include/openssl/dsa.h - boringssl.git - Git at Google

 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
  * This package is an SSL implementation written
  * by Eric Young (eay@cryptsoft.com).
  * The implementation was written so as to conform with Netscapes SSL.
  *
  * This library is free for commercial and non-commercial use as long as
  * the following conditions are aheared to.  The following conditions
  * apply to all code found in this distribution, be it the RC4, RSA,
  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  * included with this distribution is covered by the same copyright terms
  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  *
  * Copyright remains Eric Young's, and as such any Copyright notices in
  * the code are not to be removed.
  * If this package is used in a product, Eric Young should be given attribution
  * as the author of the parts of the library used.
  * This can be in the form of a textual message at program startup or
  * in documentation (online or textual) provided with the package.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. All advertising materials mentioning features or use of this software
  *    must display the following acknowledgement:
  *    "This product includes cryptographic software written by
  *     Eric Young (eay@cryptsoft.com)"
  *    The word 'cryptographic' can be left out if the rouines from the library
  *    being used are not cryptographic related :-).
  * 4. If you include any Windows specific code (or a derivative thereof) from
  *    the apps directory (application code) you must include an acknowledgement:
  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  *
  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  * The licence and distribution terms for any publically available version or
  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  * copied and put under another distribution licence
  * [including the GNU Public Licence.]
  *
  * The DSS routines are based on patches supplied by
  * Steven Schoch <schoch@sheba.arc.nasa.gov>. */

 #ifndef OPENSSL_HEADER_DSA_H
 #define OPENSSL_HEADER_DSA_H

 #include <openssl/base.h>

 #include <openssl/ex_data.h>

 #if defined(__cplusplus)
 extern "C" {
 #endif


 // DSA contains functions for signing and verifying with the Digital Signature
 // Algorithm.
 //
 // This module is deprecated and retained for legacy reasons only. It is not
 // considered a priority for performance or hardening work. Do not use it in
 // new code. Use Ed25519, ECDSA with P-256, or RSA instead.


 // Allocation and destruction.
 //
 // A |DSA| object represents a DSA key or group parameters. A given object may
 // be used concurrently on multiple threads by non-mutating functions, provided
 // no other thread is concurrently calling a mutating function. Unless otherwise
 // documented, functions which take a |const| pointer are non-mutating and
 // functions which take a non-|const| pointer are mutating.

 // DSA_new returns a new, empty DSA object or NULL on error.
 OPENSSL_EXPORT DSA *DSA_new(void);

 // DSA_free decrements the reference count of |dsa| and frees it if the
 // reference count drops to zero.
 OPENSSL_EXPORT void DSA_free(DSA *dsa);

 // DSA_up_ref increments the reference count of |dsa| and returns one. It does
 // not mutate |dsa| for thread-safety purposes and may be used concurrently.
 OPENSSL_EXPORT int DSA_up_ref(DSA *dsa);


 // Properties.

 // DSA_bits returns the size of |dsa|'s group modulus, in bits.
 OPENSSL_EXPORT unsigned DSA_bits(const DSA *dsa);

 // DSA_get0_pub_key returns |dsa|'s public key.
 OPENSSL_EXPORT const BIGNUM *DSA_get0_pub_key(const DSA *dsa);

 // DSA_get0_priv_key returns |dsa|'s private key, or NULL if |dsa| is a public
 // key.
 OPENSSL_EXPORT const BIGNUM *DSA_get0_priv_key(const DSA *dsa);

 // DSA_get0_p returns |dsa|'s group modulus.
 OPENSSL_EXPORT const BIGNUM *DSA_get0_p(const DSA *dsa);

 // DSA_get0_q returns the size of |dsa|'s subgroup.
 OPENSSL_EXPORT const BIGNUM *DSA_get0_q(const DSA *dsa);

 // DSA_get0_g returns |dsa|'s group generator.
 OPENSSL_EXPORT const BIGNUM *DSA_get0_g(const DSA *dsa);

