81 lines
1.7 KiB
C
81 lines
1.7 KiB
C
#include <cs50.h>
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#include <stdio.h>
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#include <ctype.h>
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#include <string.h>
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#include <stdlib.h>
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int shift(char c);
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int main(int argc, string argv[])
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{
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//Validate the key
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string key = argv[1];
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if (argc != 2)
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{
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printf("Usage: ./vigenere keyword\n");
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return(1);
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}
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else
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{
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// Iterate over length of key, checking for non-digits
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for (int i = 0, n = strlen(key); i < n; i++)
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{
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if (isalpha(key[i]) == false)
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{
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printf("Usage: ./vigenere keyword\n");
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return(1);
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}
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}
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}
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// Setup cipher
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int length = strlen(key);
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int k = 0;
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string plaintext = get_string("plaintext: ");
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printf("ciphertext: ");
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// iterate over input of plaintext, seperating into uppor or lower cases, then implementing cypher
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for (int i = 0, n = strlen(plaintext); i < n;i++)
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{
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char c = plaintext[i];
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char temp = 'a';
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int intkey = shift(argv[1][(k % length)]);
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if (isalpha(c))
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{
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if (isupper(c))
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{
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temp = (((plaintext[i] - 'A') + intkey) % 26) + 'A';
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k++;
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}
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else if (islower(c))
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{
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temp = (((plaintext[i] - 'a') + intkey) % 26) + 'a';
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k++;
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}
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printf("%c", temp);
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}
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else
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{
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printf("%c", c);
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}
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}
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printf("\n");
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return(0);
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}
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//Tells us how much to shift based on individual characters
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int shift(char c)
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{
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if isupper(c)
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{
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int temp = c - 65;
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return(temp);
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}
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else if islower(c)
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{
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int temp = c - 97;
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return(temp);
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}
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else
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{
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return(0);
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}
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} |