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SJCL encrypt / decrypt in Python
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import os | |
from base64 import b64decode, b64encode | |
from cryptography.hazmat.primitives import hashes | |
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes | |
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC | |
from cryptography.hazmat.backends import default_backend | |
_BACKEND = default_backend() | |
def decrypt(pwd, json): | |
iv = b64decode(json['iv']) | |
ct = b64decode(json['ct']) | |
salt = b64decode(json['salt']) | |
ts = data['ts'] / 8 | |
tag_start = len(ct) - ts | |
tag = ct[tag_start:] | |
ciphertext = ct[:tag_start] | |
mode_class = getattr(modes, json['mode'].upper()) | |
algo_class = getattr(algorithms, json['cipher'].upper()) | |
kdf = _kdf(json['ks'], iters=json['iter'], salt=salt)[0] | |
key = kdf.derive(pwd) | |
cipher = Cipher(algo_class(key), | |
mode_class(iv, tag, min_tag_length=ts), | |
backend=_BACKEND) | |
dec = cipher.decryptor() | |
result = dec.update(ciphertext) + dec.finalize() | |
return result | |
def encrypt(pwd, plaintext, mode='gcm', algorithm='aes', | |
keysize=128, tagsize=128, iters=256000): | |
ts = tagsize / 8 | |
mode_class = getattr(modes, mode.upper()) | |
algo_class = getattr(algorithms, algorithm.upper()) | |
iv = os.urandom(16) | |
kdf, salt = _kdf(keysize, iters) | |
key = kdf.derive(pwd) | |
cipher = Cipher(algo_class(key), | |
mode_class(iv, min_tag_length=ts), | |
backend=_BACKEND) | |
enc = cipher.encryptor() | |
ciphertext = enc.update(plaintext) + enc.finalize() | |
json = { | |
"v": 1, | |
"iv": b64encode(iv), | |
"salt": b64encode(salt), | |
"ct": b64encode(ciphertext + enc.tag[:ts]), | |
"iter": iters, | |
"ks": keysize, | |
"ts": tagsize, | |
"mode": mode, | |
"cipher": algorithm, | |
"adata": "" | |
} | |
return json | |
def _kdf(keysize=128, iters=256000, salt=None, **kwargs): | |
kdf_salt = salt or os.urandom(8) | |
kdf = PBKDF2HMAC(algorithm=hashes.SHA256(), | |
length=keysize / 8, | |
salt=kdf_salt, | |
iterations=iters, | |
backend=_BACKEND) | |
return kdf, kdf_salt | |
if __name__ == "__main__": | |
import json | |
blob = '{"iv":"/6dKRRAOZ60oyumLMQsBtg==","v":1,"iter":256000,"ks":128,"ts":64,"mode":"gcm","adata":"","cipher":"aes","salt":"s8+LFcBmbcc=","ct":"wTapp5CWmD6SFA=="}' | |
data = json.loads(blob) | |
result = decrypt('pwd', data) | |
assert result == "hi" | |
print decrypt('pwd', encrypt('pwd', result, tagsize=64)) |
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