 // DSA_get0_key sets |*out_pub_key| and |*out_priv_key|, if non-NULL, to |dsa|'s
 // public and private key, respectively. If |dsa| is a public key, the private
 // key will be set to NULL.
 OPENSSL_EXPORT void DSA_get0_key(const DSA *dsa, const BIGNUM **out_pub_key,
                                  const BIGNUM **out_priv_key);

 // DSA_get0_pqg sets |*out_p|, |*out_q|, and |*out_g|, if non-NULL, to |dsa|'s
 // p, q, and g parameters, respectively.
 OPENSSL_EXPORT void DSA_get0_pqg(const DSA *dsa, const BIGNUM **out_p,
                                  const BIGNUM **out_q, const BIGNUM **out_g);

 // DSA_set0_key sets |dsa|'s public and private key to |pub_key| and |priv_key|,
 // respectively, if non-NULL. On success, it takes ownership of each argument
 // and returns one. Otherwise, it returns zero.
 //
 // |priv_key| may be NULL, but |pub_key| must either be non-NULL or already
 // configured on |dsa|.
 OPENSSL_EXPORT int DSA_set0_key(DSA *dsa, BIGNUM *pub_key, BIGNUM *priv_key);

 // DSA_set0_pqg sets |dsa|'s parameters to |p|, |q|, and |g|, if non-NULL, and
 // takes ownership of them. On success, it takes ownership of each argument and
 // returns one. Otherwise, it returns zero.
 //
 // Each argument must either be non-NULL or already configured on |dsa|.
 OPENSSL_EXPORT int DSA_set0_pqg(DSA *dsa, BIGNUM *p, BIGNUM *q, BIGNUM *g);


 // Parameter generation.

 // DSA_generate_parameters_ex generates a set of DSA parameters by following
 // the procedure given in FIPS 186-4, appendix A.
 // (http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf)
 //
 // The larger prime will have a length of |bits| (e.g. 2048). The |seed| value
 // allows others to generate and verify the same parameters and should be
 // random input which is kept for reference. If |out_counter| or |out_h| are
 // not NULL then the counter and h value used in the generation are written to
 // them.
 //
 // The |cb| argument is passed to |BN_generate_prime_ex| and is thus called
 // during the generation process in order to indicate progress. See the
 // comments for that function for details. In addition to the calls made by
 // |BN_generate_prime_ex|, |DSA_generate_parameters_ex| will call it with
 // |event| equal to 2 and 3 at different stages of the process.
 //
 // It returns one on success and zero otherwise.
 OPENSSL_EXPORT int DSA_generate_parameters_ex(DSA *dsa, unsigned bits,
                                               const uint8_t *seed,
                                               size_t seed_len, int *out_counter,
                                               unsigned long *out_h,
                                               BN_GENCB *cb);

 // DSAparams_dup returns a freshly allocated |DSA| that contains a copy of the
 // parameters from |dsa|. It returns NULL on error.
 OPENSSL_EXPORT DSA *DSAparams_dup(const DSA *dsa);


 // Key generation.

 // DSA_generate_key generates a public/private key pair in |dsa|, which must
 // already have parameters setup. It returns one on success and zero on
 // error.
 OPENSSL_EXPORT int DSA_generate_key(DSA *dsa);


 // Signatures.

