pd.if.org Git - zpackage/blob - libtomcrypt/src/pk/dh/dh_import.c

   1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
   2  *
   3  * LibTomCrypt is a library that provides various cryptographic
   4  * algorithms in a highly modular and flexible manner.
   5  *
   6  * The library is free for all purposes without any express
   7  * guarantee it works.
   8  */
   9
  10 #include "tomcrypt.h"
  11
  12 #ifdef LTC_MDH
  13
  14 /**
  15   Import a DH key from a binary packet
  16   @param in     The packet to read
  17   @param inlen  The length of the input packet
  18   @param key    [out] Where to import the key to
  19   @return CRYPT_OK if successful, on error all allocated memory is freed automatically
  20 */
  21 int dh_import(const unsigned char *in, unsigned long inlen, dh_key *key)
  22 {
  23    unsigned char flags[1];
  24    int err;
  25    unsigned long version;
  26
  27    LTC_ARGCHK(in  != NULL);
  28    LTC_ARGCHK(key != NULL);
  29
  30    /* init */
  31    if ((err = mp_init_multi(&key->x, &key->y, &key->base, &key->prime, NULL)) != CRYPT_OK) {
  32       return err;
  33    }
  34
  35    /* find out what type of key it is */
  36    err = der_decode_sequence_multi(in, inlen,
  37                                    LTC_ASN1_SHORT_INTEGER, 1UL, &version,
  38                                    LTC_ASN1_BIT_STRING, 1UL, &flags,
  39                                    LTC_ASN1_EOL, 0UL, NULL);
  40    if (err != CRYPT_OK && err != CRYPT_INPUT_TOO_LONG) {
  41       goto error;
  42    }
  43
  44    if (version == 0) {
  45       if (flags[0] == 1) {
  46          key->type = PK_PRIVATE;
  47          if ((err = der_decode_sequence_multi(in, inlen,
  48                                               LTC_ASN1_SHORT_INTEGER, 1UL, &version,
  49                                               LTC_ASN1_BIT_STRING,    1UL, flags,
  50                                               LTC_ASN1_INTEGER,       1UL, key->prime,
  51                                               LTC_ASN1_INTEGER,       1UL, key->base,
  52                                               LTC_ASN1_INTEGER,       1UL, key->x,
  53                                               LTC_ASN1_EOL,           0UL, NULL)) != CRYPT_OK) {
  54             goto error;
  55          }
  56          /* compute public key: y = (base ^ x) mod prime */
  57          if ((err = mp_exptmod(key->base, key->x, key->prime, key->y)) != CRYPT_OK) {
  58             goto error;
  59          }
  60       }
  61       else if (flags[0] == 0) {
  62          key->type = PK_PUBLIC;
  63          if ((err = der_decode_sequence_multi(in, inlen,
  64                                               LTC_ASN1_SHORT_INTEGER, 1UL, &version,
  65                                               LTC_ASN1_BIT_STRING,    1UL, flags,
  66                                               LTC_ASN1_INTEGER,       1UL, key->prime,
  67                                               LTC_ASN1_INTEGER,       1UL, key->base,
  68                                               LTC_ASN1_INTEGER,       1UL, key->y,
  69                                               LTC_ASN1_EOL,           0UL, NULL)) != CRYPT_OK) {
  70             goto error;
  71          }
  72       }
  73       else {
  74          err = CRYPT_INVALID_PACKET;
  75          goto error;
  76       }
  77    }
  78    else {
  79       err = CRYPT_INVALID_PACKET;
  80       goto error;
  81    }
  82
  83    /* check public key */
  84    if ((err = dh_check_pubkey(key)) != CRYPT_OK) {
  85       goto error;
  86    }
  87
  88    return CRYPT_OK;
  89
  90 error:
  91    dh_free(key);
  92    return err;
  93 }
  94
  95 #endif /* LTC_MDH */
  96
  97 /* ref:         $Format:%D$ */
  98 /* git commit:  $Format:%H$ */
  99 /* commit time: $Format:%ai$ */