Add bootutil support for ed25519 validation
Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/bootutil/include/bootutil/image.h b/boot/bootutil/include/bootutil/image.h
index 4a9ad9d..22f6e62 100644
--- a/boot/bootutil/include/bootutil/image.h
+++ b/boot/bootutil/include/bootutil/image.h
@@ -73,6 +73,7 @@
#define IMAGE_TLV_ECDSA224 0x21 /* ECDSA of hash output */
#define IMAGE_TLV_ECDSA256 0x22 /* ECDSA of hash output */
#define IMAGE_TLV_RSA3072_PSS 0x23 /* RSA3072 of hash output */
+#define IMAGE_TLV_ED25519 0x24 /* ed25519 of hash output */
#define IMAGE_TLV_ENC_RSA2048 0x30 /* Key encrypted with RSA-OAEP-2048 */
#define IMAGE_TLV_ENC_KW128 0x31 /* Key encrypted with AES-KW-128 */
diff --git a/boot/bootutil/src/image_ed25519.c b/boot/bootutil/src/image_ed25519.c
new file mode 100644
index 0000000..ebcf00e
--- /dev/null
+++ b/boot/bootutil/src/image_ed25519.c
@@ -0,0 +1,106 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <string.h>
+
+#include "mcuboot_config/mcuboot_config.h"
+
+#ifdef MCUBOOT_SIGN_ED25519
+#include "bootutil/sign_key.h"
+
+#include "mbedtls/oid.h"
+#include "mbedtls/asn1.h"
+
+#include "bootutil_priv.h"
+
+static const uint8_t ed25519_pubkey_oid[] = MBEDTLS_OID_ISO_IDENTIFIED_ORG "\x65\x70";
+#define NUM_ED25519_BYTES 32
+
+extern int ED25519_verify(const uint8_t *message, size_t message_len,
+ const uint8_t signature[64],
+ const uint8_t public_key[32]);
+
+/*
+ * Parse the public key used for signing.
+ */
+static int
+bootutil_import_key(uint8_t **cp, uint8_t *end)
+{
+ size_t len;
+ mbedtls_asn1_buf alg;
+ mbedtls_asn1_buf param;
+
+ if (mbedtls_asn1_get_tag(cp, end, &len,
+ MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) {
+ return -1;
+ }
+ end = *cp + len;
+
+ if (mbedtls_asn1_get_alg(cp, end, &alg, ¶m)) {
+ return -2;
+ }
+
+ if (alg.len != sizeof(ed25519_pubkey_oid) - 1 ||
+ memcmp(alg.p, ed25519_pubkey_oid, sizeof(ed25519_pubkey_oid) - 1)) {
+ return -3;
+ }
+
+ if (mbedtls_asn1_get_bitstring_null(cp, end, &len)) {
+ return -4;
+ }
+ if (*cp + len != end) {
+ return -5;
+ }
+
+ if (len != NUM_ED25519_BYTES) {
+ return -6;
+ }
+
+ return 0;
+}
+
+int
+bootutil_verify_sig(uint8_t *hash, uint32_t hlen, uint8_t *sig, size_t slen,
+ uint8_t key_id)
+{
+ int rc;
+ uint8_t *pubkey;
+ uint8_t *end;
+
+ if (hlen != 32 || slen != 64) {
+ return -1;
+ }
+
+ pubkey = (uint8_t *)bootutil_keys[key_id].key;
+ end = pubkey + *bootutil_keys[key_id].len;
+
+ rc = bootutil_import_key(&pubkey, end);
+ if (rc) {
+ return -1;
+ }
+
+ rc = ED25519_verify(hash, 32, sig, pubkey);
+ if (rc == 0) {
+ return -2;
+ }
+
+ return 0;
+}
+
+#endif /* MCUBOOT_SIGN_ED25519 */
diff --git a/boot/bootutil/src/image_validate.c b/boot/bootutil/src/image_validate.c
index 6597a81..9cff0ac 100644
--- a/boot/bootutil/src/image_validate.c
+++ b/boot/bootutil/src/image_validate.c
@@ -123,9 +123,10 @@
* call. List the type of TLV we are expecting. If we aren't
* configured for any signature, don't define this macro.
*/
-#if (defined(MCUBOOT_SIGN_RSA) + \
- defined(MCUBOOT_SIGN_EC) + \
- defined(MCUBOOT_SIGN_EC256)) > 1
+#if (defined(MCUBOOT_SIGN_RSA) + \
+ defined(MCUBOOT_SIGN_EC) + \
+ defined(MCUBOOT_SIGN_EC256) + \
+ defined(MCUBOOT_SIGN_ED25519)) > 1
#error "Only a single signature type is supported!"
#endif
@@ -147,6 +148,10 @@
# define EXPECTED_SIG_TLV IMAGE_TLV_ECDSA256
# define SIG_BUF_SIZE 128
# define EXPECTED_SIG_LEN(x) ((x) >= 72) /* oids + 2 * 32 bytes */
+#elif defined(MCUBOOT_SIGN_ED25519)
+# define EXPECTED_SIG_TLV IMAGE_TLV_ED25519
+# define SIG_BUF_SIZE 64
+# define EXPECTED_SIG_LEN(x) ((x) == SIG_BUF_SIZE)
#else
# define SIG_BUF_SIZE 32 /* no signing, sha256 digest only */
#endif