


#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <openssl/hmac.h>
#include <openssl/evp.h>
#include <openssl/kdf.h>
#include <openssl/core_names.h>
#include <openssl/params.h>
#include <openssl/proverr.h>
#include "internal/cryptlib.h"
#include "internal/numbers.h"
#include "crypto/evp.h"
#include "prov/provider_ctx.h"
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/provider_util.h"
#include "internal/params.h"

typedef struct {
    void *provctx;
    EVP_MAC_CTX *macctx;         
    PROV_DIGEST digest;          
    unsigned char *secret;
    size_t secret_len;
    unsigned char *info;
    size_t info_len;
    unsigned char *salt;
    size_t salt_len;
    size_t out_len; 
    int is_kmac;
} KDF_SSKDF;

#define SSKDF_MAX_INLEN (1<<30)
#define SSKDF_KMAC128_DEFAULT_SALT_SIZE (168 - 4)
#define SSKDF_KMAC256_DEFAULT_SALT_SIZE (136 - 4)


static const unsigned char kmac_custom_str[] = { 0x4B, 0x44, 0x46 };

static OSSL_FUNC_kdf_newctx_fn sskdf_new;
static OSSL_FUNC_kdf_dupctx_fn sskdf_dup;
static OSSL_FUNC_kdf_freectx_fn sskdf_free;
static OSSL_FUNC_kdf_reset_fn sskdf_reset;
static OSSL_FUNC_kdf_derive_fn sskdf_derive;
static OSSL_FUNC_kdf_derive_fn x963kdf_derive;
static OSSL_FUNC_kdf_settable_ctx_params_fn sskdf_settable_ctx_params;
static OSSL_FUNC_kdf_set_ctx_params_fn sskdf_set_ctx_params;
static OSSL_FUNC_kdf_gettable_ctx_params_fn sskdf_gettable_ctx_params;
static OSSL_FUNC_kdf_get_ctx_params_fn sskdf_get_ctx_params;


static int SSKDF_hash_kdm(const EVP_MD *kdf_md,
                          const unsigned char *z, size_t z_len,
                          const unsigned char *info, size_t info_len,
                          unsigned int append_ctr,
                          unsigned char *derived_key, size_t derived_key_len)
{
    int ret = 0, hlen;
    size_t counter, out_len, len = derived_key_len;
    unsigned char c[4];
    unsigned char mac[EVP_MAX_MD_SIZE];
    unsigned char *out = derived_key;
    EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;

    if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
            || derived_key_len > SSKDF_MAX_INLEN
            || derived_key_len == 0)
        return 0;

    hlen = EVP_MD_get_size(kdf_md);
    if (hlen <= 0)
        return 0;
    out_len = (size_t)hlen;

    ctx = EVP_MD_CTX_create();
    ctx_init = EVP_MD_CTX_create();
    if (ctx == NULL || ctx_init == NULL)
        goto end;

    if (!EVP_DigestInit(ctx_init, kdf_md))
        goto end;

    for (counter = 1;; counter++) {
        c[0] = (unsigned char)((counter >> 24) & 0xff);
        c[1] = (unsigned char)((counter >> 16) & 0xff);
        c[2] = (unsigned char)((counter >> 8) & 0xff);
        c[3] = (unsigned char)(counter & 0xff);

        if (!(EVP_MD_CTX_copy_ex(ctx, ctx_init)
                && (append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
                && EVP_DigestUpdate(ctx, z, z_len)
                && (!append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
                && EVP_DigestUpdate(ctx, info, info_len)))
            goto end;
        if (len >= out_len) {
            if (!EVP_DigestFinal_ex(ctx, out, NULL))
                goto end;
            out += out_len;
            len -= out_len;
            if (len == 0)
                break;
        } else {
            if (!EVP_DigestFinal_ex(ctx, mac, NULL))
                goto end;
            memcpy(out, mac, len);
            break;
        }
    }
    ret = 1;
end:
    EVP_MD_CTX_destroy(ctx);
    EVP_MD_CTX_destroy(ctx_init);
    OPENSSL_cleanse(mac, sizeof(mac));
    return ret;
}

