text: /*
   * Copyright (c) 2014-2017 Dag-Erling Smørgrav
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote
   *    products derived from this software without specific prior written
   *    permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include "cryb/impl.h"
  
  #include <stdint.h>
  #include <string.h>
  
  #include <cryb/memset_s.h>
  
  #include <cryb/md2.h>
  
  /*
   * MD2 - RFC 1319
   *
   * Note 1: the pseudocode for the checksum calculation in the RFC contains
   * a significant error - consult the errata.
   *
   * Note 2: the RFC describes the algorithm as having five steps: 1) append
   * padding, 2) compute checksum, 3) initialize state, 4) compute digest
   * and 5) output.  This implementation merges the checksum and digest
   * computations, which are independent of eachother, which avoids
   * processing the message twice.  The padding is then appended and fed
   * through the checksum and digest computation, and finally the checksum
   * itself is fed through.  Note that we update the checksum *after* the
   * digest, otherwise the final step (mixing the checksum into the digest)
   * would clobber the checksum before it was used.
   */
  
  static const uint8_t md2_s[256] = {
  	0x29, 0x2e, 0x43, 0xc9, 0xa2, 0xd8, 0x7c, 0x01,
  	0x3d, 0x36, 0x54, 0xa1, 0xec, 0xf0, 0x06, 0x13,
  	0x62, 0xa7, 0x05, 0xf3, 0xc0, 0xc7, 0x73, 0x8c,
  	0x98, 0x93, 0x2b, 0xd9, 0xbc, 0x4c, 0x82, 0xca,
  	0x1e, 0x9b, 0x57, 0x3c, 0xfd, 0xd4, 0xe0, 0x16,
  	0x67, 0x42, 0x6f, 0x18, 0x8a, 0x17, 0xe5, 0x12,
  	0xbe, 0x4e, 0xc4, 0xd6, 0xda, 0x9e, 0xde, 0x49,
  	0xa0, 0xfb, 0xf5, 0x8e, 0xbb, 0x2f, 0xee, 0x7a,
  	0xa9, 0x68, 0x79, 0x91, 0x15, 0xb2, 0x07, 0x3f,
  	0x94, 0xc2, 0x10, 0x89, 0x0b, 0x22, 0x5f, 0x21,
  	0x80, 0x7f, 0x5d, 0x9a, 0x5a, 0x90, 0x32, 0x27,
  	0x35, 0x3e, 0xcc, 0xe7, 0xbf, 0xf7, 0x97, 0x03,
  	0xff, 0x19, 0x30, 0xb3, 0x48, 0xa5, 0xb5, 0xd1,
  	0xd7, 0x5e, 0x92, 0x2a, 0xac, 0x56, 0xaa, 0xc6,
  	0x4f, 0xb8, 0x38, 0xd2, 0x96, 0xa4, 0x7d, 0xb6,
  	0x76, 0xfc, 0x6b, 0xe2, 0x9c, 0x74, 0x04, 0xf1,
  	0x45, 0x9d, 0x70, 0x59, 0x64, 0x71, 0x87, 0x20,
  	0x86, 0x5b, 0xcf, 0x65, 0xe6, 0x2d, 0xa8, 0x02,
  	0x1b, 0x60, 0x25, 0xad, 0xae, 0xb0, 0xb9, 0xf6,
  	0x1c, 0x46, 0x61, 0x69, 0x34, 0x40, 0x7e, 0x0f,
  	0x55, 0x47, 0xa3, 0x23, 0xdd, 0x51, 0xaf, 0x3a,
  	0xc3, 0x5c, 0xf9, 0xce, 0xba, 0xc5, 0xea, 0x26,
  	0x2c, 0x53, 0x0d, 0x6e, 0x85, 0x28, 0x84, 0x09,
  	0xd3, 0xdf, 0xcd, 0xf4, 0x41, 0x81, 0x4d, 0x52,
  	0x6a, 0xdc, 0x37, 0xc8, 0x6c, 0xc1, 0xab, 0xfa,
  	0x24, 0xe1, 0x7b, 0x08, 0x0c, 0xbd, 0xb1, 0x4a,
  	0x78, 0x88, 0x95, 0x8b, 0xe3, 0x63, 0xe8, 0x6d,
  	0xe9, 0xcb, 0xd5, 0xfe, 0x3b, 0x00, 0x1d, 0x39,
  	0xf2, 0xef, 0xb7, 0x0e, 0x66, 0x58, 0xd0, 0xe4,
  	0xa6, 0x77, 0x72, 0xf8, 0xeb, 0x75, 0x4b, 0x0a,
  	0x31, 0x44, 0x50, 0xb4, 0x8f, 0xed, 0x1f, 0x1a,
  	0xdb, 0x99, 0x8d, 0x33, 0x9f, 0x11, 0x83, 0x14,
  };
  
