/* Copyright (c) 2020, Google Inc. * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include <openssl_grpc/hpke.h> #include <assert.h> #include <string.h> #include <openssl_grpc/aead.h> #include <openssl_grpc/bytestring.h> #include <openssl_grpc/curve25519.h> #include <openssl_grpc/digest.h> #include <openssl_grpc/err.h> #include <openssl_grpc/evp_errors.h> #include <openssl_grpc/hkdf.h> #include <openssl_grpc/rand.h> #include <openssl_grpc/sha.h> #include "../internal.h" // This file implements draft-irtf-cfrg-hpke-12. #define MAX_SEED_LEN X25519_PRIVATE_KEY_LEN #define MAX_SHARED_SECRET_LEN SHA256_DIGEST_LENGTH struct evp_hpke_kem_st { uint16_t id; size_t public_key_len; size_t private_key_len; size_t seed_len; int (*init_key)(EVP_HPKE_KEY *key, const uint8_t *priv_key, size_t priv_key_len); int (*generate_key)(EVP_HPKE_KEY *key); int (*encap_with_seed)(const EVP_HPKE_KEM *kem, uint8_t *out_shared_secret, size_t *out_shared_secret_len, uint8_t *out_enc, size_t *out_enc_len, size_t max_enc, const uint8_t *peer_public_key, size_t peer_public_key_len, const uint8_t *seed, size_t seed_len); int (*decap)(const EVP_HPKE_KEY *key, uint8_t *out_shared_secret, size_t *out_shared_secret_len, const uint8_t *enc, size_t enc_len); }; struct evp_hpke_kdf_st { uint16_t id; // We only support HKDF-based KDFs. const EVP_MD *(*hkdf_md_func)(void); }; struct evp_hpke_aead_st { uint16_t id; const EVP_AEAD *(*aead_func)(void); }; // Low-level labeled KDF functions. static const char kHpkeVersionId[] = "HPKE-v1"; static int add_label_string(CBB *cbb, const char *label) { return CBB_add_bytes(cbb, (const uint8_t *)label, strlen(label)); } static int hpke_labeled_extract(const EVP_MD *hkdf_md, uint8_t *out_key, size_t *out_len, const uint8_t *salt, size_t salt_len, const uint8_t *suite_id, size_t suite_id_len, const char *label, const uint8_t *ikm, size_t ikm_len) { // labeledIKM = concat("HPKE-v1", suite_id, label, IKM) CBB labeled_ikm; int ok = CBB_init(&labeled_ikm, 0) && add_label_string(&labeled_ikm, kHpkeVersionId) && CBB_add_bytes(&labeled_ikm, suite_id, suite_id_len) && add_label_string(&labeled_ikm, label) && CBB_add_bytes(&labeled_ikm, ikm, ikm_len) && HKDF_extract(out_key, out_len, hkdf_md, CBB_data(&labeled_ikm), CBB_len(&labeled_ikm), salt, salt_len); CBB_cleanup(&labeled_ikm); return ok; } static int hpke_labeled_expand(const EVP_MD *hkdf_md, uint8_t *out_key, size_t out_len, const uint8_t *prk, size_t prk_len, const uint8_t *suite_id, size_t suite_id_len, const char *label, const uint8_t *info, size_t info_len) { // labeledInfo = concat(I2OSP(L, 2), "HPKE-v1", suite_id, label, info) CBB labeled_info; int ok = CBB_init(&labeled_info, 0) && CBB_add_u16(&labeled_info, out_len) && add_label_string(&labeled_info, kHpkeVersionId) && CBB_add_bytes(&labeled_info, suite_id, suite_id_len) && add_label_string(&labeled_info, label) && CBB_add_bytes(&labeled_info, info, info_len) && HKDF_expand(out_key, out_len, hkdf_md, prk, prk_len, CBB_data(&labeled_info), CBB_len(&labeled_info)); CBB_cleanup(&labeled_info); return