 // DSA_SIG_st (aka |DSA_SIG|) contains a DSA signature as a pair of integers.
 struct DSA_SIG_st {
   BIGNUM *r, *s;
 };

 // DSA_SIG_new returns a freshly allocated, DIG_SIG structure or NULL on error.
 // Both |r| and |s| in the signature will be NULL.
 OPENSSL_EXPORT DSA_SIG *DSA_SIG_new(void);

 // DSA_SIG_free frees the contents of |sig| and then frees |sig| itself.
 OPENSSL_EXPORT void DSA_SIG_free(DSA_SIG *sig);

 // DSA_SIG_get0 sets |*out_r| and |*out_s|, if non-NULL, to the two components
 // of |sig|.
 OPENSSL_EXPORT void DSA_SIG_get0(const DSA_SIG *sig, const BIGNUM **out_r,
                                  const BIGNUM **out_s);

 // DSA_SIG_set0 sets |sig|'s components to |r| and |s|, neither of which may be
 // NULL. On success, it takes ownership of each argument and returns one.
 // Otherwise, it returns zero.
 OPENSSL_EXPORT int DSA_SIG_set0(DSA_SIG *sig, BIGNUM *r, BIGNUM *s);

 // DSA_do_sign returns a signature of the hash in |digest| by the key in |dsa|
 // and returns an allocated, DSA_SIG structure, or NULL on error.
 OPENSSL_EXPORT DSA_SIG *DSA_do_sign(const uint8_t *digest, size_t digest_len,
                                     const DSA *dsa);

 // DSA_do_verify verifies that |sig| is a valid signature, by the public key in
 // |dsa|, of the hash in |digest|. It returns one if so, zero if invalid and -1
 // on error.
 //
 // WARNING: do not use. This function returns -1 for error, 0 for invalid and 1
 // for valid. However, this is dangerously different to the usual OpenSSL
 // convention and could be a disaster if a user did |if (DSA_do_verify(...))|.
 // Because of this, |DSA_check_signature| is a safer version of this.
 //
 // TODO(fork): deprecate.
 OPENSSL_EXPORT int DSA_do_verify(const uint8_t *digest, size_t digest_len,
                                  const DSA_SIG *sig, const DSA *dsa);

 // DSA_do_check_signature sets |*out_valid| to zero. Then it verifies that |sig|
 // is a valid signature, by the public key in |dsa| of the hash in |digest|
 // and, if so, it sets |*out_valid| to one.
 //
 // It returns one if it was able to verify the signature as valid or invalid,
 // and zero on error.
 OPENSSL_EXPORT int DSA_do_check_signature(int *out_valid, const uint8_t *digest,
                                           size_t digest_len, const DSA_SIG *sig,
                                           const DSA *dsa);


 // ASN.1 signatures.
 //
 // These functions also perform DSA signature operations, but deal with ASN.1
 // encoded signatures as opposed to raw |BIGNUM|s. If you don't know what
 // encoding a DSA signature is in, it's probably ASN.1.

 // DSA_sign signs |digest| with the key in |dsa| and writes the resulting
 // signature, in ASN.1 form, to |out_sig| and the length of the signature to
 // |*out_siglen|. There must be, at least, |DSA_size(dsa)| bytes of space in
 // |out_sig|. It returns one on success and zero otherwise.
 //
 // (The |type| argument is ignored.)
 OPENSSL_EXPORT int DSA_sign(int type, const uint8_t *digest, size_t digest_len,
                             uint8_t *out_sig, unsigned int *out_siglen,
                             const DSA *dsa);

 // DSA_verify verifies that |sig| is a valid, ASN.1 signature, by the public
 // key in |dsa|, of the hash in |digest|. It returns one if so, zero if invalid
 // and -1 on error.
 //
 // (The |type| argument is ignored.)
 //
 // WARNING: do not use. This function returns -1 for error, 0 for invalid and 1
 // for valid. However, this is dangerously different to the usual OpenSSL
 // convention and could be a disaster if a user did |if (DSA_do_verify(...))|.
 // Because of this, |DSA_check_signature| is a safer version of this.
 //
 // TODO(fork): deprecate.
 OPENSSL_EXPORT int DSA_verify(int type, const uint8_t *digest,
                               size_t digest_len, const uint8_t *sig,
                               size_t sig_len, const DSA *dsa);

