text: /*-
   * Copyright 2005,2007,2009 Colin Percival
   * 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.
   *
   * 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 <sys/types.h>
  
  #include <stdint.h>
  #include <string.h>
  
  #include "sph/sysendian.h"
  
  #include "sph/sha256_Y.h"
  
  /*
   * Encode a length len/4 vector of (uint32_t) into a length len vector of
   * (unsigned char) in big-endian form.  Assumes len is a multiple of 4.
   */
  static void
  be32enc_vect(unsigned char *dst, const uint32_t *src, size_t len)
  {
  	size_t i;
  
  	for (i = 0; i < len / 4; i++)
  		be32enc(dst + i * 4, src[i]);
  }
  
  /*
   * Decode a big-endian length len vector of (unsigned char) into a length
   * len/4 vector of (uint32_t).  Assumes len is a multiple of 4.
   */
  static void
  be32dec_vect(uint32_t *dst, const unsigned char *src, size_t len)
  {
  	size_t i;
  
  	for (i = 0; i < len / 4; i++)
  		dst[i] = be32dec(src + i * 4);
  }
  
  /* Elementary functions used by SHA256 */
  #define Ch(x, y, z)	((x & (y ^ z)) ^ z)
  #define Maj(x, y, z)	((x & (y | z)) | (y & z))
  #define SHR(x, n)	(x >> n)
  #define ROTR(x, n)	((x >> n) | (x << (32 - n)))
  #define S0(x)		(ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
  #define S1(x)		(ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))
  #define s0(x)		(ROTR(x, 7) ^ ROTR(x, 18) ^ SHR(x, 3))
  #define s1(x)		(ROTR(x, 17) ^ ROTR(x, 19) ^ SHR(x, 10))
  
  /* SHA256 round function */
  #define RND(a, b, c, d, e, f, g, h, k)			\
  	t0 = h + S1(e) + Ch(e, f, g) + k;		\
  	t1 = S0(a) + Maj(a, b, c);			\
  	d += t0;					\
  	h  = t0 + t1;
  
  /* Adjusted round function for rotating state */
  #define RNDr(S, W, i, k)			\
  	RND(S[(64 - i) % 8], S[(65 - i) % 8],	\
  	    S[(66 - i) % 8], S[(67 - i) % 8],	\
  	    S[(68 - i) % 8], S[(69 - i) % 8],	\
  	    S[(70 - i) % 8], S[(71 - i) % 8],	\
  	    W[i] + k)
  
  /*
   * SHA256 block compression function.  The 256-bit state is transformed via
   * the 512-bit input block to produce a new state.
   */
  static void
  SHA256_Transform(uint32_t * state, const unsigned char block[64])
  {
  	uint32_t W[64];
  	uint32_t S[8];
  	uint32_t t0, t1;
  	int i;
  	/* 1. Prepare message schedule W. */
  	be32dec_vect(W, block, 64);
  
  	for (i = 16; i < 64; i++)
  		W[i] = s1(W[i - 2]) + W[i - 7] + s0(W[i - 15]) + W[i - 16];
  
  	/* 2. Initialize working variables. */
  	memcpy(S, state, 32);
  
