tpm: Add sha256 implementation

The following patch adds a SHA256 implementation based on the algorithm
description in NIST FIPS PUB 180-4. The patch includes test cases that test
the sha256 implementation and pass on big and little endian ppc64 hosts.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

3 files changed, 235 insertions, 1 deletions

diff --git a/lib/libtpm/Makefile b/lib/libtpm/Makefile
index 47fc5d0..8fa781e 100644
--- a/lib/libtpm/Makefile
+++ b/lib/libtpm/Makefile
@@ -23,7 +23,7 @@ TARGET = ../libtpm.a
 
 all: $(TARGET)
 
-SRCS = tpm_drivers.c
+SRCS = tpm_drivers.c sha256.c
 
 OBJS = $(SRCS:%.c=%.o)
 
diff --git a/lib/libtpm/sha256.c b/lib/libtpm/sha256.c
new file mode 100644
index 0000000..fb67e19
--- /dev/null
+++ b/lib/libtpm/sha256.c
@@ -0,0 +1,214 @@
+/*****************************************************************************
+ * Copyright (c) 2015-2020 IBM Corporation
+ * All rights reserved.
+ * This program and the accompanying materials
+ * are made available under the terms of the BSD License
+ * which accompanies this distribution, and is available at
+ * http://www.opensource.org/licenses/bsd-license.php
+ *
+ * Contributors:
+ *     IBM Corporation - initial implementation
+ *****************************************************************************/
+
+/*
+ *  See: NIST standard for SHA-256 in FIPS PUB 180-4
+ */
+
+#include "byteorder.h"
+#include "sha256.h"
+#include "string.h"
+
+typedef struct _sha256_ctx {
+	uint32_t h[8];
+} sha256_ctx;
+
+static inline uint32_t rotr(uint32_t x, uint8_t n)
+{
+	return (x >> n) | (x << (32 - n));
+}
+
+static inline uint32_t Ch(uint32_t x, uint32_t y, uint32_t z)
+{
+	return (x & y) | ((x ^ 0xffffffff) & z);
+}
+
+static inline uint32_t Maj(uint32_t x, uint32_t y, uint32_t z)
+{
+	return (x & y) | (x & z) | (y & z);
+}
+
+static inline uint32_t sum0(uint32_t x)
+{
+	return rotr(x, 2) ^ rotr(x, 13) ^ rotr(x, 22);
+}
+
+static inline uint32_t sum1(uint32_t x)
+{
+	return rotr(x, 6) ^ rotr(x, 11) ^ rotr(x, 25);
+}
+
+static inline uint32_t sigma0(uint32_t x)
+{
+	return rotr(x, 7) ^ rotr(x, 18) ^ (x >> 3);
+}
+
+static inline uint32_t sigma1(uint32_t x)
+{
+	return rotr(x, 17) ^ rotr(x, 19) ^ (x >> 10);
+}
+
+static void sha256_block(uint32_t *w, sha256_ctx *ctx)
+{
+	uint32_t t;
+	uint32_t a, b, c, d, e, f, g, h;
+	uint32_t T1, T2;
+
+	/*
+	 * FIPS 180-4 4.2.2: SHA256 Constants
+	 */
+	static const uint32_t sha_ko[64] = {
+		0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
+		0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
+		0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+		0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
+		0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
+		0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+		0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
+		0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
+		0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+		0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
+		0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
+		0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+		0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
+		0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
+		0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+		0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
+	};
+
+	/*
+	 * FIPS 180-4 6.2.2: step 1
+	 *
+	 *  0 <= i <= 15:
+	 *    W(t) = M(t)
