providers/implementations/signature/dsa.c - third_party/openssl - Git at Google

 /*
  * Copyright 2019 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
  */

 #include <openssl/crypto.h>
 #include <openssl/core_numbers.h>
 #include <openssl/core_names.h>
 #include <openssl/dsa.h>
 #include <openssl/params.h>
 #include <openssl/evp.h>
 #include "prov/implementations.h"
 #include "prov/provider_ctx.h"
 #include "crypto/dsa.h"

 static OSSL_OP_signature_newctx_fn dsa_newctx;
 static OSSL_OP_signature_sign_init_fn dsa_signature_init;
 static OSSL_OP_signature_verify_init_fn dsa_signature_init;
 static OSSL_OP_signature_sign_fn dsa_sign;
 static OSSL_OP_signature_verify_fn dsa_verify;
 static OSSL_OP_signature_digest_sign_init_fn dsa_digest_signverify_init;
 static OSSL_OP_signature_digest_sign_update_fn dsa_digest_signverify_update;
 static OSSL_OP_signature_digest_sign_final_fn dsa_digest_sign_final;
 static OSSL_OP_signature_digest_verify_init_fn dsa_digest_signverify_init;
 static OSSL_OP_signature_digest_verify_update_fn dsa_digest_signverify_update;
 static OSSL_OP_signature_digest_verify_final_fn dsa_digest_verify_final;
 static OSSL_OP_signature_freectx_fn dsa_freectx;
 static OSSL_OP_signature_dupctx_fn dsa_dupctx;
 static OSSL_OP_signature_get_ctx_params_fn dsa_get_ctx_params;
 static OSSL_OP_signature_gettable_ctx_params_fn dsa_gettable_ctx_params;
 static OSSL_OP_signature_set_ctx_params_fn dsa_set_ctx_params;
 static OSSL_OP_signature_settable_ctx_params_fn dsa_settable_ctx_params;
 static OSSL_OP_signature_get_ctx_md_params_fn dsa_get_ctx_md_params;
 static OSSL_OP_signature_gettable_ctx_md_params_fn dsa_gettable_ctx_md_params;
 static OSSL_OP_signature_set_ctx_md_params_fn dsa_set_ctx_md_params;
 static OSSL_OP_signature_settable_ctx_md_params_fn dsa_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 DSA structures, so
  * we use that here too.
  */

 typedef struct {
     OPENSSL_CTX *libctx;
     DSA *dsa;
     size_t mdsize;
     /* Should be big enough */
     char mdname[80];
     EVP_MD *md;
     EVP_MD_CTX *mdctx;
 } PROV_DSA_CTX;

 static void *dsa_newctx(void *provctx)
 {
     PROV_DSA_CTX *pdsactx = OPENSSL_zalloc(sizeof(PROV_DSA_CTX));

     if (pdsactx == NULL)
         return NULL;

     pdsactx->libctx = PROV_LIBRARY_CONTEXT_OF(provctx);
     return pdsactx;
 }

 static int dsa_signature_init(void *vpdsactx, void *vdsa)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     if (pdsactx == NULL || vdsa == NULL || !DSA_up_ref(vdsa))
         return 0;
     DSA_free(pdsactx->dsa);
     pdsactx->dsa = vdsa;
     return 1;
 }

 static int dsa_sign(void *vpdsactx, unsigned char *sig, size_t *siglen,
                     size_t sigsize, const unsigned char *tbs, size_t tbslen)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;
     int ret;
     unsigned int sltmp;
     size_t dsasize = DSA_size(pdsactx->dsa);

     if (sig == NULL) {
         *siglen = dsasize;
         return 1;
     }

     if (sigsize < (size_t)dsasize)
         return 0;

     if (pdsactx->mdsize != 0 && tbslen != pdsactx->mdsize)
         return 0;

     ret = dsa_sign_int(pdsactx->libctx, 0, tbs, tbslen, sig, &sltmp,
                        pdsactx->dsa);
     if (ret <= 0)
         return 0;