static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom,
                     size_t custom_len, size_t kmac_out_len,
                     size_t derived_key_len, unsigned char **out)
{
    OSSL_PARAM params[2];

    
    if (custom == NULL)
        return 1;

    params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
                                                  (void *)custom, custom_len);
    params[1] = OSSL_PARAM_construct_end();

    if (!EVP_MAC_CTX_set_params(ctx, params))
        return 0;

    
    if (kmac_out_len == 0)
        kmac_out_len = derived_key_len;
    
    else if (!(kmac_out_len == derived_key_len
            || kmac_out_len == 20
            || kmac_out_len == 28
            || kmac_out_len == 32
            || kmac_out_len == 48
            || kmac_out_len == 64))
        return 0;

    params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE,
                                            &kmac_out_len);

    if (EVP_MAC_CTX_set_params(ctx, params) <= 0)
        return 0;

    
    if (kmac_out_len > EVP_MAX_MD_SIZE) {
        *out = OPENSSL_zalloc(kmac_out_len);
        if (*out == NULL)
            return 0;
    }
    return 1;
}


static int SSKDF_mac_kdm(EVP_MAC_CTX *ctx_init,
                         const unsigned char *kmac_custom,
                         size_t kmac_custom_len, size_t kmac_out_len,
                         const unsigned char *salt, size_t salt_len,
                         const unsigned char *z, size_t z_len,
                         const unsigned char *info, size_t info_len,
                         unsigned char *derived_key, size_t derived_key_len)
{
    int ret = 0;
    size_t counter, out_len, len;
    unsigned char c[4];
    unsigned char mac_buf[EVP_MAX_MD_SIZE];
    unsigned char *out = derived_key;
    EVP_MAC_CTX *ctx = NULL;
    unsigned char *mac = mac_buf, *kmac_buffer = NULL;

    if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
            || derived_key_len > SSKDF_MAX_INLEN
            || derived_key_len == 0)
        return 0;

    if (!kmac_init(ctx_init, kmac_custom, kmac_custom_len, kmac_out_len,
                   derived_key_len, &kmac_buffer))
        goto end;
    if (kmac_buffer != NULL)
        mac = kmac_buffer;

    if (!EVP_MAC_init(ctx_init, salt, salt_len, NULL))
        goto end;

    out_len = EVP_MAC_CTX_get_mac_size(ctx_init); 
    if (out_len <= 0 || (mac == mac_buf && out_len > sizeof(mac_buf)))
        goto end;
    len = derived_key_len;

    for (counter = 1;; counter++) {
        c[0] = (unsigned char)((counter >> 24) & 0xff);
        c[1] = (unsigned char)((counter >> 16) & 0xff);
        c[2] = (unsigned char)((counter >> 8) & 0xff);
        c[3] = (unsigned char)(counter & 0xff);

        ctx = EVP_MAC_CTX_dup(ctx_init);
        if (!(ctx != NULL
                && EVP_MAC_update(ctx, c, sizeof(c))
                && EVP_MAC_update(ctx, z, z_len)
                && EVP_MAC_update(ctx, info, info_len)))
            goto end;
        if (len >= out_len) {
            if (!EVP_MAC_final(ctx, out, NULL, len))
                goto end;
            out += out_len;
            len -= out_len;
            if (len == 0)
                break;
        } else {
            if (!EVP_MAC_final(ctx, mac, NULL, out_len))
                goto end;
            memcpy(out, mac, len);
            break;
        }
        EVP_MAC_CTX_free(ctx);
        ctx = NULL;
    }
    ret = 1;
end:
    if (kmac_buffer != NULL)
        OPENSSL_clear_free(kmac_buffer, kmac_out_len);
    else
        OPENSSL_cleanse(mac_buf, sizeof(mac_buf));

