initial

ciphers/rsa_cipher.py

@@ -0,0 +1,124 @@
+import sys, rsa_key_generator as rkg, os
+
+DEFAULT_BLOCK_SIZE = 128
+BYTE_SIZE = 256
+
+def main():
+    filename = 'encrypted_file.txt'
+    response = input('Encrypte\Decrypt [e\d]: ')
+
+    if response.lower().startswith('e'):
+        mode = 'encrypt'
+    elif response.lower().startswith('d'):
+        mode = 'decrypt'
+
+    if mode == 'encrypt':
+        if not os.path.exists('rsa_pubkey.txt'):
+            rkg.makeKeyFiles('rsa', 1024)
+
+        message = input('\nEnter message: ')
+        pubKeyFilename = 'rsa_pubkey.txt'
+        print('Encrypting and writing to %s...' % (filename))
+        encryptedText = encryptAndWriteToFile(filename, pubKeyFilename, message)
+
+        print('\nEncrypted text:')
+        print(encryptedText)
+
+    elif mode == 'decrypt':
+        privKeyFilename = 'rsa_privkey.txt'
+        print('Reading from %s and decrypting...' % (filename))
+        decryptedText = readFromFileAndDecrypt(filename, privKeyFilename)
+        print('writing decryption to rsa_decryption.txt...')
+        with open('rsa_decryption.txt', 'w') as dec:
+            dec.write(decryptedText)
+
+        print('\nDecryption:')
+        print(decryptedText)
+
+
+def getBlocksFromText(message, blockSize=DEFAULT_BLOCK_SIZE):
+    messageBytes = message.encode('ascii')
+
+    blockInts = []
+    for blockStart in range(0, len(messageBytes), blockSize):
+        blockInt = 0
+        for i in range(blockStart, min(blockStart + blockSize, len(messageBytes))):
+            blockInt += messageBytes[i] * (BYTE_SIZE ** (i % blockSize))
+        blockInts.append(blockInt)
+    return blockInts
+
+
+def getTextFromBlocks(blockInts, messageLength, blockSize=DEFAULT_BLOCK_SIZE):
+    message = []
+    for blockInt in blockInts:
+        blockMessage = []
+        for i in range(blockSize - 1, -1, -1):
+            if len(message) + i < messageLength:
+                asciiNumber = blockInt // (BYTE_SIZE ** i)
+                blockInt = blockInt % (BYTE_SIZE ** i)
+                blockMessage.insert(0, chr(asciiNumber))
+        message.extend(blockMessage)
+    return ''.join(message)
+
+
+def encryptMessage(message, key, blockSize=DEFAULT_BLOCK_SIZE):
+    encryptedBlocks = []
+    n, e = key
+
+    for block in getBlocksFromText(message, blockSize):
+        encryptedBlocks.append(pow(block, e, n))
+    return encryptedBlocks
+
+
+def decryptMessage(encryptedBlocks, messageLength, key, blockSize=DEFAULT_BLOCK_SIZE):
+    decryptedBlocks = []
+    n, d = key
+    for block in encryptedBlocks:
+        decryptedBlocks.append(pow(block, d, n))
+    return getTextFromBlocks(decryptedBlocks, messageLength, blockSize)
+
+
+def readKeyFile(keyFilename):
+    fo = open(keyFilename)
+    content = fo.read()
+    fo.close()
+    keySize, n, EorD = content.split(',')
+    return (int(keySize), int(n), int(EorD))
+
+
+def encryptAndWriteToFile(messageFilename, keyFilename, message, blockSize=DEFAULT_BLOCK_SIZE):
+    keySize, n, e = readKeyFile(keyFilename)
+    if keySize < blockSize * 8:
+        sys.exit('ERROR: Block size is %s bits and key size is %s bits. The RSA cipher requires the block size to be equal to or greater than the key size. Either decrease the block size or use different keys.' % (blockSize * 8, keySize))
+
+    encryptedBlocks = encryptMessage(message, (n, e), blockSize)
+
+    for i in range(len(encryptedBlocks)):
+        encryptedBlocks[i] = str(encryptedBlocks[i])
+    encryptedContent = ','.join(encryptedBlocks)
+    encryptedContent = '%s_%s_%s' % (len(message), blockSize, encryptedContent)
+    fo = open(messageFilename, 'w')
+    fo.write(encryptedContent)
+    fo.close()
+    return encryptedContent
+
+
+def readFromFileAndDecrypt(messageFilename, keyFilename):
+    keySize, n, d = readKeyFile(keyFilename)
+    fo = open(messageFilename)
+    content = fo.read()
+    messageLength, blockSize, encryptedMessage = content.split('_')
+    messageLength = int(messageLength)
+    blockSize = int(blockSize)
+
+    if keySize < blockSize * 8:
+        sys.exit('ERROR: Block size is %s bits and key size is %s bits. The RSA cipher requires the block size to be equal to or greater than the key size. Did you specify the correct key file and encrypted file?' % (blockSize * 8, keySize))
+
+    encryptedBlocks = []
+    for block in encryptedMessage.split(','):
+        encryptedBlocks.append(int(block))
+
+    return decryptMessage(encryptedBlocks, messageLength, (n, d), blockSize)
+
+if __name__ == '__main__':
+    main()

ciphers/rsa_key_generator.py

@@ -0,0 +1,45 @@
+import random, sys, os
+import rabin_miller as rabinMiller, cryptomath_module as cryptoMath
+
+def main():
+    print('Making key files...')
+    makeKeyFiles('rsa', 1024)
+    print('Key files generation successful.')
+
+def generateKey(keySize):
+    print('Generating prime p...')
+    p = rabinMiller.generateLargePrime(keySize)
+    print('Generating prime q...')
+    q = rabinMiller.generateLargePrime(keySize)
+    n = p * q
+
+    print('Generating e that is relatively prime to (p - 1) * (q - 1)...')
+    while True:
+        e = random.randrange(2 ** (keySize - 1), 2 ** (keySize))
+        if cryptoMath.gcd(e, (p - 1) * (q - 1)) == 1:
+            break
+
+    print('Calculating d that is mod inverse of e...')
+    d = cryptoMath.findModInverse(e, (p - 1) * (q - 1))
+
+    publicKey = (n, e)
+    privateKey = (n, d)
+    return (publicKey, privateKey)
+
+def makeKeyFiles(name, keySize):
+    if os.path.exists('%s_pubkey.txt' % (name)) or os.path.exists('%s_privkey.txt' % (name)):
+        print('\nWARNING:')
+        print('"%s_pubkey.txt" or "%s_privkey.txt" already exists. \nUse a different name or delete these files and re-run this program.' % (name, name))
+        sys.exit()
+
+    publicKey, privateKey = generateKey(keySize)
+    print('\nWriting public key to file %s_pubkey.txt...' % name)
+    with open('%s_pubkey.txt' % name, 'w') as fo:
+        fo.write('%s,%s,%s' % (keySize, publicKey[0], publicKey[1]))
+
+    print('Writing private key to file %s_privkey.txt...' % name)
+    with open('%s_privkey.txt' % name, 'w') as fo:
+        fo.write('%s,%s,%s' % (keySize, privateKey[0], privateKey[1]))
+
+if __name__ == '__main__':
+    main()