     *siglen = sltmp;
     return 1;
 }

 static int dsa_verify(void *vpdsactx, const unsigned char *sig, size_t siglen,
                       const unsigned char *tbs, size_t tbslen)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     if (pdsactx->mdsize != 0 && tbslen != pdsactx->mdsize)
         return 0;

     return DSA_verify(0, tbs, tbslen, sig, siglen, pdsactx->dsa);
 }

 static int dsa_digest_signverify_init(void *vpdsactx, const char *mdname,
                                       const char *props, void *vdsa)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;
     EVP_MD *md;

     if (!dsa_signature_init(vpdsactx, vdsa))
         return 0;

     md = EVP_MD_fetch(pdsactx->libctx, mdname, props);
     if (md == NULL)
         return 0;
     pdsactx->md = md;
     pdsactx->mdsize = EVP_MD_size(md);
     pdsactx->mdctx = EVP_MD_CTX_new();
     if (pdsactx->mdctx == NULL)
         return 0;

     if (!EVP_DigestInit_ex(pdsactx->mdctx, md, NULL))
         return 0;

     return 1;
 }

 int dsa_digest_signverify_update(void *vpdsactx, const unsigned char *data,
                                  size_t datalen)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     if (pdsactx == NULL || pdsactx->mdctx == NULL)
         return 0;

     return EVP_DigestUpdate(pdsactx->mdctx, data, datalen);
 }

 int dsa_digest_sign_final(void *vpdsactx, unsigned char *sig, size_t *siglen,
                           size_t sigsize)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;
     unsigned char digest[EVP_MAX_MD_SIZE];
     unsigned int dlen = 0;

     if (pdsactx == NULL || pdsactx->mdctx == NULL)
         return 0;

     /*
      * If sig is NULL then we're just finding out the sig size. Other fields
      * are ignored. Defer to dsa_sign.
      */
     if (sig != NULL) {
         /*
          * TODO(3.0): There is the possibility that some externally provided
          * digests exceed EVP_MAX_MD_SIZE. We should probably handle that somehow -
          * but that problem is much larger than just in DSA.
          */
         if (!EVP_DigestFinal_ex(pdsactx->mdctx, digest, &dlen))
             return 0;
     }

     return dsa_sign(vpdsactx, sig, siglen, sigsize, digest, (size_t)dlen);
 }


 int dsa_digest_verify_final(void *vpdsactx, const unsigned char *sig,
                             size_t siglen)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;
     unsigned char digest[EVP_MAX_MD_SIZE];
     unsigned int dlen = 0;

     if (pdsactx == NULL || pdsactx->mdctx == NULL)
         return 0;

     /*
      * TODO(3.0): There is the possibility that some externally provided
      * digests exceed EVP_MAX_MD_SIZE. We should probably handle that somehow -
      * but that problem is much larger than just in DSA.
      */
     if (!EVP_DigestFinal_ex(pdsactx->mdctx, digest, &dlen))
         return 0;

     return dsa_verify(vpdsactx, sig, siglen, digest, (size_t)dlen);
 }

 static void dsa_freectx(void *vpdsactx)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     DSA_free(pdsactx->dsa);
     EVP_MD_CTX_free(pdsactx->mdctx);
     EVP_MD_free(pdsactx->md);

     OPENSSL_free(pdsactx);
 }

 static void *dsa_dupctx(void *vpdsactx)
 {
     PROV_DSA_CTX *srcctx = (PROV_DSA_CTX *)vpdsactx;
     PROV_DSA_CTX *dstctx;

     dstctx = OPENSSL_zalloc(sizeof(*srcctx));
     if (dstctx == NULL)
         return NULL;

     *dstctx = *srcctx;
     dstctx->dsa = NULL;
     dstctx->md = NULL;
     dstctx->mdctx = NULL;

     if (srcctx->dsa != NULL && !DSA_up_ref(srcctx->dsa))
         goto err;
     dstctx->dsa = srcctx->dsa;

