add hamming_distance

docs/crypto.md

@@ -92,8 +92,16 @@ const unsigned char *repeating_key_xor_s(const char* s, const char* key);
 
 ### hamming_distance
 
+Calculates the Hamming Distance (the number of differing bits) between two arrays of unsigned bytes
+
+```c
+unsigned int hamming_distance(unsigned char *a, unsigned char *b);
+```
+
+### hamming_distance_s
+
 Calculates the Hamming Distance (the number of differing bits) between two strings
 
 ```c
-unsigned int hamming_distance(const char *a, const char *b);
+unsigned int hamming_distance_s(const char *a, const char *b);
 ```

include/lfcrypto.h

@@ -13,6 +13,7 @@ const char *hex_to_str(const unsigned char *hex, size_t sz);
 const unsigned char* repeating_key_xor(const unsigned char* s, size_t s_sz, const unsigned char* key, size_t k_sz);
 const unsigned char *repeating_key_xor_s(const char* s, const char* key);
 
-unsigned int hamming_distance(const char *a, const char *b);
+unsigned int hamming_distance_s(const char *a, const char *b);
+unsigned int hamming_distance(unsigned char *a, unsigned char *b, size_t sz);
 
 #endif // LIBFLINT_CRYPTO_H

src/crypto.c

@@ -272,12 +272,16 @@ const unsigned char *repeating_key_xor_s(const char* s, const char* key) {
     return repeating_key_xor((unsigned char*)s, strlen(s), (unsigned char*)key, strlen(key));
 }
 
-unsigned int hamming_distance(const char *a, const char *b) {
+unsigned int hamming_distance_s(const char *a, const char *b) {
     size_t sz = strlen(a);
     if (sz != strlen(b)) {
         return -1;
     }
 
+    return hamming_distance((unsigned char *)a, (unsigned char *)b, sz);
+}
+
+unsigned int hamming_distance(unsigned char *a, unsigned char *b, size_t sz) {
     unsigned int hamming = 0;
     for (size_t i = 0; i < sz; ++i) {
         if (a[i] == b[i]) {

tests/tests.c

@@ -374,7 +374,12 @@ void test_crypto() {
     free(enc);
     free(s);
 
-    unsigned int hamming = hamming_distance("this is a test", "wokka wokka!!!");
+    unsigned char ua[2] = { 0x2, 0xF };
+    unsigned char ub[2] = { 0x4, 0xE };
+    unsigned int hamming = hamming_distance(ua, ub, 2);
+    assert(hamming == 3);
+
+    hamming = hamming_distance_s("this is a test", "wokka wokka!!!");
     assert(hamming == 37);
 
     printf("Passes all crypto tests\n");