michael@0: /*-
michael@0:  * Copyright 2005,2007,2009 Colin Percival
michael@0:  * All rights reserved.
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer in the
michael@0:  *    documentation and/or other materials provided with the distribution.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
michael@0:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
michael@0:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
michael@0:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
michael@0:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
michael@0:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
michael@0:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
michael@0:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
michael@0:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
michael@0:  * SUCH DAMAGE.
michael@0:  */
michael@0: #include <sys/types.h>
michael@0: 
michael@0: #include <stdint.h>
michael@0: #include <string.h>
michael@0: 
michael@0: #include <sys/endian.h>
michael@0: 
michael@0: #include "pbkdf2_sha256.h"
michael@0: 
michael@0: static inline uint32_t
michael@0: be32dec(const void *pp)
michael@0: {
michael@0: 	const uint8_t *p = (uint8_t const *)pp;
michael@0: 
michael@0: 	return ((uint32_t)(p[3]) +
michael@0: 		((uint32_t)(p[2]) << 8) +
michael@0: 		((uint32_t)(p[1]) << 16) +
michael@0: 		((uint32_t)(p[0]) << 24));
michael@0: }
michael@0: 
michael@0: static inline void
michael@0: be32enc(void *pp, uint32_t x)
michael@0: {
michael@0: 	uint8_t * p = (uint8_t *)pp;
michael@0: 
michael@0: 	p[3] = x & 0xff;
michael@0: 	p[2] = (x >> 8) & 0xff;
michael@0: 	p[1] = (x >> 16) & 0xff;
michael@0: 	p[0] = (x >> 24) & 0xff;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * Encode a length len/4 vector of (uint32_t) into a length len vector of
michael@0:  * (unsigned char) in big-endian form.  Assumes len is a multiple of 4.
michael@0:  */
michael@0: static void
michael@0: be32enc_vect(unsigned char *dst, const uint32_t *src, size_t len)
michael@0: {
michael@0: 	size_t i;
michael@0: 
michael@0: 	for (i = 0; i < len / 4; i++)
michael@0: 		be32enc(dst + i * 4, src[i]);
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * Decode a big-endian length len vector of (unsigned char) into a length
michael@0:  * len/4 vector of (uint32_t).  Assumes len is a multiple of 4.
michael@0:  */
michael@0: static void
michael@0: be32dec_vect(uint32_t *dst, const unsigned char *src, size_t len)
michael@0: {
michael@0: 	size_t i;
michael@0: 
michael@0: 	for (i = 0; i < len / 4; i++)
michael@0: 		dst[i] = be32dec(src + i * 4);
michael@0: }
michael@0: 
michael@0: /* Elementary functions used by SHA256 */
michael@0: #define Ch(x, y, z)	((x & (y ^ z)) ^ z)
michael@0: #define Maj(x, y, z)	((x & (y | z)) | (y & z))
michael@0: #define SHR(x, n)	(x >> n)
michael@0: #define ROTR(x, n)	((x >> n) | (x << (32 - n)))
michael@0: #define S0(x)		(ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
michael@0: #define S1(x)		(ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))
michael@0: #define s0(x)		(ROTR(x, 7) ^ ROTR(x, 18) ^ SHR(x, 3))
michael@0: #define s1(x)		(ROTR(x, 17) ^ ROTR(x, 19) ^ SHR(x, 10))
michael@0: 
michael@0: /* SHA256 round function */
michael@0: #define RND(a, b, c, d, e, f, g, h, k)			\
michael@0: 	t0 = h + S1(e) + Ch(e, f, g) + k;		\
michael@0: 	t1 = S0(a) + Maj(a, b, c);			\
michael@0: 	d += t0;					\
michael@0: 	h  = t0 + t1;
michael@0: 
michael@0: /* Adjusted round function for rotating state */
michael@0: #define RNDr(S, W, i, k)			\
michael@0: 	RND(S[(64 - i) % 8], S[(65 - i) % 8],	\
michael@0: 	    S[(66 - i) % 8], S[(67 - i) % 8],	\
michael@0: 	    S[(68 - i) % 8], S[(69 - i) % 8],	\
michael@0: 	    S[(70 - i) % 8], S[(71 - i) % 8],	\
michael@0: 	    W[i] + k)
michael@0: 
michael@0: /*
michael@0:  * SHA256 block compression function.  The 256-bit state is transformed via
michael@0:  * the 512-bit input block to produce a new state.