     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;
     }

     return dstctx;
  err:
     dsa_freectx(dstctx);
     return NULL;
 }

 static int dsa_get_ctx_params(void *vpdsactx, OSSL_PARAM *params)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;
     OSSL_PARAM *p;

     if (pdsactx == NULL || params == NULL)
         return 0;

     p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_DIGEST_SIZE);
     if (p != NULL && !OSSL_PARAM_set_size_t(p, pdsactx->mdsize))
         return 0;

     p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_DIGEST);
     if (p != NULL && !OSSL_PARAM_set_utf8_string(p, pdsactx->md == NULL
                                                     ? pdsactx->mdname
                                                     : EVP_MD_name(pdsactx->md)))
         return 0;

     return 1;
 }

 static const OSSL_PARAM known_gettable_ctx_params[] = {
     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 *dsa_gettable_ctx_params(void)
 {
     return known_gettable_ctx_params;
 }

 static int dsa_set_ctx_params(void *vpdsactx, const OSSL_PARAM params[])
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;
     const OSSL_PARAM *p;
     char *mdname;

     if (pdsactx == NULL || params == NULL)
         return 0;

     if (pdsactx->md != NULL) {
         /*
          * You cannot set the digest name/size when doing a DigestSign or
          * DigestVerify.
          */
         return 1;
     }

     p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_DIGEST_SIZE);
     if (p != NULL && !OSSL_PARAM_get_size_t(p, &pdsactx->mdsize))
         return 0;

     /*
      * We never actually use the mdname, but we do support getting it later.
      * This can be useful for applications that want to know the MD that they
      * previously set.
      */
     p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_DIGEST);
     mdname = pdsactx->mdname;
     if (p != NULL
             && !OSSL_PARAM_get_utf8_string(p, &mdname, sizeof(pdsactx->mdname)))
         return 0;

     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_END
 };

 static const OSSL_PARAM *dsa_settable_ctx_params(void)
 {
     /*
      * TODO(3.0): Should this function return a different set of settable ctx
      * params if the ctx is being used for a DigestSign/DigestVerify? In that
      * case it is not allowed to set the digest size/digest name because the
      * digest is explicitly set as part of the init.
      */
     return known_settable_ctx_params;
 }

 static int dsa_get_ctx_md_params(void *vpdsactx, OSSL_PARAM *params)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     if (pdsactx->mdctx == NULL)
         return 0;

     return EVP_MD_CTX_get_params(pdsactx->mdctx, params);
 }

 static const OSSL_PARAM *dsa_gettable_ctx_md_params(void *vpdsactx)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     if (pdsactx->md == NULL)
         return 0;

     return EVP_MD_gettable_ctx_params(pdsactx->md);
 }

 static int dsa_set_ctx_md_params(void *vpdsactx, const OSSL_PARAM params[])
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     if (pdsactx->mdctx == NULL)
         return 0;

     return EVP_MD_CTX_set_params(pdsactx->mdctx, params);
 }

 static const OSSL_PARAM *dsa_settable_ctx_md_params(void *vpdsactx)
 {
     PROV_DSA_CTX *pdsactx = (PROV_DSA_CTX *)vpdsactx;

     if (pdsactx->md == NULL)
         return 0;