 // DSA_check_signature sets |*out_valid| to zero. Then it verifies that |sig|
 // is a valid, ASN.1 signature, by the public key in |dsa|, of the hash in
 // |digest|. If so, it sets |*out_valid| to one.
 //
 // It returns one if it was able to verify the signature as valid or invalid,
 // and zero on error.
 OPENSSL_EXPORT int DSA_check_signature(int *out_valid, const uint8_t *digest,
                                        size_t digest_len, const uint8_t *sig,
                                        size_t sig_len, const DSA *dsa);

 // DSA_size returns the size, in bytes, of an ASN.1 encoded, DSA signature
 // generated by |dsa|. Parameters must already have been setup in |dsa|.
 OPENSSL_EXPORT int DSA_size(const DSA *dsa);


 // ASN.1 encoding.

 // DSA_SIG_parse parses a DER-encoded DSA-Sig-Value structure from |cbs| and
 // advances |cbs|. It returns a newly-allocated |DSA_SIG| or NULL on error.
 OPENSSL_EXPORT DSA_SIG *DSA_SIG_parse(CBS *cbs);

 // DSA_SIG_marshal marshals |sig| as a DER-encoded DSA-Sig-Value and appends the
 // result to |cbb|. It returns one on success and zero on error.
 OPENSSL_EXPORT int DSA_SIG_marshal(CBB *cbb, const DSA_SIG *sig);

 // DSA_parse_public_key parses a DER-encoded DSA public key from |cbs| and
 // advances |cbs|. It returns a newly-allocated |DSA| or NULL on error.
 OPENSSL_EXPORT DSA *DSA_parse_public_key(CBS *cbs);

 // DSA_marshal_public_key marshals |dsa| as a DER-encoded DSA public key and
 // appends the result to |cbb|. It returns one on success and zero on
 // failure.
 OPENSSL_EXPORT int DSA_marshal_public_key(CBB *cbb, const DSA *dsa);

 // DSA_parse_private_key parses a DER-encoded DSA private key from |cbs| and
 // advances |cbs|. It returns a newly-allocated |DSA| or NULL on error.
 OPENSSL_EXPORT DSA *DSA_parse_private_key(CBS *cbs);

 // DSA_marshal_private_key marshals |dsa| as a DER-encoded DSA private key and
 // appends the result to |cbb|. It returns one on success and zero on
 // failure.
 OPENSSL_EXPORT int DSA_marshal_private_key(CBB *cbb, const DSA *dsa);

 // DSA_parse_parameters parses a DER-encoded Dss-Parms structure (RFC 3279)
 // from |cbs| and advances |cbs|. It returns a newly-allocated |DSA| or NULL on
 // error.
 OPENSSL_EXPORT DSA *DSA_parse_parameters(CBS *cbs);

 // DSA_marshal_parameters marshals |dsa| as a DER-encoded Dss-Parms structure
 // (RFC 3279) and appends the result to |cbb|. It returns one on success and
 // zero on failure.
 OPENSSL_EXPORT int DSA_marshal_parameters(CBB *cbb, const DSA *dsa);


 // Conversion.

 // DSA_dup_DH returns a |DH| constructed from the parameters of |dsa|. This is
 // sometimes needed when Diffie-Hellman parameters are stored in the form of
 // DSA parameters. It returns an allocated |DH| on success or NULL on error.
 OPENSSL_EXPORT DH *DSA_dup_DH(const DSA *dsa);


 // ex_data functions.
 //
 // See |ex_data.h| for details.

 OPENSSL_EXPORT int DSA_get_ex_new_index(long argl, void *argp,
                                         CRYPTO_EX_unused *unused,
                                         CRYPTO_EX_dup *dup_unused,
                                         CRYPTO_EX_free *free_func);
 OPENSSL_EXPORT int DSA_set_ex_data(DSA *dsa, int idx, void *arg);
 OPENSSL_EXPORT void *DSA_get_ex_data(const DSA *dsa, int idx);


 // Deprecated functions.