michael@0:  */
michael@0: static void
michael@0: SHA256_Transform(uint32_t * state, const unsigned char block[64])
michael@0: {
michael@0: 	uint32_t W[64];
michael@0: 	uint32_t S[8];
michael@0: 	uint32_t t0, t1;
michael@0: 	int i;
michael@0: 
michael@0: 	/* 1. Prepare message schedule W. */
michael@0: 	be32dec_vect(W, block, 64);
michael@0: 	for (i = 16; i < 64; i++)
michael@0: 		W[i] = s1(W[i - 2]) + W[i - 7] + s0(W[i - 15]) + W[i - 16];
michael@0: 
michael@0: 	/* 2. Initialize working variables. */
michael@0: 	memcpy(S, state, 32);
michael@0: 
michael@0: 	/* 3. Mix. */
michael@0: 	RNDr(S, W, 0, 0x428a2f98);
michael@0: 	RNDr(S, W, 1, 0x71374491);
michael@0: 	RNDr(S, W, 2, 0xb5c0fbcf);
michael@0: 	RNDr(S, W, 3, 0xe9b5dba5);
michael@0: 	RNDr(S, W, 4, 0x3956c25b);
michael@0: 	RNDr(S, W, 5, 0x59f111f1);
michael@0: 	RNDr(S, W, 6, 0x923f82a4);
michael@0: 	RNDr(S, W, 7, 0xab1c5ed5);
michael@0: 	RNDr(S, W, 8, 0xd807aa98);
michael@0: 	RNDr(S, W, 9, 0x12835b01);
michael@0: 	RNDr(S, W, 10, 0x243185be);
michael@0: 	RNDr(S, W, 11, 0x550c7dc3);
michael@0: 	RNDr(S, W, 12, 0x72be5d74);
michael@0: 	RNDr(S, W, 13, 0x80deb1fe);
michael@0: 	RNDr(S, W, 14, 0x9bdc06a7);
michael@0: 	RNDr(S, W, 15, 0xc19bf174);
michael@0: 	RNDr(S, W, 16, 0xe49b69c1);
michael@0: 	RNDr(S, W, 17, 0xefbe4786);
michael@0: 	RNDr(S, W, 18, 0x0fc19dc6);
michael@0: 	RNDr(S, W, 19, 0x240ca1cc);
michael@0: 	RNDr(S, W, 20, 0x2de92c6f);
michael@0: 	RNDr(S, W, 21, 0x4a7484aa);
michael@0: 	RNDr(S, W, 22, 0x5cb0a9dc);
michael@0: 	RNDr(S, W, 23, 0x76f988da);
michael@0: 	RNDr(S, W, 24, 0x983e5152);
michael@0: 	RNDr(S, W, 25, 0xa831c66d);
michael@0: 	RNDr(S, W, 26, 0xb00327c8);
michael@0: 	RNDr(S, W, 27, 0xbf597fc7);
michael@0: 	RNDr(S, W, 28, 0xc6e00bf3);
michael@0: 	RNDr(S, W, 29, 0xd5a79147);
michael@0: 	RNDr(S, W, 30, 0x06ca6351);
michael@0: 	RNDr(S, W, 31, 0x14292967);
michael@0: 	RNDr(S, W, 32, 0x27b70a85);
michael@0: 	RNDr(S, W, 33, 0x2e1b2138);
michael@0: 	RNDr(S, W, 34, 0x4d2c6dfc);
michael@0: 	RNDr(S, W, 35, 0x53380d13);
michael@0: 	RNDr(S, W, 36, 0x650a7354);
michael@0: 	RNDr(S, W, 37, 0x766a0abb);
michael@0: 	RNDr(S, W, 38, 0x81c2c92e);
michael@0: 	RNDr(S, W, 39, 0x92722c85);
michael@0: 	RNDr(S, W, 40, 0xa2bfe8a1);
michael@0: 	RNDr(S, W, 41, 0xa81a664b);
michael@0: 	RNDr(S, W, 42, 0xc24b8b70);
michael@0: 	RNDr(S, W, 43, 0xc76c51a3);
michael@0: 	RNDr(S, W, 44, 0xd192e819);
michael@0: 	RNDr(S, W, 45, 0xd6990624);
michael@0: 	RNDr(S, W, 46, 0xf40e3585);
michael@0: 	RNDr(S, W, 47, 0x106aa070);
michael@0: 	RNDr(S, W, 48, 0x19a4c116);
michael@0: 	RNDr(S, W, 49, 0x1e376c08);
michael@0: 	RNDr(S, W, 50, 0x2748774c);
michael@0: 	RNDr(S, W, 51, 0x34b0bcb5);
michael@0: 	RNDr(S, W, 52, 0x391c0cb3);
michael@0: 	RNDr(S, W, 53, 0x4ed8aa4a);
michael@0: 	RNDr(S, W, 54, 0x5b9cca4f);
michael@0: 	RNDr(S, W, 55, 0x682e6ff3);
michael@0: 	RNDr(S, W, 56, 0x748f82ee);
michael@0: 	RNDr(S, W, 57, 0x78a5636f);
