/*
 * Copyright 2006-2021 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
 */

/*
 * 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 <openssl/bn.h>
#include "crypto/evp.h"
#include "dsa_local.h"

/* DSA pkey context structure */

typedef struct {
    /* Parameter gen parameters */
    int nbits;                  /* size of p in bits (default: 2048) */
    int qbits;                  /* size of q in bits (default: 224) */
    const EVP_MD *pmd;          /* MD for parameter generation */
    /* Keygen callback info */
    int gentmp[2];
    /* message digest */
    const EVP_MD *md;           /* MD for the signature */
} DSA_PKEY_CTX;

static int pkey_dsa_init(EVP_PKEY_CTX *ctx)
{
    DSA_PKEY_CTX *dctx = OPENSSL_malloc(sizeof(*dctx));

    if (dctx == NULL)
        return 0;
    dctx->nbits = 2048;
    dctx->qbits = 224;
    dctx->pmd = NULL;
    dctx->md = NULL;

    ctx->data = dctx;
    ctx->keygen_info = dctx->gentmp;
    ctx->keygen_info_count = 2;

    return 1;
}

static int pkey_dsa_copy(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src)
{
    DSA_PKEY_CTX *dctx, *sctx;

    if (!pkey_dsa_init(dst))
        return 0;
    sctx = src->data;
    dctx = dst->data;
    dctx->nbits = sctx->nbits;
    dctx->qbits = sctx->qbits;
    dctx->pmd = sctx->pmd;
    dctx->md = sctx->md;
    return 1;
}

static void pkey_dsa_cleanup(EVP_PKEY_CTX *ctx)
{
    DSA_PKEY_CTX *dctx = ctx->data;
    OPENSSL_free(dctx);
}

static int pkey_dsa_sign(EVP_PKEY_CTX *ctx, unsigned char *sig,
                         size_t *siglen, const unsigned char *tbs,
                         size_t tbslen)
{
    int ret;
    unsigned int sltmp;
    DSA_PKEY_CTX *dctx = ctx->data;
    /*
     * Discard const. Its marked as const because this may be a cached copy of
     * the "real" key. These calls don't make any modifications that need to
     * be reflected back in the "original" key.
     */
    DSA *dsa = (DSA *)EVP_PKEY_get0_DSA(ctx->pkey);

    if (dctx->md != NULL && tbslen != (size_t)EVP_MD_get_size(dctx->md))
        return 0;

    ret = DSA_sign(0, tbs, tbslen, sig, &sltmp, dsa);

    if (ret <= 0)
        return ret;
    *siglen = sltmp;
    return 1;
}

static int pkey_dsa_verify(EVP_PKEY_CTX *ctx,
                           const unsigned char *sig, size_t siglen,
                           const unsigned char *tbs, size_t tbslen)
{
    int ret;
    DSA_PKEY_CTX *dctx = ctx->data;
    /*
     * Discard const. Its marked as const because this may be a cached copy of
     * the "real" key. These calls don't make any modifications that need to
     * be reflected back in the "original" key.
     */
    DSA *dsa = (DSA *)EVP_PKEY_get0_DSA(ctx->pkey);

    if (dctx->md != NULL && tbslen != (size_t)EVP_MD_get_size(dctx->md))
        return 0;

    ret = DSA_verify(0, tbs, tbslen, sig, siglen, dsa);

    return ret;
}

static int pkey_dsa_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
{
    DSA_PKEY_CTX *dctx = ctx->data;

    switch (type) {
    case EVP_PKEY_CTRL_DSA_PARAMGEN_BITS:
        if (p1 < 256)
            return -2;
        dctx->nbits = p1;
        return 1;

    case EVP_PKEY_CTRL_DSA_PARAMGEN_Q_BITS:
        if (p1 != 160 && p1 != 224 && p1 && p1 != 256)
            return -2;
        dctx->qbits = p1;
        return 1;

    case EVP_PKEY_CTRL_DSA_PARAMGEN_MD:
        if (EVP_MD_get_type((const EVP_MD *)p2) != NID_sha1 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha224 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha256) {
            ERR_raise(ERR_LIB_DSA, DSA_R_INVALID_DIGEST_TYPE);
            return 0;
        }
        dctx->pmd = p2;
        return 1;

