Merging upstream version 1:9.9p1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 280 insertions, 0 deletions

diff --git a/kexmlkem768x25519.c b/kexmlkem768x25519.c
new file mode 100644
index 0000000..679446e
--- /dev/null
+++ b/kexmlkem768x25519.c
@@ -0,0 +1,280 @@
+/* $OpenBSD: kexmlkem768x25519.c,v 1.1 2024/09/02 12:13:56 djm Exp $ */
+/*
+ * Copyright (c) 2023 Markus Friedl.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+
+#include <stdio.h>
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#include <stdbool.h>
+#include <string.h>
+#include <signal.h>
+
+#include "sshkey.h"
+#include "kex.h"
+#include "sshbuf.h"
+#include "digest.h"
+#include "ssherr.h"
+#include "log.h"
+
+#ifdef USE_MLKEM768X25519
+
+#include "libcrux_mlkem768_sha3.h"
+
+int
+kex_kem_mlkem768x25519_keypair(struct kex *kex)
+{
+	struct sshbuf *buf = NULL;
+	u_char rnd[LIBCRUX_ML_KEM_KEY_PAIR_PRNG_LEN], *cp = NULL;
+	size_t need;
+	int r = SSH_ERR_INTERNAL_ERROR;
+	struct libcrux_mlkem768_keypair keypair;
+
+	if ((buf = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	need = crypto_kem_mlkem768_PUBLICKEYBYTES + CURVE25519_SIZE;
+	if ((r = sshbuf_reserve(buf, need, &cp)) != 0)
+		goto out;
+	arc4random_buf(rnd, sizeof(rnd));
+	keypair = libcrux_ml_kem_mlkem768_portable_generate_key_pair(rnd);
+	memcpy(cp, keypair.pk.value, crypto_kem_mlkem768_PUBLICKEYBYTES);
+	memcpy(kex->mlkem768_client_key, keypair.sk.value,
+	    sizeof(kex->mlkem768_client_key));
+#ifdef DEBUG_KEXECDH
+	dump_digest("client public key mlkem768:", cp,
+	    crypto_kem_mlkem768_PUBLICKEYBYTES);
+#endif
+	cp += crypto_kem_mlkem768_PUBLICKEYBYTES;
+	kexc25519_keygen(kex->c25519_client_key, cp);
+#ifdef DEBUG_KEXECDH
+	dump_digest("client public key c25519:", cp, CURVE25519_SIZE);
+#endif
+	/* success */
+	r = 0;
+	kex->client_pub = buf;
+	buf = NULL;
+ out:
+	explicit_bzero(&keypair, sizeof(keypair));
+	explicit_bzero(rnd, sizeof(rnd));
+	sshbuf_free(buf);
+	return r;
+}
+
+int
+kex_kem_mlkem768x25519_enc(struct kex *kex,
+   const struct sshbuf *client_blob, struct sshbuf **server_blobp,
+   struct sshbuf **shared_secretp)
+{
+	struct sshbuf *server_blob = NULL;
+	struct sshbuf *buf = NULL;
+	const u_char *client_pub;
+	u_char rnd[LIBCRUX_ML_KEM_ENC_PRNG_LEN];
+	u_char server_pub[CURVE25519_SIZE], server_key[CURVE25519_SIZE];
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t need;
+	int r = SSH_ERR_INTERNAL_ERROR;
+	struct libcrux_mlkem768_enc_result enc;
+	struct libcrux_mlkem768_pk mlkem_pub;
+
+	*server_blobp = NULL;
+	*shared_secretp = NULL;
+	memset(&mlkem_pub, 0, sizeof(mlkem_pub));
+
+	/* client_blob contains both KEM and ECDH client pubkeys */
+	need = crypto_kem_mlkem768_PUBLICKEYBYTES + CURVE25519_SIZE;
+	if (sshbuf_len(client_blob) != need) {
+		r = SSH_ERR_SIGNATURE_INVALID;
+		goto out;
