/*
 * Copyright (c) 2017,2023 Stephen Heumann
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

struct md5_context {
	unsigned long length;
	unsigned long length2;
	unsigned short extra;
	unsigned char reserved1[30];
	unsigned char hash[16];
	unsigned char reserved2[4];
	unsigned char block[64];
};

struct hmac_md5_context {
	union {
		struct md5_context ctx;
		unsigned char k[64];
	} u[3];
	unsigned char inner_hash[16];
};

/*
 * The context structure must be in bank 0, preferably page-aligned.
 */

/*
 * Initialize a MD5 context.
 * This must be called before any of the other MD5 functions.
 */
void md5_init(struct md5_context *context);

/*
 * Update a MD5 context based on the specified data.
 */
void md5_update(struct md5_context *context, const unsigned char *data, unsigned long length);

/*
 * Finish MD5 processing and generate the final hash code.
 */
void md5_finalize(struct md5_context *context);

/*
 * Process one 64-byte block through the MD5 hashing function.
 * This is a low-level function; users should normally not call this directly.
 */
void md5_processblock(struct md5_context *context);

/*
 * Initialize a context for HMAC-MD5 computation with a specified key.
 * This must be called before any other HMAC calls. After initialization,
 * the context can be used with either hmac_md5_update/hmac_md5_finalize
 * or hmac_md5_compute, but they should not be mixed.
 */
void hmac_md5_init(struct hmac_md5_context *context,
                   const unsigned char *key,
                   unsigned long key_length);

/*
 * Update an HMAC-MD5 context based on the specified data.
 */
void hmac_md5_update(struct hmac_md5_context *context,
                     const unsigned char *message_part,
                     unsigned long part_length);

/*
 * Finish HMAC-MD5 processing and generate the final HMAC.
 */
void hmac_md5_finalize(struct hmac_md5_context *context);

/*
 * Compute the HMAC-MD5 of a message as a single operation.
 * The context can be reused for multiple hmac_md5_compute operations.
 */
void hmac_md5_compute(struct hmac_md5_context *context,
                      const unsigned char *message,
                      unsigned long message_length);

/*
 * Get the result of an HMAC-MD5 computation following hmac_md5_finalize
 * or hmac_md5_compute.
 */
#define hmac_md5_result(context) ((context)->u[0].ctx.hash)