/*

 * Copyright 2006-2025 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

 */

/*

 * DH & DSA low level APIs are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#include <stdio.h>

#include "internal/cryptlib.h"

#include <openssl/asn1t.h>

#include <openssl/x509.h>

#include <openssl/evp.h>

#include "dh_local.h"

#include <openssl/bn.h>

#include <openssl/dsa.h>

#include <openssl/objects.h>

#include "crypto/evp.h"

/* DH pkey context structure */

typedef struct {

    /* Parameter gen parameters */

    int prime_len;

    int generator;

    int paramgen_type;

    int subprime_len;

    int pad;

    /* message digest used for parameter generation */

    const EVP_MD *md;

    int param_nid;

    /* Keygen callback info */

    int gentmp[2];

    /* KDF (if any) to use for DH */

    char kdf_type;

    /* OID to use for KDF */

    ASN1_OBJECT *kdf_oid;

    /* Message digest to use for key derivation */

    const EVP_MD *kdf_md;

    /* User key material */

    unsigned char *kdf_ukm;

    size_t kdf_ukmlen;

    /* KDF output length */

    size_t kdf_outlen;

} DH_PKEY_CTX;

static int pkey_dh_init(EVP_PKEY_CTX *ctx)

{

    DH_PKEY_CTX *dctx;

    if ((dctx = OPENSSL_zalloc(sizeof(*dctx))) == NULL)

        return 0;

    dctx->prime_len = 2048;

    dctx->subprime_len = -1;

    dctx->generator = 2;

    dctx->kdf_type = EVP_PKEY_DH_KDF_NONE;

    ctx->data = dctx;

    ctx->keygen_info = dctx->gentmp;

    ctx->keygen_info_count = 2;

    return 1;

}

static void pkey_dh_cleanup(EVP_PKEY_CTX *ctx)

{

    DH_PKEY_CTX *dctx = ctx->data;

    if (dctx != NULL) {

        OPENSSL_free(dctx->kdf_ukm);

        ASN1_OBJECT_free(dctx->kdf_oid);

        OPENSSL_free(dctx);

    }

}

static int pkey_dh_copy(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src)

{

    DH_PKEY_CTX *dctx, *sctx;

    if (!pkey_dh_init(dst))

        return 0;

    sctx = src->data;

    dctx = dst->data;

    dctx->prime_len = sctx->prime_len;

    dctx->subprime_len = sctx->subprime_len;

    dctx->generator = sctx->generator;

    dctx->paramgen_type = sctx->paramgen_type;

    dctx->pad = sctx->pad;

    dctx->md = sctx->md;

    dctx->param_nid = sctx->param_nid;

    dctx->kdf_type = sctx->kdf_type;

    dctx->kdf_oid = OBJ_dup(sctx->kdf_oid);

    if (dctx->kdf_oid == NULL)

        return 0;

    dctx->kdf_md = sctx->kdf_md;

    if (sctx->kdf_ukm != NULL) {

        dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);

        if (dctx->kdf_ukm == NULL)

            return 0;

        dctx->kdf_ukmlen = sctx->kdf_ukmlen;

    }

    dctx->kdf_outlen = sctx->kdf_outlen;

    return 1;

}

static int pkey_dh_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)

{

    DH_PKEY_CTX *dctx = ctx->data;

    switch (type) {

    case EVP_PKEY_CTRL_DH_PARAMGEN_PRIME_LEN:

        if (p1 < 256)

            return -2;

        dctx->prime_len = p1;

        return 1;

    case EVP_PKEY_CTRL_DH_PARAMGEN_SUBPRIME_LEN:

        if (dctx->paramgen_type == DH_PARAMGEN_TYPE_GENERATOR)

            return -2;

        dctx->subprime_len = p1;

        return 1;

    case EVP_PKEY_CTRL_DH_PAD:

        dctx->pad = p1;

        return 1;

    case EVP_PKEY_CTRL_DH_PARAMGEN_GENERATOR:

        if (dctx->paramgen_type != DH_PARAMGEN_TYPE_GENERATOR)

            return -2;

        dctx->generator = p1;

        return 1;

    case EVP_PKEY_CTRL_DH_PARAMGEN_TYPE:

