text: /*
   * SHA-256 hash implementation and interface functions
   * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
   *
   * Hardware crypto support Copyright 2017 Espressif Systems (Shanghai) PTE LTD
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * Alternatively, this software may be distributed under the terms of BSD
   * license.
   *
   * See README and COPYING for more details.
   */
  
  #include "utils/includes.h"
  
  #include "utils/common.h"
  #include "crypto/sha256.h"
  #include "crypto/crypto.h"
  
  
  /**
   * fast_hmac_sha256_vector - HMAC-SHA256 over data vector (RFC 2104)
   * @key: Key for HMAC operations
   * @key_len: Length of the key in bytes
   * @num_elem: Number of elements in the data vector
   * @addr: Pointers to the data areas
   * @len: Lengths of the data blocks
   * @mac: Buffer for the hash (32 bytes)
   */
  void 
  fast_hmac_sha256_vector(const uint8_t *key, size_t key_len, size_t num_elem,
  			const uint8_t *addr[], const size_t *len, uint8_t *mac)
  {
      uint8_t k_pad[64]; /* padding - key XORd with ipad/opad */
      uint8_t tk[32];
      const uint8_t *_addr[6];
      size_t _len[6], i;
  
      if (num_elem > 5) {
          /*
           * Fixed limit on the number of fragments to avoid having to
           * allocate memory (which could fail).
           */
          return;
      }
  
      /* if key is longer than 64 bytes reset it to key = SHA256(key) */
      if (key_len > 64) {
          fast_sha256_vector(1, &key, &key_len, tk);
          key = tk;
          key_len = 32;
      }
  
      /* the HMAC_SHA256 transform looks like:
       *
       * SHA256(K XOR opad, SHA256(K XOR ipad, text))
       *
       * where K is an n byte key
       * ipad is the byte 0x36 repeated 64 times
       * opad is the byte 0x5c repeated 64 times
       * and text is the data being protected 
       */
  
      /* start out by storing key in ipad */
      os_memset(k_pad, 0, sizeof(k_pad));
      os_memcpy(k_pad, key, key_len);
      /* XOR key with ipad values */
      for (i = 0; i < 64; i++) {
          k_pad[i] ^= 0x36;
      }
  
      /* perform inner SHA256 */
      _addr[0] = k_pad;
      _len[0] = 64;
      for (i = 0; i < num_elem; i++) {
          _addr[i + 1] = addr[i];
          _len[i + 1] = len[i];
      }
      fast_sha256_vector(1 + num_elem, _addr, _len, mac);
  
      os_memset(k_pad, 0, sizeof(k_pad));
      os_memcpy(k_pad, key, key_len);
      /* XOR key with opad values */
      for (i = 0; i < 64; i++) {
          k_pad[i] ^= 0x5c;
      }
  
      /* perform outer SHA256 */
      _addr[0] = k_pad;
      _len[0] = 64;
      _addr[1] = mac;
      _len[1] = SHA256_MAC_LEN;
      fast_sha256_vector(2, _addr, _len, mac);
  }
  
  
  /**
   * fast_hmac_sha256 - HMAC-SHA256 over data buffer (RFC 2104)
   * @key: Key for HMAC operations
   * @key_len: Length of the key in bytes
   * @data: Pointers to the data area
   * @data_len: Length of the data area
   * @mac: Buffer for the hash (20 bytes)
   */
  void 
  fast_hmac_sha256(const uint8_t *key, size_t key_len, const uint8_t *data,
  		 size_t data_len, uint8_t *mac)
  {
      fast_hmac_sha256_vector(key, key_len, 1, &data, &data_len, mac);
  }
  
  
  /**
   * fast_sha256_prf - SHA256-based Pseudo-Random Function (IEEE 802.11r, 8.5.1.5.2)
   * @key: Key for PRF
   * @key_len: Length of the key in bytes
   * @label: A unique label for each purpose of the PRF
   * @data: Extra data to bind into the key
   * @data_len: Length of the data
   * @buf: Buffer for the generated pseudo-random key
   * @buf_len: Number of bytes of key to generate
   *
   * This function is used to derive new, cryptographically separate keys from a
   * given key.
   */
  void 
  fast_sha256_prf(const uint8_t *key, size_t key_len, const char *label,
  		const uint8_t *data, size_t data_len, uint8_t *buf, size_t buf_len)
  {
      uint16_t counter = 1;
      size_t pos, plen;
      uint8_t hash[SHA256_MAC_LEN];
      const uint8_t *addr[4];
      size_t len[4];
      uint8_t counter_le[2], length_le[2];
  
      addr[0] = counter_le;
      len[0] = 2;
      addr[1] = (uint8_t *) label;
      len[1] = os_strlen(label);
      addr[2] = data;
      len[2] = data_len;
      addr[3] = length_le;
      len[3] = sizeof(length_le);
  
      WPA_PUT_LE16(length_le, buf_len * 8);
      pos = 0;
      while (pos < buf_len) {
          plen = buf_len - pos;
          WPA_PUT_LE16(counter_le, counter);
          if (plen >= SHA256_MAC_LEN) {
              fast_hmac_sha256_vector(key, key_len, 4, addr, len,
  		                    &buf[pos]);
              pos += SHA256_MAC_LEN;
          } else {
              fast_hmac_sha256_vector(key, key_len, 4, addr, len, hash);
              os_memcpy(&buf[pos], hash, plen);
              break;
          }
          counter++;
      }
  }
  