ok; } // KEM implementations. // dhkem_extract_and_expand implements the ExtractAndExpand operation in the // DHKEM construction. See section 4.1 of draft-irtf-cfrg-hpke-12. static int dhkem_extract_and_expand(uint16_t kem_id, const EVP_MD *hkdf_md, uint8_t *out_key, size_t out_len, const uint8_t *dh, size_t dh_len, const uint8_t *kem_context, size_t kem_context_len) { // concat("KEM", I2OSP(kem_id, 2)) uint8_t suite_id[5] = {'K', 'E', 'M', kem_id >> 8, kem_id & 0xff}; uint8_t prk[EVP_MAX_MD_SIZE]; size_t prk_len; return hpke_labeled_extract(hkdf_md, prk, &prk_len, NULL, 0, suite_id, sizeof(suite_id), "eae_prk", dh, dh_len) && hpke_labeled_expand(hkdf_md, out_key, out_len, prk, prk_len, suite_id, sizeof(suite_id), "shared_secret", kem_context, kem_context_len); } static int x25519_init_key(EVP_HPKE_KEY *key, const uint8_t *priv_key, size_t priv_key_len) { if (priv_key_len != X25519_PRIVATE_KEY_LEN) { OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR); return 0; } OPENSSL_memcpy(key->private_key, priv_key, priv_key_len); X25519_public_from_private(key->public_key, priv_key); return 1; } static int x25519_generate_key(EVP_HPKE_KEY *key) { X25519_keypair(key->public_key, key->private_key); return 1; } static int x25519_encap_with_seed( const EVP_HPKE_KEM *kem, uint8_t *out_shared_secret, size_t *out_shared_secret_len, uint8_t *out_enc, size_t *out_enc_len, size_t max_enc, const uint8_t *peer_public_key, size_t peer_public_key_len, const uint8_t *seed, size_t seed_len) { if (max_enc < X25519_PUBLIC_VALUE_LEN) { OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_BUFFER_SIZE); return 0; } if (seed_len != X25519_PRIVATE_KEY_LEN) { OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR); return 0; } X25519_public_from_private(out_enc, seed); uint8_t dh[X25519_SHARED_KEY_LEN]; if (peer_public_key_len != X25519_PUBLIC_VALUE_LEN || !X25519(dh, seed, peer_public_key)) { OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_PEER_KEY); return 0; } uint8_t kem_context[2 * X25519_PUBLIC_VALUE_LEN]; OPENSSL_memcpy(kem_context, out_enc, X25519_PUBLIC_VALUE_LEN); OPENSSL_memcpy(kem_context + X25519_PUBLIC_VALUE_LEN, peer_public_key, X25519_PUBLIC_VALUE_LEN); if (!dhkem_extract_and_expand(kem->id, EVP_sha256(), out_shared_secret, SHA256_DIGEST_LENGTH, dh, sizeof(dh), kem_context, sizeof(kem_context))) { return 0; } *out_enc_len = X25519_PUBLIC_VALUE_LEN; *out_shared_secret_len = SHA256_DIGEST_LENGTH; return 1; } static int x25519_decap(const EVP_HPKE_KEY *key, uint8_t *out_shared_secret, size_t *out_shared_secret_len, const uint8_t *enc, size_t enc_len) { uint8_t dh[X25519_SHARED_KEY_LEN]; if (enc_len != X25519_PUBLIC_VALUE_LEN || !X25519(dh, key->private_key, enc)) { OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_PEER_KEY); return 0; } uint8_t kem_context[2 * X25519_PUBLIC_VALUE_LEN]; OPENSSL_memcpy(kem_context, enc, X25519_PUBLIC_VALUE_LEN); OPENSSL_memcpy(kem_context + X25519_PUBLIC_VALUE_LEN, key->public_key, X25519_PUBLIC_VALUE_LEN); if (!dhkem_extract_and_expand(key->kem->id, EVP_sha256(), out_shared_secret, SHA256_DIGEST_LENGTH, dh, sizeof(dh), kem_context, sizeof(kem_context))) { return 0; } *out_shared_secret_len = SHA256_DIGEST_LENGTH; return 1; } const EVP_HPKE_KEM *EVP_hpke_x25519_hkdf_sha256(void) { static const EVP_HPKE_KEM kKEM = { /*id=*/EVP_HPKE_DHKEM_X25519_HKDF_SHA256, /*public_key_len=*/X25519_PUBLIC_VALUE_LEN, /*private_key_len=*/X25519_PRIVATE_KEY_LEN, /*seed_len=*/X25519_PRIVATE_KEY_LEN, x25519_init_key, x25519_generate_key, x25519_encap_with_seed, x25519_decap, }; return &kKEM; } uint16_t EVP_HPKE_KEM_id(const EVP_HPKE_KEM *kem) { return kem->id; } void EVP_HPKE_KEY_zero(EVP_HPKE_KEY *key) { OPENSSL_memset(key, 0, sizeof(EVP_HPKE_KEY)); } void EVP_HPKE_KEY_cleanup(EVP_HPKE_KEY *key) { // Nothing to clean up for now, but we may introduce a cleanup process in the // future. } EVP_HPKE_KEY *EVP_HPKE_KEY_new(void) { EVP_HPKE_KEY *key = OPENSSL_malloc(sizeof(EVP_HPKE_KEY)); if (key == NULL) { OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE); return NULL; } EVP_HPKE_KEY_zero(key); return key; } void EVP_HPKE_KEY_free(EVP_HPKE_KEY *key) { if (key != NULL) { EVP_HPKE_KEY_cleanup(key); OPENSSL_free(key); } } int EVP_HPKE_KEY_copy(EVP_HPKE_KEY *dst, const EVP_HPKE_KEY *src) { // For now, |EVP_HPKE_KEY| is trivially copyable. OPENSSL_memcpy(dst, src, sizeof(EVP_HPKE_KEY)); return 1; } int EVP_HPKE_KEY_init(EVP_HPKE_KEY *key, const EVP_HPKE_KEM *kem, const uint8_t *priv_key, size_t priv_key_len) { EVP_HPKE_KEY_zero(key); key->kem = kem; if (!kem->init_key(key, priv_key, priv_key_len)) { key->kem = NULL; return 0; } return 1; } int EVP_HPKE_KEY_generate(EVP_HPKE_KEY *key, const EVP_HPKE_KEM *kem) { EVP_HPKE_KEY_zero(key); key->kem = kem; if (!kem->generate_key(key)) { key->kem = NULL; return 0; } return 1; } const EVP_HPKE_KEM *EVP_HPKE_KEY_kem(const EVP_HPKE_KEY *key) { return key->kem; } int EVP_HPKE_KEY_public_key(const EVP_HPKE_KEY *key, uint8_t *out, size_t *out_len, size_t max_out) { if (max_out < key->kem->public_key_len) { OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_BUFFER_SIZE); return 0; } OPENSSL_memcpy(out, key->public_key, key->kem->public_key_len); *out_len = key->kem->public_key_len; return 1; } int EVP_HPKE_KEY_private_key(const EVP_HPKE_KEY *key, uint8_t *out, size_t *out_len, size_t max_out) { if (max_out < key->kem->private_key_len) { OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_BUFFER_SIZE); return 0; } OPENSSL_memcpy(out, key->private_key, key->kem->private_key_len); *out_len = key->kem->private_key_len; return 1; } // Supported KDFs and AEADs. const EVP_HPKE_KDF *EVP_hpke_hkdf_sha256(void) { static const EVP_HPKE_KDF kKDF = {EVP_HPKE_HKDF_SHA256, &EVP_sha256}; return &kKDF; } uint16_t