diff options
Diffstat (limited to 'src/eddsa.c')
| -rw-r--r-- | src/eddsa.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/src/eddsa.c b/src/eddsa.c new file mode 100644 index 0000000..d043f89 --- /dev/null +++ b/src/eddsa.c @@ -0,0 +1,232 @@ +/* + * Copyright (c) 2019-2021 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/obj_mac.h> + +#include "fido.h" +#include "fido/eddsa.h" + +#if defined(LIBRESSL_VERSION_NUMBER) +EVP_PKEY * +EVP_PKEY_new_raw_public_key(int type, ENGINE *e, const unsigned char *key, + size_t keylen) +{ + (void)type; + (void)e; + (void)key; + (void)keylen; + + fido_log_debug("%s: unimplemented", __func__); + + return (NULL); +} + +int +EVP_PKEY_get_raw_public_key(const EVP_PKEY *pkey, unsigned char *pub, + size_t *len) +{ + (void)pkey; + (void)pub; + (void)len; + + fido_log_debug("%s: unimplemented", __func__); + + return (0); +} +#endif /* LIBRESSL_VERSION_NUMBER */ + +#if defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x3040000f +int +EVP_DigestVerify(EVP_MD_CTX *ctx, const unsigned char *sigret, size_t siglen, + const unsigned char *tbs, size_t tbslen) +{ + (void)ctx; + (void)sigret; + (void)siglen; + (void)tbs; + (void)tbslen; + + fido_log_debug("%s: unimplemented", __func__); + + return (0); +} +#endif /* LIBRESSL_VERSION_NUMBER < 0x3040000f */ + +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) +{ + eddsa_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))); + } + + return (0); /* ignore */ +} + +int +eddsa_pk_decode(const cbor_item_t *item, eddsa_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); +} + +eddsa_pk_t * +eddsa_pk_new(void) +{ + return (calloc(1, sizeof(eddsa_pk_t))); +} + +void +eddsa_pk_free(eddsa_pk_t **pkp) +{ + eddsa_pk_t *pk; + + if (pkp == NULL || (pk = *pkp) == NULL) + return; + + freezero(pk, sizeof(*pk)); + *pkp = NULL; +} + +int +eddsa_pk_from_ptr(eddsa_pk_t *pk, const void *ptr, size_t len) +{ + EVP_PKEY *pkey; + + if (len < sizeof(*pk)) + return (FIDO_ERR_INVALID_ARGUMENT); + + memcpy(pk, ptr, sizeof(*pk)); + + if ((pkey = eddsa_pk_to_EVP_PKEY(pk)) == NULL) { + fido_log_debug("%s: eddsa_pk_to_EVP_PKEY", __func__); + return (FIDO_ERR_INVALID_ARGUMENT); + } + + EVP_PKEY_free(pkey); + + return (FIDO_OK); +} + +EVP_PKEY * +eddsa_pk_to_EVP_PKEY(const eddsa_pk_t *k) +{ + EVP_PKEY *pkey = NULL; + + if ((pkey = EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL, k->x, + sizeof(k->x))) == NULL) + fido_log_debug("%s: EVP_PKEY_new_raw_public_key", __func__); + + return (pkey); +} + +int +eddsa_pk_from_EVP_PKEY(eddsa_pk_t *pk, const EVP_PKEY *pkey) +{ + size_t len = 0; + + if (EVP_PKEY_base_id(pkey) != EVP_PKEY_ED25519) + return (FIDO_ERR_INVALID_ARGUMENT); + if (EVP_PKEY_get_raw_public_key(pkey, NULL, &len) != 1 || + len != sizeof(pk->x)) + return (FIDO_ERR_INTERNAL); + if (EVP_PKEY_get_raw_public_key(pkey, pk->x, &len) != 1 || + len != sizeof(pk->x)) + return (FIDO_ERR_INTERNAL); + + return (FIDO_OK); +} + +int +eddsa_verify_sig(const fido_blob_t *dgst, EVP_PKEY *pkey, + const fido_blob_t *sig) +{ + EVP_MD_CTX *mdctx = NULL; + int ok = -1; + + if (EVP_PKEY_base_id(pkey) != EVP_PKEY_ED25519) { + fido_log_debug("%s: EVP_PKEY_base_id", __func__); + goto fail; + } + + /* EVP_DigestVerify needs ints */ + if (dgst->len > INT_MAX || sig->len > INT_MAX) { + fido_log_debug("%s: dgst->len=%zu, sig->len=%zu", __func__, + dgst->len, sig->len); + return (-1); + } + + if ((mdctx = EVP_MD_CTX_new()) == NULL) { + fido_log_debug("%s: EVP_MD_CTX_new", __func__); + goto fail; + } + + if (EVP_DigestVerifyInit(mdctx, NULL, NULL, NULL, pkey) != 1) { + fido_log_debug("%s: EVP_DigestVerifyInit", __func__); + goto fail; + } + + if (EVP_DigestVerify(mdctx, sig->ptr, sig->len, dgst->ptr, + dgst->len) != 1) { + fido_log_debug("%s: EVP_DigestVerify", __func__); + goto fail; + } + + ok = 0; +fail: + EVP_MD_CTX_free(mdctx); + + return (ok); +} + +int +eddsa_pk_verify_sig(const fido_blob_t *dgst, const eddsa_pk_t *pk, + const fido_blob_t *sig) +{ + EVP_PKEY *pkey; + int ok = -1; + + if ((pkey = eddsa_pk_to_EVP_PKEY(pk)) == NULL || + eddsa_verify_sig(dgst, pkey, sig) < 0) { + fido_log_debug("%s: eddsa_verify_sig", __func__); + goto fail; + } + + ok = 0; +fail: + EVP_PKEY_free(pkey); + + return (ok); +} |