1 files changed, 296 insertions, 0 deletions
diff --git a/src/es384.c b/src/es384.c
new file mode 100644
index 0000000..013d285
--- /dev/null
+++ b/src/es384.c
@@ -0,0 +1,296 @@
+/*
+ * Copyright (c) 2022 Yubico AB. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <openssl/bn.h>
+#include <openssl/ecdsa.h>
+#include <openssl/obj_mac.h>
+
+#include "fido.h"
+#include "fido/es384.h"
+
+#if OPENSSL_VERSION_NUMBER >= 0x30000000
+#define get0_EC_KEY(x)	EVP_PKEY_get0_EC_KEY((x))
+#else
+#define get0_EC_KEY(x)	EVP_PKEY_get0((x))
+#endif
+
+static int
+decode_coord(const cbor_item_t *item, void *xy, size_t xy_len)
+{
+	if (cbor_isa_bytestring(item) == false ||
+	    cbor_bytestring_is_definite(item) == false ||
+	    cbor_bytestring_length(item) != xy_len) {
+		fido_log_debug("%s: cbor type", __func__);
+		return (-1);
+	}
+
+	memcpy(xy, cbor_bytestring_handle(item), xy_len);
+
+	return (0);
+}
+
+static int
+decode_pubkey_point(const cbor_item_t *key, const cbor_item_t *val, void *arg)
+{
+	es384_pk_t *k = arg;
+
+	if (cbor_isa_negint(key) == false ||
+	    cbor_int_get_width(key) != CBOR_INT_8)
+		return (0); /* ignore */
+
+	switch (cbor_get_uint8(key)) {
+	case 1: /* x coordinate */
+		return (decode_coord(val, &k->x, sizeof(k->x)));
+	case 2: /* y coordinate */
+		return (decode_coord(val, &k->y, sizeof(k->y)));
+	}
+
+	return (0); /* ignore */
+}
+
+int
+es384_pk_decode(const cbor_item_t *item, es384_pk_t *k)
+{
+	if (cbor_isa_map(item) == false ||
+	    cbor_map_is_definite(item) == false ||
+	    cbor_map_iter(item, k, decode_pubkey_point) < 0) {
+		fido_log_debug("%s: cbor type", __func__);
+		return (-1);
+	}
+
+	return (0);
+}
+
+es384_pk_t *
+es384_pk_new(void)
+{
+	return (calloc(1, sizeof(es384_pk_t)));
+}
+
+void
+es384_pk_free(es384_pk_t **pkp)
+{
+	es384_pk_t *pk;
+
+	if (pkp == NULL || (pk = *pkp) == NULL)
+		return;
+
+	freezero(pk, sizeof(*pk));
+	*pkp = NULL;
+}
+
+int
+es384_pk_from_ptr(es384_pk_t *pk, const void *ptr, size_t len)
+{
+	const uint8_t	*p = ptr;
+	EVP_PKEY	*pkey;
+
+	if (len < sizeof(*pk))
+		return (FIDO_ERR_INVALID_ARGUMENT);
+
+	if (len == sizeof(*pk) + 1 && *p == 0x04)
+		memcpy(pk, ++p, sizeof(*pk)); /* uncompressed format */
+	else
+		memcpy(pk, ptr, sizeof(*pk)); /* libfido2 x||y format */
+
+	if ((pkey = es384_pk_to_EVP_PKEY(pk)) == NULL) {
+		fido_log_debug("%s: es384_pk_to_EVP_PKEY", __func__);
+		explicit_bzero(pk, sizeof(*pk));
+		return (FIDO_ERR_INVALID_ARGUMENT);
+	}
+
+	EVP_PKEY_free(pkey);
+
+	return (FIDO_OK);
+}
+
+EVP_PKEY *
+es384_pk_to_EVP_PKEY(const es384_pk_t *k)
+{
+	BN_CTX		*bnctx = NULL;
+	EC_KEY		*ec = NULL;
+	EC_POINT	*q = NULL;
+	EVP_PKEY	*pkey = NULL;
+	BIGNUM		*x = NULL;
+	BIGNUM		*y = NULL;
+	const EC_GROUP	*g = NULL;
+	int		 ok = -1;
+
+	if ((bnctx = BN_CTX_new()) == NULL)
+		goto fail;
+
+	BN_CTX_start(bnctx);
+
+	if ((x = BN_CTX_get(bnctx)) == NULL ||
+	    (y = BN_CTX_get(bnctx)) == NULL)
+		goto fail;
+
+	if (BN_bin2bn(k->x, sizeof(k->x), x) == NULL ||
+	    BN_bin2bn(k->y, sizeof(k->y), y) == NULL) {
+		fido_log_debug("%s: BN_bin2bn", __func__);
+		goto fail;
+	}
+
+	if ((ec = EC_KEY_new_by_curve_name(NID_secp384r1)) == NULL ||
+	    (g = EC_KEY_get0_group(ec)) == NULL) {
+		fido_log_debug("%s: EC_KEY init", __func__);
+		goto fail;
+	}
+
+	if ((q = EC_POINT_new(g)) == NULL ||