EVP_HPKE_KDF_id(const EVP_HPKE_KDF *kdf) { return kdf->id; } const EVP_HPKE_AEAD *EVP_hpke_aes_128_gcm(void) { static const EVP_HPKE_AEAD kAEAD = {EVP_HPKE_AES_128_GCM, &EVP_aead_aes_128_gcm}; return &kAEAD; } const EVP_HPKE_AEAD *EVP_hpke_aes_256_gcm(void) { static const EVP_HPKE_AEAD kAEAD = {EVP_HPKE_AES_256_GCM, &EVP_aead_aes_256_gcm}; return &kAEAD; } const EVP_HPKE_AEAD *EVP_hpke_chacha20_poly1305(void) { static const EVP_HPKE_AEAD kAEAD = {EVP_HPKE_CHACHA20_POLY1305, &EVP_aead_chacha20_poly1305}; return &kAEAD; } uint16_t EVP_HPKE_AEAD_id(const EVP_HPKE_AEAD *aead) { return aead->id; } const EVP_AEAD *EVP_HPKE_AEAD_aead(const EVP_HPKE_AEAD *aead) { return aead->aead_func(); } // HPKE implementation. // This is strlen("HPKE") + 3 * sizeof(uint16_t). #define HPKE_SUITE_ID_LEN 10 // The suite_id for non-KEM pieces of HPKE is defined as concat("HPKE", // I2OSP(kem_id, 2), I2OSP(kdf_id, 2), I2OSP(aead_id, 2)). static int hpke_build_suite_id(const EVP_HPKE_CTX *ctx, uint8_t out[HPKE_SUITE_ID_LEN]) { CBB cbb; int ret = CBB_init_fixed(&cbb, out, HPKE_SUITE_ID_LEN) && add_label_string(&cbb, "HPKE") && CBB_add_u16(&cbb, EVP_HPKE_DHKEM_X25519_HKDF_SHA256) && CBB_add_u16(&cbb, ctx->kdf->id) && CBB_add_u16(&cbb, ctx->aead->id); CBB_cleanup(&cbb); return ret; } #define HPKE_MODE_BASE 0 static int hpke_key_schedule(EVP_HPKE_CTX *ctx, const uint8_t *shared_secret, size_t shared_secret_len, const uint8_t *info, size_t info_len) { uint8_t suite_id[HPKE_SUITE_ID_LEN]; if (!hpke_build_suite_id(ctx, suite_id)) { return 0; } // psk_id_hash = LabeledExtract("", "psk_id_hash", psk_id) // TODO(davidben): Precompute this value and store it with the EVP_HPKE_KDF. const EVP_MD *hkdf_md = ctx->kdf->hkdf_md_func(); uint8_t psk_id_hash[EVP_MAX_MD_SIZE]; size_t psk_id_hash_len; if (!hpke_labeled_extract(hkdf_md, psk_id_hash, &psk_id_hash_len, NULL, 0, suite_id, sizeof(suite_id), "psk_id_hash", NULL, 0)) { return 0; } // info_hash = LabeledExtract("", "info_hash", info) uint8_t info_hash[EVP_MAX_MD_SIZE]; size_t info_hash_len; if (!hpke_labeled_extract(hkdf_md, info_hash, &info_hash_len, NULL, 0, suite_id, sizeof(suite_id), "info_hash", info, info_len)) { return 0; } // key_schedule_context = concat(mode, psk_id_hash, info_hash) uint8_t context[sizeof(uint8_t) + 2 * EVP_MAX_MD_SIZE]; size_t context_len; CBB context_cbb; if (!CBB_init_fixed(&context_cbb, context, sizeof(context)) || !CBB_add_u8(&context_cbb, HPKE_MODE_BASE) || !CBB_add_bytes(&context_cbb, psk_id_hash, psk_id_hash_len) || !CBB_add_bytes(&context_cbb, info_hash, info_hash_len) || !CBB_finish(&context_cbb, NULL, &context_len)) { return 0; } // secret = LabeledExtract(shared_secret, "secret", psk) uint8_t secret[EVP_MAX_MD_SIZE]; size_t secret_len; if (!hpke_labeled_extract(hkdf_md, secret, &secret_len, shared_secret, shared_secret_len, suite_id, sizeof(suite_id), "secret", NULL, 0)) { return 0; } // key = LabeledExpand(secret, "key", key_schedule_context, Nk) const