     return EVP_MD_settable_ctx_params(pdsactx->md);
 }

 const OSSL_DISPATCH dsa_signature_functions[] = {
     { OSSL_FUNC_SIGNATURE_NEWCTX, (void (*)(void))dsa_newctx },
     { OSSL_FUNC_SIGNATURE_SIGN_INIT, (void (*)(void))dsa_signature_init },
     { OSSL_FUNC_SIGNATURE_SIGN, (void (*)(void))dsa_sign },
     { OSSL_FUNC_SIGNATURE_VERIFY_INIT, (void (*)(void))dsa_signature_init },
     { OSSL_FUNC_SIGNATURE_VERIFY, (void (*)(void))dsa_verify },
     { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_INIT,
       (void (*)(void))dsa_digest_signverify_init },
     { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_UPDATE,
       (void (*)(void))dsa_digest_signverify_update },
     { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_FINAL,
       (void (*)(void))dsa_digest_sign_final },
     { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_INIT,
       (void (*)(void))dsa_digest_signverify_init },
     { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_UPDATE,
       (void (*)(void))dsa_digest_signverify_update },
     { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_FINAL,
       (void (*)(void))dsa_digest_verify_final },
     { OSSL_FUNC_SIGNATURE_FREECTX, (void (*)(void))dsa_freectx },
     { OSSL_FUNC_SIGNATURE_DUPCTX, (void (*)(void))dsa_dupctx },
     { OSSL_FUNC_SIGNATURE_GET_CTX_PARAMS, (void (*)(void))dsa_get_ctx_params },
     { OSSL_FUNC_SIGNATURE_GETTABLE_CTX_PARAMS,
       (void (*)(void))dsa_gettable_ctx_params },
     { OSSL_FUNC_SIGNATURE_SET_CTX_PARAMS, (void (*)(void))dsa_set_ctx_params },
     { OSSL_FUNC_SIGNATURE_SETTABLE_CTX_PARAMS,
       (void (*)(void))dsa_settable_ctx_params },
     { OSSL_FUNC_SIGNATURE_GET_CTX_MD_PARAMS,
       (void (*)(void))dsa_get_ctx_md_params },
     { OSSL_FUNC_SIGNATURE_GETTABLE_CTX_MD_PARAMS,
       (void (*)(void))dsa_gettable_ctx_md_params },
     { OSSL_FUNC_SIGNATURE_SET_CTX_MD_PARAMS,
       (void (*)(void))dsa_set_ctx_md_params },
     { OSSL_FUNC_SIGNATURE_SETTABLE_CTX_MD_PARAMS,
       (void (*)(void))dsa_settable_ctx_md_params },
     { 0, NULL }
 };
	/*
	* Copyright 2019 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
	*/

	#include <openssl/crypto.h>
	#include <openssl/core_numbers.h>
	#include <openssl/core_names.h>
	#include <openssl/dsa.h>
	#include <openssl/params.h>
	#include <openssl/evp.h>
	#include "prov/implementations.h"
	#include "prov/provider_ctx.h"
	#include "crypto/dsa.h"

	static OSSL_OP_signature_newctx_fn dsa_newctx;
	static OSSL_OP_signature_sign_init_fn dsa_signature_init;
	static OSSL_OP_signature_verify_init_fn dsa_signature_init;
	static OSSL_OP_signature_sign_fn dsa_sign;
	static OSSL_OP_signature_verify_fn dsa_verify;
	static OSSL_OP_signature_digest_sign_init_fn dsa_digest_signverify_init;
	static OSSL_OP_signature_digest_sign_update_fn dsa_digest_signverify_update;
	static OSSL_OP_signature_digest_sign_final_fn dsa_digest_sign_final;
	static OSSL_OP_signature_digest_verify_init_fn dsa_digest_signverify_init;
	static OSSL_OP_signature_digest_verify_update_fn dsa_digest_signverify_update;
	static OSSL_OP_signature_digest_verify_final_fn dsa_digest_verify_final;
	static OSSL_OP_signature_freectx_fn dsa_freectx;
	static OSSL_OP_signature_dupctx_fn dsa_dupctx;
	static OSSL_OP_signature_get_ctx_params_fn dsa_get_ctx_params;
	static OSSL_OP_signature_gettable_ctx_params_fn dsa_gettable_ctx_params;
	static OSSL_OP_signature_set_ctx_params_fn dsa_set_ctx_params;
	static OSSL_OP_signature_settable_ctx_params_fn dsa_settable_ctx_params;
	static OSSL_OP_signature_get_ctx_md_params_fn dsa_get_ctx_md_params;
	static OSSL_OP_signature_gettable_ctx_md_params_fn dsa_gettable_ctx_md_params;
	static OSSL_OP_signature_set_ctx_md_params_fn dsa_set_ctx_md_params;
	static OSSL_OP_signature_settable_ctx_md_params_fn dsa_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 DSA structures, so
	* we use that here too.
	*/

