sec/Security/vmdh.c

   1 /*
   2  *  vmdh.c
   3  *  Security
   4  *
   5  *  Created by Michael Brouwer on 11/7/06.
   6  *  Copyright (c) 2006-2007 Apple Inc. All Rights Reserved.
   7  *
   8  */
   9
  10 /*!
  11         @header vmdh
  12         The functions provided in vmdh.h implement the crypto exchange required
  13     for a Diffie-Hellman voicemail exchange.
  14 */
  15
  16
  17 #include "vmdh.h"
  18 #include <CommonCrypto/CommonCryptor.h>
  19 #include <security_utilities/debugging.h>
  20 #include <string.h>
  21 #include <Security/SecInternal.h>
  22 #include <Security/SecDH.h>
  23
  24 vmdh_t vmdh_create(uint32_t g, const uint8_t *p, size_t p_len,
  25     const uint8_t *recip, size_t recip_len) {
  26         SecDHContext dh;
  27         if (SecDHCreate(g, p, p_len, 0/*l*/, recip, recip_len, &dh))
  28                 return NULL;
  29         return (vmdh_t)dh;
  30 }
  31
  32 bool vmdh_generate_key(vmdh_t vmdh, uint8_t *pub_key, size_t *pub_key_len) {
  33         return !SecDHGenerateKeypair((SecDHContext)vmdh, pub_key, pub_key_len);
  34 }
  35
  36 bool vmdh_encrypt_password(vmdh_t vmdh,
  37         const uint8_t *pub_key, size_t pub_key_len,
  38     const uint8_t *pw, size_t pw_len, uint8_t *encpw, size_t *encpw_len) {
  39         uint8_t aes_key[kCCKeySizeAES128];
  40         size_t aes_key_len = kCCKeySizeAES128;
  41
  42         if (SecDHComputeKey((SecDHContext)vmdh, pub_key, pub_key_len,
  43                 aes_key, &aes_key_len)) {
  44                 return false;
  45         }
  46
  47     /* Use the first 16 bytes in aes_key as an AES key. */
  48         if (CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
  49                 kCCOptionPKCS7Padding, aes_key, kCCKeySizeAES128, NULL,
  50                 pw, pw_len, encpw, *encpw_len, encpw_len)) {
  51                 return false;
  52         }
  53
  54         /* Zero out key material. */
  55         bzero(aes_key, kCCKeySizeAES128);
  56
  57     return true;
  58 }
  59
  60 void vmdh_destroy(vmdh_t vmdh) {
  61     return SecDHDestroy((SecDHContext)vmdh);
  62 }