EVP_AEAD *aead = EVP_HPKE_AEAD_aead(ctx->aead); uint8_t key[EVP_AEAD_MAX_KEY_LENGTH]; const size_t kKeyLen = EVP_AEAD_key_length(aead); if (!hpke_labeled_expand(hkdf_md, key, kKeyLen, secret, secret_len, suite_id, sizeof(suite_id), "key", context, context_len) || !EVP_AEAD_CTX_init(&ctx->aead_ctx, aead, key, kKeyLen, EVP_AEAD_DEFAULT_TAG_LENGTH, NULL)) { return 0; } // base_nonce = LabeledExpand(secret, "base_nonce", key_schedule_context, Nn) if (!hpke_labeled_expand(hkdf_md, ctx->base_nonce, EVP_AEAD_nonce_length(aead), secret, secret_len, suite_id, sizeof(suite_id), "base_nonce", context, context_len)) { return 0; } // exporter_secret = LabeledExpand(secret, "exp", key_schedule_context, Nh) if (!hpke_labeled_expand(hkdf_md, ctx->exporter_secret, EVP_MD_size(hkdf_md), secret, secret_len, suite_id, sizeof(suite_id), "exp", context, context_len)) { return 0; } return 1; } void EVP_HPKE_CTX_zero(EVP_HPKE_CTX *ctx) { OPENSSL_memset(ctx, 0, sizeof(EVP_HPKE_CTX)); EVP_AEAD_CTX_zero(&ctx->aead_ctx); } void EVP_HPKE_CTX_cleanup(EVP_HPKE_CTX *ctx) { EVP_AEAD_CTX_cleanup(&ctx->aead_ctx); } EVP_HPKE_CTX *EVP_HPKE_CTX_new(void) { EVP_HPKE_CTX *ctx = OPENSSL_malloc(sizeof(EVP_HPKE_CTX)); if (ctx == NULL) { OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE); return NULL; } EVP_HPKE_CTX_zero(ctx); return ctx; } void EVP_HPKE_CTX_free(EVP_HPKE_CTX *ctx) { if (ctx != NULL) { EVP_HPKE_CTX_cleanup(ctx); OPENSSL_free(ctx); } } int EVP_HPKE_CTX_setup_sender(EVP_HPKE_CTX *ctx, uint8_t *out_enc, size_t *out_enc_len, size_t max_enc, const EVP_HPKE_KEM *kem, const EVP_HPKE_KDF *kdf, const EVP_HPKE_AEAD *aead, const uint8_t *peer_public_key, size_t peer_public_key_len, const uint8_t *info, size_t info_len) { uint8_t seed[MAX_SEED_LEN]; RAND_bytes(seed, kem->seed_len); return EVP_HPKE_CTX_setup_sender_with_seed_for_testing( ctx, out_enc, out_enc_len, max_enc, kem, kdf, aead, peer_public_key, peer_public_key_len, info, info_len, seed, kem->seed_len); } int EVP_HPKE_CTX_setup_sender_with_seed_for_testing( EVP_HPKE_CTX *ctx, uint8_t *out_enc, size_t *out_enc_len, size_t max_enc, const EVP_HPKE_KEM *kem, const EVP_HPKE_KDF *kdf, const EVP_HPKE_AEAD *aead, const uint8_t *peer_public_key, size_t peer_public_key_len, const uint8_t *info, size_t info_len, const uint8_t *seed, size_t seed_len) { EVP_HPKE_CTX_zero(ctx); ctx->is_sender = 1; ctx->kdf = kdf; ctx->aead = aead; uint8_t shared_secret[MAX_SHARED_SECRET_LEN]; size_t shared_secret_len; if (!kem->encap_with_seed(kem, shared_secret, &shared_secret_len, out_enc, out_enc_len, max_enc, peer_public_key, peer_public_key_len, seed, seed_len) || !hpke_key_schedule(ctx, shared_secret, shared_secret_len, info, info_len)) { EVP_HPKE_CTX_cleanup(ctx); return 0; } return 1; } int EVP_HPKE_CTX_setup_recipient(EVP_HPKE_CTX *ctx, const EVP_HPKE_KEY *key, const EVP_HPKE_KDF *kdf, const EVP_HPKE_AEAD *aead, const uint8_t *enc, size_t enc_len, const