  	/* 3. Mix. */
  	RNDr(S, W, 0, 0x428a2f98);
  	RNDr(S, W, 1, 0x71374491);
  	RNDr(S, W, 2, 0xb5c0fbcf);
  	RNDr(S, W, 3, 0xe9b5dba5);
  	RNDr(S, W, 4, 0x3956c25b);
  	RNDr(S, W, 5, 0x59f111f1);
  	RNDr(S, W, 6, 0x923f82a4);
  	RNDr(S, W, 7, 0xab1c5ed5);
  	RNDr(S, W, 8, 0xd807aa98);
  	RNDr(S, W, 9, 0x12835b01);
  	RNDr(S, W, 10, 0x243185be);
  	RNDr(S, W, 11, 0x550c7dc3);
  	RNDr(S, W, 12, 0x72be5d74);
  	RNDr(S, W, 13, 0x80deb1fe);
  	RNDr(S, W, 14, 0x9bdc06a7);
  	RNDr(S, W, 15, 0xc19bf174);
  	RNDr(S, W, 16, 0xe49b69c1);
  	RNDr(S, W, 17, 0xefbe4786);
  	RNDr(S, W, 18, 0x0fc19dc6);
  	RNDr(S, W, 19, 0x240ca1cc);
  	RNDr(S, W, 20, 0x2de92c6f);
  	RNDr(S, W, 21, 0x4a7484aa);
  	RNDr(S, W, 22, 0x5cb0a9dc);
  	RNDr(S, W, 23, 0x76f988da);
  	RNDr(S, W, 24, 0x983e5152);
  	RNDr(S, W, 25, 0xa831c66d);
  	RNDr(S, W, 26, 0xb00327c8);
  	RNDr(S, W, 27, 0xbf597fc7);
  	RNDr(S, W, 28, 0xc6e00bf3);
  	RNDr(S, W, 29, 0xd5a79147);
  	RNDr(S, W, 30, 0x06ca6351);
  	RNDr(S, W, 31, 0x14292967);
  	RNDr(S, W, 32, 0x27b70a85);
  	RNDr(S, W, 33, 0x2e1b2138);
  	RNDr(S, W, 34, 0x4d2c6dfc);
  	RNDr(S, W, 35, 0x53380d13);
  	RNDr(S, W, 36, 0x650a7354);
  	RNDr(S, W, 37, 0x766a0abb);
  	RNDr(S, W, 38, 0x81c2c92e);
  	RNDr(S, W, 39, 0x92722c85);
  	RNDr(S, W, 40, 0xa2bfe8a1);
  	RNDr(S, W, 41, 0xa81a664b);
  	RNDr(S, W, 42, 0xc24b8b70);
  	RNDr(S, W, 43, 0xc76c51a3);
  	RNDr(S, W, 44, 0xd192e819);
  	RNDr(S, W, 45, 0xd6990624);
  	RNDr(S, W, 46, 0xf40e3585);
  	RNDr(S, W, 47, 0x106aa070);
  	RNDr(S, W, 48, 0x19a4c116);
  	RNDr(S, W, 49, 0x1e376c08);
  	RNDr(S, W, 50, 0x2748774c);
  	RNDr(S, W, 51, 0x34b0bcb5);
  	RNDr(S, W, 52, 0x391c0cb3);
  	RNDr(S, W, 53, 0x4ed8aa4a);
  	RNDr(S, W, 54, 0x5b9cca4f);
  	RNDr(S, W, 55, 0x682e6ff3);
  	RNDr(S, W, 56, 0x748f82ee);
  	RNDr(S, W, 57, 0x78a5636f);
  	RNDr(S, W, 58, 0x84c87814);
  	RNDr(S, W, 59, 0x8cc70208);
  	RNDr(S, W, 60, 0x90befffa);
  	RNDr(S, W, 61, 0xa4506ceb);
  	RNDr(S, W, 62, 0xbef9a3f7);
  	RNDr(S, W, 63, 0xc67178f2);
  
  	/* 4. Mix local working variables into global state */
  	for (i = 0; i < 8; i++) {
  		state[i] += S[i];
  	
  }
  
  	/* Clean the stack. */
  	memset(W, 0, 256);
  	memset(S, 0, 32);
  	t0 = t1 = 0;
  }
  
  static unsigned char PAD[64] = {
  	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  };
  
  /* Add padding and terminating bit-count. */
  static void
  SHA256_Pad(SHA256_CTX_Y * ctx)
  {
  	unsigned char len[8];
  	uint32_t r, plen;
  
  	/*
  	 * Convert length to a vector of bytes -- we do this now rather
  	 * than later because the length will change after we pad.
  	 */
  	be32enc_vect(len, ctx->count, 8);
  
