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+/* Functions to compute SHA256 message digest of files or memory blocks.
+ according to the definition of SHA256 in FIPS 180-2.
+ Copyright (C) 2007 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+/* Written by Ulrich Drepper <drepper@redhat.com>, 2007. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <endian.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include "sha256.h"
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+# ifdef _LIBC
+# include <byteswap.h>
+# define SWAP(n) bswap_32 (n)
+# else
+# define SWAP(n) \
+ (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
+# endif
+#else
+# define SWAP(n) (n)
+#endif
+
+
+/* This array contains the bytes used to pad the buffer to the next
+ 64-byte boundary. (FIPS 180-2:5.1.1) */
+static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
+
+
+/* Constants for SHA256 from FIPS 180-2:4.2.2. */
+static const uint32_t K[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
+ };
+
+
+/* Process LEN bytes of BUFFER, accumulating context into CTX.
+ It is assumed that LEN % 64 == 0. */
+static void
+sha256_process_block (const void *buffer, size_t len, struct sha256_ctx *ctx)
+{
+ const uint32_t *words = buffer;
+ size_t nwords = len / sizeof (uint32_t);
+ uint32_t a = ctx->H[0];
+ uint32_t b = ctx->H[1];
+ uint32_t c = ctx->H[2];
+ uint32_t d = ctx->H[3];
+ uint32_t e = ctx->H[4];
+ uint32_t f = ctx->H[5];
+ uint32_t g = ctx->H[6];
+ uint32_t h = ctx->H[7];
+
+ /* First increment the byte count. FIPS 180-2 specifies the possible
+ length of the file up to 2^64 bits. Here we only compute the
+ number of bytes. Do a double word increment. */
+ ctx->total[0] += len;
+ if (ctx->total[0] < len)
+ ++ctx->total[1];
+
+ /* Process all bytes in the buffer with 64 bytes in each round of
+ the loop. */
+ while (nwords > 0)
+ {
+ uint32_t W[64];
+ uint32_t a_save = a;
+ uint32_t b_save = b;
+ uint32_t c_save = c;
+ uint32_t d_save = d;
+ uint32_t e_save = e;
+ uint32_t f_save = f;
+ uint32_t g_save = g;
+ uint32_t h_save = h;
+
+ /* Operators defined in FIPS 180-2:4.1.2. */
+#define Ch(x, y, z) ((x & y) ^ (~x & z))
+#define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
+#define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22))
+#define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25))
+#define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3))
+#define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10))
+
+ /* It is unfortunate that C does not provide an operator for
+ cyclic rotation. Hope the C compiler is smart enough. */
+#define CYCLIC(w, s) ((w >> s) | (w << (32 - s)))
+
+ /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2. */
+ for (unsigned int t = 0; t < 16; ++t)
+ {
+ W[t] = SWAP (*words);
+ ++words;
+ }
+ for (unsigned int t = 16; t < 64; ++t)
+ W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16];
+
+ /* The actual computation according to FIPS 180-2:6.2.2 step 3. */
+ for (unsigned int t = 0; t < 64; ++t)
+ {
+ uint32_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t];
+ uint32_t T2 = S0 (a) + Maj (a, b, c);
+ h = g;
+ g = f;
+ f = e;
+ e = d + T1;
+ d = c;
+ c = b;
+ b = a;
+ a = T1 + T2;
+ }
+
+ /* Add the starting values of the context according to FIPS 180-2:6.2.2
+ step 4. */
+ a += a_save;
+ b += b_save;
+ c += c_save;
+ d += d_save;
+ e += e_save;
+ f += f_save;
+ g += g_save;
+ h += h_save;
+
+ /* Prepare for the next round. */
+ nwords -= 16;
+ }
+
+ /* Put checksum in context given as argument. */
+ 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;
+}
+
+
+/* Initialize structure containing state of computation.
