text: /*
   * Copyright (c) 2006-2019, Pelion and affiliates.
   * SPDX-License-Identifier: Apache-2.0
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   *  FIPS-180-2 compliant SHA-256 implementation
   *
   *  This file is derived from sha256.h in mbed TLS 2.3.0.
   */
  /*
   *  The SHA-256 Secure Hash Standard was published by NIST in 2002.
   *
   *  http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
   */
  
  #include "nsconfig.h"
  #include "ns_sha256.h"
  
  #ifndef NS_USE_EXTERNAL_MBED_TLS
  
  #include <string.h>
  
  /* Implementation that should never be optimized out by the compiler */
  static void ns_zeroize(void *v, size_t n)
  {
      volatile unsigned char *p = v;
      while (n--) {
          *p++ = 0;
      }
  }
  
  /*
   * 32-bit integer manipulation macros (big endian)
   */
  #ifndef GET_UINT32_BE
  #define GET_UINT32_BE(n,b,i)                            \
  (                                                       \
      (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
          | ( (uint32_t) (b)[(i) + 1] << 16 )             \
          | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
          | ( (uint32_t) (b)[(i) + 3]       )             \
  )
  #endif
  
  #ifndef PUT_UINT32_BE
  #define PUT_UINT32_BE(n,b,i)                            \
  do {                                                    \
      (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
      (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
      (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
      (b)[(i) + 3] = (unsigned char) ( (n)       );       \
  } while( 0 )
  #endif
  
  void ns_sha256_init(ns_sha256_context *ctx)
  {
      memset(ctx, 0, sizeof(ns_sha256_context));
  }
  
  void ns_sha256_free(ns_sha256_context *ctx)
  {
      ns_zeroize(ctx, sizeof(ns_sha256_context));
  }
  
  void ns_sha256_clone(ns_sha256_context *dst,
                       const ns_sha256_context *src)
  {
      *dst = *src;
  }
  
  /*
   * SHA-256 context setup
   */
  void ns_sha256_starts(ns_sha256_context *ctx)
  {
      ctx->total[0] = 0;
      ctx->total[1] = 0;
  
      /* SHA-256 */
      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;
  }
  
  static const uint32_t K[] = {
      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,
  };
  
  #define  SHR(x,n) ((x & 0xFFFFFFFF) >> n)
  #define ROTR(x,n) (SHR(x,n) | (x << (32 - n)))
  
  #define S0(x) (ROTR(x, 7) ^ ROTR(x,18) ^  SHR(x, 3))
  #define S1(x) (ROTR(x,17) ^ ROTR(x,19) ^  SHR(x,10))
  
  #define S2(x) (ROTR(x, 2) ^ ROTR(x,13) ^ ROTR(x,22))
  #define S3(x) (ROTR(x, 6) ^ ROTR(x,11) ^ ROTR(x,25))
  
  #define F0(x,y,z) ((x & y) | (z & (x | y)))
  #define F1(x,y,z) (z ^ (x & (y ^ z)))
  
  #define R(t)                                              \
  (                                                         \
      W[t & 15] += S1(W[(t -  2) & 15]) + W[(t - 7) & 15] + \
                   S0(W[(t - 15) & 15])                     \
  )
  
  #define P(a,b,c,d,e,f,g,h,x,K)                  \
  {                                               \
      temp1 = h + S3(e) + F1(e,f,g) + K + x;      \
      temp2 = S2(a) + F0(a,b,c);                  \
      d += temp1; h = temp1 + temp2;              \
  }
  
  static void ns_sha256_process(ns_sha256_context *ctx, const unsigned char data[64])
  {
      uint32_t temp1, temp2, W[16];
      uint32_t A[8];
      unsigned int i;
  
      for (i = 0; i < 8; i++) {
          A[i] = ctx->state[i];
      }
  
      for (i = 0; i < 64; i++) {
          uint32_t Wi;
          if (i < 16) {
              Wi = GET_UINT32_BE(W[i], data, 4 * i);
          } else {
              Wi = R(i);
          }
  
          P(A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], Wi, K[i]);
  
          temp1 = A[7];
          A[7] = A[6];
          A[6] = A[5];
          A[5] = A[4];
          A[4] = A[3];
          A[3] = A[2];
          A[2] = A[1];
          A[1] = A[0];
          A[0] = temp1;
      }
  
      for (i = 0; i < 8; i++) {
          ctx->state[i] += A[i];
      }
  }
  
  /*
   * SHA-256 process buffer
   */
  void ns_sha256_update(ns_sha256_context *ctx, const void *inputv,
                        size_t ilen)
  {
      const unsigned char *input = inputv;
      size_t fill;
      uint32_t left;
  
      if (ilen == 0) {
          return;
      }
  
      left = ctx->total[0] & 0x3F;
      fill = 64 - left;
  
      ctx->total[0] += (uint32_t) ilen;
      ctx->total[0] &= 0xFFFFFFFF;
  
      if (ctx->total[0] < (uint32_t) ilen) {
          ctx->total[1]++;
      }
  
      if (left && ilen >= fill) {
          memcpy((void *)(ctx->buffer + left), input, fill);
          ns_sha256_process(ctx, ctx->buffer);
          input += fill;
          ilen  -= fill;
          left = 0;
      }
  
      while (ilen >= 64) {
          ns_sha256_process(ctx, input);
          input += 64;
          ilen  -= 64;
      }
  
      if (ilen > 0) {
          memcpy((void *)(ctx->buffer + left), input, ilen);
      }
  }
  
  /*
   * SHA-256 final digest
   */
  void ns_sha256_finish_nbits(ns_sha256_context *ctx, void *outputv, unsigned obits)
  {
      unsigned char *output = outputv;
      uint32_t last, padn;
      uint32_t high, low;
      unsigned char msglen[8];
      unsigned int i;
  
      high = (ctx->total[0] >> 29)
             | (ctx->total[1] <<  3);
      low  = (ctx->total[0] <<  3);
  
      PUT_UINT32_BE(high, msglen, 0);
      PUT_UINT32_BE(low,  msglen, 4);
  
      last = ctx->total[0] & 0x3F;
      padn = (last < 56) ? (56 - last) : (120 - last);
  
      /* Const compound literals need not designate distinct objects - this could
       * potentially save ROM over declaring the padding array.
       */
      ns_sha256_update(ctx, (const unsigned char[64]) {
          0x80
      }, padn);
      ns_sha256_update(ctx, msglen, 8);
  
      for (i = 0; i < 8 && obits > 0; i++, obits -= 32) {
          PUT_UINT32_BE(ctx->state[i], output, 4 * i);
      }
  }
  
  void ns_sha256_finish(ns_sha256_context *ctx, void *output)
  {
      ns_sha256_finish_nbits(ctx, output, 256);
  }
  
  /*
   * output = SHA-256( input buffer )
   */
  void ns_sha256_nbits(const void *input, size_t ilen,
                       void *output, unsigned obits)
  {
      ns_sha256_context ctx;
  
      ns_sha256_init(&ctx);
      ns_sha256_starts(&ctx);
      ns_sha256_update(&ctx, input, ilen);
      ns_sha256_finish_nbits(&ctx, output, obits);
      ns_sha256_free(&ctx);
  }
  
  void ns_sha256(const void *input, size_t ilen,
                 void *output)
  {
      ns_sha256_nbits(input, ilen, output, 256);
  }
  #endif /* NS_USE_EXTERNAL_MBED_TLS */
  