87 lines
1.8 KiB
C
87 lines
1.8 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdbool.h>
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#define BUFF_SIZE 32
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// Vérification que la clé est bien composée de lettres majuscules uniquement
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bool check_key(char* key) {
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for (size_t i=0; i < strlen(key); i++) {
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if ('A' > key[i] || key[i] > 'Z')
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return false;
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}
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return true;
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}
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// Chiffre/ Déchiffre uniquement les lettres, incrémente k_uses si la clé est utilisée
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char enc(char in, char k, int action, int* k_uses) {
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if ('a' <= in && in <= 'z')
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in += 'A'-'a';
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if ('A' > in || in > 'Z')
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return in;
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(*k_uses)++;
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return ((in - 'A' + (action * (k-'A')) +('Z'-'A'+1))%('Z'-'A'+1))+'A';
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}
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int vigenere(char* src, char* key, int action) {
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FILE* fp = fopen(src, "r");
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char buffer[BUFF_SIZE];
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int k_uses = 0;
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int klength = strlen(key);
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while (fgets(buffer, klength, fp)) {
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for (int i=0; i < BUFF_SIZE; i++) {
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if (buffer[i] == '\0') {
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printf("%s", buffer);
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break;
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}
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buffer[i] = enc(buffer[i], key[k_uses%klength], action, &k_uses);
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}
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}
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fclose(fp);
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return 0;
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}
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int main(int argc, char* argv[]) {
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char* src = NULL;
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char* key = NULL;
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int action = 0;
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for (int i=1; i < argc; i++) {
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if (!strcmp(argv[i], "-e")) {
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action = 1;
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src = argv[i+1];
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i++;
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} else if (!strcmp(argv[i], "-d")) {
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action = -1;
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src = argv[i+1];
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i++;
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} else if (!strcmp(argv[i], "-k")) {
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key = argv[i+1];
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i++;
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} else {
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printf("Unknown option %s\n", argv[i]);
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}
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}
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if (!src || !key || !action) {
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printf("Usage: %s -[e|d] <file> -k <key>\n", argv[0]);
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return 1;
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}
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if (!check_key(key)) {
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printf("Clé de chiffrement invalide. Utilisez seulement des lettres majuscules.\n");
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return 1;
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}
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return vigenere(src, key, action);
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}
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