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Diffstat (limited to '')
| -rw-r--r-- | src/es384.c | 296 |
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); +} |