/*

 * Copyright 2020-2024 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

 */

/*

 * ECDSA low level APIs are deprecated for public use, but still ok for

 * internal use - SM2 implementation uses ECDSA_size() function.

 */

#include "internal/deprecated.h"

#include <string.h> /* memcpy */

#include <openssl/crypto.h>

#include <openssl/core_dispatch.h>

#include <openssl/core_names.h>

#include <openssl/dsa.h>

#include <openssl/params.h>

#include <openssl/evp.h>

#include <openssl/err.h>

#include <openssl/proverr.h>

#include "internal/nelem.h"

#include "internal/sizes.h"

#include "internal/cryptlib.h"

#include "internal/sm3.h"

#include "prov/implementations.h"

#include "prov/providercommon.h"

#include "prov/provider_ctx.h"

#include "crypto/ec.h"

#include "crypto/sm2.h"

#include "prov/der_sm2.h"

static OSSL_FUNC_signature_newctx_fn sm2sig_newctx;

static OSSL_FUNC_signature_sign_init_fn sm2sig_signature_init;

static OSSL_FUNC_signature_verify_init_fn sm2sig_signature_init;

static OSSL_FUNC_signature_sign_fn sm2sig_sign;

static OSSL_FUNC_signature_verify_fn sm2sig_verify;

static OSSL_FUNC_signature_digest_sign_init_fn sm2sig_digest_signverify_init;

static OSSL_FUNC_signature_digest_sign_update_fn sm2sig_digest_signverify_update;

static OSSL_FUNC_signature_digest_sign_final_fn sm2sig_digest_sign_final;

static OSSL_FUNC_signature_digest_verify_init_fn sm2sig_digest_signverify_init;

static OSSL_FUNC_signature_digest_verify_update_fn sm2sig_digest_signverify_update;

static OSSL_FUNC_signature_digest_verify_final_fn sm2sig_digest_verify_final;

static OSSL_FUNC_signature_freectx_fn sm2sig_freectx;

static OSSL_FUNC_signature_dupctx_fn sm2sig_dupctx;

static OSSL_FUNC_signature_get_ctx_params_fn sm2sig_get_ctx_params;

static OSSL_FUNC_signature_gettable_ctx_params_fn sm2sig_gettable_ctx_params;

static OSSL_FUNC_signature_set_ctx_params_fn sm2sig_set_ctx_params;

static OSSL_FUNC_signature_settable_ctx_params_fn sm2sig_settable_ctx_params;

static OSSL_FUNC_signature_get_ctx_md_params_fn sm2sig_get_ctx_md_params;

static OSSL_FUNC_signature_gettable_ctx_md_params_fn sm2sig_gettable_ctx_md_params;

static OSSL_FUNC_signature_set_ctx_md_params_fn sm2sig_set_ctx_md_params;

static OSSL_FUNC_signature_settable_ctx_md_params_fn sm2sig_settable_ctx_md_params;

/*

 * What's passed as an actual key is defined by the KEYMGMT interface.

 * We happen to know that our KEYMGMT simply passes EC structures, so

 * we use that here too.

 */

typedef struct {

    OSSL_LIB_CTX *libctx;

    char *propq;

    EC_KEY *ec;

    /*

     * Flag to determine if the 'z' digest needs to be computed and fed to the

     * hash function.

     * This flag should be set on initialization and the computation should

     * be performed only once, on first update.

     */

    unsigned int flag_compute_z_digest : 1;

    char mdname[OSSL_MAX_NAME_SIZE];

    /* The Algorithm Identifier of the combined signature algorithm */

    unsigned char aid_buf[OSSL_MAX_ALGORITHM_ID_SIZE];

    size_t aid_len;

    /* main digest */

    EVP_MD *md;

    EVP_MD_CTX *mdctx;

    size_t mdsize;

    /* SM2 ID used for calculating the Z value */

    unsigned char *id;

    size_t id_len;

} PROV_SM2_CTX;

static int sm2sig_set_mdname(PROV_SM2_CTX *psm2ctx, const char *mdname)

{

    if (psm2ctx->md == NULL) /* We need an SM3 md to compare with */

        psm2ctx->md = EVP_MD_fetch(psm2ctx->libctx, psm2ctx->mdname,

            psm2ctx->propq);

    if (psm2ctx->md == NULL)

        return 0;