#ifdef OPENSSL_NO_DSA

        if (p1 != DH_PARAMGEN_TYPE_GENERATOR)

            return -2;

#else

        if (p1 < 0 || p1 > 2)

            return -2;

#endif

        dctx->paramgen_type = p1;

        return 1;

    case EVP_PKEY_CTRL_DH_RFC5114:

        if (p1 < 1 || p1 > 3 || dctx->param_nid != NID_undef)

            return -2;

        dctx->param_nid = p1;

        return 1;

    case EVP_PKEY_CTRL_DH_NID:

        if (p1 <= 0 || dctx->param_nid != NID_undef)

            return -2;

        dctx->param_nid = p1;

        return 1;

    case EVP_PKEY_CTRL_PEER_KEY:

        /* Default behaviour is OK */

        return 1;

    case EVP_PKEY_CTRL_DH_KDF_TYPE:

        if (p1 == -2)

            return dctx->kdf_type;

        if (p1 != EVP_PKEY_DH_KDF_NONE && p1 != EVP_PKEY_DH_KDF_X9_42)

            return -2;

        dctx->kdf_type = p1;

        return 1;

    case EVP_PKEY_CTRL_DH_KDF_MD:

        dctx->kdf_md = p2;

        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_MD:

        *(const EVP_MD **)p2 = dctx->kdf_md;

        return 1;

    case EVP_PKEY_CTRL_DH_KDF_OUTLEN:

        if (p1 <= 0)

            return -2;

        dctx->kdf_outlen = (size_t)p1;

        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_OUTLEN:

        *(int *)p2 = (int)dctx->kdf_outlen;

        return 1;

    case EVP_PKEY_CTRL_DH_KDF_UKM:

        OPENSSL_free(dctx->kdf_ukm);

        dctx->kdf_ukm = p2;

        if (p2)

            dctx->kdf_ukmlen = p1;

        else

            dctx->kdf_ukmlen = 0;

        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_UKM:

        *(unsigned char **)p2 = dctx->kdf_ukm;

        return (int)dctx->kdf_ukmlen;

    case EVP_PKEY_CTRL_DH_KDF_OID:

        ASN1_OBJECT_free(dctx->kdf_oid);

        dctx->kdf_oid = p2;

        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_OID:

        *(ASN1_OBJECT **)p2 = dctx->kdf_oid;

        return 1;

    default:

        return -2;

    }

}

static int pkey_dh_ctrl_str(EVP_PKEY_CTX *ctx,

    const char *type, const char *value)

{

    if (strcmp(type, "dh_paramgen_prime_len") == 0) {

        int len;

        len = atoi(value);

        return EVP_PKEY_CTX_set_dh_paramgen_prime_len(ctx, len);

    }

    if (strcmp(type, "dh_rfc5114") == 0) {

        DH_PKEY_CTX *dctx = ctx->data;

        int id;

        id = atoi(value);

        if (id < 0 || id > 3)

            return -2;

        dctx->param_nid = id;

        return 1;

    }

    if (strcmp(type, "dh_param") == 0) {

        DH_PKEY_CTX *dctx = ctx->data;

        int nid = OBJ_sn2nid(value);

        if (nid == NID_undef) {

            ERR_raise(ERR_LIB_DH, DH_R_INVALID_PARAMETER_NAME);

            return -2;

        }

        dctx->param_nid = nid;

        return 1;

    }

    if (strcmp(type, "dh_paramgen_generator") == 0) {

        int len;

        len = atoi(value);

        return EVP_PKEY_CTX_set_dh_paramgen_generator(ctx, len);

    }

    if (strcmp(type, "dh_paramgen_subprime_len") == 0) {

        int len;

        len = atoi(value);

        return EVP_PKEY_CTX_set_dh_paramgen_subprime_len(ctx, len);

    }

    if (strcmp(type, "dh_paramgen_type") == 0) {

        int typ;

        typ = atoi(value);

        return EVP_PKEY_CTX_set_dh_paramgen_type(ctx, typ);