  void
  md2_init(md2_ctx *ctx)
  {
  
  	memset(ctx, 0, sizeof *ctx);
  }
  
  static void
  md2_compute(md2_ctx *ctx, const uint8_t *block)
  {
  	unsigned int j, k;
  	uint8_t l, t;
  
  	for (j = 0; j < 16; j++) {
  		ctx->state[j + 16] = block[j];
  		ctx->state[j + 32] = block[j] ^ ctx->state[j];
  	}
  	t = 0;
  	for (j = 0; j < 18; ++j) {
  		for (k = 0; k < 48; ++k) {
  			ctx->state[k] = ctx->state[k] ^ md2_s[t];
  			t = ctx->state[k];
  		}
  		t = t + j;
  	}
  	l = ctx->cksum[15];
  	for (j = 0; j < 16; ++j) {
  		ctx->cksum[j] ^= md2_s[block[j] ^ l];
  		l = ctx->cksum[j];
  	}
  }
  
  void
  md2_update(md2_ctx *ctx, const void *buf, size_t len)
  {
  	size_t copylen;
  
  	while (len) {
  		if (ctx->blocklen > 0 || len < sizeof ctx->block) {
  			copylen = sizeof ctx->block - ctx->blocklen;
  			if (copylen > len)
  				copylen = len;
  			memcpy(ctx->block + ctx->blocklen, buf, copylen);
  			ctx->blocklen += copylen;
  			if (ctx->blocklen == sizeof ctx->block) {
  				md2_compute(ctx, ctx->block);
  				ctx->blocklen = 0;
  			}
  		} else {
  			copylen = sizeof ctx->block;
  			md2_compute(ctx, buf);
  		}
  		buf += copylen;
  		len -= copylen;
  	}
  }
  
  void
  md2_final(md2_ctx *ctx, uint8_t *digest)
  {
  	unsigned int i;
  	uint8_t x;
  
  	x = sizeof ctx->block - ctx->blocklen;
  	for (i = ctx->blocklen; i < sizeof ctx->block; i++)
  		ctx->block[i] = x;
  	md2_compute(ctx, ctx->block);
  	md2_compute(ctx, ctx->cksum);
  	memcpy(digest, ctx->state, MD2_DIGEST_LEN);
  	memset_s(&ctx, 0, sizeof ctx, sizeof ctx);
  }
  
  void md2_complete(const void *buf, size_t len, uint8_t *digest)
  {
  	md2_ctx ctx;
  
  	md2_init(&ctx);
  	md2_update(&ctx, buf, len);
  	md2_final(&ctx, digest);
  }
  
  digest_algorithm md2_digest = {
  	.name			 = "md2",
  	.contextlen		 = sizeof(md2_ctx),
  	.blocklen		 = MD2_BLOCK_LEN,
  	.digestlen		 = MD2_DIGEST_LEN,
  	.init			 = (digest_init_func)md2_init,
  	.update			 = (digest_update_func)md2_update,
  	.final			 = (digest_final_func)md2_final,
  	.complete		 = (digest_complete_func)md2_complete,
  };
  