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gpg: Implement Kyber encryption.
* g10/build-packet.c (do_pubkey_enc): Support Kyber. * g10/pkglue.c (do_encrypt_kem): Implement. -- Note that the code does only work for ky768_cv25519 for now. GnuPG-bug-id: 6815
This commit is contained in:
Werner Koch
parent
4c20d2d273
commit
c736052e9c
@ -987,9 +987,14 @@ do_pubkey_enc( IOBUF out, int ctb, PKT_pubkey_enc *enc )
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if (enc->pubkey_algo == PUBKEY_ALGO_KYBER && i == 2)
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iobuf_put (a, enc->seskey_algo);
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if (enc->pubkey_algo == PUBKEY_ALGO_ECDH && i == 1)
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if (i == 1 && enc->pubkey_algo == PUBKEY_ALGO_ECDH)
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rc = gpg_mpi_write_opaque_nohdr (a, enc->data[i]);
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else if (enc->pubkey_algo == PUBKEY_ALGO_ECDH)
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else if (i == 1 && enc->pubkey_algo == PUBKEY_ALGO_KYBER)
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rc = gpg_mpi_write_opaque_32 (a, enc->data[i], NULL);
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else if (i == 2 && enc->pubkey_algo == PUBKEY_ALGO_KYBER)
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rc = gpg_mpi_write_opaque_nohdr (a, enc->data[i]);
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else if (enc->pubkey_algo == PUBKEY_ALGO_ECDH
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|| enc->pubkey_algo == PUBKEY_ALGO_KYBER)
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rc = sos_write (a, enc->data[i], NULL);
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else
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rc = gpg_mpi_write (a, enc->data[i], NULL);
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209
g10/pkglue.c
209
g10/pkglue.c
@ -423,9 +423,214 @@ static gpg_error_t
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do_encrypt_kem (PKT_public_key *pk, gcry_mpi_t data, int seskey_algo,
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gcry_mpi_t *resarr)
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{
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gpg_error_t err;
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int i;
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unsigned int nbits, n;
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gcry_sexp_t s_data = NULL;
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gcry_cipher_hd_t hd = NULL;
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log_debug ("Implement Kyber encryption\n");
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return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
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const unsigned char *ecc_pubkey;
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size_t ecc_pubkey_len;
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const unsigned char *kyber_pubkey;
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size_t kyber_pubkey_len;
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const unsigned char *seskey;
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size_t seskey_len;
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unsigned char *enc_seskey = NULL;
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size_t enc_seskey_len;
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unsigned char ecc_ct[GCRY_KEM_ECC_X25519_ENCAPS_LEN];
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size_t ecc_ct_len = GCRY_KEM_ECC_X25519_ENCAPS_LEN;
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unsigned char ecc_ecdh[GCRY_KEM_RAW_X25519_SHARED_LEN];
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size_t ecc_ecdh_len = GCRY_KEM_RAW_X25519_SHARED_LEN;
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unsigned char ecc_ss[GCRY_KEM_RAW_X25519_SHARED_LEN];
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size_t ecc_ss_len = GCRY_KEM_RAW_X25519_SHARED_LEN;
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unsigned char kyber_ct[GCRY_KEM_MLKEM768_ENCAPS_LEN];
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size_t kyber_ct_len = GCRY_KEM_MLKEM768_ENCAPS_LEN;
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unsigned char kyber_ss[GCRY_KEM_MLKEM768_SHARED_LEN];
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size_t kyber_ss_len = GCRY_KEM_MLKEM768_SHARED_LEN;
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char fixedinfo[1+MAX_FINGERPRINT_LEN];
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int fixedlen;
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unsigned char kek[32]; /* AES-256 is mandatory. */
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size_t kek_len = 32;
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/* For later error checking we make sure the array is cleared. */
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resarr[0] = resarr[1] = resarr[2] = NULL;
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/* As of now we use KEM only for the combined Kyber and thus a
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* second public key is expected. Right now we take the keys
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* directly from the PK->data elements. */
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/* FIXME: This is only for cv25519 */
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ecc_pubkey = gcry_mpi_get_opaque (pk->pkey[1], &nbits);
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ecc_pubkey_len = (nbits+7)/8;
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if (ecc_pubkey_len != 33)
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{
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if (opt.verbose)
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log_info ("%s: ECC public key length invalid (%zu)\n",
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__func__, ecc_pubkey_len);
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err = gpg_error (GPG_ERR_INV_DATA);
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goto leave;
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}
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ecc_pubkey++; /* Remove the 0x40 prefix. */
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ecc_pubkey_len--;
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if (DBG_CRYPTO)
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log_printhex (ecc_pubkey, ecc_pubkey_len, "ECC pubkey:");
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err = gcry_kem_encap (GCRY_KEM_RAW_X25519,
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ecc_pubkey, ecc_pubkey_len,
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ecc_ct, ecc_ct_len,
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ecc_ecdh, ecc_ecdh_len,
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NULL, 0);
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if (err)
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{
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if (opt.verbose)
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log_info ("%s: gcry_kem_encap for ECC failed\n", __func__);
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goto leave;
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}
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if (DBG_CRYPTO)
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{
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log_printhex (ecc_ct, ecc_ct_len, "ECC ephem:");
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log_printhex (ecc_ecdh, ecc_ecdh_len, "ECC ecdh:");
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}
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err = gnupg_ecc_kem_kdf (ecc_ss, ecc_ss_len,
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GCRY_MD_SHA3_256,
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ecc_ecdh, ecc_ecdh_len,
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ecc_ct, ecc_ct_len,
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ecc_pubkey, ecc_pubkey_len);
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if (err)
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{
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if (opt.verbose)
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log_info ("%s: kdf for ECC failed\n", __func__);
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goto leave;
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}
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if (DBG_CRYPTO)
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log_printhex (ecc_ss, ecc_ss_len, "ECC shared:");
