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Advanced Substitution Cipher Implementation with ASCII Encoding and Decoding

DESCRIPTION

This document details an advanced implementation of a substitution cipher model, utilizing ASCII encoding for cleartext characters. The encipher and decipher tables facilitate the substitution process by mapping plaintext characters to their corresponding ciphertext characters. The provided code snippet demonstrates a loop for reading input characters, encoding or decoding based on specified tasks, and writing the output characters. This resource is beneficial for developers and cryptography enthusiasts looking to understand and implement secure text encryption.

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Advanced Substitution Cipher Implementation with ASCII Encoding and Decoding

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Presentation Transcript

  1. IM cipher code

  2. Cipher model • Substitution cipher • For cleartext character, substitute character in encipher table • For ciphertext character, substitute character in decipher table

  3. ASCII Table (first half)

  4. Format of encryption table

  5. Encipher Table charencr[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 'b', '.', 0, 'c', '[', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 'R', 'u', ',', 'q', '\t', 'Y', '\n', '\'', 'n', 's', 'v', 'e', 'H', 'o', 'N', 'M', 'r', '=', '0', ';', 'z', '/', '`', 'E', '\"', 'k', '&', '5', '>', 'i', 'p', ')', '$', '!', '2', 'O', '(', 'I', 'J', '%', 'Z', 'g', '\\', '{', 'h', '7', 'S', 'P', 'a', ' ', 'W', 'x', 'y', 'T', '+', '8', '-', 'L', '9', 'f', '#', 'F', '\r', 'B', '3', 'D', ']', 'V', '?', '*', 'G', '6', 'w', '@', '}', '|', 'C', 'l', '_', 'j', 'K', '^', '1', 't', 'Q', '<', 'U', 'd', 'm', ':', 'A', 'X', '\f', '4', '~', 0, 0, 0 };

  6. Decipher Table char decr[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, '$', '&', 0, '|', '^', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 'Q', 'A', '8', '\\', '@', 'G', ':', '\'', 'D', '?', 'e', 'V', '\"', 'X', '\n', '5', '2', 'r', 'B', '`', '}', ';', 'g', 'M', 'W', 'Z', 'y', '3', 'u', '1', '<', 'd', 'i', 'z', '_', 'l', 'a', '7', ']', 'f', ',', 'E', 'F', 'p', 'Y', '/', '.', 'C', 'O', 't', ' ', 'N', 'U', 'v', 'c', 'R', '{', '%', 'H', '\r', 'J', 'b', 'q', 'n', '6', 'P', '\t', '\f', 'w', '+', '[', 'I', 'L', '=', 'o', '9', 'm', 'x', '(', '-', '>', '#', '0', ')', 's', '!', '*', 'h', 'S', 'T', '4', 'K', 'k', 'j', '~', 0, 0, 0};

  7. Basic code snippet while (fin.get(inchar)) { if (((int) inchar) < 32) //for debugging cout<< "Read (" << (int)inchar << ") "; if (task == 'e') // we are encoding { outchar= encr[(int)inchar]; } else { outchar= decr[(int)inchar]; } fout << outchar; if (((int) inchar) < 32) //for debugging cout<< ": Wrote " << outchar << endl; }

  8. example [root@bridge ~]# psad -m /var/log/messages.1 --gnuplot --CSV-fields "dst:not192.168.10.0/24 dp:countuniq" --gnuplot-graph points --gnuplot-xrange 0:10000 --gnuplot-file-prefix test1 [+] Entering Gnuplot mode... [+] Parsing iptables log messages from file: /var/log/messages.1 [+] Parsed 71992 iptables log messages. [+] Writing parsed iptables data to: test1.dat [+] Writing gnuplot directive file: test1.gnu [root@bridge ~]# gnuplottest1.gnu f1jjQ$]1@?6*R~FqRKtD?RolRMUD1MCj6Ml*ttD6*tN=Roo6_<KCjQRooOx+oG@*C?tR,?tQ&_jQ=k0N=`"N=rNrM0zR?K&Vj<_Q<_@^,Roo6_<KCjQo61DKwRKj@_QtRoo6_<KCjQom1D_6*Rr&=rrrrRoo6_<KCjQoG@C*oK1*G@mRQ*tQ=.feFRI_Q*1@_6R%_<KCjQRlj?*NNN.feFRaD1t@_6R@KQD]C*tRCj6Rl*ttD6*tRG1jlRG@C*&RMUD1MCj6Ml*ttD6*tN=.feFRaD1t*?RE=kk0R@KQD]C*tRCj6Rl*ttD6*tN.feFR81@Q@_6RKD1t*?R@KQD]C*tR?DQDRQj&RQ*tQ=N?DQ.feFR81@Q@_6R6_<KCjQR?@1*VQ@U*RG@C*&RQ*tQ=N6_<..f1jjQ$]1@?6*R~FqR6_<KCjQRQ*tQ=N6_<.

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