sec/Security/SecPBKDF.c

   1 /*
   2  *  SecPBKDF.c
   3  *
   4  *  Copyright 2010 Apple Inc. All rights reserved.
   5  *
   6  */
   7
   8 #include "Security/SecPBKDF.h"
   9 #include "Security/pbkdf2.h"
  10
  11 #include <CommonCrypto/CommonHMAC.h>
  12
  13 #include <string.h>
  14
  15 /* CC Based HMAC PRF functions */
  16 void hmac_sha1_PRF(const uint8_t *key,
  17                    size_t key_len,
  18                    const uint8_t *text,
  19                    size_t text_len,
  20                    uint8_t digest[CC_SHA1_DIGEST_LENGTH])
  21 {
  22     CCHmacContext hmac_sha1_context;
  23
  24     CCHmacInit(&hmac_sha1_context, kCCHmacAlgSHA1, key, key_len);
  25     CCHmacUpdate(&hmac_sha1_context, text, text_len);
  26     CCHmacFinal(&hmac_sha1_context, digest);
  27 }
  28
  29
  30 /* This implements the HMAC SHA-1 version of pbkdf2 and allocates a local buffer for the HMAC */
  31 void pbkdf2_hmac_sha1(const uint8_t *passwordPtr, size_t passwordLen,
  32                       const uint8_t *saltPtr, size_t saltLen,
  33                       uint32_t iterationCount,
  34                       void *dkPtr, size_t dkLen)
  35 {
  36     // MAX(salt_length + 4, 20 /* SHA1 Digest size */) + 2 * 20;
  37     // salt_length + HASH_SIZE is bigger than either salt + 4 and digestSize.
  38     const size_t kBigEnoughSize = (saltLen + CC_SHA1_DIGEST_LENGTH) + 2 * CC_SHA1_DIGEST_LENGTH;
  39     uint8_t temp_data[kBigEnoughSize];
  40
  41     pbkdf2(hmac_sha1_PRF, CC_SHA1_DIGEST_LENGTH,
  42            passwordPtr, passwordLen,
  43            saltPtr, saltLen,
  44            iterationCount,
  45            dkPtr, dkLen,
  46            temp_data);
  47
  48     bzero(temp_data, kBigEnoughSize);
  49 }
  50
  51
  52 void SecKeyFromPassphraseDataHMACSHA1(CFDataRef password, CFDataRef salt, uint32_t interationCount, CFMutableDataRef derivedKey)
  53 {
  54     pbkdf2_hmac_sha1(CFDataGetBytePtr(password), CFDataGetLength(password),
  55                      CFDataGetBytePtr(salt), CFDataGetLength(salt),
  56                      interationCount,
  57                      CFDataGetMutableBytePtr(derivedKey), CFDataGetLength(derivedKey));
  58
  59 }