sha256.h File Reference

Interface to a SHA-256 implementation. More...

#include <stddef.h>
#include <stdint.h>

Macros
#define	SHA256_BLOCK_SIZE   (64)
	Block size.
#define	SHA256_DIGEST_SIZE   (32)
	Digest size.
#define	SHA256_STATE_BLOCKS   (SHA256_DIGEST_SIZE / 4)
	Number of blocks in state.

Functions
void	tc_sha256_init (sha256_state *s)
	The SHA state. More...
void	tc_sha256_update (sha256_state *s, const uint8_t *data, size_t datalen)
	SHA256 update procedure Hashes data_length bytes addressed by data into state s. More...
void	tc_sha256_final (uint8_t *digest, sha256_state *s)
	SHA256 final procedure Inserts the completed hash computation into digest. More...

Detailed Description

Interface to a SHA-256 implementation.

Overview: SHA-256 is a NIST approved cryptographic hashing algorithm specified in FIPS 180. A hash algorithm maps data of arbitrary size to data of fixed length.

Security: SHA-256 provides 128 bits of security against collision attacks and 256 bits of security against pre-image attacks. SHA-256 does NOT behave like a random oracle, but it can be used as one if the string being hashed is prefix-free encoded before hashing.

Usage: 1) call tc_sha256_init to initialize a struct tc_sha256_state_struct before hashing a new string.

2) call tc_sha256_update to hash the next string segment; tc_sha256_update can be called as many times as needed to hash all of the segments of a string; the order is important.

3) call tc_sha256_final to out put the digest from a hashing operation.

Function Documentation

tc_sha256_final()

void tc_sha256_final	(	uint8_t *	digest,
		sha256_state *	s
	)

SHA256 final procedure Inserts the completed hash computation into digest.

Returns

returns 1 returns 0 if: s == NULL, s->iv == NULL, digest == NULL

Note

Assumes: s has been initialized by tc_sha256_init digest points to at least SHA256_DIGEST_SIZE bytes

Warning

The state buffer 'leftover' is left in memory after processing If your application intends to have sensitive data in this buffer, remind to erase it after the data has been processed

Parameters

digest	unsigned eight bit integer
s	Sha256 state struct

tc_sha256_init()

void tc_sha256_init

(

sha256_state *

s

)

The SHA state.

SHA256 initialization procedure Initializes s

Parameters

s	Sha256 state struct

tc_sha256_update()

void tc_sha256_update	(	sha256_state *	s,
		const uint8_t *	data,
		size_t	datalen
	)

SHA256 update procedure Hashes data_length bytes addressed by data into state s.

Note

Assumes s has been initialized by tc_sha256_init

Warning

The state buffer 'leftover' is left in memory after processing If your application intends to have sensitive data in this buffer, remind to erase it after the data has been processed

Parameters

s	Sha256 state struct
data	message to hash
datalen	length of message to hash