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      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  * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com
     10  */
     11 #include "tomcrypt.h"
     12 
     13 /**
     14    @file dsa_import.c
     15    DSA implementation, import a DSA key, Tom St Denis
     16 */
     17 
     18 #ifdef MDSA
     19 
     20 /**
     21    Import a DSA key
     22    @param in       The binary packet to import from
     23    @param inlen    The length of the binary packet
     24    @param key      [out] Where to store the imported key
     25    @return CRYPT_OK if successful, upon error this function will free all allocated memory
     26 */
     27 int dsa_import(const unsigned char *in, unsigned long inlen, dsa_key *key)
     28 {
     29    unsigned char flags[1];
     30    int           err;
     31 
     32    LTC_ARGCHK(in  != NULL);
     33    LTC_ARGCHK(key != NULL);
     34    LTC_ARGCHK(ltc_mp.name != NULL);
     35 
     36    /* init key */
     37    if (mp_init_multi(&key->p, &key->g, &key->q, &key->x, &key->y, NULL) != CRYPT_OK) {
     38       return CRYPT_MEM;
     39    }
     40 
     41    /* get key type */
     42    if ((err = der_decode_sequence_multi(in, inlen,
     43                                   LTC_ASN1_BIT_STRING, 1UL, flags,
     44                                   LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
     45       goto error;
     46    }
     47 
     48    if (flags[0] == 1) {
     49       if ((err = der_decode_sequence_multi(in, inlen,
     50                                  LTC_ASN1_BIT_STRING,   1UL, flags,
     51                                  LTC_ASN1_INTEGER,      1UL, key->g,
     52                                  LTC_ASN1_INTEGER,      1UL, key->p,
     53                                  LTC_ASN1_INTEGER,      1UL, key->q,
     54                                  LTC_ASN1_INTEGER,      1UL, key->y,
     55                                  LTC_ASN1_INTEGER,      1UL, key->x,
     56                                  LTC_ASN1_EOL,          0UL, NULL)) != CRYPT_OK) {
     57          goto error;
     58       }
     59       key->type = PK_PRIVATE;
     60    } else {
     61       if ((err = der_decode_sequence_multi(in, inlen,
     62                                  LTC_ASN1_BIT_STRING,   1UL, flags,
     63                                  LTC_ASN1_INTEGER,      1UL, key->g,
     64                                  LTC_ASN1_INTEGER,      1UL, key->p,
     65                                  LTC_ASN1_INTEGER,      1UL, key->q,
     66                                  LTC_ASN1_INTEGER,      1UL, key->y,
     67                                  LTC_ASN1_EOL,          0UL, NULL)) != CRYPT_OK) {
     68          goto error;
     69       }
     70       key->type = PK_PUBLIC;
     71   }
     72   key->qord = mp_unsigned_bin_size(key->q);
     73 
     74   if (key->qord >= MDSA_MAX_GROUP || key->qord <= 15 ||
     75       (unsigned long)key->qord >= mp_unsigned_bin_size(key->p) || (mp_unsigned_bin_size(key->p) - key->qord) >= MDSA_DELTA) {
     76       err = CRYPT_INVALID_PACKET;
     77       goto error;
     78    }
     79 
     80   return CRYPT_OK;
     81 error:
     82    mp_clear_multi(key->p, key->g, key->q, key->x, key->y, NULL);
     83    return err;
     84 }
     85 
     86 #endif
     87 
     88 /* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_import.c,v $ */
     89 /* $Revision: 1.12 $ */
     90 /* $Date: 2006/03/31 14:15:35 $ */
     91