 // d2i_DSA_SIG parses a DER-encoded DSA-Sig-Value structure from |len| bytes at
 // |*inp|, as described in |d2i_SAMPLE|.
 //
 // Use |DSA_SIG_parse| instead.
 OPENSSL_EXPORT DSA_SIG *d2i_DSA_SIG(DSA_SIG **out_sig, const uint8_t **inp,
                                     long len);

 // i2d_DSA_SIG marshals |in| to a DER-encoded DSA-Sig-Value structure, as
 // described in |i2d_SAMPLE|.
 //
 // Use |DSA_SIG_marshal| instead.
 OPENSSL_EXPORT int i2d_DSA_SIG(const DSA_SIG *in, uint8_t **outp);

 // d2i_DSAPublicKey parses a DER-encoded DSA public key from |len| bytes at
 // |*inp|, as described in |d2i_SAMPLE|.
 //
 // Use |DSA_parse_public_key| instead.
 OPENSSL_EXPORT DSA *d2i_DSAPublicKey(DSA **out, const uint8_t **inp, long len);

 // i2d_DSAPublicKey marshals |in| as a DER-encoded DSA public key, as described
 // in |i2d_SAMPLE|.
 //
 // Use |DSA_marshal_public_key| instead.
 OPENSSL_EXPORT int i2d_DSAPublicKey(const DSA *in, uint8_t **outp);

 // d2i_DSAPrivateKey parses a DER-encoded DSA private key from |len| bytes at
 // |*inp|, as described in |d2i_SAMPLE|.
 //
 // Use |DSA_parse_private_key| instead.
 OPENSSL_EXPORT DSA *d2i_DSAPrivateKey(DSA **out, const uint8_t **inp, long len);

 // i2d_DSAPrivateKey marshals |in| as a DER-encoded DSA private key, as
 // described in |i2d_SAMPLE|.
 //
 // Use |DSA_marshal_private_key| instead.
 OPENSSL_EXPORT int i2d_DSAPrivateKey(const DSA *in, uint8_t **outp);

 // d2i_DSAparams parses a DER-encoded Dss-Parms structure (RFC 3279) from |len|
 // bytes at |*inp|, as described in |d2i_SAMPLE|.
 //
 // Use |DSA_parse_parameters| instead.
 OPENSSL_EXPORT DSA *d2i_DSAparams(DSA **out, const uint8_t **inp, long len);

 // i2d_DSAparams marshals |in|'s parameters as a DER-encoded Dss-Parms structure
 // (RFC 3279), as described in |i2d_SAMPLE|.
 //
 // Use |DSA_marshal_parameters| instead.
 OPENSSL_EXPORT int i2d_DSAparams(const DSA *in, uint8_t **outp);

 // DSA_generate_parameters is a deprecated version of
 // |DSA_generate_parameters_ex| that creates and returns a |DSA*|. Don't use
 // it.
 OPENSSL_EXPORT DSA *DSA_generate_parameters(int bits, unsigned char *seed,
                                             int seed_len, int *counter_ret,
                                             unsigned long *h_ret,
                                             void (*callback)(int, int, void *),
                                             void *cb_arg);


 #if defined(__cplusplus)
 }  // extern C

 extern "C++" {

 BSSL_NAMESPACE_BEGIN

 BORINGSSL_MAKE_DELETER(DSA, DSA_free)
 BORINGSSL_MAKE_UP_REF(DSA, DSA_up_ref)
 BORINGSSL_MAKE_DELETER(DSA_SIG, DSA_SIG_free)

 BSSL_NAMESPACE_END

 }  // extern C++

 #endif

 #define DSA_R_BAD_Q_VALUE 100
 #define DSA_R_MISSING_PARAMETERS 101
 #define DSA_R_MODULUS_TOO_LARGE 102
 #define DSA_R_NEED_NEW_SETUP_VALUES 103
 #define DSA_R_BAD_VERSION 104
 #define DSA_R_DECODE_ERROR 105
 #define DSA_R_ENCODE_ERROR 106
 #define DSA_R_INVALID_PARAMETERS 107
 #define DSA_R_TOO_MANY_ITERATIONS 108

