def multiply_ciphers(cipher1, cipher2, public_key_file):
cipher1 = pyrsa_sq_mul.unpack_bigint(cipher1)
cipher2 = pyrsa_sq_mul.unpack_bigint(cipher2)
key = open(public_key_file,'r').read()
rsakey = RSA.importKey(key)
mult_cipher_int = (cipher1 * cipher2) % rsakey.n
mult_cipher_str = pyrsa_sq_mul.pack_bigint(mult_cipher_int)
return mult_cipher_str
def decrypt_RSA(private_key_file, cipher, state='sm'):
key = open(private_key_file,'r').read()
rsakey = RSA.importKey(key)
if state == 'sm':
cipher_int = pyrsa_sq_mul.unpack_bigint(cipher)
decrypted_byte_message_int = pyrsa_sq_mul.square_multiply(cipher_int, rsakey.d, rsakey.n)
decrypted_byte_message_str = pyrsa_sq_mul.pack_bigint(decrypted_byte_message_int)
elif state == 'part3':
cipher_rsa = PKCS1_OAEP.new(rsakey)
decrypted_byte_message_str = cipher_rsa.decrypt(cipher)
return decrypted_byte_message_str
def encrypt_RSA(public_key_file, message, state='sm'):
key = open(public_key_file,'r').read()
rsakey = RSA.importKey(key)
if state == 'sm':
if isinstance(message, int):
byte_message_int = message
else:
byte_message_int = pyrsa_sq_mul.unpack_bigint(message)
encrypt_byte_message_int = pyrsa_sq_mul.square_multiply(byte_message_int, rsakey.e, rsakey.n)
encrypt_byte_message_str = pyrsa_sq_mul.pack_bigint(encrypt_byte_message_int)
elif state == 'part3':
cipher_rsa = PKCS1_OAEP.new(rsakey)
encrypt_byte_message_str = cipher_rsa.encrypt(message)
return encrypt_byte_message_str
'''Part II: Protocol Attack'''
print('Part II-------------')
plain_int = 100
print('Encrypting: {}\n'.format(plain_int))
cipher_int = encrypt_RSA('mykey.pem.pub', plain_int)
print('Result:\n{}\n'.format(b64encode(cipher_int)))
attack_num = 2
cipher_attack = encrypt_RSA('mykey.pem.pub', attack_num)
cipher_modified = multiply_ciphers(cipher_int, cipher_attack, 'mykey.pem.pub')
print('Modified to: {}\n'.format(b64encode(cipher_modified)))
decrypt_cipher_modified = decrypt_RSA('mykey.pem.priv', cipher_modified)
print('Decrypted: {}'.format(pyrsa_sq_mul.unpack_bigint(decrypt_cipher_modified)))
'''Part III: Implementing RSA with Padding (Local testing)'''
print('Part III-------------')
part3_private_key, part3_public_key = generate_RSA()
print('The public key is:\n{}\n'.format(part3_public_key))
print('The private key is:\n{}\n'.format(part3_private_key))
with open("mydata.txt", 'rb') as f_message_data:
message_data = f_message_data.read()
print('The message to encrypt is:\n{}\n'.format(message_data))
cipher_pkcs = encrypt_RSA('part3.pem.pub', message_data, 'part3')
print('The cipher text after encryption is:\n{}\n'.format(b64encode(cipher_pkcs)))
decrypt_cipher_pkcs = decrypt_RSA('part3.pem.priv', cipher_pkcs, 'part3')