/*

 * Copyright 1995-2024 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

 */

/*

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

 * internal use.

 */

#include "internal/deprecated.h"

#include <openssl/bn.h>

#include "internal/cryptlib.h"

#include "dsa_local.h"

#include "crypto/asn1_dsa.h"

#include "crypto/dsa.h"

DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)

{

    return dsa->meth->dsa_do_sign(dgst, dlen, dsa);

}

#ifndef OPENSSL_NO_DEPRECATED_3_0

int DSA_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)

{

    return dsa->meth->dsa_sign_setup(dsa, ctx_in, kinvp, rp);

}

#endif

DSA_SIG *DSA_SIG_new(void)

{

    DSA_SIG *sig = OPENSSL_zalloc(sizeof(*sig));

    if (sig == NULL)

        ERR_raise(ERR_LIB_DSA, ERR_R_MALLOC_FAILURE);

    return sig;

}

void DSA_SIG_free(DSA_SIG *sig)

{

    if (sig == NULL)

        return;

    BN_clear_free(sig->r);

    BN_clear_free(sig->s);

    OPENSSL_free(sig);

}

DSA_SIG *d2i_DSA_SIG(DSA_SIG **psig, const unsigned char **ppin, long len)

{

    DSA_SIG *sig;

    if (len < 0)

        return NULL;

    if (psig != NULL && *psig != NULL) {

        sig = *psig;

    } else {

        sig = DSA_SIG_new();

        if (sig == NULL)

            return NULL;

    }

    if (sig->r == NULL)

        sig->r = BN_new();

    if (sig->s == NULL)

        sig->s = BN_new();

    if (sig->r == NULL || sig->s == NULL

        || ossl_decode_der_dsa_sig(sig->r, sig->s, ppin, (size_t)len) == 0) {

        if (psig == NULL || *psig == NULL)

            DSA_SIG_free(sig);

        return NULL;

    }

    if (psig != NULL && *psig == NULL)

        *psig = sig;

    return sig;

}

int i2d_DSA_SIG(const DSA_SIG *sig, unsigned char **ppout)

{

    BUF_MEM *buf = NULL;

    size_t encoded_len;

    WPACKET pkt;

    if (ppout == NULL) {

        if (!WPACKET_init_null(&pkt, 0))

            return -1;

    } else if (*ppout == NULL) {

        if ((buf = BUF_MEM_new()) == NULL

                || !WPACKET_init_len(&pkt, buf, 0)) {

            BUF_MEM_free(buf);

            return -1;

        }

    } else {

        if (!WPACKET_init_static_len(&pkt, *ppout, SIZE_MAX, 0))

            return -1;

    }

    if (!ossl_encode_der_dsa_sig(&pkt, sig->r, sig->s)

            || !WPACKET_get_total_written(&pkt, &encoded_len)

            || !WPACKET_finish(&pkt)) {

        BUF_MEM_free(buf);

        WPACKET_cleanup(&pkt);

        return -1;

    }

    if (ppout != NULL) {

        if (*ppout == NULL) {

            *ppout = (unsigned char *)buf->data;

            buf->data = NULL;

            BUF_MEM_free(buf);

        } else {

            *ppout += encoded_len;

        }

    }

    return (int)encoded_len;

}

int DSA_size(const DSA *dsa)

{

    int ret = -1;

    DSA_SIG sig;

    if (dsa->params.q != NULL) {

        sig.r = sig.s = dsa->params.q;

        ret = i2d_DSA_SIG(&sig, NULL);

        if (ret < 0)

            ret = 0;

    }

    return ret;

}

void DSA_SIG_get0(const DSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps)

{

    if (pr != NULL)

        *pr = sig->r;

    if (ps != NULL)

        *ps = sig->s;

}

int DSA_SIG_set0(DSA_SIG *sig, BIGNUM *r, BIGNUM *s)

{

    if (r == NULL || s == NULL)

        return 0;

    BN_clear_free(sig->r);

    BN_clear_free(sig->s);

    sig->r = r;

    sig->s = s;

    return 1;

}

int ossl_dsa_sign_int(int type, const unsigned char *dgst, int dlen,

                      unsigned char *sig, unsigned int *siglen, DSA *dsa)

{

    DSA_SIG *s;

    if (sig == NULL) {

        *siglen = DSA_size(dsa);

        return 1;

    }

    /* legacy case uses the method table */

    if (dsa->libctx == NULL || dsa->meth != DSA_get_default_method())

        s = DSA_do_sign(dgst, dlen, dsa);

    else

        s = ossl_dsa_do_sign_int(dgst, dlen, dsa);

    if (s == NULL) {

        *siglen = 0;

        return 0;

    }

    *siglen = i2d_DSA_SIG(s, &sig);

    DSA_SIG_free(s);

    return 1;

}

int DSA_sign(int type, const unsigned char *dgst, int dlen,

             unsigned char *sig, unsigned int *siglen, DSA *dsa)

{

    return ossl_dsa_sign_int(type, dgst, dlen, sig, siglen, dsa);

}

/* data has already been hashed (probably with SHA or SHA-1). */

/*-

 * returns

 *      1: correct signature

 *      0: incorrect signature

 *     -1: error

 */

int DSA_verify(int type, const unsigned char *dgst, int dgst_len,

               const unsigned char *sigbuf, int siglen, DSA *dsa)

{

    DSA_SIG *s;

    const unsigned char *p = sigbuf;

    unsigned char *der = NULL;

    int derlen = -1;

    int ret = -1;

    s = DSA_SIG_new();

    if (s == NULL)

        return ret;

    if (d2i_DSA_SIG(&s, &p, siglen) == NULL)

        goto err;

    /* Ensure signature uses DER and doesn't have trailing garbage */

    derlen = i2d_DSA_SIG(s, &der);

    if (derlen != siglen || memcmp(sigbuf, der, derlen))

        goto err;

    ret = DSA_do_verify(dgst, dgst_len, s, dsa);

 err:

    OPENSSL_clear_free(der, derlen);

    DSA_SIG_free(s);

    return ret;

}