 #endif  // OPENSSL_HEADER_DSA_H
	/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
	* All rights reserved.
	*
	* This package is an SSL implementation written
	* by Eric Young (eay@cryptsoft.com).
	* The implementation was written so as to conform with Netscapes SSL.
	*
	* This library is free for commercial and non-commercial use as long as
	* the following conditions are aheared to. The following conditions
	* apply to all code found in this distribution, be it the RC4, RSA,
	* lhash, DES, etc., code; not just the SSL code. The SSL documentation
	* included with this distribution is covered by the same copyright terms
	* except that the holder is Tim Hudson (tjh@cryptsoft.com).
	*
	* Copyright remains Eric Young's, and as such any Copyright notices in
	* the code are not to be removed.
	* If this package is used in a product, Eric Young should be given attribution
	* as the author of the parts of the library used.
	* This can be in the form of a textual message at program startup or
	* in documentation (online or textual) provided with the package.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. All advertising materials mentioning features or use of this software
	* must display the following acknowledgement:
	* "This product includes cryptographic software written by
	* Eric Young (eay@cryptsoft.com)"
	* The word 'cryptographic' can be left out if the rouines from the library
	* being used are not cryptographic related :-).
	* 4. If you include any Windows specific code (or a derivative thereof) from
	* the apps directory (application code) you must include an acknowledgement:
	* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
	*
	* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	* SUCH DAMAGE.
	*
	* The licence and distribution terms for any publically available version or
	* derivative of this code cannot be changed. i.e. this code cannot simply be
	* copied and put under another distribution licence
	* [including the GNU Public Licence.]
	*
	* The DSS routines are based on patches supplied by
	* Steven Schoch <schoch@sheba.arc.nasa.gov>. */

	#ifndef OPENSSL_HEADER_DSA_H
	#define OPENSSL_HEADER_DSA_H

	#include <openssl/base.h>

	#include <openssl/ex_data.h>

	#if defined(__cplusplus)
	extern "C" {
	#endif


	// DSA contains functions for signing and verifying with the Digital Signature
	// Algorithm.
	//
	// This module is deprecated and retained for legacy reasons only. It is not
	// considered a priority for performance or hardening work. Do not use it in
	// new code. Use Ed25519, ECDSA with P-256, or RSA instead.


	// Allocation and destruction.
	//
	// A \|DSA\| object represents a DSA key or group parameters. A given object may
	// be used concurrently on multiple threads by non-mutating functions, provided
	// no other thread is concurrently calling a mutating function. Unless otherwise
	// documented, functions which take a \|const\| pointer are non-mutating and
	// functions which take a non-\|const\| pointer are mutating.

	// DSA_new returns a new, empty DSA object or NULL on error.
	OPENSSL_EXPORT DSA *DSA_new(void);

	// DSA_free decrements the reference count of \|dsa\| and frees it if the
	// reference count drops to zero.
	OPENSSL_EXPORT void DSA_free(DSA *dsa);

	// DSA_up_ref increments the reference count of \|dsa\| and returns one. It does
	// not mutate \|dsa\| for thread-safety purposes and may be used concurrently.
	OPENSSL_EXPORT int DSA_up_ref(DSA *dsa);


	// Properties.