michael@0: 	RNDr(S, W, 58, 0x84c87814);
michael@0: 	RNDr(S, W, 59, 0x8cc70208);
michael@0: 	RNDr(S, W, 60, 0x90befffa);
michael@0: 	RNDr(S, W, 61, 0xa4506ceb);
michael@0: 	RNDr(S, W, 62, 0xbef9a3f7);
michael@0: 	RNDr(S, W, 63, 0xc67178f2);
michael@0: 
michael@0: 	/* 4. Mix local working variables into global state. */
michael@0: 	for (i = 0; i < 8; i++)
michael@0: 		state[i] += S[i];
michael@0: 
michael@0: 	/* Clean the stack. */
michael@0: 	memset(W, 0, 256);
michael@0: 	memset(S, 0, 32);
michael@0: 	t0 = t1 = 0;
michael@0: }
michael@0: 
michael@0: static unsigned char PAD[64] = {
michael@0: 	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
michael@0: 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
michael@0: 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
michael@0: 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
michael@0: };
michael@0: 
michael@0: /* Add padding and terminating bit-count. */
michael@0: static void
michael@0: SHA256_Pad(SHA256_CTX * ctx)
michael@0: {
michael@0: 	unsigned char len[8];
michael@0: 	uint32_t r, plen;
michael@0: 
michael@0: 	/*
michael@0: 	 * Convert length to a vector of bytes -- we do this now rather
michael@0: 	 * than later because the length will change after we pad.
michael@0: 	 */
michael@0: 	be32enc_vect(len, ctx->count, 8);
michael@0: 
michael@0: 	/* Add 1--64 bytes so that the resulting length is 56 mod 64. */
michael@0: 	r = (ctx->count[1] >> 3) & 0x3f;
michael@0: 	plen = (r < 56) ? (56 - r) : (120 - r);
michael@0: 	SHA256_Update(ctx, PAD, (size_t)plen);
michael@0: 
michael@0: 	/* Add the terminating bit-count. */
michael@0: 	SHA256_Update(ctx, len, 8);
michael@0: }
michael@0: 
michael@0: /* SHA-256 initialization.  Begins a SHA-256 operation. */
michael@0: void
michael@0: SHA256_Init(SHA256_CTX * ctx)
michael@0: {
michael@0: 
michael@0: 	/* Zero bits processed so far. */
michael@0: 	ctx->count[0] = ctx->count[1] = 0;
michael@0: 
michael@0: 	/* Magic initialization constants. */
michael@0: 	ctx->state[0] = 0x6A09E667;
michael@0: 	ctx->state[1] = 0xBB67AE85;
michael@0: 	ctx->state[2] = 0x3C6EF372;
michael@0: 	ctx->state[3] = 0xA54FF53A;
michael@0: 	ctx->state[4] = 0x510E527F;
michael@0: 	ctx->state[5] = 0x9B05688C;
michael@0: 	ctx->state[6] = 0x1F83D9AB;
michael@0: 	ctx->state[7] = 0x5BE0CD19;
michael@0: }
michael@0: 
michael@0: /* Add bytes into the hash. */
michael@0: void
michael@0: SHA256_Update(SHA256_CTX * ctx, const void *in, size_t len)
michael@0: {
michael@0: 	uint32_t bitlen[2];
michael@0: 	uint32_t r;
michael@0: 	const unsigned char *src = in;
michael@0: 
michael@0: 	/* Number of bytes left in the buffer from previous updates. */
michael@0: 	r = (ctx->count[1] >> 3) & 0x3f;
michael@0: 
michael@0: 	/* Convert the length into a number of bits. */
michael@0: 	bitlen[1] = ((uint32_t)len) << 3;
michael@0: 	bitlen[0] = (uint32_t)(len >> 29);
michael@0: 
michael@0: 	/* Update number of bits. */