    /* XOF digests don't work */

    if (EVP_MD_xof(psm2ctx->md)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);

        return 0;

    }

    if (mdname == NULL)

        return 1;

    if (strlen(mdname) >= sizeof(psm2ctx->mdname)

        || !EVP_MD_is_a(psm2ctx->md, mdname)) {

        ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST, "digest=%s",

            mdname);

        return 0;

    }

    OPENSSL_strlcpy(psm2ctx->mdname, mdname, sizeof(psm2ctx->mdname));

    return 1;

}

static void *sm2sig_newctx(void *provctx, const char *propq)

{

    PROV_SM2_CTX *ctx = OPENSSL_zalloc(sizeof(PROV_SM2_CTX));

    if (ctx == NULL)

        return NULL;

    ctx->libctx = PROV_LIBCTX_OF(provctx);

    if (propq != NULL && (ctx->propq = OPENSSL_strdup(propq)) == NULL) {

        OPENSSL_free(ctx);

        return NULL;

    }

    ctx->mdsize = SM3_DIGEST_LENGTH;

    strcpy(ctx->mdname, OSSL_DIGEST_NAME_SM3);

    return ctx;

}

static int sm2sig_signature_init(void *vpsm2ctx, void *ec,

    const OSSL_PARAM params[])

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    if (!ossl_prov_is_running()

        || psm2ctx == NULL)

        return 0;

    if (ec == NULL && psm2ctx->ec == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);

        return 0;

    }

    if (ec != NULL) {

        if (!EC_KEY_up_ref(ec))

            return 0;

        EC_KEY_free(psm2ctx->ec);

        psm2ctx->ec = ec;

    }

    return sm2sig_set_ctx_params(psm2ctx, params);

}

static int sm2sig_sign(void *vpsm2ctx, unsigned char *sig, size_t *siglen,

    size_t sigsize, const unsigned char *tbs, size_t tbslen)

{

    PROV_SM2_CTX *ctx = (PROV_SM2_CTX *)vpsm2ctx;

    int ret;

    unsigned int sltmp;

    /* SM2 uses ECDSA_size as well */

    size_t ecsize = ECDSA_size(ctx->ec);

    if (sig == NULL) {

        *siglen = ecsize;

        return 1;

    }

    if (sigsize < (size_t)ecsize)

        return 0;

    if (ctx->mdsize != 0 && tbslen != ctx->mdsize)

        return 0;

    ret = ossl_sm2_internal_sign(tbs, tbslen, sig, &sltmp, ctx->ec);

    if (ret <= 0)

        return 0;

    *siglen = sltmp;

    return 1;

}

static int sm2sig_verify(void *vpsm2ctx, const unsigned char *sig, size_t siglen,

    const unsigned char *tbs, size_t tbslen)

{

    PROV_SM2_CTX *ctx = (PROV_SM2_CTX *)vpsm2ctx;

    if (ctx->mdsize != 0 && tbslen != ctx->mdsize)

        return 0;

    return ossl_sm2_internal_verify(tbs, tbslen, sig, siglen, ctx->ec);

}

static void free_md(PROV_SM2_CTX *ctx)

{

    EVP_MD_CTX_free(ctx->mdctx);

    EVP_MD_free(ctx->md);

    ctx->mdctx = NULL;

    ctx->md = NULL;

}

static int sm2sig_digest_signverify_init(void *vpsm2ctx, const char *mdname,

    void *ec, const OSSL_PARAM params[])

{

    PROV_SM2_CTX *ctx = (PROV_SM2_CTX *)vpsm2ctx;

    int md_nid;

    WPACKET pkt;

    int ret = 0;

    unsigned char *aid = NULL;

    if (!sm2sig_signature_init(vpsm2ctx, ec, params)

        || !sm2sig_set_mdname(ctx, mdname))

        return ret;

    if (ctx->mdctx == NULL) {

        ctx->mdctx = EVP_MD_CTX_new();

        if (ctx->mdctx == NULL)

            goto error;

    }

    md_nid = EVP_MD_get_type(ctx->md);

    /*

     * We do not care about DER writing errors.

     * All it really means is that for some reason, there's no

     * AlgorithmIdentifier to be had, but the operation itself is

     * still valid, just as long as it's not used to construct

     * anything that needs an AlgorithmIdentifier.

