diff options
Diffstat (limited to '')
| -rw-r--r-- | src/es256.c | 541 |
1 files changed, 541 insertions, 0 deletions
diff --git a/src/es256.c b/src/es256.c new file mode 100644 index 0000000..17efb0a --- /dev/null +++ b/src/es256.c @@ -0,0 +1,541 @@ +/* + * Copyright (c) 2018-2022 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/es256.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 const int es256_nid = NID_X9_62_prime256v1; + +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) +{ + es256_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 +es256_pk_decode(const cbor_item_t *item, es256_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); +} + +cbor_item_t * +es256_pk_encode(const es256_pk_t *pk, int ecdh) +{ + cbor_item_t *item = NULL; + struct cbor_pair argv[5]; + int alg; + int ok = -1; + + memset(argv, 0, sizeof(argv)); + + if ((item = cbor_new_definite_map(5)) == NULL) + goto fail; + + /* kty */ + if ((argv[0].key = cbor_build_uint8(1)) == NULL || + (argv[0].value = cbor_build_uint8(2)) == NULL || + !cbor_map_add(item, argv[0])) + goto fail; + + /* + * "The COSEAlgorithmIdentifier used is -25 (ECDH-ES + + * HKDF-256) although this is NOT the algorithm actually + * used. Setting this to a different value may result in + * compatibility issues." + */ + if (ecdh) + alg = COSE_ECDH_ES256; + else + alg = COSE_ES256; + + /* alg */ + if ((argv[1].key = cbor_build_uint8(3)) == NULL || + (argv[1].value = cbor_build_negint8((uint8_t)(-alg - 1))) == NULL || + !cbor_map_add(item, argv[1])) + goto fail; + + /* crv */ + if ((argv[2].key = cbor_build_negint8(0)) == NULL || + (argv[2].value = cbor_build_uint8(1)) == NULL || + !cbor_map_add(item, argv[2])) + goto fail; + + /* x */ + if ((argv[3].key = cbor_build_negint8(1)) == NULL || + (argv[3].value = cbor_build_bytestring(pk->x, + sizeof(pk->x))) == NULL || !cbor_map_add(item, argv[3])) + goto fail; + + /* y */ + if ((argv[4].key = cbor_build_negint8(2)) == NULL || + (argv[4].value = cbor_build_bytestring(pk->y, + sizeof(pk->y))) == NULL || !cbor_map_add(item, argv[4])) + goto fail; + + ok = 0; +fail: + if (ok < 0) { + if (item != NULL) { + cbor_decref(&item); + item = NULL; + } + } + + for (size_t i = 0; i < 5; i++) { + if (argv[i].key) + cbor_decref(&argv[i].key); + if (argv[i].value) + cbor_decref(&argv[i].value); + } + + return (item); +} + +es256_sk_t * +es256_sk_new(void) +{ + return (calloc(1, sizeof(es256_sk_t))); +} + +void +es256_sk_free(es256_sk_t **skp) +{ + es256_sk_t *sk; + + if (skp == NULL || (sk = *skp) == NULL) + return; + + freezero(sk, sizeof(*sk)); + *skp = NULL; +} + +es256_pk_t * +es256_pk_new(void) +{ + return (calloc(1, sizeof(es256_pk_t))); +} + +void +es256_pk_free(es256_pk_t **pkp) +{ + es256_pk_t *pk; + + if (pkp == NULL || (pk = *pkp) == NULL) + return; + + freezero(pk, sizeof(*pk)); + *pkp = NULL; +} + +int +es256_pk_from_ptr(es256_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 = es256_pk_to_EVP_PKEY(pk)) == NULL) { + fido_log_debug("%s: es256_pk_to_EVP_PKEY", __func__); + explicit_bzero(pk, sizeof(*pk)); + return (FIDO_ERR_INVALID_ARGUMENT); + } + + EVP_PKEY_free(pkey); + + return (FIDO_OK); +} + +int +es256_pk_set_x(es256_pk_t *pk, const unsigned char *x) +{ + memcpy(pk->x, x, sizeof(pk->x)); + + return (0); +} + +int +es256_pk_set_y(es256_pk_t *pk, const unsigned char *y) +{ + memcpy(pk->y, y, sizeof(pk->y)); + + return (0); +} + +int +es256_sk_create(es256_sk_t *key) +{ + EVP_PKEY_CTX *pctx = NULL; + EVP_PKEY_CTX *kctx = NULL; + EVP_PKEY *p = NULL; + EVP_PKEY *k = NULL; + const EC_KEY *ec; + const BIGNUM *d; + int n; + int ok = -1; + + if ((pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_EC, NULL)) == NULL || + EVP_PKEY_paramgen_init(pctx) <= 0 || + EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, es256_nid) <= 0 || + EVP_PKEY_paramgen(pctx, &p) <= 0) { + fido_log_debug("%s: EVP_PKEY_paramgen", __func__); + goto fail; + } + + if ((kctx = EVP_PKEY_CTX_new(p, NULL)) == NULL || + EVP_PKEY_keygen_init(kctx) <= 0 || EVP_PKEY_keygen(kctx, &k) <= 0) { + fido_log_debug("%s: EVP_PKEY_keygen", __func__); + goto fail; + } + + if ((ec = EVP_PKEY_get0_EC_KEY(k)) == NULL || + (d = EC_KEY_get0_private_key(ec)) == NULL || + (n = BN_num_bytes(d)) < 0 || (size_t)n > sizeof(key->d) || + (n = BN_bn2bin(d, key->d)) < 0 || (size_t)n > sizeof(key->d)) { + fido_log_debug("%s: EC_KEY_get0_private_key", __func__); + goto fail; + } + + ok = 0; +fail: + if (p != NULL) + EVP_PKEY_free(p); + if (k != NULL) + EVP_PKEY_free(k); + if (pctx != NULL) + EVP_PKEY_CTX_free(pctx); + if (kctx != NULL) + EVP_PKEY_CTX_free(kctx); + + return (ok); +} + +EVP_PKEY * +es256_pk_to_EVP_PKEY(const es256_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(es256_nid)) == 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 +es256_pk_from_EC_KEY(es256_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(es256_nid)) == 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 +es256_pk_from_EVP_PKEY(es256_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 (es256_pk_from_EC_KEY(pk, ec)); +} + +EVP_PKEY * +es256_sk_to_EVP_PKEY(const es256_sk_t *k) +{ + BN_CTX *bnctx = NULL; + EC_KEY *ec = NULL; + EVP_PKEY *pkey = NULL; + BIGNUM *d = NULL; + int ok = -1; + + if ((bnctx = BN_CTX_new()) == NULL) + goto fail; + + BN_CTX_start(bnctx); + + if ((d = BN_CTX_get(bnctx)) == NULL || + BN_bin2bn(k->d, sizeof(k->d), d) == NULL) { + fido_log_debug("%s: BN_bin2bn", __func__); + goto fail; + } + + if ((ec = EC_KEY_new_by_curve_name(es256_nid)) == NULL || + EC_KEY_set_private_key(ec, d) == 0) { + fido_log_debug("%s: EC_KEY_set_private_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 (ok < 0 && pkey != NULL) { + EVP_PKEY_free(pkey); + pkey = NULL; + } + + return (pkey); +} + +int +es256_derive_pk(const es256_sk_t *sk, es256_pk_t *pk) +{ + BIGNUM *d = NULL; + EC_KEY *ec = NULL; + EC_POINT *q = NULL; + const EC_GROUP *g = NULL; + int ok = -1; + + if ((d = BN_bin2bn(sk->d, (int)sizeof(sk->d), NULL)) == NULL || + (ec = EC_KEY_new_by_curve_name(es256_nid)) == NULL || + (g = EC_KEY_get0_group(ec)) == NULL || + (q = EC_POINT_new(g)) == NULL) { + fido_log_debug("%s: get", __func__); + goto fail; + } + + if (EC_POINT_mul(g, q, d, NULL, NULL, NULL) == 0 || + EC_KEY_set_public_key(ec, q) == 0 || + es256_pk_from_EC_KEY(pk, ec) != FIDO_OK) { + fido_log_debug("%s: set", __func__); + goto fail; + } + + ok = 0; +fail: + if (d != NULL) + BN_clear_free(d); + if (q != NULL) + EC_POINT_free(q); + if (ec != NULL) + EC_KEY_free(ec); + + return (ok); +} + +int +es256_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 +es256_pk_verify_sig(const fido_blob_t *dgst, const es256_pk_t *pk, + const fido_blob_t *sig) +{ + EVP_PKEY *pkey; + int ok = -1; + + if ((pkey = es256_pk_to_EVP_PKEY(pk)) == NULL || + es256_verify_sig(dgst, pkey, sig) < 0) { + fido_log_debug("%s: es256_verify_sig", __func__); + goto fail; + } + + ok = 0; +fail: + EVP_PKEY_free(pkey); + + return (ok); +} |