86 lines
2.2 KiB
Markdown
86 lines
2.2 KiB
Markdown
# crypto
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Cryptographic tools
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## Functions
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### b64_encode
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Encodes an `unsigned char *` into base64. User is responsible for freeing the
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`char *` that is returned.
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```c
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char *b64_encode(const unsigned char *s, size_t sz);
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```
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### b64_decode
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Decodes a base64 encoded set of bytes into an `unsigned char *`. User is responsible
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for freeing the `unsigned char *` that is returned. `decode_sz` is an optional argument
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in case you need to know the size of the decoded data, otherwise you can just pass `NULL`.
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```c
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unsigned char *b64_decode(const char *s, size_t sz, size_t *decode_sz);
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```
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### hex_encode
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Encodes an array of bytes into a string in hex representation. For example, converts
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`[0xDE, 0xAD, 0xBE, 0xEF]` into `"DEADBEEF"`. The returned string will always be in capital
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letters with no leading `0x`. User is responsible for the freeing of the returned string
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```c
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const char *hex_encode(const unsigned char *hex, size_t sz);
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// Example
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const char *s = hex_encode(h, 4);
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assert(strcmp(s, "DEADBEEF") == 0);
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free(s);
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```
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### hex_decode
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Decodes a string of characters representing hexadecimal bytes into an array of `unsigned char`.
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For example, converts `"DEADBEEF"` into `[0xDE, 0xAD, 0xBE, 0xEF]`. User is reponsible for the
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freeing of the returned byte array
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```c
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unsigned char *hex_decode(const char *orig, size_t *sz);
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// Example
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unsigned char *s = hex_decode("DEADBEEF", &s_sz);
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unsigned char h[4] = {
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0xDE, 0xAD, 0xBE, 0xEF
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};
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for (size_t i = 0; i < 4; ++i) {
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assert(s[i] == h[i]);
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}
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free(s);
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```
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### hex_to_str
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Converts an array of `unsigned char` into a string based on the ASCII values of each byte. User is
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responsible for freeing the returned string.
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```c
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const char *hex_to_str(const unsigned char *hex, size_t sz);
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```
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### repeating_key_xor
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Performs a repeating-key XOR encryption on an array of bytes. User is responsible for freeing the returned array
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```c
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const unsigned char* repeating_key_xor(const unsigned char* s, size_t s_sz, const unsigned char* key, size_t k_sz);
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```
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### repeating_key_xor_s
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Performs a repeating-key XOR encryption on a string. Returns the encrypted string as an array of bytes. User is
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responsible for freeing the returned array
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```c
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const unsigned char *repeating_key_xor_s(const char* s, const char* key);
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```
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