     */

    ctx->aid_len = 0;

    if (WPACKET_init_der(&pkt, ctx->aid_buf, sizeof(ctx->aid_buf))

        && ossl_DER_w_algorithmIdentifier_SM2_with_MD(&pkt, -1, ctx->ec, md_nid)

        && WPACKET_finish(&pkt)) {

        WPACKET_get_total_written(&pkt, &ctx->aid_len);

        aid = WPACKET_get_curr(&pkt);

    }

    WPACKET_cleanup(&pkt);

    if (aid != NULL && ctx->aid_len != 0)

        memmove(ctx->aid_buf, aid, ctx->aid_len);

    if (!EVP_DigestInit_ex2(ctx->mdctx, ctx->md, params))

        goto error;

    ctx->flag_compute_z_digest = 1;

    ret = 1;

error:

    return ret;

}

static int sm2sig_compute_z_digest(PROV_SM2_CTX *ctx)

{

    uint8_t *z = NULL;

    int ret = 1;

    if (ctx->flag_compute_z_digest) {

        /* Only do this once */

        ctx->flag_compute_z_digest = 0;

        if ((z = OPENSSL_zalloc(ctx->mdsize)) == NULL

            /* get hashed prefix 'z' of tbs message */

            || !ossl_sm2_compute_z_digest(z, ctx->md, ctx->id, ctx->id_len,

                ctx->ec)

            || !EVP_DigestUpdate(ctx->mdctx, z, ctx->mdsize))

            ret = 0;

        OPENSSL_free(z);

    }

    return ret;

}

int sm2sig_digest_signverify_update(void *vpsm2ctx, const unsigned char *data,

    size_t datalen)

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    if (psm2ctx == NULL || psm2ctx->mdctx == NULL)

        return 0;

    return sm2sig_compute_z_digest(psm2ctx)

        && EVP_DigestUpdate(psm2ctx->mdctx, data, datalen);

}

int sm2sig_digest_sign_final(void *vpsm2ctx, unsigned char *sig, size_t *siglen,

    size_t sigsize)

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    unsigned char digest[EVP_MAX_MD_SIZE];

    unsigned int dlen = 0;

    if (psm2ctx == NULL || psm2ctx->mdctx == NULL)

        return 0;

    /*

     * If sig is NULL then we're just finding out the sig size. Other fields

     * are ignored. Defer to sm2sig_sign.

     */

    if (sig != NULL) {

        if (!(sm2sig_compute_z_digest(psm2ctx)

                && EVP_DigestFinal_ex(psm2ctx->mdctx, digest, &dlen)))

            return 0;

    }

    return sm2sig_sign(vpsm2ctx, sig, siglen, sigsize, digest, (size_t)dlen);

}

int sm2sig_digest_verify_final(void *vpsm2ctx, const unsigned char *sig,

    size_t siglen)

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    unsigned char digest[EVP_MAX_MD_SIZE];

    unsigned int dlen = 0;

    int md_size;

    if (psm2ctx == NULL || psm2ctx->mdctx == NULL)

        return 0;

    md_size = EVP_MD_get_size(psm2ctx->md);

    if (md_size <= 0 || md_size > (int)sizeof(digest))

        return 0;

    if (!(sm2sig_compute_z_digest(psm2ctx)

            && EVP_DigestFinal_ex(psm2ctx->mdctx, digest, &dlen)))

        return 0;

    return sm2sig_verify(vpsm2ctx, sig, siglen, digest, (size_t)dlen);

}

static void sm2sig_freectx(void *vpsm2ctx)

{

    PROV_SM2_CTX *ctx = (PROV_SM2_CTX *)vpsm2ctx;

    free_md(ctx);

    EC_KEY_free(ctx->ec);

    OPENSSL_free(ctx->propq);

    OPENSSL_free(ctx->id);

    OPENSSL_free(ctx);

}

static void *sm2sig_dupctx(void *vpsm2ctx)

{

    PROV_SM2_CTX *srcctx = (PROV_SM2_CTX *)vpsm2ctx;

    PROV_SM2_CTX *dstctx;

    dstctx = OPENSSL_zalloc(sizeof(*srcctx));

    if (dstctx == NULL)

        return NULL;