michael@0: 	if ((ctx->count[1] += bitlen[1]) < bitlen[1])
michael@0: 		ctx->count[0]++;
michael@0: 	ctx->count[0] += bitlen[0];
michael@0: 
michael@0: 	/* Handle the case where we don't need to perform any transforms. */
michael@0: 	if (len < 64 - r) {
michael@0: 		memcpy(&ctx->buf[r], src, len);
michael@0: 		return;
michael@0: 	}
michael@0: 
michael@0: 	/* Finish the current block. */
michael@0: 	memcpy(&ctx->buf[r], src, 64 - r);
michael@0: 	SHA256_Transform(ctx->state, ctx->buf);
michael@0: 	src += 64 - r;
michael@0: 	len -= 64 - r;
michael@0: 
michael@0: 	/* Perform complete blocks. */
michael@0: 	while (len >= 64) {
michael@0: 		SHA256_Transform(ctx->state, src);
michael@0: 		src += 64;
michael@0: 		len -= 64;
michael@0: 	}
michael@0: 
michael@0: 	/* Copy left over data into buffer. */
michael@0: 	memcpy(ctx->buf, src, len);
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * SHA-256 finalization.  Pads the input data, exports the hash value,
michael@0:  * and clears the context state.
michael@0:  */
michael@0: void
michael@0: SHA256_Final(unsigned char digest[32], SHA256_CTX * ctx)
michael@0: {
michael@0: 
michael@0: 	/* Add padding. */
michael@0: 	SHA256_Pad(ctx);
michael@0: 
michael@0: 	/* Write the hash. */
michael@0: 	be32enc_vect(digest, ctx->state, 32);
michael@0: 
michael@0: 	/* Clear the context state. */
michael@0: 	memset((void *)ctx, 0, sizeof(*ctx));
michael@0: }
michael@0: 
michael@0: /* Initialize an HMAC-SHA256 operation with the given key. */
michael@0: void
michael@0: HMAC_SHA256_Init(HMAC_SHA256_CTX * ctx, const void * _K, size_t Klen)
michael@0: {
michael@0: 	unsigned char pad[64];
michael@0: 	unsigned char khash[32];
michael@0: 	const unsigned char * K = _K;
michael@0: 	size_t i;
michael@0: 
michael@0: 	/* If Klen > 64, the key is really SHA256(K). */
michael@0: 	if (Klen > 64) {
michael@0: 		SHA256_Init(&ctx->ictx);
michael@0: 		SHA256_Update(&ctx->ictx, K, Klen);
michael@0: 		SHA256_Final(khash, &ctx->ictx);
michael@0: 		K = khash;
michael@0: 		Klen = 32;
michael@0: 	}
michael@0: 
michael@0: 	/* Inner SHA256 operation is SHA256(K xor [block of 0x36] || data). */
michael@0: 	SHA256_Init(&ctx->ictx);
michael@0: 	memset(pad, 0x36, 64);
michael@0: 	for (i = 0; i < Klen; i++)
michael@0: 		pad[i] ^= K[i];
michael@0: 	SHA256_Update(&ctx->ictx, pad, 64);
michael@0: 
michael@0: 	/* Outer SHA256 operation is SHA256(K xor [block of 0x5c] || hash). */
michael@0: 	SHA256_Init(&ctx->octx);
michael@0: 	memset(pad, 0x5c, 64);
michael@0: 	for (i = 0; i < Klen; i++)
michael@0: 		pad[i] ^= K[i];
michael@0: 	SHA256_Update(&ctx->octx, pad, 64);
michael@0: 
michael@0: 	/* Clean the stack. */
michael@0: 	memset(khash, 0, 32);
michael@0: }
michael@0: 
michael@0: /* Add bytes to the HMAC-SHA256 operation. */
michael@0: void
michael@0: HMAC_SHA256_Update(HMAC_SHA256_CTX * ctx, const void *in, size_t len)
michael@0: {
