update

pbincli/sjcl_simple.py

@@ -0,0 +1,89 @@
+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)))