    *dstctx = *srcctx;

    dstctx->ec = NULL;

    dstctx->propq = NULL;

    dstctx->md = NULL;

    dstctx->mdctx = NULL;

    dstctx->id = NULL;

    if (srcctx->ec != NULL && !EC_KEY_up_ref(srcctx->ec))

        goto err;

    dstctx->ec = srcctx->ec;

    if (srcctx->propq != NULL) {

        dstctx->propq = OPENSSL_strdup(srcctx->propq);

        if (dstctx->propq == NULL)

            goto err;

    }

    if (srcctx->md != NULL && !EVP_MD_up_ref(srcctx->md))

        goto err;

    dstctx->md = srcctx->md;

    if (srcctx->mdctx != NULL) {

        dstctx->mdctx = EVP_MD_CTX_new();

        if (dstctx->mdctx == NULL

            || !EVP_MD_CTX_copy_ex(dstctx->mdctx, srcctx->mdctx))

            goto err;

    }

    if (srcctx->id != NULL) {

        dstctx->id = OPENSSL_malloc(srcctx->id_len);

        if (dstctx->id == NULL)

            goto err;

        dstctx->id_len = srcctx->id_len;

        memcpy(dstctx->id, srcctx->id, srcctx->id_len);

    }

    return dstctx;

err:

    sm2sig_freectx(dstctx);

    return NULL;

}

static int sm2sig_get_ctx_params(void *vpsm2ctx, OSSL_PARAM *params)

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    OSSL_PARAM *p;

    if (psm2ctx == NULL)

        return 0;

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_ALGORITHM_ID);

    if (p != NULL

        && !OSSL_PARAM_set_octet_string(p,

            psm2ctx->aid_len == 0 ? NULL : psm2ctx->aid_buf,

            psm2ctx->aid_len))

        return 0;

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_DIGEST_SIZE);

    if (p != NULL && !OSSL_PARAM_set_size_t(p, psm2ctx->mdsize))

        return 0;

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_DIGEST);

    if (p != NULL && !OSSL_PARAM_set_utf8_string(p, psm2ctx->md == NULL ? psm2ctx->mdname : EVP_MD_get0_name(psm2ctx->md)))

        return 0;

    return 1;

}

static const OSSL_PARAM known_gettable_ctx_params[] = {

    OSSL_PARAM_octet_string(OSSL_SIGNATURE_PARAM_ALGORITHM_ID, NULL, 0),

    OSSL_PARAM_size_t(OSSL_SIGNATURE_PARAM_DIGEST_SIZE, NULL),

    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_DIGEST, NULL, 0),

    OSSL_PARAM_END

};

static const OSSL_PARAM *sm2sig_gettable_ctx_params(ossl_unused void *vpsm2ctx,

    ossl_unused void *provctx)

{

    return known_gettable_ctx_params;

}

static int sm2sig_set_ctx_params(void *vpsm2ctx, const OSSL_PARAM params[])

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    const OSSL_PARAM *p;

    size_t mdsize;

    if (psm2ctx == NULL)

        return 0;

    if (ossl_param_is_empty(params))

        return 1;

    p = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_DIST_ID);

    if (p != NULL) {

        void *tmp_id = NULL;

        size_t tmp_idlen = 0;

        /*

         * If the 'z' digest has already been computed, the ID is set too late

         */

        if (!psm2ctx->flag_compute_z_digest)

            return 0;

        if (p->data_size != 0

            && !OSSL_PARAM_get_octet_string(p, &tmp_id, 0, &tmp_idlen))

            return 0;

        OPENSSL_free(psm2ctx->id);

        psm2ctx->id = tmp_id;

        psm2ctx->id_len = tmp_idlen;

    }

    /*

     * The following code checks that the size is the same as the SM3 digest

     * size returning an error otherwise.

     * If there is ever any different digest algorithm allowed with SM2

     * this needs to be adjusted accordingly.

     */

    p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_DIGEST_SIZE);

    if (p != NULL && (!OSSL_PARAM_get_size_t(p, &mdsize) || mdsize != psm2ctx->mdsize))

        return 0;

    p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_DIGEST);

    if (p != NULL) {

        char *mdname = NULL;

        if (!OSSL_PARAM_get_utf8_string(p, &mdname, 0))

            return 0;

        if (!sm2sig_set_mdname(psm2ctx, mdname)) {

            OPENSSL_free(mdname);

            return 0;

        }

        OPENSSL_free(mdname);

    }

    return 1;