	// DSA_bits returns the size of \|dsa\|'s group modulus, in bits.
	OPENSSL_EXPORT unsigned DSA_bits(const DSA *dsa);

	// DSA_get0_pub_key returns \|dsa\|'s public key.
	OPENSSL_EXPORT const BIGNUM DSA_get0_pub_key(const DSA dsa);

	// DSA_get0_priv_key returns \|dsa\|'s private key, or NULL if \|dsa\| is a public
	// key.
	OPENSSL_EXPORT const BIGNUM DSA_get0_priv_key(const DSA dsa);

	// DSA_get0_p returns \|dsa\|'s group modulus.
	OPENSSL_EXPORT const BIGNUM DSA_get0_p(const DSA dsa);

	// DSA_get0_q returns the size of \|dsa\|'s subgroup.
	OPENSSL_EXPORT const BIGNUM DSA_get0_q(const DSA dsa);

	// DSA_get0_g returns \|dsa\|'s group generator.
	OPENSSL_EXPORT const BIGNUM DSA_get0_g(const DSA dsa);

	// DSA_get0_key sets \|out_pub_key\| and \|out_priv_key\|, if non-NULL, to \|dsa\|'s
	// public and private key, respectively. If \|dsa\| is a public key, the private
	// key will be set to NULL.
	OPENSSL_EXPORT void DSA_get0_key(const DSA dsa, const BIGNUM *out_pub_key,
	const BIGNUM **out_priv_key);

	// DSA_get0_pqg sets \|out_p\|, \|out_q\|, and \|*out_g\|, if non-NULL, to \|dsa\|'s
	// p, q, and g parameters, respectively.
	OPENSSL_EXPORT void DSA_get0_pqg(const DSA dsa, const BIGNUM *out_p,
	const BIGNUM out_q, const BIGNUM out_g);

	// DSA_set0_key sets \|dsa\|'s public and private key to \|pub_key\| and \|priv_key\|,
	// respectively, if non-NULL. On success, it takes ownership of each argument
	// and returns one. Otherwise, it returns zero.
	//
	// \|priv_key\| may be NULL, but \|pub_key\| must either be non-NULL or already
	// configured on \|dsa\|.
	OPENSSL_EXPORT int DSA_set0_key(DSA dsa, BIGNUM pub_key, BIGNUM *priv_key);

	// DSA_set0_pqg sets \|dsa\|'s parameters to \|p\|, \|q\|, and \|g\|, if non-NULL, and
	// takes ownership of them. On success, it takes ownership of each argument and
	// returns one. Otherwise, it returns zero.
	//
	// Each argument must either be non-NULL or already configured on \|dsa\|.
	OPENSSL_EXPORT int DSA_set0_pqg(DSA dsa, BIGNUM p, BIGNUM q, BIGNUM g);


	// Parameter generation.

	// DSA_generate_parameters_ex generates a set of DSA parameters by following
	// the procedure given in FIPS 186-4, appendix A.
	// (http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf)
	//
	// The larger prime will have a length of \|bits\| (e.g. 2048). The \|seed\| value
	// allows others to generate and verify the same parameters and should be
	// random input which is kept for reference. If \|out_counter\| or \|out_h\| are
	// not NULL then the counter and h value used in the generation are written to
	// them.
	//
	// The \|cb\| argument is passed to \|BN_generate_prime_ex\| and is thus called
	// during the generation process in order to indicate progress. See the
	// comments for that function for details. In addition to the calls made by
	// \|BN_generate_prime_ex\|, \|DSA_generate_parameters_ex\| will call it with
	// \|event\| equal to 2 and 3 at different stages of the process.
	//
	// It returns one on success and zero otherwise.
	OPENSSL_EXPORT int DSA_generate_parameters_ex(DSA *dsa, unsigned bits,
	const uint8_t *seed,
	size_t seed_len, int *out_counter,
	unsigned long *out_h,
	BN_GENCB *cb);

	// DSAparams_dup returns a freshly allocated \|DSA\| that contains a copy of the
	// parameters from \|dsa\|. It returns NULL on error.
	OPENSSL_EXPORT DSA DSAparams_dup(const DSA dsa);


	// Key generation.

	// DSA_generate_key generates a public/private key pair in \|dsa\|, which must
	// already have parameters setup. It returns one on success and zero on
	// error.
	OPENSSL_EXPORT int DSA_generate_key(DSA *dsa);


	// Signatures.

