Add google-endpoints to third_party/.

third_party/google-endpoints/jwkest/aes_key_wrap.py

+"""
+Key wrapping and unwrapping as defined in RFC 3394.
+Also a padding mechanism that was used in openssl at one time.  
+The purpose of this algorithm is to encrypt a key multiple times to add an
+extra layer of security.
+ 
+Personally, I wouldn't recommend using this for most applications.  
+Just use AES/mode CTR to encrypt your keys, the same as you would any other
+data.
+The time to use this code is when you need compatibility with another system
+that implements the RFC.
+(For example, these functions are compatible with the openssl functions of
+the same name.)
+ 
+Performance should be reasonable, since the heavy lifting is all done in
+PyCrypto's AES.
+"""
+from __future__ import division
+
+try:
+    from builtins import hex
+    from builtins import range
+except ImportError:
+    pass
+import struct
+from Crypto.Cipher import AES
+
+QUAD = struct.Struct('>Q')
+
+
+def aes_unwrap_key_and_iv(kek, wrapped):
+    n = (len(wrapped) // 8) - 1
+    #NOTE: R[0] is never accessed, left in for consistency with RFC indices
+    r = [None] + [wrapped[i * 8:i * 8 + 8] for i in range(1, n + 1)]
+    a = QUAD.unpack(wrapped[:8])[0]
+    decrypt = AES.new(kek).decrypt
+    for j in range(5, -1, -1):  #counting down
+        for i in range(n, 0, -1):  #(n, n-1, ..., 1)
+            ciphertext = QUAD.pack(a ^ (n * j + i)) + r[i]
+            B = decrypt(ciphertext)
+            a = QUAD.unpack(B[:8])[0]
+            r[i] = B[8:]
+    return b"".join(r[1:]), a
+
+
+def aes_unwrap_key(kek, wrapped, iv=0xa6a6a6a6a6a6a6a6):
+    key, key_iv = aes_unwrap_key_and_iv(kek, wrapped)
+    if key_iv != iv:
+        raise ValueError(
+            "Integrity Check Failed: " + hex(key_iv) + " (expected " + hex(
+                iv) + ")")
+    return key
+
+
+def aes_unwrap_key_withpad(kek, wrapped):
+    key, key_iv = aes_unwrap_key_and_iv(kek, wrapped)
+    key_iv = "{0:016X}".format(key_iv)
+    if key_iv[:8] != "A65959A6":
+        raise ValueError(
+            "Integrity Check Failed: " + key_iv[:8] + " (expected A65959A6)")
+    key_len = int(key_iv[8:], 16)
+    return key[:key_len]
+
+
+def aes_wrap_key(kek, plaintext, iv=0xa6a6a6a6a6a6a6a6):
+    n = len(plaintext) // 8
+    r = [None] + [plaintext[i * 8:i * 8 + 8] for i in range(0, n)]
+    a = iv
+    encrypt = AES.new(kek).encrypt
+    for j in range(6):
+        for i in range(1, n + 1):
+            b = encrypt(QUAD.pack(a) + r[i])
+            a = QUAD.unpack(b[:8])[0] ^ (n * j + i)
+            r[i] = b[8:]
+    return QUAD.pack(a) + b''.join(r[1:])
+
+
+def aes_wrap_key_withpad(kek, plaintext):
+    iv = 0xA65959A600000000 + len(plaintext)
+    plaintext += "\0" * (8 - len(plaintext) % 8)
+    return aes_wrap_key(kek, plaintext, iv)
+
+
+def test():
+    #test vector from RFC 3394
+    import binascii
+
+    KEK = binascii.unhexlify("000102030405060708090A0B0C0D0E0F")
+    CIPHER = binascii.unhexlify(
+        "1FA68B0A8112B447AEF34BD8FB5A7B829D3E862371D2CFE5")
+    PLAIN = binascii.unhexlify("00112233445566778899AABBCCDDEEFF")
+    assert aes_unwrap_key(KEK, CIPHER) == PLAIN
+    assert aes_wrap_key(KEK, PLAIN) == CIPHER