	typedef struct {
	OPENSSL_CTX *libctx;
	DSA *dsa;
	size_t mdsize;
	/* Should be big enough */
	char mdname[80];
	EVP_MD *md;
	EVP_MD_CTX *mdctx;
	} PROV_DSA_CTX;

	static void dsa_newctx(void provctx)
	{
	PROV_DSA_CTX *pdsactx = OPENSSL_zalloc(sizeof(PROV_DSA_CTX));

	if (pdsactx == NULL)
	return NULL;

	pdsactx->libctx = PROV_LIBRARY_CONTEXT_OF(provctx);
	return pdsactx;
	}

	static int dsa_signature_init(void vpdsactx, void vdsa)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	if (pdsactx == NULL \|\| vdsa == NULL \|\| !DSA_up_ref(vdsa))
	return 0;
	DSA_free(pdsactx->dsa);
	pdsactx->dsa = vdsa;
	return 1;
	}

	static int dsa_sign(void vpdsactx, unsigned char sig, size_t *siglen,
	size_t sigsize, const unsigned char *tbs, size_t tbslen)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;
	int ret;
	unsigned int sltmp;
	size_t dsasize = DSA_size(pdsactx->dsa);

	if (sig == NULL) {
	*siglen = dsasize;
	return 1;
	}

	if (sigsize < (size_t)dsasize)
	return 0;

	if (pdsactx->mdsize != 0 && tbslen != pdsactx->mdsize)
	return 0;

	ret = dsa_sign_int(pdsactx->libctx, 0, tbs, tbslen, sig, &sltmp,
	pdsactx->dsa);
	if (ret <= 0)
	return 0;

	*siglen = sltmp;
	return 1;
	}

	static int dsa_verify(void vpdsactx, const unsigned char sig, size_t siglen,
	const unsigned char *tbs, size_t tbslen)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	if (pdsactx->mdsize != 0 && tbslen != pdsactx->mdsize)
	return 0;

	return DSA_verify(0, tbs, tbslen, sig, siglen, pdsactx->dsa);
	}

	static int dsa_digest_signverify_init(void vpdsactx, const char mdname,
	const char props, void vdsa)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;
	EVP_MD *md;

	if (!dsa_signature_init(vpdsactx, vdsa))
	return 0;

	md = EVP_MD_fetch(pdsactx->libctx, mdname, props);
	if (md == NULL)
	return 0;
	pdsactx->md = md;
	pdsactx->mdsize = EVP_MD_size(md);
	pdsactx->mdctx = EVP_MD_CTX_new();
	if (pdsactx->mdctx == NULL)
	return 0;

	if (!EVP_DigestInit_ex(pdsactx->mdctx, md, NULL))
	return 0;

	return 1;
	}

	int dsa_digest_signverify_update(void vpdsactx, const unsigned char data,
	size_t datalen)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	if (pdsactx == NULL \|\| pdsactx->mdctx == NULL)
	return 0;

	return EVP_DigestUpdate(pdsactx->mdctx, data, datalen);
	}

	int dsa_digest_sign_final(void vpdsactx, unsigned char sig, size_t *siglen,
	size_t sigsize)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;
	unsigned char digest[EVP_MAX_MD_SIZE];
	unsigned int dlen = 0;

	if (pdsactx == NULL \|\| pdsactx->mdctx == NULL)
	return 0;