  	/* Add 1--64 bytes so that the resulting length is 56 mod 64 */
  	r = (ctx->count[1] >> 3) & 0x3f;
  	plen = (r < 56) ? (56 - r) : (120 - r);
  	SHA256_Update_Y(ctx, PAD, (size_t)plen);
  
  	/* Add the terminating bit-count */
  	SHA256_Update_Y(ctx, len, 8);
  }
  
  /* SHA-256 initialization.  Begins a SHA-256 operation. */
  void
  SHA256_Init_Y(SHA256_CTX_Y * ctx)
  {
  
  	/* Zero bits processed so far */
  	ctx->count[0] = ctx->count[1] = 0;
  
  	/* Magic initialization constants */
  	ctx->state[0] = 0x6A09E667;
  	ctx->state[1] = 0xBB67AE85;
  	ctx->state[2] = 0x3C6EF372;
  	ctx->state[3] = 0xA54FF53A;
  	ctx->state[4] = 0x510E527F;
  	ctx->state[5] = 0x9B05688C;
  	ctx->state[6] = 0x1F83D9AB;
  	ctx->state[7] = 0x5BE0CD19;
  }
  
  /* Add bytes into the hash */
  void
  SHA256_Update_Y(SHA256_CTX_Y * ctx, const void *in, size_t len)
  {
  	uint32_t bitlen[2];
  	uint32_t r;
  	const unsigned char *src = in;
  
  	/* Number of bytes left in the buffer from previous updates */
  	r = (ctx->count[1] >> 3) & 0x3f;
  	
  	/* Convert the length into a number of bits */
  	bitlen[1] = ((uint32_t)len) << 3;
  	bitlen[0] = (uint32_t)(len >> 29);
  
  	/* Update number of bits */
  	if ((ctx->count[1] += bitlen[1]) < bitlen[1])
  		ctx->count[0]++;
  	ctx->count[0] += bitlen[0];
  
  	/* Handle the case where we don't need to perform any transforms */
  	if (len < 64 - r) {
  
  		memcpy(&ctx->buf[r], src, len);
  		return;
  	}
  
  	/* Finish the current block */
  	memcpy(&ctx->buf[r], src, 64 - r);
  	
  	SHA256_Transform(ctx->state, ctx->buf);
  	src += 64 - r;
  	len -= 64 - r;
  
  	/* Perform complete blocks */
  
  	while (len >= 64) {
  		SHA256_Transform(ctx->state, src);
  		src += 64;
  		len -= 64;
  	}
  
  	/* Copy left over data into buffer */
  	memcpy(ctx->buf, src, len);
  }
  
  /*
   * SHA-256 finalization.  Pads the input data, exports the hash value,
   * and clears the context state.
   */
  void
  SHA256_Final_Y(unsigned char digest[32], SHA256_CTX_Y * ctx)
  {
  	/* Add padding */
  	SHA256_Pad(ctx);
  
  	/* Write the hash */
  	be32enc_vect(digest, ctx->state, 32);
  
  	/* Clear the context state */
  	memset((void *)ctx, 0, sizeof(*ctx));
  }
  
  /* Initialize an HMAC-SHA256 operation with the given key. */
  void
  HMAC_SHA256_Init_Y(HMAC_SHA256_CTX_Y * ctx, const void * _K, size_t Klen)
  {
  	unsigned char pad[64];
  	unsigned char khash[32];
  	const unsigned char * K = _K;
  	size_t i;
  
  	/* If Klen > 64, the key is really SHA256(K). */
  	if (Klen > 64) {
  		SHA256_Init_Y(&ctx->ictx);
  		SHA256_Update_Y(&ctx->ictx, K, Klen);
  		SHA256_Final_Y(khash, &ctx->ictx);
  		K = khash;
  		Klen = 32;
  	}
  
  	/* Inner SHA256 operation is SHA256(K xor [block of 0x36] || data). */
  	SHA256_Init_Y(&ctx->ictx);
  	memset(pad, 0x36, 64);
  	for (i = 0; i < Klen; i++) {
  		pad[i] ^= K[i];
      }
  	SHA256_Update_Y(&ctx->ictx, pad, 64);
  