+	}
+	client_pub = sshbuf_ptr(client_blob);
+#ifdef DEBUG_KEXECDH
+	dump_digest("client public key mlkem768:", client_pub,
+	    crypto_kem_mlkem768_PUBLICKEYBYTES);
+	dump_digest("client public key 25519:",
+	    client_pub + crypto_kem_mlkem768_PUBLICKEYBYTES,
+	    CURVE25519_SIZE);
+#endif
+	/* check public key validity */
+	memcpy(mlkem_pub.value, client_pub, crypto_kem_mlkem768_PUBLICKEYBYTES);
+	if (!libcrux_ml_kem_mlkem768_portable_validate_public_key(&mlkem_pub)) {
+		r = SSH_ERR_SIGNATURE_INVALID;
+		goto out;
+	}
+
+	/* allocate buffer for concatenation of KEM key and ECDH shared key */
+	/* the buffer will be hashed and the result is the shared secret */
+	if ((buf = sshbuf_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	/* allocate space for encrypted KEM key and ECDH pub key */
+	if ((server_blob = sshbuf_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	/* generate and encrypt KEM key with client key */
+	arc4random_buf(rnd, sizeof(rnd));
+	enc = libcrux_ml_kem_mlkem768_portable_encapsulate(&mlkem_pub, rnd);
+	/* generate ECDH key pair, store server pubkey after ciphertext */
+	kexc25519_keygen(server_key, server_pub);
+	if ((r = sshbuf_put(buf, enc.snd, sizeof(enc.snd))) != 0 ||
+	    (r = sshbuf_put(server_blob, enc.fst.value, sizeof(enc.fst.value))) != 0 ||
+	    (r = sshbuf_put(server_blob, server_pub, sizeof(server_pub))) != 0)
+		goto out;
+	/* append ECDH shared key */
+	client_pub += crypto_kem_mlkem768_PUBLICKEYBYTES;
+	if ((r = kexc25519_shared_key_ext(server_key, client_pub, buf, 1)) < 0)
+		goto out;
+	if ((r = ssh_digest_buffer(kex->hash_alg, buf, hash, sizeof(hash))) != 0)
+		goto out;
+#ifdef DEBUG_KEXECDH
+	dump_digest("server public key 25519:", server_pub, CURVE25519_SIZE);
+	dump_digest("server cipher text:",
+	    enc.fst.value, sizeof(enc.fst.value));
+	dump_digest("server kem key:", enc.snd, sizeof(enc.snd));
+	dump_digest("concatenation of KEM key and ECDH shared key:",
+	    sshbuf_ptr(buf), sshbuf_len(buf));
+#endif
+	/* string-encoded hash is resulting shared secret */
+	sshbuf_reset(buf);
+	if ((r = sshbuf_put_string(buf, hash,
+	    ssh_digest_bytes(kex->hash_alg))) != 0)
+		goto out;
+#ifdef DEBUG_KEXECDH
+	dump_digest("encoded shared secret:", sshbuf_ptr(buf), sshbuf_len(buf));
+#endif
+	/* success */
+	r = 0;
+	*server_blobp = server_blob;
+	*shared_secretp = buf;
+	server_blob = NULL;
+	buf = NULL;
+ out:
+	explicit_bzero(hash, sizeof(hash));
+	explicit_bzero(server_key, sizeof(server_key));
+	explicit_bzero(rnd, sizeof(rnd));
+	explicit_bzero(&enc, sizeof(enc));
+	sshbuf_free(server_blob);
+	sshbuf_free(buf);
+	return r;
+}
+
+int
+kex_kem_mlkem768x25519_dec(struct kex *kex,
+    const struct sshbuf *server_blob, struct sshbuf **shared_secretp)
+{
+	struct sshbuf *buf = NULL;
+	u_char mlkem_key[crypto_kem_mlkem768_BYTES];