	/*
	* If sig is NULL then we're just finding out the sig size. Other fields
	* are ignored. Defer to dsa_sign.
	*/
	if (sig != NULL) {
	/*
	* TODO(3.0): There is the possibility that some externally provided
	* digests exceed EVP_MAX_MD_SIZE. We should probably handle that somehow -
	* but that problem is much larger than just in DSA.
	*/
	if (!EVP_DigestFinal_ex(pdsactx->mdctx, digest, &dlen))
	return 0;
	}

	return dsa_sign(vpdsactx, sig, siglen, sigsize, digest, (size_t)dlen);
	}


	int dsa_digest_verify_final(void vpdsactx, const unsigned char sig,
	size_t siglen)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;
	unsigned char digest[EVP_MAX_MD_SIZE];
	unsigned int dlen = 0;

	if (pdsactx == NULL \|\| pdsactx->mdctx == NULL)
	return 0;

	/*
	* TODO(3.0): There is the possibility that some externally provided
	* digests exceed EVP_MAX_MD_SIZE. We should probably handle that somehow -
	* but that problem is much larger than just in DSA.
	*/
	if (!EVP_DigestFinal_ex(pdsactx->mdctx, digest, &dlen))
	return 0;

	return dsa_verify(vpdsactx, sig, siglen, digest, (size_t)dlen);
	}

	static void dsa_freectx(void *vpdsactx)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	DSA_free(pdsactx->dsa);
	EVP_MD_CTX_free(pdsactx->mdctx);
	EVP_MD_free(pdsactx->md);

	OPENSSL_free(pdsactx);
	}

	static void dsa_dupctx(void vpdsactx)
	{
	PROV_DSA_CTX srcctx = (PROV_DSA_CTX )vpdsactx;
	PROV_DSA_CTX *dstctx;

	dstctx = OPENSSL_zalloc(sizeof(*srcctx));
	if (dstctx == NULL)
	return NULL;

	dstctx = srcctx;
	dstctx->dsa = NULL;
	dstctx->md = NULL;
	dstctx->mdctx = NULL;

	if (srcctx->dsa != NULL && !DSA_up_ref(srcctx->dsa))
	goto err;
	dstctx->dsa = srcctx->dsa;

	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;
	}

	return dstctx;
	err:
	dsa_freectx(dstctx);
	return NULL;
	}

	static int dsa_get_ctx_params(void vpdsactx, OSSL_PARAM params)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;
	OSSL_PARAM *p;

	if (pdsactx == NULL \|\| params == NULL)
	return 0;

	p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_DIGEST_SIZE);
	if (p != NULL && !OSSL_PARAM_set_size_t(p, pdsactx->mdsize))
	return 0;

	p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_DIGEST);
	if (p != NULL && !OSSL_PARAM_set_utf8_string(p, pdsactx->md == NULL
	? pdsactx->mdname
	: EVP_MD_name(pdsactx->md)))
	return 0;

	return 1;
	}

	static const OSSL_PARAM known_gettable_ctx_params[] = {
	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 *dsa_gettable_ctx_params(void)
	{
	return known_gettable_ctx_params;
	}

	static int dsa_set_ctx_params(void *vpdsactx, const OSSL_PARAM params[])
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;
	const OSSL_PARAM *p;
	char *mdname;

	if (pdsactx == NULL \|\| params == NULL)
	return 0;

	if (pdsactx->md != NULL) {
	/*
	* You cannot set the digest name/size when doing a DigestSign or
	* DigestVerify.
	*/
	return 1;
	}

	p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_DIGEST_SIZE);
	if (p != NULL && !OSSL_PARAM_get_size_t(p, &pdsactx->mdsize))
	return 0;

	/*
	* We never actually use the mdname, but we do support getting it later.
	* This can be useful for applications that want to know the MD that they
	* previously set.
	*/
	p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_DIGEST);
	mdname = pdsactx->mdname;
	if (p != NULL
	&& !OSSL_PARAM_get_utf8_string(p, &mdname, sizeof(pdsactx->mdname)))
	return 0;

