/* See LICENSE file for copyright and license details. */
#ifndef LIBSHA2_H
#define LIBSHA2_H 1
#include <stdint.h>
#include <stddef.h>
/**
* Algorithms supported by libsha2
*/
enum libsha2_algorithm {
/**
* SHA-224, outputs 28 bytes
*/
LIBSHA2_224,
/**
* SHA-256, outputs 32 bytes
*/
LIBSHA2_256,
/**
* SHA-384, outputs 48 bytes
*/
LIBSHA2_384,
/**
* SHA-512, outputs 64 bytes
*/
LIBSHA2_512,
/**
* SHA-512/224, outputs 28 bytes
*/
LIBSHA2_512_224,
/**
* SHA-512/256, outputs 32 bytes
*/
LIBSHA2_512_256
};
/**
* Data structure that describes the state of a hashing process
*
* Data that could just as well be allocated (with `auto`) are
* allocated here so that is is easier to wipe the data without
* exposing two versions of each function: one to wipe data,
* and one not to wipe data to gain speed, now you can use use
* `explicit_bzero` (or `memset`) when you are done.
*
* This data structure is flat (it contains dynamic pointers)
* and can be marshalled and unmarshalled naïvely, and does
* not need destroyed; however, if you when to marshall it
* using as little memory as possible, this are comments
* about data that does not need to be mashalled
*/
struct libsha2_state {
/**
* The size of the message, as far as processed, in bits;
*/
size_t message_size;
/**
* Round constants
*/
union {
/**
* For 32-bit algorithms
*/
uint32_t b32[64];
/**
* For 64-bit algorithms
*/
uint64_t b64[80];
} k;
/**
* Words
*
* Does not need to be marshalled
*/
union {
/**
* For 32-bit algorithms
*/
uint32_t b32[64];
/**
* For 64-bit algorithms
*/
uint64_t b64[80];
} w;
/**
* Hashing values
*/
union {
/**
* For 32-bit algorithms
*/
uint32_t b32[8];
/**
* For 64-bit algorithms
*/
uint64_t b64[8];
} h;
/**
* Temporary hashing values
*
* Does not need to be marshalled
*/
union {
/**
* For 32-bit algorithms
*/
uint32_t b32[8];
/**
* For 64-bit algorithms
*/
uint64_t b64[8];
} work_h;
/**
* Space for chunks to process, limited
* to 64 bytes on 32-bit algorithms
*/
unsigned char chunk[128];
/**
* Space for storing the last bits and
* the padding
*
* Does not need to be marshalled
*/
char appendix[256];
/**
* The size of the chunks, in bytes
*/
size_t chunk_size;
/**
* The algorithm that is used
*/
enum libsha2_algorithm algorithm;
int __padding1;
};
/**
* Initialise a state
*
* @parma state The state that should be initialised
* @parma algorithm The hashing algorithm
* @return Zero on success, -1 on error
*/
#if defined(__GNUC__)
__attribute__((__leaf__, __nothrow__, __nonnull__))
#endif
int libsha2_init(struct libsha2_state *restrict, enum libsha2_algorithm);
/**
* Get the output size of the algorithm specified for a state
*
* @parma state The state
* @return The number of bytes in the output, zero on error
*/
#if defined(__GNUC__)
__attribute__((__nothrow__, __nonnull__, __pure__))
#endif
size_t libsha2_state_output_size(const struct libsha2_state *restrict);
/**
* Get the output size of an algorithm
*
* @parma algorithm The hashing algorithm
* @return The number of bytes in the output, zero on error
*/
#if defined(__GNUC__)
__attribute__((__leaf__, __nothrow__, __const__))
#endif
size_t libsha2_algorithm_output_size(enum libsha2_algorithm);
/**
* Absorb more of the message
*
* @param state The hashing state
* @param message The message, in bits, must be equivalent to 0 modulus 8
* @param msglen The length of the message
*/
#if defined(__GNUC__)
__attribute__((__nonnull__, __nothrow__))
#endif
void libsha2_update(struct libsha2_state *restrict, const char *restrict, size_t);
/**
* Absorb the last part of the message and output a hash
*
* @param state The hashing state
* @param message The message, in bits
* @param msglen The length of the message, zero if there is nothing more to absorb
* @param output The output buffer for the hash
*/
#if defined(__GNUC__)
__attribute__((__nonnull__(1, 4), __nothrow__))
#endif
void libsha2_digest(struct libsha2_state *restrict, const char *restrict, size_t, char *);
/**
* Calculate the checksum for a file,
* the content of the file is assumed non-sensitive
*
* @param fd The file descriptor of the file
* @param algorithm The hashing algorithm
* @param hashsum Output buffer for the hash
* @return Zero on success, -1 on error
*/
#if defined(__GNUC__)
__attribute__((__nonnull__, __leaf__))
#endif
int libsha2_sum_fd(int, enum libsha2_algorithm, char *restrict);
/**
* Convert a binary hashsum to lower case hexadecimal representation
*
* @param output Output array, should have an allocation size of at least `2 * n + 1`
* @param hashsum The hashsum to convert
* @param n The size of `hashsum`
*/
#if defined(__GNUC__)
__attribute__((__leaf__, __nonnull__, __nothrow__))
#endif
void libsha2_behex_lower(char *restrict, const char *restrict, size_t);
/**
* Convert a binary hashsum to upper case hexadecimal representation
*
* @param output Output array, should have an allocation size of at least `2 * n + 1`
* @param hashsum The hashsum to convert
* @param n The size of `hashsum`
*/
#if defined(__GNUC__)
__attribute__((__leaf__, __nonnull__, __nothrow__))
#endif
void libsha2_behex_upper(char *restrict, const char *restrict, size_t);
/**
* Convert a hexadecimal hashsum (both lower case, upper
* case and mixed is supported) to binary representation
*
* @param output Output array, should have an allocation
* size of at least `strlen(hashsum) / 2`
* @param hashsum The hashsum to convert
*/
#if defined(__GNUC__)
__attribute__((__leaf__, __nonnull__, __nothrow__))
#endif
void libsha2_unhex(char *restrict, const char *restrict);
/**
* Marshal a state into a buffer
*
* @param state The state to marshal
* @param buf Output buffer, `NULL` to only return the required size
* @return The number of bytes marshalled to `buf`
*/
#if defined(__GNUC__)
__attribute__((__leaf__, __nonnull__(1), __nothrow__))
#endif
size_t libsha2_marshal(const struct libsha2_state *restrict, char *restrict);
/**
* Unmarshal a state from a buffer
*
* @param state Output parameter for the unmarshalled state
* @param buf The buffer from which the state shall be unmarshalled
* @param bufsize The maximum number of bytes that can be unmarshalled
* @return The number of read bytes, 0 on failure
*/
#if defined(__GNUC__)
__attribute__((__leaf__, __nonnull__, __nothrow__))
#endif
size_t libsha2_unmarshal(struct libsha2_state *restrict, const char *restrict, size_t);
#endif
