Crypt::ECB Encryption with No Padding

Blowfish Cipher Tutorials - Herong's Tutorial Examples

∟Crypt::ECB Encryption with No Padding

A tutorial example is provided to show how to use Crypt::ECB to perform encryption with no padding. The plaintext must be multiples of 8-byte blocks.

Since the ECB (Electronic CodeBook) operation mode is so simple, Crypt::ECB does not need to offer many options. If we use it with Crypt::Blowfish, there are only two options:

With no padding - No padding will be supported. The plaintext must be in multiples of 8-byte blocks.
With default padding - The default padding will be used. The plaintext can be any size.

With no padding, we can simply create a new Crypt::ECB object with two method calls:

   $cipher = Crypt::ECB->new($keyStr, 'Blowfish');
   $cipher->padding(PADDING_NONE);

To help us understanding how Crypt::ECB works without padding, I wrote the following example Perl script, Crypt-ECB-Blowfish-Encryption.pl:

#- Crypt-ECB-Blowfish-Encryption.pl
#- Copyright (c) 2015 HerongYang.com, All Rights Reserved.
   use Crypt::ECB;
   my ($keyHex, $plainHex) = @ARGV;

   print("Crypt::ECB Encryption Test - output in Hex:\n");
   $keyHex = "1122334455667788" unless $keyHex;
   $plainHex = "0123456789abcdef" unless $plainHex;
   $keyStr = pack("H*", $keyHex);
   $plainStr = pack("H*", $plainHex);
   print("   Secret Key     ($keyHex)\n");
   print("   Plaintext      ($plainHex)\n");
      
   print("Creating Crypt::ECB with secret key ...\n");
   $cipher = Crypt::ECB->new($keyStr, 'Blowfish');
   $cipher->padding(PADDING_NONE);

   print("Encrypting plaintext...\n");
   $cipherStr = $cipher->encrypt($plainStr);
   $cipherHex = unpack("H*", $cipherStr);
   print("   Ciphertext     ($cipherHex)\n");

   print("Decrypting ciphertext...\n");
   $decryptStr = $cipher->decrypt($cipherStr);
   $decryptHex = unpack("H*", $decryptStr);
   print("   Decrypted text ($decryptHex)\n");

   $keyStr = $cipher->key();
   $keyHex = unpack("H*", $keyStr);
   print("   Secret Key     ($keyHex)\n");

   $padding = $cipher->padding();
   print("   Padding        ($padding)\n");

If you run this example script in a command window, you will get:

C:\Herong>perl Crypt-ECB-Blowfish-Encryption.pl

Crypt::ECB Encryption Test - output in Hex:
   Secret Key     (1122334455667788)
   Plaintext      (0123456789abcdef)
Creating Crypt::ECB with secret key ...
Encrypting plaintext...
   Ciphertext     (103248f0eea98e89)
Decrypting ciphertext...
   Decrypted text (0123456789abcdef)
   Secret Key     (1122334455667788)
   Padding        (0)