}

static const OSSL_PARAM known_settable_ctx_params[] = {

    OSSL_PARAM_size_t(OSSL_SIGNATURE_PARAM_DIGEST_SIZE, NULL),

    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_DIGEST, NULL, 0),

    OSSL_PARAM_octet_string(OSSL_PKEY_PARAM_DIST_ID, NULL, 0),

    OSSL_PARAM_END

};

static const OSSL_PARAM *sm2sig_settable_ctx_params(ossl_unused void *vpsm2ctx,

    ossl_unused void *provctx)

{

    return known_settable_ctx_params;

}

static int sm2sig_get_ctx_md_params(void *vpsm2ctx, OSSL_PARAM *params)

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    if (psm2ctx->mdctx == NULL)

        return 0;

    return EVP_MD_CTX_get_params(psm2ctx->mdctx, params);

}

static const OSSL_PARAM *sm2sig_gettable_ctx_md_params(void *vpsm2ctx)

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    if (psm2ctx->md == NULL)

        return 0;

    return EVP_MD_gettable_ctx_params(psm2ctx->md);

}

static int sm2sig_set_ctx_md_params(void *vpsm2ctx, const OSSL_PARAM params[])

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    if (psm2ctx->mdctx == NULL)

        return 0;

    return EVP_MD_CTX_set_params(psm2ctx->mdctx, params);

}

static const OSSL_PARAM *sm2sig_settable_ctx_md_params(void *vpsm2ctx)

{

    PROV_SM2_CTX *psm2ctx = (PROV_SM2_CTX *)vpsm2ctx;

    if (psm2ctx->md == NULL)

        return 0;

    return EVP_MD_settable_ctx_params(psm2ctx->md);

}

const OSSL_DISPATCH ossl_sm2_signature_functions[] = {

    { OSSL_FUNC_SIGNATURE_NEWCTX, (void (*)(void))sm2sig_newctx },

    { OSSL_FUNC_SIGNATURE_SIGN_INIT, (void (*)(void))sm2sig_signature_init },

    { OSSL_FUNC_SIGNATURE_SIGN, (void (*)(void))sm2sig_sign },

    { OSSL_FUNC_SIGNATURE_VERIFY_INIT, (void (*)(void))sm2sig_signature_init },

    { OSSL_FUNC_SIGNATURE_VERIFY, (void (*)(void))sm2sig_verify },

    { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_INIT,

        (void (*)(void))sm2sig_digest_signverify_init },

    { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_UPDATE,

        (void (*)(void))sm2sig_digest_signverify_update },

    { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_FINAL,

        (void (*)(void))sm2sig_digest_sign_final },

    { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_INIT,

        (void (*)(void))sm2sig_digest_signverify_init },

    { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_UPDATE,

        (void (*)(void))sm2sig_digest_signverify_update },

    { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_FINAL,

        (void (*)(void))sm2sig_digest_verify_final },

    { OSSL_FUNC_SIGNATURE_FREECTX, (void (*)(void))sm2sig_freectx },

    { OSSL_FUNC_SIGNATURE_DUPCTX, (void (*)(void))sm2sig_dupctx },

    { OSSL_FUNC_SIGNATURE_GET_CTX_PARAMS, (void (*)(void))sm2sig_get_ctx_params },

    { OSSL_FUNC_SIGNATURE_GETTABLE_CTX_PARAMS,

        (void (*)(void))sm2sig_gettable_ctx_params },

    { OSSL_FUNC_SIGNATURE_SET_CTX_PARAMS, (void (*)(void))sm2sig_set_ctx_params },

    { OSSL_FUNC_SIGNATURE_SETTABLE_CTX_PARAMS,

        (void (*)(void))sm2sig_settable_ctx_params },

    { OSSL_FUNC_SIGNATURE_GET_CTX_MD_PARAMS,

        (void (*)(void))sm2sig_get_ctx_md_params },

    { OSSL_FUNC_SIGNATURE_GETTABLE_CTX_MD_PARAMS,

        (void (*)(void))sm2sig_gettable_ctx_md_params },

    { OSSL_FUNC_SIGNATURE_SET_CTX_MD_PARAMS,

        (void (*)(void))sm2sig_set_ctx_md_params },

    { OSSL_FUNC_SIGNATURE_SETTABLE_CTX_MD_PARAMS,

        (void (*)(void))sm2sig_settable_ctx_md_params },

    OSSL_DISPATCH_END

};