    }

    if (strcmp(type, "dh_pad") == 0) {

        int pad;

        pad = atoi(value);

        return EVP_PKEY_CTX_set_dh_pad(ctx, pad);

    }

    return -2;

}

static DH *ffc_params_generate(OSSL_LIB_CTX *libctx, DH_PKEY_CTX *dctx,

    BN_GENCB *pcb)

{

    DH *ret;

    int rv = 0;

    int res;

    int prime_len = dctx->prime_len;

    int subprime_len = dctx->subprime_len;

    if (dctx->paramgen_type > DH_PARAMGEN_TYPE_FIPS_186_4)

        return NULL;

    ret = DH_new();

    if (ret == NULL)

        return NULL;

    if (subprime_len == -1) {

        if (prime_len >= 2048)

            subprime_len = 256;

        else

            subprime_len = 160;

    }

    if (dctx->md != NULL)

        ossl_ffc_set_digest(&ret->params, EVP_MD_get0_name(dctx->md), NULL);

#ifndef FIPS_MODULE

    if (dctx->paramgen_type == DH_PARAMGEN_TYPE_FIPS_186_2)

        rv = ossl_ffc_params_FIPS186_2_generate(libctx, &ret->params,

            FFC_PARAM_TYPE_DH,

            prime_len, subprime_len, &res,

            pcb);

    else

#endif

        /* For FIPS we always use the DH_PARAMGEN_TYPE_FIPS_186_4 generator */

        if (dctx->paramgen_type >= DH_PARAMGEN_TYPE_FIPS_186_2)

            rv = ossl_ffc_params_FIPS186_4_generate(libctx, &ret->params,

                FFC_PARAM_TYPE_DH,

                prime_len, subprime_len, &res,

                pcb);

    if (rv <= 0) {

        DH_free(ret);

        return NULL;

    }

    return ret;

}

static int pkey_dh_paramgen(EVP_PKEY_CTX *ctx,

    EVP_PKEY *pkey)

{

    DH *dh = NULL;

    DH_PKEY_CTX *dctx = ctx->data;

    BN_GENCB *pcb = NULL;

    int ret;

    /*

     * Look for a safe prime group for key establishment. Which uses

     * either RFC_3526 (modp_XXXX) or RFC_7919 (ffdheXXXX).

     * RFC_5114 is also handled here for param_nid = (1..3)

     */

    if (dctx->param_nid != NID_undef) {

        int type = dctx->param_nid <= 3 ? EVP_PKEY_DHX : EVP_PKEY_DH;

        if ((dh = DH_new_by_nid(dctx->param_nid)) == NULL)

            return 0;

        EVP_PKEY_assign(pkey, type, dh);

        return 1;

    }

    if (ctx->pkey_gencb != NULL) {

        pcb = BN_GENCB_new();

        if (pcb == NULL)

            return 0;

        evp_pkey_set_cb_translate(pcb, ctx);

    }

#ifdef FIPS_MODULE

    dctx->paramgen_type = DH_PARAMGEN_TYPE_FIPS_186_4;

#endif /* FIPS_MODULE */

    if (dctx->paramgen_type >= DH_PARAMGEN_TYPE_FIPS_186_2) {

        dh = ffc_params_generate(NULL, dctx, pcb);

        BN_GENCB_free(pcb);

        if (dh == NULL)

            return 0;

        EVP_PKEY_assign(pkey, EVP_PKEY_DHX, dh);

        return 1;

    }

    dh = DH_new();

    if (dh == NULL) {

        BN_GENCB_free(pcb);

        return 0;

    }

    ret = DH_generate_parameters_ex(dh,

        dctx->prime_len, dctx->generator, pcb);

    BN_GENCB_free(pcb);

    if (ret)

        EVP_PKEY_assign_DH(pkey, dh);

    else

        DH_free(dh);

    return ret;

}

static int pkey_dh_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)

{

    DH_PKEY_CTX *dctx = ctx->data;

    DH *dh = NULL;

    if (ctx->pkey == NULL && dctx->param_nid == NID_undef) {

        ERR_raise(ERR_LIB_DH, DH_R_NO_PARAMETERS_SET);

        return 0;

