The DEScalc.html page is used to access the DES Calculator. To use the calculator fill in the Input Data value (being 16 hexadecimal digits), and the DES Key (being 32 hexadecimal digits), and press either the Encrypt or Decrypt button, as required. The resulting value will be displayed, along with the trace of the calculation, at the level of detail specified by te Trace Level radio buttons. If there is an error in the supplied values, an error message will be displayed in red.
An example DES test value, taken from
"H. Katzan, The Standard Data Encryption Algorithm,
pp75-94, Petrocelli Books Inc., New York, 1977" is:
Key: 5B5A57676A56676E Plaintext: 675A69675E5A6B5A Ciphertext: 974AFFBF86022D1F
Encrypting the plaintext with the key should give the ciphertext, decrypting the ciphertext with the key should give the plaintext.
The Trace produced looks like (at level 2):
setKey(5b5a57676a56676e) encryptDES(675a69675e5a6b5a) IP: L0=ffb2194d, R0=004df6fb Rnd1 f(R0=004df6fb, SK1=38 09 1b 26 2f 3a 27 0f ) = 746fc91a Rnd2 f(R1=8bddd057, SK2=28 09 19 32 1d 32 1f 2f ) = 7add38ae Rnd3 f(R2=7a90ce55, SK3=39 05 29 32 3f 2b 27 0b ) = a5e3f499 Rnd4 f(R3=2e3e24ce, SK4=29 2f 0d 10 19 2f 1d 3f ) = c5403e1c Rnd5 f(R4=bfd0f049, SK5=03 25 1d 13 1f 3b 37 2a ) = 91a62c82 Rnd6 f(R5=bf98084c, SK6=1b 35 05 19 3b 0d 35 3b ) = 6aeb6bc3 Rnd7 f(R6=d53b9b8a, SK7=03 3c 07 09 13 3f 39 3e ) = 1e9f7513 Rnd8 f(R7=a1077d5f, SK8=06 34 26 1b 3f 1d 37 38 ) = 59d1851c Rnd9 f(R8=8cea1e96, SK9=07 34 2a 09 37 3f 38 3c ) = 0fc4b474 Rnd10 f(R9=aec3c92b, SK10=06 33 26 0c 3e 15 3f 38 ) = 8de55e67 Rnd11 f(R10=010f40f1, SK11=06 02 33 0d 26 1f 28 3f ) = dced7991 Rnd12 f(R11=722eb0ba, SK12=14 16 30 2c 3d 37 3a 34 ) = 898d0def Rnd13 f(R12=88824d1e, SK13=30 0a 36 24 2e 12 2f 3f ) = 34cee3c3 Rnd14 f(R13=46e05379, SK14=34 0a 38 27 2d 3f 2a 17 ) = 6a4754b1 Rnd15 f(R14=e2c519af, SK15=38 1b 18 22 1d 32 1f 37 ) = 5bac9dc6 Rnd16 f(R15=1d4ccebf, SK16=38 0b 08 2e 3d 2f 0e 17 ) = e448c462 FP: L=974affbf, R=86022d1f returns 974affbf86022d1f 974affbf86022d1f
The provides details of:
You can install the DES Calculator on your own system by uploading the following files, and saving them all in the same directory:
Then open your local saved copy of DEScalc.html in your favorite (Java enabled) web browser. You may need to install a suitable Java v1.4 plugin for your browser - this is available from the J2SE Java distributions, which are included in the useful programs area for this course (CD only). You will need to copy/link the appropriate browser plugin file from the J2SE installation area to the plugin directory for your browser and restart it.
If you want to look under the hood, the sources are available in the
jarfile. Copy it onto your system, extract
files with "
jar xvf DEScalc.jar", and look at the
README file for more information. A Unix Makefile for
building the sources using the Java SDK is included. The source code is
written for clarity, ease of relation to the algorithm description, and
ease of tracing intermediate values, not for efficiency! It is
designed to be used to help students in my cryptography course better
understand the operation of this cipher, as for example by doing my
The DES Calculator applet was written by Lawrie Brown from ADFA, Canberra Australia. Lawrie's code is Copyright © 2005 by Lawrie Brown. Permission to reuse this code as desired is granted, provided due acknowledgement is given of the author and source of the original code.