+	 * 16 <= i <= 79:
+	 *    W(t) = sigma1(W(t-2)) + W(t-7) + sigma0(W(t-15)) + W(t-16)
+	 */
+
+	/* w(0)..w(15) are in big endian format */
+	for (t = 0; t <= 15; t++)
+		w[t] = be32_to_cpu(w[t]);
+
+	for (t = 16; t <= 63; t++)
+		w[t] = sigma1(w[t-2]) + w[t-7] + sigma0(w[t-15]) + w[t-16];
+
+	/*
+	 * step 2: a = H0, b = H1, c = H2, d = H3, e = H4, f = H5, g = H6, h = H7
+	 */
+	a = ctx->h[0];
+	b = ctx->h[1];
+	c = ctx->h[2];
+	d = ctx->h[3];
+	e = ctx->h[4];
+	f = ctx->h[5];
+	g = ctx->h[6];
+	h = ctx->h[7];
+
+	/*
+	 * step 3: For i = 0 to 63:
+	 *    T1 = h + sum1(e) + Ch(e,f,g) + K(t) + W(t);
+	 *    T2 = sum0(a) + Maj(a,b,c)
+	 *    h = g; g = f; f = e; e = d + T1; d = c; c = b; b = a; a + T1 + T2
+	 */
+	for (t = 0; t <= 63; t++) {
+		T1 = h + sum1(e) + Ch(e, f, g) + sha_ko[t] + w[t];
+		T2 = sum0(a) + Maj(a, b, c);
+		h = g;
+		g = f;
+		f = e;
+		e = d + T1;
+		d = c;
+		c = b;
+		b = a;
+		a = T1 + T2;
+	}
+
+	/*
+	 * step 4:
+	 *    H0 = a + H0, H1 = b + H1, H2 = c + H2, H3 = d + H3, H4 = e + H4
+	 */
+	ctx->h[0] += a;
+	ctx->h[1] += b;
+	ctx->h[2] += c;
+	ctx->h[3] += d;
+	ctx->h[4] += e;
+	ctx->h[5] += f;
+	ctx->h[6] += g;
+	ctx->h[7] += h;
+}
+
+static void sha256_do(sha256_ctx *ctx, const uint8_t *data32, uint32_t length)
+{
+	uint32_t offset;
+	uint16_t num;
+	uint32_t bits = 0;
+	uint32_t w[64];
+	uint64_t tmp;
+
+	/* treat data in 64-byte chunks */
+	for (offset = 0; length - offset >= 64; offset += 64) {
+		memcpy(w, data32 + offset, 64);
+		sha256_block((uint32_t *)w, ctx);
+		bits += (64 * 8);
+	}
+
+	/* last block with less than 64 bytes */
+	num = length - offset;
+	bits += (num << 3);
+
+	memcpy(w, data32 + offset, num);
+	/*
+	 * FIPS 180-4 5.1: Padding the Message
+	 */
+	((uint8_t *)w)[num] = 0x80;
+	if (64 - (num + 1) > 0)
+		memset( &((uint8_t *)w)[num + 1], 0, 64 - (num + 1));
+
+	if (num >= 56) {
+		/* cannot append number of bits here */
+		sha256_block((uint32_t *)w, ctx);
+		memset(w, 0, 60);
+	}
+
+	/* write number of bits to end of block */
+	tmp = cpu_to_be64(bits);
+	memcpy(&w[14], &tmp, 8);
+
+	sha256_block(w, ctx);
+
+	/* need to switch result's endianness */
+	for (num = 0; num < 8; num++)
+		ctx->h[num] = cpu_to_be32(ctx->h[num]);
+}
+
+void sha256(const uint8_t *data, uint32_t length, uint8_t *hash)
+{
+	sha256_ctx ctx = {
+		.h = {
+			/*
+			 * FIPS 180-4: 6.2.1
+			 *   -> 5.3.3: initial hash value
+			 */
+			0x6a09e667,
+			0xbb67ae85,
+			0x3c6ef372,
+			0xa54ff53a,
+			0x510e527f,
+			0x9b05688c,
+			0x1f83d9ab,
+			0x5be0cd19
+		}
+	};
+
+	sha256_do(&ctx, data, length);
+	memcpy(hash, ctx.h, sizeof(ctx.h));
+}
diff --git a/lib/libtpm/sha256.h b/lib/libtpm/sha256.h
new file mode 100644
index 0000000..04b774b
--- /dev/null
+++ b/lib/libtpm/sha256.h
@@ -0,0 +1,20 @@
+/*****************************************************************************
+ * Copyright (c) 2015-2020 IBM Corporation
+ * All rights reserved.
+ * This program and the accompanying materials
+ * are made available under the terms of the BSD License
+ * which accompanies this distribution, and is available at
+ * http://www.opensource.org/licenses/bsd-license.php
+ *
+ * Contributors:
+ *     IBM Corporation - initial implementation
+ *****************************************************************************/
+
+#ifndef __SHA256_H
+#define __SHA256_H
+
+#include "types.h"
+
+void sha256(const uint8_t *data, uint32_t length, uint8_t *hash);
+
+#endif /* __SHA256_H */