Hashes

Incremental MD5 and SHA-256 hash generation, sometimes with hardware acceleration. More...

Collaboration diagram for Hashes:

Macros
#define	SYS_HASH_SIZE   32
	Maximum digest buffer size in bytes.
#define	SYS_HASH_CAPACITY   4
	Maximum number of concurrent hash contexts available.

Typedefs
typedef enum sys_hash_algorithm_t	sys_hash_algorithm_t
	Hash algorithm identifiers.
typedef struct sys_hash_t	sys_hash_t
	Hash context.

Enumerations
enum	sys_hash_algorithm_t { sys_hash_md5 = 1, sys_hash_sha256 }
	Hash algorithm identifiers. More...

Lifecycle
sys_hash_t *	sys_hash_init (sys_hash_algorithm_t algorithm)
	Initialize a new hash context. More...
void	sys_hash_deinit (sys_hash_t *hash)
	Release a hash context. More...

Methods
size_t	sys_hash_size (const sys_hash_t *hash)
	Return the digest size in bytes for a hash context. More...
bool	sys_hash_update (sys_hash_t *hash, sys_iostream_t *stream, size_t size)
	Update a hash context by reading more data from a stream. More...
const uint8_t *	sys_hash_finalize (sys_hash_t *hash)
	Finalize the hash computation. More...
uintptr_t	sys_hash_djb2 (const char *str)
	Compute a djb2 hash for a NULL-terminated string. More...

Detailed Description

Incremental MD5 and SHA-256 hash generation, sometimes with hardware acceleration.

MD5 is not considered secure, but it is still useful for checksums and other non-security purposes. SHA-256 is recommended for security-sensitive uses and may have hardware acceleration on some platforms.

Enumeration Type Documentation

sys_hash_algorithm_t

enum sys_hash_algorithm_t

Hash algorithm identifiers.

Enumerator
sys_hash_md5	MD5 digest.
sys_hash_sha256	SHA-256 digest.

Definition at line 54 of file hash.h.

                                  {
  sys_hash_md5 = 1, 
  sys_hash_sha256,  
} sys_hash_algorithm_t;

Function Documentation

sys_hash_deinit()

void sys_hash_deinit

(

sys_hash_t *

hash

)

Release a hash context.

Parameters

hash	Pointer to the hash context to release.

Releases all resources associated with the hash context and renders it unusable. After this call, the handle must not be used again.

sys_hash_djb2()

uintptr_t sys_hash_djb2

(

const char *

str

)

Compute a djb2 hash for a NULL-terminated string.

Parameters

str	The NULL-terminated string to hash.

Returns

The computed hash value.

sys_hash_finalize()

const uint8_t* sys_hash_finalize

(

sys_hash_t *

hash

)

Finalize the hash computation.

Parameters

hash	Pointer to the hash context.

Returns

Pointer to the computed digest stored inside the hash context, or NULL on failure.

The returned pointer remains owned by the hash context and is valid until sys_hash_deinit() is called for that handle.

sys_hash_init()

sys_hash_t* sys_hash_init

(

sys_hash_algorithm_t

algorithm

)

Initialize a new hash context.

Parameters

algorithm

The hash algorithm to use.

Returns

Initialized hash context, or NULL if the algorithm is unsupported or no implementation capacity remains.

Allocates and initializes a hash context from an implementation-defined static capacity. The returned handle is ready for use with sys_hash_update() and sys_hash_finalize(). Call sys_hash_deinit() to release the slot for reuse.

sys_hash_size()

size_t sys_hash_size

(

const sys_hash_t *

hash

)

Return the digest size in bytes for a hash context.

Parameters

hash	Pointer to the hash context.

Returns

The digest size in bytes, or 0 if the context is invalid.

sys_hash_update()

bool sys_hash_update	(	sys_hash_t *	hash,
		sys_iostream_t *	stream,
		size_t	size
	)

Update a hash context by reading more data from a stream.

Parameters

hash	Pointer to the hash context.
stream	The stream to read from.
size	Number of bytes to read from stream and feed into the hash, or 0 to read until end of stream. Call this repeatedly (e.g. once per chunk as it becomes available, each with an explicit size) to hash a stream incrementally, or once with size 0 to hash all of its remaining bytes in one call.

Returns

true on success, false on error - including a short read (stream had fewer than size bytes left, when size is nonzero).