+ (FIPS 180-2:5.3.2) */
+void
+__sha256_init_ctx (ctx)
+ struct sha256_ctx *ctx;
+{
+ ctx->H[0] = 0x6a09e667;
+ ctx->H[1] = 0xbb67ae85;
+ ctx->H[2] = 0x3c6ef372;
+ ctx->H[3] = 0xa54ff53a;
+ ctx->H[4] = 0x510e527f;
+ ctx->H[5] = 0x9b05688c;
+ ctx->H[6] = 0x1f83d9ab;
+ ctx->H[7] = 0x5be0cd19;
+
+ ctx->total[0] = ctx->total[1] = 0;
+ ctx->buflen = 0;
+}
+
+
+/* Process the remaining bytes in the internal buffer and the usual
+ prolog according to the standard and write the result to RESBUF.
+
+ IMPORTANT: On some systems it is required that RESBUF is correctly
+ aligned for a 32 bits value. */
+void *
+__sha256_finish_ctx (ctx, resbuf)
+ struct sha256_ctx *ctx;
+ void *resbuf;
+{
+ /* Take yet unprocessed bytes into account. */
+ uint32_t bytes = ctx->buflen;
+ size_t pad;
+
+ /* Now count remaining bytes. */
+ ctx->total[0] += bytes;
+ if (ctx->total[0] < bytes)
+ ++ctx->total[1];
+
+ pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
+ memcpy (&ctx->buffer[bytes], fillbuf, pad);
+
+ /* Put the 64-bit file length in *bits* at the end of the buffer. */
+ *(uint32_t *) &ctx->buffer[bytes + pad + 4] = SWAP (ctx->total[0] << 3);
+ *(uint32_t *) &ctx->buffer[bytes + pad] = SWAP ((ctx->total[1] << 3) |
+ (ctx->total[0] >> 29));
+
+ /* Process last bytes. */
+ sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
+
+ /* Put result from CTX in first 32 bytes following RESBUF. */
+ for (unsigned int i = 0; i < 8; ++i)
+ ((uint32_t *) resbuf)[i] = SWAP (ctx->H[i]);
+
+ return resbuf;
+}
+
+
+void
+__sha256_process_bytes (buffer, len, ctx)
+ const void *buffer;
+ size_t len;
+ struct sha256_ctx *ctx;
+{
+ /* When we already have some bits in our internal buffer concatenate
+ both inputs first. */
+ if (ctx->buflen != 0)
+ {
+ size_t left_over = ctx->buflen;
+ size_t add = 128 - left_over > len ? len : 128 - left_over;
+
+ memcpy (&ctx->buffer[left_over], buffer, add);
+ ctx->buflen += add;
+
+ if (ctx->buflen > 64)
+ {
+ sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
+
+ ctx->buflen &= 63;
+ /* The regions in the following copy operation cannot overlap. */
+ memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
+ ctx->buflen);
+ }
+
+ buffer = (const char *) buffer + add;
+ len -= add;
+ }
+
+ /* Process available complete blocks. */
+ if (len >= 64)
+ {
+#if !_STRING_ARCH_unaligned
+/* To check alignment gcc has an appropriate operator. Other
+ compilers don't. */
+# if __GNUC__ >= 2
+# define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0)
+# else
+# define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint32_t) != 0)
+# endif
+ if (UNALIGNED_P (buffer))
+ while (len > 64)
+ {
+ sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
+ buffer = (const char *) buffer + 64;
+ len -= 64;
+ }
+ else
+#endif
+ {
+ sha256_process_block (buffer, len & ~63, ctx);
+ buffer = (const char *) buffer + (len & ~63);
+ len &= 63;
+ }
+ }
+
+ /* Move remaining bytes into internal buffer. */
+ if (len > 0)
+ {
+ size_t left_over = ctx->buflen;
+
+ memcpy (&ctx->buffer[left_over], buffer, len);
+ left_over += len;
+ if (left_over >= 64)
+ {
+ sha256_process_block (ctx->buffer, 64, ctx);
+ left_over -= 64;
+ memcpy (ctx->buffer, &ctx->buffer[64], left_over);
+ }
+ ctx->buflen = left_over;
+ }
+}
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