The Key to Cryptography: Difference between revisions
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imported>Kmk21 Created page with "This problem asks us to rotate the characters in a string by the value of the character in the same position in a key string. If you use ascii math and char arrays this is ea..." |
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encrypt[i] = (((plain[i] - 'A') + (key[i] - 'A')) %26) + 'A' | encrypt[i] = (((plain[i] - 'A') + (key[i] - 'A')) %26) + 'A' | ||
plain[i] = (((encrypt[i] - 'A') - (key[i] - 'A') + 26) % 26) + 'A' | plain[i] = (((encrypt[i] - 'A') - (key[i] - 'A') + 26) % 26) + 'A' | ||
| Line 11: | Line 12: | ||
[[Category:Ecna2016]] | [[Category:Ecna2016]] | ||
[[Category:Algorithm Trivial]] | [[Category:Algorithm Trivial]] | ||
[[Category:Implementation | [[Category:Implementation Trivial]] | ||
[[Category:ASCII]] | [[Category:ASCII]] | ||
[[Category:Modulus]] | [[Category:Modulus]] | ||
Latest revision as of 22:29, 2 November 2017
This problem asks us to rotate the characters in a string by the value of the character in the same position in a key string.
If you use ascii math and char arrays this is easy.
encrypt[i] = (((plain[i] - 'A') + (key[i] - 'A')) %26) + 'A'
plain[i] = (((encrypt[i] - 'A') - (key[i] - 'A') + 26) % 26) + 'A'
be sure to add 26 when modding after doing a subtraction.