    EVP_MAC_CTX_free(ctx);
    return ret;
}

static void *sskdf_new(void *provctx)
{
    KDF_SSKDF *ctx;

    if (!ossl_prov_is_running())
        return NULL;

    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)
        ctx->provctx = provctx;
    return ctx;
}

static void sskdf_reset(void *vctx)
{
    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
    void *provctx = ctx->provctx;

    EVP_MAC_CTX_free(ctx->macctx);
    ossl_prov_digest_reset(&ctx->digest);
    OPENSSL_clear_free(ctx->secret, ctx->secret_len);
    OPENSSL_clear_free(ctx->info, ctx->info_len);
    OPENSSL_clear_free(ctx->salt, ctx->salt_len);
    memset(ctx, 0, sizeof(*ctx));
    ctx->provctx = provctx;
}

static void sskdf_free(void *vctx)
{
    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;

    if (ctx != NULL) {
        sskdf_reset(ctx);
        OPENSSL_free(ctx);
    }
}

static void *sskdf_dup(void *vctx)
{
    const KDF_SSKDF *src = (const KDF_SSKDF *)vctx;
    KDF_SSKDF *dest;

    dest = sskdf_new(src->provctx);
    if (dest != NULL) {
        if (src->macctx != NULL) {
            dest->macctx = EVP_MAC_CTX_dup(src->macctx);
            if (dest->macctx == NULL)
                goto err;
        }
        if (!ossl_prov_memdup(src->info, src->info_len,
                              &dest->info, &dest->info_len)
                || !ossl_prov_memdup(src->salt, src->salt_len,
                                     &dest->salt , &dest->salt_len)
                || !ossl_prov_memdup(src->secret, src->secret_len,
                                     &dest->secret, &dest->secret_len)
                || !ossl_prov_digest_copy(&dest->digest, &src->digest))
            goto err;
        dest->out_len = src->out_len;
        dest->is_kmac = src->is_kmac;
    }
    return dest;

 err:
    sskdf_free(dest);
    return NULL;
}

static size_t sskdf_size(KDF_SSKDF *ctx)
{
    int len;
    const EVP_MD *md = NULL;

    if (ctx->is_kmac)
        return SIZE_MAX;

    md = ossl_prov_digest_md(&ctx->digest);
    if (md == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
        return 0;
    }
    len = EVP_MD_get_size(md);
    return (len <= 0) ? 0 : (size_t)len;
}

static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen,
                        const OSSL_PARAM params[])
{
    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
    const EVP_MD *md;

    if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
        return 0;
    if (ctx->secret == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
        return 0;
    }
    md = ossl_prov_digest_md(&ctx->digest);

    if (ctx->macctx != NULL) {
        
        int ret;
        const unsigned char *custom = NULL;
        size_t custom_len = 0;
        int default_salt_len;
        EVP_MAC *mac = EVP_MAC_CTX_get0_mac(ctx->macctx);

        if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_HMAC)) {
            
            if (md == NULL) {
                ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
                return 0;
            }
            default_salt_len = EVP_MD_get_size(md);
            if (default_salt_len <= 0)
                return 0;
        } else if (ctx->is_kmac) {
            
            custom = kmac_custom_str;
            custom_len = sizeof(kmac_custom_str);
            if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128))
                default_salt_len = SSKDF_KMAC128_DEFAULT_SALT_SIZE;
            else
                default_salt_len = SSKDF_KMAC256_DEFAULT_SALT_SIZE;
        } else {
            ERR_raise(ERR_LIB_PROV, PROV_R_UNSUPPORTED_MAC_TYPE);
            return 0;
        }
        