    }

    if (dctx->param_nid != NID_undef)

        dh = DH_new_by_nid(dctx->param_nid);

    else

        dh = DH_new();

    if (dh == NULL)

        return 0;

    EVP_PKEY_assign(pkey, ctx->pmeth->pkey_id, dh);

    /* Note: if error return, pkey is freed by parent routine */

    if (ctx->pkey != NULL && !EVP_PKEY_copy_parameters(pkey, ctx->pkey))

        return 0;

    return DH_generate_key((DH *)EVP_PKEY_get0_DH(pkey));

}

static int pkey_dh_derive(EVP_PKEY_CTX *ctx, unsigned char *key,

    size_t *keylen)

{

    int ret;

    DH *dh;

    const DH *dhpub;

    DH_PKEY_CTX *dctx = ctx->data;

    BIGNUM *dhpubbn;

    if (ctx->pkey == NULL || ctx->peerkey == NULL) {

        ERR_raise(ERR_LIB_DH, DH_R_KEYS_NOT_SET);

        return 0;

    }

    dh = (DH *)EVP_PKEY_get0_DH(ctx->pkey);

    dhpub = EVP_PKEY_get0_DH(ctx->peerkey);

    if (dhpub == NULL || dh == NULL) {

        ERR_raise(ERR_LIB_DH, DH_R_KEYS_NOT_SET);

        return 0;

    }

    dhpubbn = dhpub->pub_key;

    if (dctx->kdf_type == EVP_PKEY_DH_KDF_NONE) {

        if (key == NULL) {

            *keylen = DH_size(dh);

            return 1;

        }

        if (dctx->pad)

            ret = DH_compute_key_padded(key, dhpubbn, dh);

        else

            ret = DH_compute_key(key, dhpubbn, dh);

        if (ret <= 0)

            return ret;

        *keylen = ret;

        return 1;

    } else if (dctx->kdf_type == EVP_PKEY_DH_KDF_X9_42) {

        unsigned char *Z = NULL;

        int Zlen = 0;

        if (!dctx->kdf_outlen || !dctx->kdf_oid)

            return 0;

        if (key == NULL) {

            *keylen = dctx->kdf_outlen;

            return 1;

        }

        if (*keylen != dctx->kdf_outlen)

            return 0;

        ret = 0;

        if ((Zlen = DH_size(dh)) <= 0)

            return 0;

        if ((Z = OPENSSL_malloc(Zlen)) == NULL)

            return 0;

        if (DH_compute_key_padded(Z, dhpubbn, dh) <= 0)

            goto err;

        if (!DH_KDF_X9_42(key, *keylen, Z, Zlen, dctx->kdf_oid,

                dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md))

            goto err;

        *keylen = dctx->kdf_outlen;

        ret = 1;

    err:

        OPENSSL_clear_free(Z, Zlen);

        return ret;

    }

    return 0;

}

static const EVP_PKEY_METHOD dh_pkey_meth = {

    EVP_PKEY_DH,

    0,

    pkey_dh_init,

    pkey_dh_copy,

    pkey_dh_cleanup,

    0,

    pkey_dh_paramgen,

    0,

    pkey_dh_keygen,

    0,

    0,

    0,

    0,

    0, 0,

    0, 0, 0, 0,

    0, 0,

    0, 0,

    0,

    pkey_dh_derive,

    pkey_dh_ctrl,

    pkey_dh_ctrl_str

};

const EVP_PKEY_METHOD *ossl_dh_pkey_method(void)

{

    return &dh_pkey_meth;

}

static const EVP_PKEY_METHOD dhx_pkey_meth = {

    EVP_PKEY_DHX,

    0,

    pkey_dh_init,

    pkey_dh_copy,

    pkey_dh_cleanup,

    0,

    pkey_dh_paramgen,

    0,

    pkey_dh_keygen,

    0,

    0,

    0,

    0,

    0, 0,

    0, 0, 0, 0,

    0, 0,

    0, 0,

    0,

    pkey_dh_derive,

    pkey_dh_ctrl,

    pkey_dh_ctrl_str

};

const EVP_PKEY_METHOD *ossl_dhx_pkey_method(void)

{

    return &dhx_pkey_meth;

}