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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
#include "tomcrypt_private.h"
#ifdef LTC_MDH
/**
Import a DH key from a binary packet
@param in The packet to read
@param inlen The length of the input packet
@param key [out] Where to import the key to
@return CRYPT_OK if successful, on error all allocated memory is freed automatically
*/
int dh_import(const unsigned char *in, unsigned long inlen, dh_key *key)
{
unsigned char flags[1];
int err;
unsigned long version;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(key != NULL);
/* init */
if ((err = mp_init_multi(&key->x, &key->y, &key->base, &key->prime, NULL)) != CRYPT_OK) {
return err;
}
/* find out what type of key it is */
err = der_decode_sequence_multi(in, inlen,
LTC_ASN1_SHORT_INTEGER, 1UL, &version,
LTC_ASN1_BIT_STRING, 1UL, &flags,
LTC_ASN1_EOL, 0UL, NULL);
if (err != CRYPT_OK && err != CRYPT_INPUT_TOO_LONG) {
goto error;
}
if (version == 0) {
if (flags[0] == 1) {
key->type = PK_PRIVATE;
if ((err = der_decode_sequence_multi(in, inlen,
LTC_ASN1_SHORT_INTEGER, 1UL, &version,
LTC_ASN1_BIT_STRING, 1UL, flags,
LTC_ASN1_INTEGER, 1UL, key->prime,
LTC_ASN1_INTEGER, 1UL, key->base,
LTC_ASN1_INTEGER, 1UL, key->x,
LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
goto error;
}
/* compute public key: y = (base ^ x) mod prime */
if ((err = mp_exptmod(key->base, key->x, key->prime, key->y)) != CRYPT_OK) {
goto error;
}
}
else if (flags[0] == 0) {
key->type = PK_PUBLIC;
if ((err = der_decode_sequence_multi(in, inlen,
LTC_ASN1_SHORT_INTEGER, 1UL, &version,
LTC_ASN1_BIT_STRING, 1UL, flags,
LTC_ASN1_INTEGER, 1UL, key->prime,
LTC_ASN1_INTEGER, 1UL, key->base,
LTC_ASN1_INTEGER, 1UL, key->y,
LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
goto error;
}
}
else {
err = CRYPT_INVALID_PACKET;
goto error;
}
}
else {
err = CRYPT_INVALID_PACKET;
goto error;
}
/* check public key */
if ((err = dh_check_pubkey(key)) != CRYPT_OK) {
goto error;
}
return CRYPT_OK;
error:
dh_free(key);
return err;
}
#endif /* LTC_MDH */
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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