openssl/apps/kdf.c

/*
 * Copyright 2019-2025 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <string.h>

#include "apps.h"
#include "progs.h"
#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/kdf.h>
#include <openssl/params.h>

typedef enum OPTION_choice {
    OPT_COMMON,
    OPT_KDFOPT,
    OPT_BIN,
    OPT_KEYLEN,
    OPT_OUT,
    OPT_CIPHER,
    OPT_DIGEST,
    OPT_MAC,
    OPT_PROV_ENUM
} OPTION_CHOICE;

const OPTIONS kdf_options[] = {
    { OPT_HELP_STR, 1, '-', "Usage: %s [options] kdf_name\n" },

    OPT_SECTION("General"),
    { "help", OPT_HELP, '-', "Display this summary" },
    { "kdfopt", OPT_KDFOPT, 's', "KDF algorithm control parameters in n:v form" },
    { "cipher", OPT_CIPHER, 's', "Cipher" },
    { "digest", OPT_DIGEST, 's', "Digest" },
    { "mac", OPT_MAC, 's', "MAC" },
    { OPT_MORE_STR, 1, '-', "See 'Supported Controls' in the EVP_KDF_ docs\n" },
    { "keylen", OPT_KEYLEN, 's', "The size of the output derived key" },

    OPT_SECTION("Output"),
    { "out", OPT_OUT, '>', "Output to filename rather than stdout" },
    { "binary", OPT_BIN, '-',
        "Output in binary format (default is hexadecimal)" },

    OPT_PROV_OPTIONS,

    OPT_PARAMETERS(),
    { "kdf_name", 0, 0, "Name of the KDF algorithm" },
    { NULL }
};

static char *alloc_kdf_algorithm_name(STACK_OF(OPENSSL_STRING) **optp,
    const char *name, const char *arg)
{
    size_t len = strlen(name) + strlen(arg) + 2;
    char *res;

    if (*optp == NULL)
        *optp = sk_OPENSSL_STRING_new_null();
    if (*optp == NULL)
        return NULL;

    res = app_malloc(len, "algorithm name");
    BIO_snprintf(res, len, "%s:%s", name, arg);
    if (sk_OPENSSL_STRING_push(*optp, res))
        return res;
    OPENSSL_free(res);
    return NULL;
}

int kdf_main(int argc, char **argv)
{
    int ret = 1, out_bin = 0;
    OPTION_CHOICE o;
    STACK_OF(OPENSSL_STRING) *opts = NULL;
    char *prog, *hexout = NULL;
    const char *outfile = NULL;
    unsigned char *dkm_bytes = NULL;
    int dkm_len = 0;
    BIO *out = NULL;
    EVP_KDF *kdf = NULL;
    EVP_KDF_CTX *ctx = NULL;
    char *digest = NULL, *cipher = NULL, *mac = NULL;

    prog = opt_init(argc, argv, kdf_options);
    while ((o = opt_next()) != OPT_EOF) {
        switch (o) {
        default:
        opthelp:
            BIO_printf(bio_err, "%s: Use -help for summary.\n", prog);
            goto err;
        case OPT_HELP:
            opt_help(kdf_options);
            ret = 0;
            goto err;
        case OPT_BIN:
            out_bin = 1;
            break;
        case OPT_KEYLEN:
            dkm_len = atoi(opt_arg());
            break;
        case OPT_OUT:
            outfile = opt_arg();
            break;
        case OPT_KDFOPT:
            if (opts == NULL)
                opts = sk_OPENSSL_STRING_new_null();
            if (opts == NULL || !sk_OPENSSL_STRING_push(opts, opt_arg()))
                goto opthelp;
            break;
        case OPT_CIPHER:
            OPENSSL_free(cipher);
            cipher = alloc_kdf_algorithm_name(&opts, "cipher", opt_arg());
            if (cipher == NULL)
                goto opthelp;
            break;
        case OPT_DIGEST:
            OPENSSL_free(digest);
            digest = alloc_kdf_algorithm_name(&opts, "digest", opt_arg());
            if (digest == NULL)
                goto opthelp;
            break;
        case OPT_MAC:
            OPENSSL_free(mac);
            mac = alloc_kdf_algorithm_name(&opts, "mac", opt_arg());
            if (mac == NULL)
                goto opthelp;
            break;
        case OPT_PROV_CASES:
            if (!opt_provider(o))
                goto err;
            break;
        }
    }

    /* One argument, the KDF name. */
    argc = opt_num_rest();
    argv = opt_rest();
    if (argc != 1)
        goto opthelp;

    if ((kdf = EVP_KDF_fetch(app_get0_libctx(), argv[0],
             app_get0_propq()))
        == NULL) {
        BIO_printf(bio_err, "Invalid KDF name %s\n", argv[0]);
        goto opthelp;
    }

    ctx = EVP_KDF_CTX_new(kdf);
    if (ctx == NULL)
        goto err;

    if (opts != NULL) {
        int ok = 1;
        OSSL_PARAM *params = app_params_new_from_opts(opts, EVP_KDF_settable_ctx_params(kdf));

        if (params == NULL)
            goto err;

        if (!EVP_KDF_CTX_set_params(ctx, params)) {
            BIO_printf(bio_err, "KDF parameter error\n");
            ERR_print_errors(bio_err);
            ok = 0;
        }
        app_params_free(params);
        if (!ok)
            goto err;
    }

    out = bio_open_default(outfile, 'w', out_bin ? FORMAT_BINARY : FORMAT_TEXT);
    if (out == NULL)
        goto err;

    if (dkm_len <= 0) {
        BIO_printf(bio_err, "Invalid derived key length.\n");
        goto err;
    }
    dkm_bytes = app_malloc(dkm_len, "out buffer");
    if (dkm_bytes == NULL)
        goto err;

    if (!EVP_KDF_derive(ctx, dkm_bytes, dkm_len, NULL)) {
        BIO_printf(bio_err, "EVP_KDF_derive failed\n");
        goto err;
    }

    if (out_bin) {
        BIO_write(out, dkm_bytes, dkm_len);
    } else {
        hexout = OPENSSL_buf2hexstr(dkm_bytes, dkm_len);
        if (hexout == NULL) {
            BIO_printf(bio_err, "Memory allocation failure\n");
            goto err;
        }
        BIO_printf(out, "%s\n\n", hexout);
    }

    ret = 0;
err:
    if (ret != 0)
        ERR_print_errors(bio_err);
    OPENSSL_clear_free(dkm_bytes, dkm_len);
    sk_OPENSSL_STRING_free(opts);
    EVP_KDF_free(kdf);
    EVP_KDF_CTX_free(ctx);
    BIO_free(out);
    OPENSSL_free(hexout);
    OPENSSL_free(cipher);
    OPENSSL_free(digest);
    OPENSSL_free(mac);
    return ret;
}