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/* FIXME: This is only for kyber768 */
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kyber_pubkey = gcry_mpi_get_opaque (pk->pkey[2], &nbits);
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kyber_pubkey_len = (nbits+7)/8;
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if (kyber_pubkey_len != GCRY_KEM_MLKEM768_PUBKEY_LEN)
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{
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if (opt.verbose)
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log_info ("%s: Kyber public key length invalid (%zu)\n",
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__func__, kyber_pubkey_len);
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err = gpg_error (GPG_ERR_INV_DATA);
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goto leave;
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}
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if (DBG_CRYPTO)
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log_printhex (kyber_pubkey, kyber_pubkey_len, "|!trunc|Kyber pubkey:");
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err = gcry_kem_encap (GCRY_KEM_MLKEM768,
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kyber_pubkey, kyber_pubkey_len,
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kyber_ct, kyber_ct_len,
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kyber_ss, kyber_ss_len,
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NULL, 0);
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if (err)
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{
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if (opt.verbose)
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log_info ("%s: gcry_kem_encap for ECC failed\n", __func__);
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goto leave;
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}
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if (DBG_CRYPTO)
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{
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log_printhex (kyber_ct, kyber_ct_len, "|!trunc|Kyber ephem:");
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log_printhex (kyber_ss, kyber_ss_len, "Kyber shared:");
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}
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fixedinfo[0] = seskey_algo;
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v5_fingerprint_from_pk (pk, fixedinfo+1, NULL);
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fixedlen = 33;
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err = gnupg_kem_combiner (kek, kek_len,
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ecc_ss, ecc_ss_len, ecc_ct, ecc_ct_len,
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kyber_ss, kyber_ss_len, kyber_ct, kyber_ct_len,
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fixedinfo, fixedlen);
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if (err)
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{
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if (opt.verbose)
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log_info ("%s: KEM combiner failed\n", __func__);
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goto leave;
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}
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if (DBG_CRYPTO)
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log_printhex (kek, kek_len, "KEK:");
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err = gcry_cipher_open (&hd, GCRY_CIPHER_AES256,
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GCRY_CIPHER_MODE_AESWRAP, 0);
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if (!err)
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err = gcry_cipher_setkey (hd, kek, kek_len);
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if (err)
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{
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if (opt.verbose)
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log_error ("%s: failed to initialize AESWRAP: %s\n", __func__,
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gpg_strerror (err));
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goto leave;
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}
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err = gcry_sexp_build (&s_data, NULL, "%m", data);
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if (err)
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goto leave;
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n = gcry_cipher_get_algo_keylen (seskey_algo);
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seskey = gcry_mpi_get_opaque (data, &nbits);
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seskey_len = (nbits+7)/8;
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if (seskey_len != n)
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{
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if (opt.verbose)
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log_info ("%s: session key length %zu"
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" does not match the length for algo %d\n",
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__func__, seskey_len, seskey_algo);
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err = gpg_error (GPG_ERR_INV_DATA);
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goto leave;
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}
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if (DBG_CRYPTO)
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log_printhex (seskey, seskey_len, "seskey:");
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enc_seskey_len = 1 + seskey_len + 8;
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enc_seskey = xtrymalloc (enc_seskey_len);
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if (!enc_seskey || enc_seskey_len > 254)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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enc_seskey[0] = enc_seskey_len - 1;
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err = gcry_cipher_encrypt (hd, enc_seskey+1, enc_seskey_len-1,
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seskey, seskey_len);
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if (err)
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{
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log_error ("%s: wrapping session key failed\n", __func__);
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goto leave;
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}
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if (DBG_CRYPTO)
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log_printhex (enc_seskey, enc_seskey_len, "enc_seskey:");
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resarr[0] = gcry_mpi_set_opaque_copy (NULL, ecc_ct, 8 * ecc_ct_len);
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if (resarr[0])
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resarr[1] = gcry_mpi_set_opaque_copy (NULL, kyber_ct, 8 * kyber_ct_len);
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if (resarr[1])
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resarr[2] = gcry_mpi_set_opaque_copy (NULL, enc_seskey, 8 * enc_seskey_len);
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if (!resarr[0] || !resarr[1] || !resarr[2])
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{
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err = gpg_error_from_syserror ();
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for (i=0; i < 3; i++)
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gcry_mpi_release (resarr[i]), resarr[i] = NULL;
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}
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leave:
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wipememory (ecc_ct, ecc_ct_len);
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wipememory (ecc_ecdh, ecc_ecdh_len);
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wipememory (ecc_ss, ecc_ss_len);
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wipememory (kyber_ct, kyber_ct_len);
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wipememory (kyber_ss, kyber_ss_len);
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wipememory (kek, kek_len);
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xfree (enc_seskey);
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gcry_cipher_close (hd);
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return err;
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}
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