mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-18 01:00:15 +00:00
126 lines
4.3 KiB
Python
126 lines
4.3 KiB
Python
from __future__ import print_function
|
|
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()
|