// SPDX-License-Identifier: BSD-2-Clause

/*-

 * Copyright 2005,2007,2009 Colin Percival

 * All rights reserved.

 */

#include <zebra.h>

#include "sha256.h"

#if !HAVE_DECL_BE32DEC

static inline uint32_t be32dec(const void *pp)

{

  const uint8_t *p = (uint8_t const *)pp;

  return ((uint32_t)(p[3]) + ((uint32_t)(p[2]) << 8)

    + ((uint32_t)(p[1]) << 16) + ((uint32_t)(p[0]) << 24));

}

#endif

#if !HAVE_DECL_BE32ENC

static inline void be32enc(void *pp, uint32_t x)

{

  uint8_t *p = (uint8_t *)pp;

  p[3] = x & 0xff;

  p[2] = (x >> 8) & 0xff;

  p[1] = (x >> 16) & 0xff;

  p[0] = (x >> 24) & 0xff;

}

#endif

/*

 * 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. */

  explicit_bzero(W, 256);

  explicit_bzero(S, 32);

  explicit_bzero(&t0, sizeof(t0));

  explicit_bzero(&t1, sizeof(t0));

}

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 *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(ctx, PAD, (size_t)plen);

  /* Add the terminating bit-count */

  SHA256_Update(ctx, len, 8);

}

/* SHA-256 initialization.  Begins a SHA-256 operation. */

void SHA256_Init(SHA256_CTX *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(SHA256_CTX *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(unsigned char digest[32], SHA256_CTX *ctx)

{

  /* Add padding */

  SHA256_Pad(ctx);

  /* Write the hash */

  be32enc_vect(digest, ctx->state, 32);

  /* Clear the context state */

  explicit_bzero((void *)ctx, sizeof(*ctx));

}

/* Initialize an HMAC-SHA256 operation with the given key. */

void HMAC__SHA256_Init(HMAC_SHA256_CTX *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(&ctx->ictx);

    SHA256_Update(&ctx->ictx, K, Klen);

    SHA256_Final(khash, &ctx->ictx);

    K = khash;

    Klen = 32;

  }

  /* Inner SHA256 operation is SHA256(K xor [block of 0x36] || data). */

  SHA256_Init(&ctx->ictx);

  memset(pad, 0x36, 64);

  for (i = 0; i < Klen; i++)

    pad[i] ^= K[i];

  SHA256_Update(&ctx->ictx, pad, 64);

  /* Outer SHA256 operation is SHA256(K xor [block of 0x5c] || hash). */

  SHA256_Init(&ctx->octx);

  memset(pad, 0x5c, 64);

  for (i = 0; i < Klen; i++)

    pad[i] ^= K[i];

  SHA256_Update(&ctx->octx, pad, 64);

  /* Clean the stack. */

  explicit_bzero(khash, 32);

}

/* Add bytes to the HMAC-SHA256 operation. */

void HMAC__SHA256_Update(HMAC_SHA256_CTX *ctx, const void *in, size_t len)

{

  /* Feed data to the inner SHA256 operation. */

  SHA256_Update(&ctx->ictx, in, len);

}

/* Finish an HMAC-SHA256 operation. */

void HMAC__SHA256_Final(unsigned char digest[32], HMAC_SHA256_CTX *ctx)

{

  unsigned char ihash[32];

  /* Finish the inner SHA256 operation. */

  SHA256_Final(ihash, &ctx->ictx);

  /* Feed the inner hash to the outer SHA256 operation. */

  SHA256_Update(&ctx->octx, ihash, 32);

  /* Finish the outer SHA256 operation. */

  SHA256_Final(digest, &ctx->octx);

  /* Clean the stack. */

  explicit_bzero(ihash, 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 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(&PShctx, passwd, passwdlen);

  HMAC__SHA256_Update(&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));

    HMAC__SHA256_Update(&hctx, ivec, 4);

    HMAC__SHA256_Final(U, &hctx);

    /* T_i = U_1 ... */

    memcpy(T, U, 32);

    for (j = 2; j <= c; j++) {

      /* Compute U_j. */

      HMAC__SHA256_Init(&hctx, passwd, passwdlen);

      HMAC__SHA256_Update(&hctx, U, 32);

      HMAC__SHA256_Final(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. */

  explicit_bzero(&PShctx, sizeof(HMAC_SHA256_CTX));

}