    case EVP_PKEY_CTRL_MD:
        if (EVP_MD_get_type((const EVP_MD *)p2) != NID_sha1 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_dsa &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_dsaWithSHA &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha224 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha256 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha384 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha512 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_224 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_256 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_384 &&
            EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_512) {
            ERR_raise(ERR_LIB_DSA, DSA_R_INVALID_DIGEST_TYPE);
            return 0;
        }
        dctx->md = p2;
        return 1;

    case EVP_PKEY_CTRL_GET_MD:
        *(const EVP_MD **)p2 = dctx->md;
        return 1;

    case EVP_PKEY_CTRL_DIGESTINIT:
    case EVP_PKEY_CTRL_PKCS7_SIGN:
    case EVP_PKEY_CTRL_CMS_SIGN:
        return 1;

    case EVP_PKEY_CTRL_PEER_KEY:
        ERR_raise(ERR_LIB_DSA, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    default:
        return -2;

    }
}

static int pkey_dsa_ctrl_str(EVP_PKEY_CTX *ctx,
                             const char *type, const char *value)
{
    if (strcmp(type, "dsa_paramgen_bits") == 0) {
        int nbits;
        nbits = atoi(value);
        return EVP_PKEY_CTX_set_dsa_paramgen_bits(ctx, nbits);
    }
    if (strcmp(type, "dsa_paramgen_q_bits") == 0) {
        int qbits = atoi(value);
        return EVP_PKEY_CTX_set_dsa_paramgen_q_bits(ctx, qbits);
    }
    if (strcmp(type, "dsa_paramgen_md") == 0) {
        const EVP_MD *md = EVP_get_digestbyname(value);

        if (md == NULL) {
            ERR_raise(ERR_LIB_DSA, DSA_R_INVALID_DIGEST_TYPE);
            return 0;
        }
        return EVP_PKEY_CTX_set_dsa_paramgen_md(ctx, md);
    }
    return -2;
}

static int pkey_dsa_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
    DSA *dsa = NULL;
    DSA_PKEY_CTX *dctx = ctx->data;
    BN_GENCB *pcb;
    int ret, res;

    if (ctx->pkey_gencb) {
        pcb = BN_GENCB_new();
        if (pcb == NULL)
            return 0;
        evp_pkey_set_cb_translate(pcb, ctx);
    } else
        pcb = NULL;
    dsa = DSA_new();
    if (dsa == NULL) {
        BN_GENCB_free(pcb);
        return 0;
    }
    if (dctx->md != NULL)
        ossl_ffc_set_digest(&dsa->params, EVP_MD_get0_name(dctx->md), NULL);

    ret = ossl_ffc_params_FIPS186_4_generate(NULL, &dsa->params,
                                             FFC_PARAM_TYPE_DSA, dctx->nbits,
                                             dctx->qbits, &res, pcb);
    BN_GENCB_free(pcb);
    if (ret > 0)
        EVP_PKEY_assign_DSA(pkey, dsa);
    else
        DSA_free(dsa);
    return ret;
}

static int pkey_dsa_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
    DSA *dsa = NULL;

    if (ctx->pkey == NULL) {
        ERR_raise(ERR_LIB_DSA, DSA_R_NO_PARAMETERS_SET);
        return 0;
    }
    dsa = DSA_new();
    if (dsa == NULL)
        return 0;
    EVP_PKEY_assign_DSA(pkey, dsa);
    /* Note: if error return, pkey is freed by parent routine */
    if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
        return 0;
    return DSA_generate_key((DSA *)EVP_PKEY_get0_DSA(pkey));
}

static const EVP_PKEY_METHOD dsa_pkey_meth = {
    EVP_PKEY_DSA,
    EVP_PKEY_FLAG_AUTOARGLEN,
    pkey_dsa_init,
    pkey_dsa_copy,
    pkey_dsa_cleanup,

    0,
    pkey_dsa_paramgen,

    0,
    pkey_dsa_keygen,

    0,
    pkey_dsa_sign,

    0,
    pkey_dsa_verify,

    0, 0,

    0, 0, 0, 0,

    0, 0,

    0, 0,

    0, 0,

    pkey_dsa_ctrl,
    pkey_dsa_ctrl_str
};

const EVP_PKEY_METHOD *ossl_dsa_pkey_method(void)
{
    return &dsa_pkey_meth;
}