PrivateBin CLI on python 3
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8 years ago
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=256, 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=256, iters=256000, salt=None, **kwargs):
kdf_salt = salt or os.urandom(8)
print("Salt: {}".format(kdf_salt))
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)))