Implementing-cryptography-using-python

54 Chapter 2 ■ Cryptographic Protocols and Perfect Secrecy
Hello World
48656c6c6f20576f726c64
87521618088882533792115812
48656c6c6f20576f726c64
Hello World
While examining the following code, notice the use of binascii along with
the hexlify() and unhexlify() methods. The hexlify() method returns the
hexadecimal representation of binary data. Each byte of the data is converted
into a two-digit hex representation. The resulting output will be twice as long
as the length of the data. The unhexlify() method returns the binary representation
of the data. As you may have guessed, the unhexlify() method is the
inverse of the hexlify() method:
import binascii
def text2int(msg):
print (msg)
# convert string to hex
#hexstr = msg.encode('hex')
msg = msg.encode()
hexstr = binascii.hexlify(msg)
print (hexstr)
# convert hex to integer
integer_m = int(hexstr, 16)
print (integer_m)
# convert integer back to hex
back2hex = format(integer_m, 'x')
print (back2hex)
# convert back to string
evenpad = ('0' * (len(back2hex) % 2)) + back2hex
#plaintext = evenpad.decode('hex')
plaintext = binascii.unhexlify(evenpad)
print (plaintext)
text2int("Hello World")
Hello World
b'48656c6c6f20576f726c64'
87521618088882533792115812
48656c6c6f20576f726c64
b'Hello World'