+	    EC_POINT_set_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
+	    EC_KEY_set_public_key(ec, q) == 0) {
+		fido_log_debug("%s: EC_KEY_set_public_key", __func__);
+		goto fail;
+	}
+
+	if ((pkey = EVP_PKEY_new()) == NULL ||
+	    EVP_PKEY_assign_EC_KEY(pkey, ec) == 0) {
+		fido_log_debug("%s: EVP_PKEY_assign_EC_KEY", __func__);
+		goto fail;
+	}
+
+	ec = NULL; /* at this point, ec belongs to evp */
+
+	ok = 0;
+fail:
+	if (bnctx != NULL) {
+		BN_CTX_end(bnctx);
+		BN_CTX_free(bnctx);
+	}
+
+	if (ec != NULL)
+		EC_KEY_free(ec);
+	if (q != NULL)
+		EC_POINT_free(q);
+
+	if (ok < 0 && pkey != NULL) {
+		EVP_PKEY_free(pkey);
+		pkey = NULL;
+	}
+
+	return (pkey);
+}
+
+int
+es384_pk_from_EC_KEY(es384_pk_t *pk, const EC_KEY *ec)
+{
+	BN_CTX		*bnctx = NULL;
+	BIGNUM		*x = NULL;
+	BIGNUM		*y = NULL;
+	const EC_POINT	*q = NULL;
+	EC_GROUP	*g = NULL;
+	size_t		 dx;
+	size_t		 dy;
+	int		 ok = FIDO_ERR_INTERNAL;
+	int		 nx;
+	int		 ny;
+
+	if ((q = EC_KEY_get0_public_key(ec)) == NULL ||
+	    (g = EC_GROUP_new_by_curve_name(NID_secp384r1)) == NULL ||
+	    (bnctx = BN_CTX_new()) == NULL)
+		goto fail;
+
+	BN_CTX_start(bnctx);
+
+	if ((x = BN_CTX_get(bnctx)) == NULL ||
+	    (y = BN_CTX_get(bnctx)) == NULL)
+		goto fail;
+
+	if (EC_POINT_is_on_curve(g, q, bnctx) != 1) {
+		fido_log_debug("%s: EC_POINT_is_on_curve", __func__);
+		ok = FIDO_ERR_INVALID_ARGUMENT;
+		goto fail;
+	}
+
+	if (EC_POINT_get_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
+	    (nx = BN_num_bytes(x)) < 0 || (size_t)nx > sizeof(pk->x) ||
+	    (ny = BN_num_bytes(y)) < 0 || (size_t)ny > sizeof(pk->y)) {
+		fido_log_debug("%s: EC_POINT_get_affine_coordinates_GFp",
+		    __func__);
+		goto fail;
+	}
+
+	dx = sizeof(pk->x) - (size_t)nx;
+	dy = sizeof(pk->y) - (size_t)ny;
+
+	if ((nx = BN_bn2bin(x, pk->x + dx)) < 0 || (size_t)nx > sizeof(pk->x) ||
+	    (ny = BN_bn2bin(y, pk->y + dy)) < 0 || (size_t)ny > sizeof(pk->y)) {
+		fido_log_debug("%s: BN_bn2bin", __func__);
+		goto fail;
+	}
+
+	ok = FIDO_OK;
+fail:
+	EC_GROUP_free(g);
+
+	if (bnctx != NULL) {
+		BN_CTX_end(bnctx);
+		BN_CTX_free(bnctx);
+	}
+
+	return (ok);
+}
+
+int
+es384_pk_from_EVP_PKEY(es384_pk_t *pk, const EVP_PKEY *pkey)
+{
+	const EC_KEY *ec;
+
+	if (EVP_PKEY_base_id(pkey) != EVP_PKEY_EC ||
+	    (ec = get0_EC_KEY(pkey)) == NULL)
+		return (FIDO_ERR_INVALID_ARGUMENT);
+
+	return (es384_pk_from_EC_KEY(pk, ec));
+}
+
+int
+es384_verify_sig(const fido_blob_t *dgst, EVP_PKEY *pkey,
+    const fido_blob_t *sig)
+{
+	EVP_PKEY_CTX	*pctx = NULL;
+	int		 ok = -1;
+
+	if (EVP_PKEY_base_id(pkey) != EVP_PKEY_EC) {
+		fido_log_debug("%s: EVP_PKEY_base_id", __func__);
+		goto fail;
+	}
+
+	if ((pctx = EVP_PKEY_CTX_new(pkey, NULL)) == NULL ||
+	    EVP_PKEY_verify_init(pctx) != 1 ||
+	    EVP_PKEY_verify(pctx, sig->ptr, sig->len, dgst->ptr,
+	    dgst->len) != 1) {
+		fido_log_debug("%s: EVP_PKEY_verify", __func__);
+		goto fail;
+	}
+
+	ok = 0;
+fail:
+	EVP_PKEY_CTX_free(pctx);
+
+	return (ok);
+}
+
+int
+es384_pk_verify_sig(const fido_blob_t *dgst, const es384_pk_t *pk,
+    const fido_blob_t *sig)
+{
+	EVP_PKEY	*pkey;
+	int		 ok = -1;
+
+	if ((pkey = es384_pk_to_EVP_PKEY(pk)) == NULL ||
+	    es384_verify_sig(dgst, pkey, sig) < 0) {
+		fido_log_debug("%s: es384_verify_sig", __func__);
+		goto fail;
+	}
+
+	ok = 0;
+fail:
+	EVP_PKEY_free(pkey);
+
+	return (ok);
+}