	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_END
	};

	static const OSSL_PARAM *dsa_settable_ctx_params(void)
	{
	/*
	* TODO(3.0): Should this function return a different set of settable ctx
	* params if the ctx is being used for a DigestSign/DigestVerify? In that
	* case it is not allowed to set the digest size/digest name because the
	* digest is explicitly set as part of the init.
	*/
	return known_settable_ctx_params;
	}

	static int dsa_get_ctx_md_params(void vpdsactx, OSSL_PARAM params)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	if (pdsactx->mdctx == NULL)
	return 0;

	return EVP_MD_CTX_get_params(pdsactx->mdctx, params);
	}

	static const OSSL_PARAM dsa_gettable_ctx_md_params(void vpdsactx)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	if (pdsactx->md == NULL)
	return 0;

	return EVP_MD_gettable_ctx_params(pdsactx->md);
	}

	static int dsa_set_ctx_md_params(void *vpdsactx, const OSSL_PARAM params[])
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	if (pdsactx->mdctx == NULL)
	return 0;

	return EVP_MD_CTX_set_params(pdsactx->mdctx, params);
	}

	static const OSSL_PARAM dsa_settable_ctx_md_params(void vpdsactx)
	{
	PROV_DSA_CTX pdsactx = (PROV_DSA_CTX )vpdsactx;

	if (pdsactx->md == NULL)
	return 0;

	return EVP_MD_settable_ctx_params(pdsactx->md);
	}

	const OSSL_DISPATCH dsa_signature_functions[] = {
	{ OSSL_FUNC_SIGNATURE_NEWCTX, (void (*)(void))dsa_newctx },
	{ OSSL_FUNC_SIGNATURE_SIGN_INIT, (void (*)(void))dsa_signature_init },
	{ OSSL_FUNC_SIGNATURE_SIGN, (void (*)(void))dsa_sign },
	{ OSSL_FUNC_SIGNATURE_VERIFY_INIT, (void (*)(void))dsa_signature_init },
	{ OSSL_FUNC_SIGNATURE_VERIFY, (void (*)(void))dsa_verify },
	{ OSSL_FUNC_SIGNATURE_DIGEST_SIGN_INIT,
	(void (*)(void))dsa_digest_signverify_init },
	{ OSSL_FUNC_SIGNATURE_DIGEST_SIGN_UPDATE,
	(void (*)(void))dsa_digest_signverify_update },
	{ OSSL_FUNC_SIGNATURE_DIGEST_SIGN_FINAL,
	(void (*)(void))dsa_digest_sign_final },
	{ OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_INIT,
	(void (*)(void))dsa_digest_signverify_init },
	{ OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_UPDATE,
	(void (*)(void))dsa_digest_signverify_update },
	{ OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_FINAL,
	(void (*)(void))dsa_digest_verify_final },
	{ OSSL_FUNC_SIGNATURE_FREECTX, (void (*)(void))dsa_freectx },
	{ OSSL_FUNC_SIGNATURE_DUPCTX, (void (*)(void))dsa_dupctx },
	{ OSSL_FUNC_SIGNATURE_GET_CTX_PARAMS, (void (*)(void))dsa_get_ctx_params },
	{ OSSL_FUNC_SIGNATURE_GETTABLE_CTX_PARAMS,
	(void (*)(void))dsa_gettable_ctx_params },
	{ OSSL_FUNC_SIGNATURE_SET_CTX_PARAMS, (void (*)(void))dsa_set_ctx_params },
	{ OSSL_FUNC_SIGNATURE_SETTABLE_CTX_PARAMS,
	(void (*)(void))dsa_settable_ctx_params },
	{ OSSL_FUNC_SIGNATURE_GET_CTX_MD_PARAMS,
	(void (*)(void))dsa_get_ctx_md_params },
	{ OSSL_FUNC_SIGNATURE_GETTABLE_CTX_MD_PARAMS,
	(void (*)(void))dsa_gettable_ctx_md_params },
	{ OSSL_FUNC_SIGNATURE_SET_CTX_MD_PARAMS,
	(void (*)(void))dsa_set_ctx_md_params },
	{ OSSL_FUNC_SIGNATURE_SETTABLE_CTX_MD_PARAMS,
	(void (*)(void))dsa_settable_ctx_md_params },
	{ 0, NULL }
	};