====== crypto ======
Cryptographic tools
Any functions that return string representations of bytes in hexadecimal format will always be formatted with no leading ''%%0x%%'' and lower case letters
===== Functions =====
==== b64_encode ====
Encodes an ''%%unsigned char *%%'' into base64. User is responsible for freeing the ''%%char *%%'' that is returned.
char *b64_encode(const unsigned char *s, size_t sz);
==== b64_decode ====
Decodes a base64 encoded set of bytes into an ''%%unsigned char *%%''. User is responsible for freeing the ''%%unsigned char *%%'' that is returned. ''%%decode_sz%%'' is an optional argument in case you need to know the size of the decoded data, otherwise you can just pass ''%%NULL%%''.
unsigned char *b64_decode(const char *s, size_t sz, size_t *decode_sz);
==== hex_encode ====
Encodes an array of bytes into a string in hex representation. For example, converts ''%%[0xDE, 0xAD, 0xBE, 0xEF]%%'' into ''%%"deadbeef"%%''. User is responsible for freeing the returned string
const char *hex_encode(const unsigned char *hex, size_t sz);
// Example
unsigned char h[4] = {
0xde, 0xad, 0xbe, 0xef
};
const char *s = hex_encode(h, 4);
assert(strcmp(s, "deadbeef") == 0);
free(s);
==== hex_decode ====
Decodes a string of characters representing hexadecimal bytes into an array of ''%%unsigned char%%''. Characters can be in upper or lower case, and can start with a leading ''%%0x%%'' or not. For example, converts ''%%"DEADBEEF"%%'' into ''%%[0xde, 0xad, 0xbe, 0xef]%%''. User is reponsible for the freeing of the returned byte array
unsigned char *hex_decode(const char *orig, size_t *sz);
// Example
unsigned char *s = hex_decode("DEADBEEF", &s_sz);
unsigned char h[4] = {
0xDE, 0xAD, 0xBE, 0xEF
};
for (size_t i = 0; i < 4; ++i) {
assert(s[i] == h[i]);
}
free(s);
==== hex_to_str ====
Converts an array of ''%%unsigned char%%'' into a string based on the ASCII values of each byte. User is responsible for freeing the returned string.
const char *hex_to_str(const unsigned char *hex, size_t sz);
==== repeating_key_xor ====
Performs a repeating-key XOR encryption on an array of bytes. User is responsible for freeing the returned array
const unsigned char* repeating_key_xor(const unsigned char* s, size_t s_sz, const unsigned char* key, size_t k_sz);
==== repeating_key_xor_s ====
Performs a repeating-key XOR encryption on a string. Returns the encrypted string as an array of bytes. User is responsible for freeing the returned array
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
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
unsigned int hamming_distance_s(const char *a, const char *b);