  	/* Outer SHA256 operation is SHA256(K xor [block of 0x5c] || hash). */
  	SHA256_Init_Y(&ctx->octx);
  	memset(pad, 0x5c, 64);
  	for (i = 0; i < Klen; i++)
     {
  		pad[i] ^= K[i];
     }
  	SHA256_Update_Y(&ctx->octx, pad, 64);
  
  	/* Clean the stack. */
  	memset(khash, 0, 32);
  }
  
  /* Add bytes to the HMAC-SHA256 operation. */
  void
  HMAC_SHA256_Update_Y(HMAC_SHA256_CTX_Y * ctx, const void *in, size_t len)
  {
  	/* Feed data to the inner SHA256 operation. */
  	SHA256_Update_Y(&ctx->ictx, in, len);
  }
  
  /* Finish an HMAC-SHA256 operation. */
  void
  HMAC_SHA256_Final_Y(unsigned char digest[32], HMAC_SHA256_CTX_Y * ctx)
  {
  	unsigned char ihash[32];
  
  	/* Finish the inner SHA256 operation. */
  	SHA256_Final_Y(ihash, &ctx->ictx);
  
  	/* Feed the inner hash to the outer SHA256 operation. */
  	SHA256_Update_Y(&ctx->octx, ihash, 32);
  
  	/* Finish the outer SHA256 operation. */
  	SHA256_Final_Y(digest, &ctx->octx);
  
  	/* Clean the stack. */
  	memset(ihash, 0, 32);
  }
  
  /**
   * PBKDF2_SHA256(passwd, passwdlen, salt, saltlen, c, buf, dkLen):
   * Compute PBKDF2(passwd, salt, c, dkLen) using HMAC-SHA256 as the PRF, and
   * write the output to buf.  The value dkLen must be at most 32 * (2^32 - 1).
   */
  
  void
  PBKDF2_SHA256(const uint8_t * passwd, size_t passwdlen, const uint8_t * salt,
  size_t saltlen, uint64_t c, uint8_t * buf, size_t dkLen)
  {
  	HMAC_SHA256_CTX_Y PShctx, hctx;
  	size_t i;
  	uint8_t ivec[4];
  	uint8_t U[32];
  	uint8_t T[32];
  	uint64_t j;
  	int k;
  	size_t clen;
  
  	/* Compute HMAC state after processing P and S. */
  	HMAC_SHA256_Init_Y(&PShctx, passwd, passwdlen);
  	HMAC_SHA256_Update_Y(&PShctx, salt, saltlen);
  
  	/* Iterate through the blocks. */
  	for (i = 0; i * 32 < dkLen; i++) {
  		/* Generate INT(i + 1). */
  		be32enc(ivec, (uint32_t)(i + 1));
  
  		/* Compute U_1 = PRF(P, S || INT(i)). */
  		memcpy(&hctx, &PShctx, sizeof(HMAC_SHA256_CTX_Y));
  		HMAC_SHA256_Update_Y(&hctx, ivec, 4);
  		HMAC_SHA256_Final_Y(U, &hctx);
  
  		/* T_i = U_1 ... */
  		memcpy(T, U, 32);
  
  		for (j = 2; j <= c; j++) {
  			/* Compute U_j. */
  			HMAC_SHA256_Init_Y(&hctx, passwd, passwdlen);
  			HMAC_SHA256_Update_Y(&hctx, U, 32);
  			HMAC_SHA256_Final_Y(U, &hctx);
  
  			/* ... xor U_j ... */
  			for (k = 0; k < 32; k++)
  				T[k] ^= U[k];
  		}
  
  		/* Copy as many bytes as necessary into buf. */
  		clen = dkLen - i * 32;
  		if (clen > 32)
  			clen = 32;
  		memcpy(&buf[i * 32], T, clen);
  	}
  
  	/* Clean PShctx, since we never called _Final on it. */
  	memset(&PShctx, 0, sizeof(HMAC_SHA256_CTX_Y));
  }
  