        if (ctx->salt == NULL || ctx->salt_len <= 0) {
            ctx->salt = OPENSSL_zalloc(default_salt_len);
            if (ctx->salt == NULL)
                return 0;
            ctx->salt_len = default_salt_len;
        }
        ret = SSKDF_mac_kdm(ctx->macctx,
                            custom, custom_len, ctx->out_len,
                            ctx->salt, ctx->salt_len,
                            ctx->secret, ctx->secret_len,
                            ctx->info, ctx->info_len, key, keylen);
        return ret;
    } else {
        
        if (md == NULL) {
            ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
            return 0;
        }
        return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
                              ctx->info, ctx->info_len, 0, key, keylen);
    }
}

static int x963kdf_derive(void *vctx, unsigned char *key, size_t keylen,
                          const OSSL_PARAM params[])
{
    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
    const EVP_MD *md;

    if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
        return 0;

    if (ctx->secret == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
        return 0;
    }

    if (ctx->macctx != NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED);
        return 0;
    }

    
    md = ossl_prov_digest_md(&ctx->digest);
    if (md == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
        return 0;
    }

    return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
                          ctx->info, ctx->info_len, 1, key, keylen);
}

static int sskdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
{
    const OSSL_PARAM *p;
    KDF_SSKDF *ctx = vctx;
    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
    size_t sz;
    int r;

    if (params == NULL)
        return 1;

    if (!ossl_prov_macctx_load_from_params(&ctx->macctx, params,
                                           NULL, NULL, NULL, libctx))
        return 0;
    if (ctx->macctx != NULL) {
         if (EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
                          OSSL_MAC_NAME_KMAC128)
             || EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
                             OSSL_MAC_NAME_KMAC256)) {
             ctx->is_kmac = 1;
         }
    }

    if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
        return 0;

    r = ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SECRET,
                                     &ctx->secret, &ctx->secret_len);
    if (r == -1)
        r = ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_KEY,
                                         &ctx->secret, &ctx->secret_len);
    if (r == 0)
        return 0;

    if (ossl_param_get1_concat_octet_string(params, OSSL_KDF_PARAM_INFO,
                                            &ctx->info, &ctx->info_len, 0) == 0)
        return 0;

    if (ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SALT,
                                     &ctx->salt, &ctx->salt_len) == 0)
            return 0;

    if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC_SIZE))
        != NULL) {
        if (!OSSL_PARAM_get_size_t(p, &sz) || sz == 0)
            return 0;
        ctx->out_len = sz;
    }
    return 1;
}

static const OSSL_PARAM *sskdf_settable_ctx_params(ossl_unused void *ctx,
                                                   ossl_unused void *provctx)
{
    static const OSSL_PARAM known_settable_ctx_params[] = {
        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
        OSSL_PARAM_size_t(OSSL_KDF_PARAM_MAC_SIZE, NULL),
        OSSL_PARAM_END
    };
    return known_settable_ctx_params;
}

static int sskdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
{
    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
    OSSL_PARAM *p;

    if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
        return OSSL_PARAM_set_size_t(p, sskdf_size(ctx));
    return -2;
}

static const OSSL_PARAM *sskdf_gettable_ctx_params(ossl_unused void *ctx,
                                                   ossl_unused void *provctx)
{
    static const OSSL_PARAM known_gettable_ctx_params[] = {
        OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
        OSSL_PARAM_END
    };
    return known_gettable_ctx_params;
}

const OSSL_DISPATCH ossl_kdf_sskdf_functions[] = {
    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
    { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))sskdf_derive },
    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
      (void(*)(void))sskdf_settable_ctx_params },
    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
      (void(*)(void))sskdf_gettable_ctx_params },
    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
    OSSL_DISPATCH_END
};

const OSSL_DISPATCH ossl_kdf_x963_kdf_functions[] = {
    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
    { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))x963kdf_derive },
    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
      (void(*)(void))sskdf_settable_ctx_params },
    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
      (void(*)(void))sskdf_gettable_ctx_params },
    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
    OSSL_DISPATCH_END
};