+	const u_char *ciphertext, *server_pub;
+	u_char hash[SSH_DIGEST_MAX_LENGTH];
+	size_t need;
+	int r;
+	struct libcrux_mlkem768_sk mlkem_priv;
+	struct libcrux_mlkem768_ciphertext mlkem_ciphertext;
+
+	*shared_secretp = NULL;
+	memset(&mlkem_priv, 0, sizeof(mlkem_priv));
+	memset(&mlkem_ciphertext, 0, sizeof(mlkem_ciphertext));
+
+	need = crypto_kem_mlkem768_CIPHERTEXTBYTES + CURVE25519_SIZE;
+	if (sshbuf_len(server_blob) != need) {
+		r = SSH_ERR_SIGNATURE_INVALID;
+		goto out;
+	}
+	ciphertext = sshbuf_ptr(server_blob);
+	server_pub = ciphertext + crypto_kem_mlkem768_CIPHERTEXTBYTES;
+	/* hash concatenation of KEM key and ECDH shared key */
+	if ((buf = sshbuf_new()) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	memcpy(mlkem_priv.value, kex->mlkem768_client_key,
+	    sizeof(kex->mlkem768_client_key));
+	memcpy(mlkem_ciphertext.value, ciphertext,
+	    sizeof(mlkem_ciphertext.value));
+#ifdef DEBUG_KEXECDH
+	dump_digest("server cipher text:", mlkem_ciphertext.value,
+	    sizeof(mlkem_ciphertext.value));
+	dump_digest("server public key c25519:", server_pub, CURVE25519_SIZE);
+#endif
+	libcrux_ml_kem_mlkem768_portable_decapsulate(&mlkem_priv,
+	    &mlkem_ciphertext, mlkem_key);
+	if ((r = sshbuf_put(buf, mlkem_key, sizeof(mlkem_key))) != 0)
+		goto out;
+	if ((r = kexc25519_shared_key_ext(kex->c25519_client_key, server_pub,
+	    buf, 1)) < 0)
+		goto out;
+	if ((r = ssh_digest_buffer(kex->hash_alg, buf,
+	    hash, sizeof(hash))) != 0)
+		goto out;
+#ifdef DEBUG_KEXECDH
+	dump_digest("client kem key:", mlkem_key, sizeof(mlkem_key));
+	dump_digest("concatenation of KEM key and ECDH shared key:",
+	    sshbuf_ptr(buf), sshbuf_len(buf));
+#endif
+	sshbuf_reset(buf);
+	if ((r = sshbuf_put_string(buf, hash,
+	    ssh_digest_bytes(kex->hash_alg))) != 0)
+		goto out;
+#ifdef DEBUG_KEXECDH
+	dump_digest("encoded shared secret:", sshbuf_ptr(buf), sshbuf_len(buf));
+#endif
+	/* success */
+	r = 0;
+	*shared_secretp = buf;
+	buf = NULL;
+ out:
+	explicit_bzero(hash, sizeof(hash));
+	explicit_bzero(&mlkem_priv, sizeof(mlkem_priv));
+	explicit_bzero(&mlkem_ciphertext, sizeof(mlkem_ciphertext));
+	explicit_bzero(mlkem_key, sizeof(mlkem_key));
+	sshbuf_free(buf);
+	return r;
+}
+#else /* USE_MLKEM768X25519 */
+int
+kex_kem_mlkem768x25519_keypair(struct kex *kex)
+{
+	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
+}
+
+int
+kex_kem_mlkem768x25519_enc(struct kex *kex,
+   const struct sshbuf *client_blob, struct sshbuf **server_blobp,
+   struct sshbuf **shared_secretp)
+{
+	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
+}
+
+int
+kex_kem_mlkem768x25519_dec(struct kex *kex,
+    const struct sshbuf *server_blob, struct sshbuf **shared_secretp)
+{
+	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
+}
+#endif /* USE_MLKEM768X25519 */