crypto/fipsmodule/aes/key_wrap.c

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 *    "This product includes software developed by the OpenSSL Project
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 *    "This product includes software developed by the OpenSSL Project
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#include <openssl/aes.h>

#include <limits.h>
#include <string.h>

#include <openssl/mem.h>

#include "../../internal.h"


// kDefaultIV is the default IV value given in RFC 3394, 2.2.3.1.
static const uint8_t kDefaultIV[] = {
    0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
};

static const unsigned kBound = 6;

int AES_wrap_key(const AES_KEY *key, const uint8_t *iv, uint8_t *out,
                 const uint8_t *in, size_t in_len) {
  // See RFC 3394, section 2.2.1. Additionally, note that section 2 requires the
  // plaintext be at least two 8-byte blocks.

  if (in_len > INT_MAX - 8 || in_len < 16 || in_len % 8 != 0) {
    return -1;
  }

  if (iv == NULL) {
    iv = kDefaultIV;
  }

  OPENSSL_memmove(out + 8, in, in_len);
  uint8_t A[AES_BLOCK_SIZE];
  OPENSSL_memcpy(A, iv, 8);

  size_t n = in_len / 8;

  for (unsigned j = 0; j < kBound; j++) {
    for (size_t i = 1; i <= n; i++) {
      OPENSSL_memcpy(A + 8, out + 8 * i, 8);
      AES_encrypt(A, A, key);

      uint32_t t = (uint32_t)(n * j + i);
      A[7] ^= t & 0xff;
      A[6] ^= (t >> 8) & 0xff;
      A[5] ^= (t >> 16) & 0xff;
      A[4] ^= (t >> 24) & 0xff;
      OPENSSL_memcpy(out + 8 * i, A + 8, 8);
    }
  }

  OPENSSL_memcpy(out, A, 8);
  return (int)in_len + 8;
}

int AES_unwrap_key(const AES_KEY *key, const uint8_t *iv, uint8_t *out,
                   const uint8_t *in, size_t in_len) {
  // See RFC 3394, section 2.2.2. Additionally, note that section 2 requires the
  // plaintext be at least two 8-byte blocks, so the ciphertext must be at least
  // three blocks.

  if (in_len > INT_MAX || in_len < 24 || in_len % 8 != 0) {
    return -1;
  }

  if (iv == NULL) {
    iv = kDefaultIV;
  }

  uint8_t A[AES_BLOCK_SIZE];
  OPENSSL_memcpy(A, in, 8);
  OPENSSL_memmove(out, in + 8, in_len - 8);

  size_t n = (in_len / 8) - 1;

  for (unsigned j = kBound - 1; j < kBound; j--) {
    for (size_t i = n; i > 0; i--) {
      uint32_t t = (uint32_t)(n * j + i);
      A[7] ^= t & 0xff;
      A[6] ^= (t >> 8) & 0xff;
      A[5] ^= (t >> 16) & 0xff;
      A[4] ^= (t >> 24) & 0xff;
      OPENSSL_memcpy(A + 8, out + 8 * (i - 1), 8);
      AES_decrypt(A, A, key);
      OPENSSL_memcpy(out + 8 * (i - 1), A + 8, 8);
    }
  }

  if (CRYPTO_memcmp(A, iv, 8) != 0) {
    return -1;
  }

  return (int)in_len - 8;
}