/*      $OpenBSD: hkdf_evp.c,v 1.22 2025/05/21 03:53:20 kenjiro Exp $ */
/* ====================================================================
 * Copyright (c) 2016-2018 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
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 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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 *    openssl-core@openssl.org.
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 * 5. Products derived from this software may not be called "OpenSSL"
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 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
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 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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 */

#include <stdlib.h>
#include <string.h>

#include <openssl/hmac.h>
#include <openssl/hkdf.h>
#include <openssl/kdf.h>

#include "err_local.h"
#include "evp_local.h"

#define HKDF_MAXBUF 1024

typedef struct {
        int mode;
        const EVP_MD *md;
        unsigned char *salt;
        size_t salt_len;
        unsigned char *key;
        size_t key_len;
        unsigned char info[HKDF_MAXBUF];
        size_t info_len;
} HKDF_PKEY_CTX;

static int
pkey_hkdf_init(EVP_PKEY_CTX *ctx)
{
        HKDF_PKEY_CTX *kctx;

        if ((kctx = calloc(1, sizeof(*kctx))) == NULL) {
                KDFerror(ERR_R_MALLOC_FAILURE);
                return 0;
        }

        ctx->data = kctx;

        return 1;
}

static void
pkey_hkdf_cleanup(EVP_PKEY_CTX *ctx)
{
        HKDF_PKEY_CTX *kctx = ctx->data;

        if (kctx == NULL)
                return;

        freezero(kctx->salt, kctx->salt_len);
        freezero(kctx->key, kctx->key_len);
        freezero(kctx, sizeof(*kctx));
}

static int
pkey_hkdf_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
{
        HKDF_PKEY_CTX *kctx = ctx->data;

        switch (type) {
        case EVP_PKEY_CTRL_HKDF_MD:
                if (p2 == NULL)
                        return 0;

                kctx->md = p2;
                return 1;

        case EVP_PKEY_CTRL_HKDF_MODE:
                kctx->mode = p1;
                return 1;

        case EVP_PKEY_CTRL_HKDF_SALT:
                if (p1 == 0 || p2 == NULL)
                        return 1;

                if (p1 < 0)
                        return 0;

                freezero(kctx->salt, kctx->salt_len);
                if ((kctx->salt = malloc(p1)) == NULL)
                        return 0;
                memcpy(kctx->salt, p2, p1);

                kctx->salt_len = p1;
                return 1;

        case EVP_PKEY_CTRL_HKDF_KEY:
                if (p1 < 0)
                        return 0;

                freezero(kctx->key, kctx->key_len);
                kctx->key = NULL;
                kctx->key_len = 0;

                /* Match OpenSSL's behavior. */
                if (p1 == 0 || p2 == NULL)
                        return 0;

                if ((kctx->key = malloc(p1)) == NULL)
                        return 0;
                memcpy(kctx->key, p2, p1);

                kctx->key_len = p1;
                return 1;

        case EVP_PKEY_CTRL_HKDF_INFO:
                if (p1 == 0 || p2 == NULL)
                        return 1;

                if (p1 < 0 || p1 > (int)(HKDF_MAXBUF - kctx->info_len))
                        return 0;

                memcpy(kctx->info + kctx->info_len, p2, p1);
                kctx->info_len += p1;
                return 1;

        default:
                return -2;
        }
}

static int
pkey_hkdf_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,
    const char *value)
{
        if (strcmp(type, "mode") == 0) {
                int mode;

                if (strcmp(value, "EXTRACT_AND_EXPAND") == 0)
                        mode = EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND;
                else if (strcmp(value, "EXTRACT_ONLY") == 0)
                        mode = EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY;
                else if (strcmp(value, "EXPAND_ONLY") == 0)
                        mode = EVP_PKEY_HKDEF_MODE_EXPAND_ONLY;
                else
                        return 0;

                return EVP_PKEY_CTX_hkdf_mode(ctx, mode);
        }

        if (strcmp(type, "md") == 0)
                return EVP_PKEY_CTX_md(ctx, EVP_PKEY_OP_DERIVE,
                    EVP_PKEY_CTRL_HKDF_MD, value);

        if (strcmp(type, "salt") == 0)
                return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT,
                    value);

        if (strcmp(type, "hexsalt") == 0)
                return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT,
                    value);

        if (strcmp(type, "key") == 0)
                return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);

        if (strcmp(type, "hexkey") == 0)
                return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);

        if (strcmp(type, "info") == 0)
                return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO,
                    value);

        if (strcmp(type, "hexinfo") == 0)
                return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO,
                    value);

        KDFerror(KDF_R_UNKNOWN_PARAMETER_TYPE);
        return -2;
}

static int
pkey_hkdf_derive_init(EVP_PKEY_CTX *ctx)
{
        HKDF_PKEY_CTX *kctx = ctx->data;

        freezero(kctx->key, kctx->key_len);
        freezero(kctx->salt, kctx->salt_len);
        explicit_bzero(kctx, sizeof(*kctx));

        return 1;
}

static int
pkey_hkdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
    size_t *keylen)
{
        HKDF_PKEY_CTX *kctx = ctx->data;

        if (kctx->md == NULL) {
                KDFerror(KDF_R_MISSING_MESSAGE_DIGEST);
                return 0;
        }
        if (kctx->key == NULL) {
                KDFerror(KDF_R_MISSING_KEY);
                return 0;
        }

        switch (kctx->mode) {
        case EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND:
                return HKDF(key, *keylen, kctx->md, kctx->key, kctx->key_len,
                    kctx->salt, kctx->salt_len, kctx->info, kctx->info_len);

        case EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY:
                if (key == NULL) {
                        *keylen = EVP_MD_size(kctx->md);
                        return 1;
                }
                return HKDF_extract(key, keylen, kctx->md, kctx->key,
                    kctx->key_len, kctx->salt, kctx->salt_len);

        case EVP_PKEY_HKDEF_MODE_EXPAND_ONLY:
                return HKDF_expand(key, *keylen, kctx->md, kctx->key,
                    kctx->key_len, kctx->info, kctx->info_len);

        default:
                return 0;
        }
}

const EVP_PKEY_METHOD hkdf_pkey_meth = {
        .pkey_id = EVP_PKEY_HKDF,
        .flags = 0,

        .init = pkey_hkdf_init,
        .copy = NULL,
        .cleanup = pkey_hkdf_cleanup,

        .derive_init = pkey_hkdf_derive_init,
        .derive = pkey_hkdf_derive,
        .ctrl = pkey_hkdf_ctrl,
        .ctrl_str = pkey_hkdf_ctrl_str,
};