michael@0: 
michael@0: 	/* Feed data to the inner SHA256 operation. */
michael@0: 	SHA256_Update(&ctx->ictx, in, len);
michael@0: }
michael@0: 
michael@0: /* Finish an HMAC-SHA256 operation. */
michael@0: void
michael@0: HMAC_SHA256_Final(unsigned char digest[32], HMAC_SHA256_CTX * ctx)
michael@0: {
michael@0: 	unsigned char ihash[32];
michael@0: 
michael@0: 	/* Finish the inner SHA256 operation. */
michael@0: 	SHA256_Final(ihash, &ctx->ictx);
michael@0: 
michael@0: 	/* Feed the inner hash to the outer SHA256 operation. */
michael@0: 	SHA256_Update(&ctx->octx, ihash, 32);
michael@0: 
michael@0: 	/* Finish the outer SHA256 operation. */
michael@0: 	SHA256_Final(digest, &ctx->octx);
michael@0: 
michael@0: 	/* Clean the stack. */
michael@0: 	memset(ihash, 0, 32);
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * PBKDF2_SHA256(passwd, passwdlen, salt, saltlen, c, buf, dkLen):
michael@0:  * Compute PBKDF2(passwd, salt, c, dkLen) using HMAC-SHA256 as the PRF, and
michael@0:  * write the output to buf.  The value dkLen must be at most 32 * (2^32 - 1).
michael@0:  */
michael@0: void
michael@0: PBKDF2_SHA256(const uint8_t * passwd, size_t passwdlen, const uint8_t * salt,
michael@0:     size_t saltlen, uint64_t c, uint8_t * buf, size_t dkLen)
michael@0: {
michael@0: 	HMAC_SHA256_CTX PShctx, hctx;
michael@0: 	size_t i;
michael@0: 	uint8_t ivec[4];
michael@0: 	uint8_t U[32];
michael@0: 	uint8_t T[32];
michael@0: 	uint64_t j;
michael@0: 	int k;
michael@0: 	size_t clen;
michael@0: 
michael@0: 	/* Compute HMAC state after processing P and S. */
michael@0: 	HMAC_SHA256_Init(&PShctx, passwd, passwdlen);
michael@0: 	HMAC_SHA256_Update(&PShctx, salt, saltlen);
michael@0: 
michael@0: 	/* Iterate through the blocks. */
michael@0: 	for (i = 0; i * 32 < dkLen; i++) {
michael@0: 		/* Generate INT(i + 1). */
michael@0: 		be32enc(ivec, (uint32_t)(i + 1));
michael@0: 
michael@0: 		/* Compute U_1 = PRF(P, S || INT(i)). */
michael@0: 		memcpy(&hctx, &PShctx, sizeof(HMAC_SHA256_CTX));
michael@0: 		HMAC_SHA256_Update(&hctx, ivec, 4);
michael@0: 		HMAC_SHA256_Final(U, &hctx);
michael@0: 
michael@0: 		/* T_i = U_1 ... */
michael@0: 		memcpy(T, U, 32);
michael@0: 
michael@0: 		for (j = 2; j <= c; j++) {
michael@0: 			/* Compute U_j. */
michael@0: 			HMAC_SHA256_Init(&hctx, passwd, passwdlen);
michael@0: 			HMAC_SHA256_Update(&hctx, U, 32);
michael@0: 			HMAC_SHA256_Final(U, &hctx);
michael@0: 
michael@0: 			/* ... xor U_j ... */
michael@0: 			for (k = 0; k < 32; k++)
michael@0: 				T[k] ^= U[k];
michael@0: 		}
michael@0: 
michael@0: 		/* Copy as many bytes as necessary into buf. */
michael@0: 		clen = dkLen - i * 32;
michael@0: 		if (clen > 32)
michael@0: 			clen = 32;
michael@0: 		memcpy(&buf[i * 32], T, clen);
michael@0: 	}
michael@0: 
michael@0: 	/* Clean PShctx, since we never called _Final on it. */
michael@0: 	memset(&PShctx, 0, sizeof(HMAC_SHA256_CTX));
michael@0: }