faset over fra Z3950 til google books

python/gdata/tlslite/utils/Python_AES.py

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+"""Pure-Python AES implementation."""
+
+from cryptomath import *
+
+from AES import *
+from rijndael import rijndael
+
+def new(key, mode, IV):
+    return Python_AES(key, mode, IV)
+
+class Python_AES(AES):
+    def __init__(self, key, mode, IV):
+        AES.__init__(self, key, mode, IV, "python")
+        self.rijndael = rijndael(key, 16)
+        self.IV = IV
+
+    def encrypt(self, plaintext):
+        AES.encrypt(self, plaintext)
+
+        plaintextBytes = stringToBytes(plaintext)
+        chainBytes = stringToBytes(self.IV)
+
+        #CBC Mode: For each block...
+        for x in range(len(plaintextBytes)/16):
+
+            #XOR with the chaining block
+            blockBytes = plaintextBytes[x*16 : (x*16)+16]
+            for y in range(16):
+                blockBytes[y] ^= chainBytes[y]
+            blockString = bytesToString(blockBytes)
+
+            #Encrypt it
+            encryptedBytes = stringToBytes(self.rijndael.encrypt(blockString))
+
+            #Overwrite the input with the output
+            for y in range(16):
+                plaintextBytes[(x*16)+y] = encryptedBytes[y]
+
+            #Set the next chaining block
+            chainBytes = encryptedBytes
+
+        self.IV = bytesToString(chainBytes)
+        return bytesToString(plaintextBytes)
+
+    def decrypt(self, ciphertext):
+        AES.decrypt(self, ciphertext)
+
+        ciphertextBytes = stringToBytes(ciphertext)
+        chainBytes = stringToBytes(self.IV)
+
+        #CBC Mode: For each block...
+        for x in range(len(ciphertextBytes)/16):
+
+            #Decrypt it
+            blockBytes = ciphertextBytes[x*16 : (x*16)+16]
+            blockString = bytesToString(blockBytes)
+            decryptedBytes = stringToBytes(self.rijndael.decrypt(blockString))
+
+            #XOR with the chaining block and overwrite the input with output
+            for y in range(16):
+                decryptedBytes[y] ^= chainBytes[y]
+                ciphertextBytes[(x*16)+y] = decryptedBytes[y]
+
+            #Set the next chaining block
+            chainBytes = blockBytes
+
+        self.IV = bytesToString(chainBytes)
+        return bytesToString(ciphertextBytes)