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DES Algorithm - PHP Implementation in mcrypt
Part:
1
2
(Continued from previous part...)
If you run this script, you should get:
Test 1 - DES ECB 64-bit:
The key : 0123456789abcdef
The IV : 1234567890abcdef
The plaintext : 4e6f77206973207468652074696d6520666f7220616c6c20
The ciphertext: 3fa40e8a984d48156a271787ab8883f9893d51ec4b563b53
The expected : 3fa40e8a984d43156a271787ab8883f9893d51ec4b563b53
Test 2 - DES CBC 64-bit:
The key : 0123456789abcdef
The IV : 1234567890abcdef
The plaintext : 4e6f77206973207468652074696d6520666f7220616c6c20
The ciphertext: e5c7cdde872bf27c43e934008c389c0f683788499a7c05f6
The expected : e5c7cdde872bf27c43e934008c389c0f683788499a7c05f6
Test 3 - DES CFB 8-bit:
The key : 0123456789abcdef
The IV : 1234567890abcdef
The plaintext : 4e6f77206973207468652074696d6520666f7220616c6c20
The ciphertext: f31fda07011462ee187f43d80a7cd9b5b0d290da6e5b9a87
The expected : f31fda07011462ee187f43d80a7cd9b5b0d290da6e5b9a87
Test 4 - DES OFB 8-bit:
The key : 0123456789abcdef
The IV : 1234567890abcdef
The plaintext : 4e6f77206973207468652074696d6520666f7220616c6c20
The ciphertext: f34a2850c9c64985d684ad96d772e2f243ea499abee8ae95
The expected : f34a2850c9c64985d684ad96d772e2f243ea499abee8ae95
Output looks very good. All 4 test cases match the expected ciphertext message documented in
http://www.itl.nist.gov/fipspubs/fip81.htm.
Block Padding in mcrypt
"mycypt" offers a very simple padding method which simply adds 0x00 to the end of the plaintext message
to make it multiples of 8 bytes (64 bits) for ECB and CBC modes. There is no need for padding for CFB
and OFB modes because they are operated on 8-bit blocks.
Other PHP Implementations of DES Algorithm
If you search "DES algorithm implement in PHP" on Google, you will see Paul Tero's DES page
at http://www.tero.co.uk/des/. It offers
a source code version of DES implementation in PHP.
Conclusion
- mcrypt extension offers DES 64-bit ECB, 64-bit CBC, 8-bit CFB and 8-bit OFB operation modes.
- mcrypt pads plaintext messages with 0x00 bytes.
Part:
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2
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