uint8_t *info, size_t info_len) { EVP_HPKE_CTX_zero(ctx); ctx->is_sender = 0; ctx->kdf = kdf; ctx->aead = aead; uint8_t shared_secret[MAX_SHARED_SECRET_LEN]; size_t shared_secret_len; if (!key->kem->decap(key, shared_secret, &shared_secret_len, enc, enc_len) || !hpke_key_schedule(ctx, shared_secret, sizeof(shared_secret), info, info_len)) { EVP_HPKE_CTX_cleanup(ctx); return 0; } return 1; } static void hpke_nonce(const EVP_HPKE_CTX *ctx, uint8_t *out_nonce, size_t nonce_len) { assert(nonce_len >= 8); // Write padded big-endian bytes of |ctx->seq| to |out_nonce|. OPENSSL_memset(out_nonce, 0, nonce_len); uint64_t seq_copy = ctx->seq; for (size_t i = 0; i < 8; i++) { out_nonce[nonce_len - i - 1] = seq_copy & 0xff; seq_copy >>= 8; } // XOR the encoded sequence with the |ctx->base_nonce|. for (size_t i = 0; i < nonce_len; i++) { out_nonce[i] ^= ctx->base_nonce[i]; } } int EVP_HPKE_CTX_open(EVP_HPKE_CTX *ctx, uint8_t *out, size_t *out_len, size_t max_out_len, const uint8_t *in, size_t in_len, const uint8_t *ad, size_t ad_len) { if (ctx->is_sender) { OPENSSL_PUT_ERROR(EVP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); return 0; } if (ctx->seq == UINT64_MAX) { OPENSSL_PUT_ERROR(EVP, ERR_R_OVERFLOW); return 0; } uint8_t nonce[EVP_AEAD_MAX_NONCE_LENGTH]; const size_t nonce_len = EVP_AEAD_nonce_length(ctx->aead_ctx.aead); hpke_nonce(ctx, nonce, nonce_len); if (!EVP_AEAD_CTX_open(&ctx->aead_ctx, out, out_len, max_out_len, nonce, nonce_len, in, in_len, ad, ad_len)) { return 0; } ctx->seq++; return 1; } int EVP_HPKE_CTX_seal(EVP_HPKE_CTX *ctx, uint8_t *out, size_t *out_len, size_t max_out_len, const uint8_t *in, size_t in_len, const uint8_t *ad, size_t ad_len) { if (!ctx->is_sender) { OPENSSL_PUT_ERROR(EVP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); return 0; } if (ctx->seq == UINT64_MAX) { OPENSSL_PUT_ERROR(EVP, ERR_R_OVERFLOW); return 0; } uint8_t nonce[EVP_AEAD_MAX_NONCE_LENGTH]; const size_t nonce_len = EVP_AEAD_nonce_length(ctx->aead_ctx.aead); hpke_nonce(ctx, nonce, nonce_len); if (!EVP_AEAD_CTX_seal(&ctx->aead_ctx, out, out_len, max_out_len, nonce, nonce_len, in, in_len, ad, ad_len)) { return 0; } ctx->seq++; return 1; } int EVP_HPKE_CTX_export(const EVP_HPKE_CTX *ctx, uint8_t *out, size_t secret_len, const uint8_t *context, size_t context_len) { uint8_t suite_id[HPKE_SUITE_ID_LEN]; if (!hpke_build_suite_id(ctx, suite_id)) { return 0; } const EVP_MD *hkdf_md = ctx->kdf->hkdf_md_func(); if (!hpke_labeled_expand(hkdf_md, out, secret_len, ctx->exporter_secret, EVP_MD_size(hkdf_md), suite_id, sizeof(suite_id), "sec", context, context_len)) { return 0; } return 1; } size_t EVP_HPKE_CTX_max_overhead(const EVP_HPKE_CTX *ctx) { assert(ctx->is_sender); return EVP_AEAD_max_overhead(EVP_AEAD_CTX_aead(&ctx->aead_ctx)); } const EVP_HPKE_AEAD *EVP_HPKE_CTX_aead(const EVP_HPKE_CTX *ctx) { return ctx->aead; } const EVP_HPKE_KDF *EVP_HPKE_CTX_kdf(const EVP_HPKE_CTX *ctx) { return ctx->kdf; }