tc_sha256.h File Reference

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

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

Go to the source code of this file.

Data Structures
struct	tc_sha256_state_struct

Macros
#define	TC_SHA256_BLOCK_SIZE   (64)
#define	TC_SHA256_DIGEST_SIZE   (32)
#define	TC_SHA256_STATE_BLOCKS   (TC_SHA256_DIGEST_SIZE/4)

Typedefs
typedef struct tc_sha256_state_struct *	TCSha256State_t

Functions
int	tc_sha256_init (TCSha256State_t s)
	SHA256 initialization procedure Initializes s. More...
int	tc_sha256_update (TCSha256State_t s, const uint8_t *data, size_t datalen)
	SHA256 update procedure Hashes data_length bytes addressed by data into state s. More...
int	tc_sha256_final (uint8_t *digest, TCSha256State_t 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.

Macro Definition Documentation

TC_SHA256_BLOCK_SIZE

#define TC_SHA256_BLOCK_SIZE   (64)

TC_SHA256_DIGEST_SIZE

#define TC_SHA256_DIGEST_SIZE   (32)

TC_SHA256_STATE_BLOCKS

#define TC_SHA256_STATE_BLOCKS   (TC_SHA256_DIGEST_SIZE/4)

Typedef Documentation

TCSha256State_t

typedef struct tc_sha256_state_struct* TCSha256State_t

Function Documentation

tc_sha256_final()

int tc_sha256_final	(	uint8_t *	digest,
		TCSha256State_t	s
	)

SHA256 final procedure Inserts the completed hash computation into digest.

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: s == NULL, s->iv == NULL, digest == NULL

Note

Assumes: s has been initialized by tc_sha256_init digest points to at least TC_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
Sha256	state struct

tc_sha256_init()

int tc_sha256_init

(

TCSha256State_t

s

)

SHA256 initialization procedure Initializes s.

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if s == NULL

Parameters

s	Sha256 state struct

tc_sha256_update()

int tc_sha256_update	(	TCSha256State_t	s,
		const uint8_t *	data,
		size_t	datalen
	)

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

Returns

returns TC_CRYPTO_SUCCESS (1) returns TC_CRYPTO_FAIL (0) if: s == NULL, s->iv == NULL, data == NULL

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