ajout crypto

crypto/TP1/Ex3/Xtea_hash.c

@@ -0,0 +1,64 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#define DELTA 0x9E3779B9
+#define ROUNDS 32
+#define BLOCK_SIZE 24
+
+void encrypt(uint32_t v[2], uint32_t const key[4]) {
+    uint32_t v0 = v[0], v1 = v[1], sum = 0;
+    for (int i = 0; i < ROUNDS; i++) {
+        v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
+        sum += DELTA;
+        v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum >> 11) & 3]);
+    }
+    v[0] = v0;
+    v[1] = v1;
+}
+
+void xtea_hash(const char *filename, uint64_t *hash) {
+    int fd = open(filename, O_RDONLY);
+    if (fd < 0) {
+        perror("Error opening file");
+        exit(1);
+    }
+    
+    uint64_t current_hash = 0;
+    uint8_t buffer[BLOCK_SIZE];
+    ssize_t bytes_read;
+    
+    while ((bytes_read = read(fd, buffer, BLOCK_SIZE)) > 0) {
+        if (bytes_read < BLOCK_SIZE) {
+            memset(buffer + bytes_read, 0, BLOCK_SIZE - bytes_read);
+            buffer[BLOCK_SIZE - 1] = BLOCK_SIZE - bytes_read;
+        }
+        
+        uint32_t x[2];
+        uint32_t k[4];
+        memcpy(x, buffer, 8);
+        memcpy(k, buffer + 8, 16);
+        
+        encrypt(x, k);
+        uint64_t hashed_block = ((uint64_t)x[0] << 32) | x[1];
+        current_hash ^= hashed_block;
+    }
+    
+    close(fd);
+    *hash = current_hash;
+}
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file>\n", argv[0]);
+        return 1;
+    }
+    
+    uint64_t hash;
+    xtea_hash(argv[1], &hash);
+    printf("Hash: %016lx\n", hash);
+    return 0;
+}