Digest Functions

Data Structures
struct	Digest

Macros
#define	DIGEST_BLOCKSIZE   64
	Internal block size in bytes used by all supported digest algorithms.

Typedefs
typedef struct Digest	Digest

Enumerations
enum	DigestType { DIGEST_MD5 , DIGEST_SHA1 , DIGEST_SHA256 , DIGEST_COUNT }
	Supported message digest algorithms. More...

Functions
void	digestInit (Digest *digest, DigestType type)
void	digestUpdate (Digest *digest, uint8 *data, uint32 size)
void	digestFinish (Digest *digest, uint8 *out)

Variables
uint32	DigestSize [DIGEST_COUNT]

Detailed Description

Cryptographic hash functions including MD5, SHA-1, and SHA-256.

The digest API provides incremental hashing through a simple three-step process:

1. Initialize a context with digestInit()
2. Feed data in chunks with digestUpdate() (can be called multiple times)
3. Finalize and retrieve the hash with digestFinish()

All supported algorithms use a 64-byte internal block size and can process data of any length. Contexts can be reused by calling digestInit() again.

Example:

Digest ctx;
digestInit(&ctx, DIGEST_SHA256);
digestUpdate(&ctx, (uint8*)"Hello ", 6);
digestUpdate(&ctx, (uint8*)"World", 5);
uint8 hash[32];
digestFinish(&ctx, hash);
// hash now contains the SHA-256 of "Hello World"

Typedef Documentation

Digest

typedef struct Digest Digest

Digest context structure.

Contains the state for computing a message digest incrementally. All fields are internal and should not be accessed directly.

Enumeration Type Documentation

DigestType

enum DigestType

Supported message digest algorithms.

Enumerator
DIGEST_MD5	MD5 - 128-bit (16 bytes) - Not cryptographically secure.
DIGEST_SHA1	SHA-1 - 160-bit (20 bytes) - Deprecated for security.
DIGEST_SHA256	SHA-256 - 256-bit (32 bytes) - Secure and recommended.

Definition at line 37 of file digest.h.

Function Documentation

digestFinish()

void digestFinish	(	Digest *	digest,
		uint8 *	out
	)

Finalizes the digest computation and outputs the hash.

Completes the digest computation by adding padding and length as required by the algorithm specification, then outputs the final hash value. After calling this function, digestInit() must be called again to reuse the context.

Parameters

digest	Digest context that has been updated with data
out	Buffer to receive the hash output, must be at least DigestSize[type] bytes

Example:

uint8 hash[32];  // SHA-256 produces 32 bytes
digestFinish(&ctx, hash);

digestInit()

void digestInit	(	Digest *	digest,
		DigestType	type
	)

Initializes a digest context for computing a message digest.

Must be called before using digestUpdate() or digestFinish(). The context can be reused after digestFinish() by calling digestInit() again.

Parameters

digest	Digest context to initialize
type	Algorithm to use (DIGEST_MD5, DIGEST_SHA1, or DIGEST_SHA256)

Example:

Digest ctx;
digestInit(&ctx, DIGEST_SHA256);

digestUpdate()

void digestUpdate	(	Digest *	digest,
		uint8 *	data,
		uint32	size
	)

Incrementally processes data for the message digest.

Can be called multiple times to hash data in chunks. All data passed to digestUpdate() is accumulated until digestFinish() is called to produce the final hash.

Parameters

digest	Initialized digest context
data	Data to process
size	Number of bytes to process

Example:

digestUpdate(&ctx, (uint8*)"Hello ", 6);
digestUpdate(&ctx, (uint8*)"World", 5);

Variable Documentation

DigestSize

uint32 DigestSize[DIGEST_COUNT]

extern

Size in bytes of the resulting digest for each algorithm. Index with DigestType: DigestSize[DIGEST_MD5] = 16, DigestSize[DIGEST_SHA1] = 20, DigestSize[DIGEST_SHA256] = 32