Hashing routines
================

Libucw contains two cryptographic hash algorithms: MD5 (RFC 1321) and SHA1 (RFC
3174).

- <<md5,MD5>>
- <<sha1,SHA1>>
- <<usage,Common usage>>

[[md5]]
MD5
---
!!ucw/md5.h

[[sha1]]
SHA1
----
!!ucw/sha1.h

[[usage]]
Usage
-----

There are two ways you can use the hashing routines.

- Single-shot interface. If you have an in-memory buffer of the whole
  message you want to hash, you can use this.

  char *message = "Hello world";
  byte output[MD5_SIZE];
  md5_hash_buffer(output, message, strlen(message));

- Multi-shot interface. If you have the message scattered in many
  buffers or you get it by parts, you do not need to concatenate the
  parts together.

  byte buffer[MAX_BUFFER];
  uns buffer_len;
  md5_context c;
  md5_init(&c);
  while(buffer_len = get_chunk(buffer, MAX_BUFFER)) {
    md5_update(&c, buffer, buffer_len);
  }
  byte output[MD5_SIZE];
  memcpy(output, md5_final(&c), MD5_SIZE);

SHA1 has the same interface, so the same two ways apply.

See also <<string:mem_to_hex()>>.