--- /dev/null
+/* 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.h"
+
+/**
+ @file dsa_encrypt_key.c
+ DSA Crypto, Tom St Denis
+*/
+
+#ifdef LTC_MDSA
+
+/**
+ Encrypt a symmetric key with DSA
+ @param in The symmetric key you want to encrypt
+ @param inlen The length of the key to encrypt (octets)
+ @param out [out] The destination for the ciphertext
+ @param outlen [in/out] The max size and resulting size of the ciphertext
+ @param prng An active PRNG state
+ @param wprng The index of the PRNG you wish to use
+ @param hash The index of the hash you want to use
+ @param key The DSA key you want to encrypt to
+ @return CRYPT_OK if successful
+*/
+int dsa_encrypt_key(const unsigned char *in, unsigned long inlen,
+ unsigned char *out, unsigned long *outlen,
+ prng_state *prng, int wprng, int hash,
+ dsa_key *key)
+{
+ unsigned char *expt, *skey;
+ void *g_pub, *g_priv;
+ unsigned long x, y;
+ int err;
+
+ LTC_ARGCHK(in != NULL);
+ LTC_ARGCHK(out != NULL);
+ LTC_ARGCHK(outlen != NULL);
+ LTC_ARGCHK(key != NULL);
+
+ /* check that wprng/cipher/hash are not invalid */
+ if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
+ return err;
+ }
+
+ if ((err = hash_is_valid(hash)) != CRYPT_OK) {
+ return err;
+ }
+
+ if (inlen > hash_descriptor[hash].hashsize) {
+ return CRYPT_INVALID_HASH;
+ }
+
+ /* make a random key and export the public copy */
+ if ((err = mp_init_multi(&g_pub, &g_priv, NULL)) != CRYPT_OK) {
+ return err;
+ }
+
+ expt = XMALLOC(mp_unsigned_bin_size(key->p) + 1);
+ skey = XMALLOC(MAXBLOCKSIZE);
+ if (expt == NULL || skey == NULL) {
+ if (expt != NULL) {
+ XFREE(expt);
+ }
+ if (skey != NULL) {
+ XFREE(skey);
+ }
+ mp_clear_multi(g_pub, g_priv, NULL);
+ return CRYPT_MEM;
+ }
+
+ /* make a random g_priv, g_pub = g^x pair
+ private key x should be in range: 1 <= x <= q-1 (see FIPS 186-4 B.1.2)
+ */
+ if ((err = rand_bn_upto(g_priv, key->q, prng, wprng)) != CRYPT_OK) {
+ goto LBL_ERR;
+ }
+
+ /* compute y */
+ if ((err = mp_exptmod(key->g, g_priv, key->p, g_pub)) != CRYPT_OK) {
+ goto LBL_ERR;
+ }
+
+ /* make random key */
+ x = mp_unsigned_bin_size(key->p) + 1;
+ if ((err = dsa_shared_secret(g_priv, key->y, key, expt, &x)) != CRYPT_OK) {
+ goto LBL_ERR;
+ }
+
+ y = MAXBLOCKSIZE;
+ if ((err = hash_memory(hash, expt, x, skey, &y)) != CRYPT_OK) {
+ goto LBL_ERR;
+ }
+
+ /* Encrypt key */
+ for (x = 0; x < inlen; x++) {
+ skey[x] ^= in[x];
+ }
+
+ err = der_encode_sequence_multi(out, outlen,
+ LTC_ASN1_OBJECT_IDENTIFIER, hash_descriptor[hash].OIDlen, hash_descriptor[hash].OID,
+ LTC_ASN1_INTEGER, 1UL, g_pub,
+ LTC_ASN1_OCTET_STRING, inlen, skey,
+ LTC_ASN1_EOL, 0UL, NULL);
+
+LBL_ERR:
+#ifdef LTC_CLEAN_STACK
+ /* clean up */
+ zeromem(expt, mp_unsigned_bin_size(key->p) + 1);
+ zeromem(skey, MAXBLOCKSIZE);
+#endif
+
+ XFREE(skey);
+ XFREE(expt);
+
+ mp_clear_multi(g_pub, g_priv, NULL);
+ return err;
+}
+
+#endif
+/* ref: $Format:%D$ */
+/* git commit: $Format:%H$ */
+/* commit time: $Format:%ai$ */
+