90 lines
2.9 KiB
C
90 lines
2.9 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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#include "tomcrypt_private.h"
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#ifdef LTC_MDH
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/**
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Import a DH key from a binary packet
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@param in The packet to read
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@param inlen The length of the input packet
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@param key [out] Where to import the key to
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@return CRYPT_OK if successful, on error all allocated memory is freed automatically
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*/
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int dh_import(const unsigned char *in, unsigned long inlen, dh_key *key)
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{
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unsigned char flags[1];
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int err;
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unsigned long version;
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LTC_ARGCHK(in != NULL);
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LTC_ARGCHK(key != NULL);
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/* init */
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if ((err = dh_init(key)) != CRYPT_OK) {
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return err;
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}
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/* find out what type of key it is */
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err = der_decode_sequence_multi(in, inlen,
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LTC_ASN1_SHORT_INTEGER, 1UL, &version,
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LTC_ASN1_BIT_STRING, 1UL, &flags,
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LTC_ASN1_EOL, 0UL, NULL);
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if (err != CRYPT_OK && err != CRYPT_INPUT_TOO_LONG) {
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goto error;
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}
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if (version == 0) {
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if (flags[0] == 1) {
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key->type = PK_PRIVATE;
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if ((err = der_decode_sequence_multi(in, inlen,
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LTC_ASN1_SHORT_INTEGER, 1UL, &version,
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LTC_ASN1_BIT_STRING, 1UL, flags,
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LTC_ASN1_INTEGER, 1UL, key->prime,
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LTC_ASN1_INTEGER, 1UL, key->base,
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LTC_ASN1_INTEGER, 1UL, key->x,
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LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
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goto error;
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}
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/* compute public key: y = (base ^ x) mod prime */
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if ((err = ltc_mp_exptmod(key->base, key->x, key->prime, key->y)) != CRYPT_OK) {
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goto error;
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}
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}
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else if (flags[0] == 0) {
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key->type = PK_PUBLIC;
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if ((err = der_decode_sequence_multi(in, inlen,
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LTC_ASN1_SHORT_INTEGER, 1UL, &version,
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LTC_ASN1_BIT_STRING, 1UL, flags,
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LTC_ASN1_INTEGER, 1UL, key->prime,
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LTC_ASN1_INTEGER, 1UL, key->base,
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LTC_ASN1_INTEGER, 1UL, key->y,
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LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) {
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goto error;
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}
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}
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else {
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err = CRYPT_INVALID_PACKET;
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goto error;
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}
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}
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else {
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err = CRYPT_INVALID_PACKET;
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goto error;
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}
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/* check public key */
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if ((err = dh_check_pubkey(key)) != CRYPT_OK) {
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goto error;
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}
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return CRYPT_OK;
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error:
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dh_free(key);
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return err;
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}
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#endif /* LTC_MDH */
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