient/lib/sjcl.js') var aeskey = sjcl.codec.hex.toBits('12538243c49f1c58e6f7b0687bbd65b2') var iv = sjcl.codec.hex.toBits('250c3041c00a605a4100e264abbc588b') -plaintext = "La chaire est triste, hélas ! et j'ai lu tous les livres." -var secret = sjcl.encrypt(aeskey, plaintext,{mode:'ocb2', iv:iv, adata:"", tag:128}) -var secret2 = sjcl.json.decode(secret) +var plaintext = "La chaire est triste, hélas ! et j'ai lu tous les livres." +var header = sjcl.codec.utf8String.toBits('Mallarmé') +var secret = sjcl.encrypt(aeskey, plaintext,{mode:'ocb2', iv:iv, adata:header, ts:128}) print(secret) -print(sjcl.codec.hex.fromBits(secret2.ct)) diff --git a/crypto/ocb.py b/crypto/ocb.py index 08814c7..7383ee6 100644 --- a/crypto/ocb.py +++ b/crypto/ocb.py @@ -2,27 +2,74 @@ from aespython import key_expander, aes_cipher, ocb_mode import json import base64 -def hex2byte(hexstring): - return map(ord, hexstring.decode("hex")) -def byte2hex(byteslist): - return str(bytearray(byteslist)).encode("hex") +class sjcl(ocb_mode.OCBMode): + """convenience class to wrap the sjcl objects encryption and decryption""" + def __init__(self, key, keylen): + KE = key_expander.KeyExpander(keylen) + expended_key = KE.expand(key) + cipher = aes_cipher.AESCipher(expanded_key) + ocb_mode.OCBMode.__init__(self, cipher, len(key)) + + @staticmethod + def hex2byte(hexstring): + """convert a hexstring to a list of bytes""" + return map(ord, hexstring.decode("hex")) + + @staticmethod + def byte2hex(byteslist): + """convert a list of bytes to a hexstring""" + return str(bytearray(byteslist)).encode("hex") + + @staticmethod + def pad(b64string): + """pad a base64 string with = so that its lengh is divisible by 4""" + return b64string + ''.join(['='] * (len(b64string) % 4)) + + def encrypt_sjclobject(self, plaintext, header): + """encrypt a message and return in in the sjcl object format""" + tag, ciphertext = ocb_mode.OCBMode.encrypt_block(self, plaintext, header) + sjcl_object = {"iv": base64.b64encode(bytearray(self._iv)).rstrip("="), + "mode": "ocb2", + "ts": 128, + "ct": base64.b64encode(bytearray(ciphertext) + + bytearray(tag)).rstrip("="), + "adata": base64.b64encode(header).rstrip("=") + } + return json.dumps(sjcl_object) + + def decrypt_sjclobject(self, objectstring): + """takes a sjcl object and return a list of bytes.""" + sjcl_object = json.loads(objectstring) + iv = map(ord, base64.b64decode(pad(sjcl_object['iv']))) + self.set_iv(iv) + ct = map(ord, base64.b64decode(pad(sjcl_object['ct']))) + try: + header = map(ord, base64.b64decode(pad(sjcl_object['adata']))) + except KeyError: + header = [] + #sjcl appends the tag at the end of the cipher text (it's 16 bytes long) + tag = ct[-16:] + ciphertext = ct[:-16] + isValid, plaintext = ocb_mode.OCBMode.decrypt_block(self, header, ciphertext, tag) + if not isValid: + raise Exception("can't authenticate the data") + else: + return plaintext + if __name__=="__main__": - KE = key_expander.KeyExpander(128) - key = hex2byte('12538243c49f1c58e6f7b0687bbd65b2') - expanded_key = KE.expand(key) - aes_cipher_128 = aes_cipher.AESCipher(expanded_key) - aes_ocb_128 = ocb_mode.OCBMode(aes_cipher_128, 16) - iv = hex2byte('250c3041c00a605a4100e264abbc588b') - aes_ocb_128.set_iv(iv) - plaintext = "La chaire est triste, hélas ! et j'ai lu tous les livres.".encode("hex") - header = "".encode("hex") - (tag,ciphertext) = aes_ocb_128.encrypt_block(hex2byte(plaintext), hex2byte(header)) - sjcl_object = {"iv": base64.b64encode(bytearray(iv)).rstrip("="), - "mode": "ocb2", - "tag": 128, - "ct": base64.b64encode(bytearray(ciphertext) + - bytearray(tag)).rstrip("=") - } - print json.dumps(sjcl_object) + key = sjcl.hex2byte('12538243c49f1c58e6f7b0687bbd65b2') + iv = sjcl.hex2byte('250c3041c00a605a4100e264abbc588b') + sjclmode = sjcl(key, 128) + sjclmode.set_iv(iv) + plaintext = map(ord, "La chaire est triste, hélas ! et j'ai lu \ +tous les livres.") + header = bytearray("Mallarmé") + test = sjclmode.encrypt_sjclobject(plaintext, header) + print test + print str(bytearray(sjclmode.decrypt_sjclobject(test))) + + + + |