	// DSA_SIG_st (aka \|DSA_SIG\|) contains a DSA signature as a pair of integers.
	struct DSA_SIG_st {
	BIGNUM r, s;
	};

	// DSA_SIG_new returns a freshly allocated, DIG_SIG structure or NULL on error.
	// Both \|r\| and \|s\| in the signature will be NULL.
	OPENSSL_EXPORT DSA_SIG *DSA_SIG_new(void);

	// DSA_SIG_free frees the contents of \|sig\| and then frees \|sig\| itself.
	OPENSSL_EXPORT void DSA_SIG_free(DSA_SIG *sig);

	// DSA_SIG_get0 sets \|out_r\| and \|out_s\|, if non-NULL, to the two components
	// of \|sig\|.
	OPENSSL_EXPORT void DSA_SIG_get0(const DSA_SIG sig, const BIGNUM *out_r,
	const BIGNUM **out_s);

	// DSA_SIG_set0 sets \|sig\|'s components to \|r\| and \|s\|, neither of which may be
	// NULL. On success, it takes ownership of each argument and returns one.
	// Otherwise, it returns zero.
	OPENSSL_EXPORT int DSA_SIG_set0(DSA_SIG sig, BIGNUM r, BIGNUM *s);

	// DSA_do_sign returns a signature of the hash in \|digest\| by the key in \|dsa\|
	// and returns an allocated, DSA_SIG structure, or NULL on error.
	OPENSSL_EXPORT DSA_SIG DSA_do_sign(const uint8_t digest, size_t digest_len,
	const DSA *dsa);

	// DSA_do_verify verifies that \|sig\| is a valid signature, by the public key in
	// \|dsa\|, of the hash in \|digest\|. It returns one if so, zero if invalid and -1
	// on error.
	//
	// WARNING: do not use. This function returns -1 for error, 0 for invalid and 1
	// for valid. However, this is dangerously different to the usual OpenSSL
	// convention and could be a disaster if a user did \|if (DSA_do_verify(...))\|.
	// Because of this, \|DSA_check_signature\| is a safer version of this.
	//
	// TODO(fork): deprecate.
	OPENSSL_EXPORT int DSA_do_verify(const uint8_t *digest, size_t digest_len,
	const DSA_SIG sig, const DSA dsa);

	// DSA_do_check_signature sets \|*out_valid\| to zero. Then it verifies that \|sig\|
	// is a valid signature, by the public key in \|dsa\| of the hash in \|digest\|
	// and, if so, it sets \|*out_valid\| to one.
	//
	// It returns one if it was able to verify the signature as valid or invalid,
	// and zero on error.
	OPENSSL_EXPORT int DSA_do_check_signature(int out_valid, const uint8_t digest,
	size_t digest_len, const DSA_SIG *sig,
	const DSA *dsa);


	// ASN.1 signatures.
	//
	// These functions also perform DSA signature operations, but deal with ASN.1
	// encoded signatures as opposed to raw \|BIGNUM\|s. If you don't know what
	// encoding a DSA signature is in, it's probably ASN.1.

	// DSA_sign signs \|digest\| with the key in \|dsa\| and writes the resulting
	// signature, in ASN.1 form, to \|out_sig\| and the length of the signature to
	// \|*out_siglen\|. There must be, at least, \|DSA_size(dsa)\| bytes of space in
	// \|out_sig\|. It returns one on success and zero otherwise.
	//
	// (The \|type\| argument is ignored.)
	OPENSSL_EXPORT int DSA_sign(int type, const uint8_t *digest, size_t digest_len,
	uint8_t out_sig, unsigned int out_siglen,
	const DSA *dsa);

	// DSA_verify verifies that \|sig\| is a valid, ASN.1 signature, by the public
	// key in \|dsa\|, of the hash in \|digest\|. It returns one if so, zero if invalid
	// and -1 on error.
	//
	// (The \|type\| argument is ignored.)
	//
	// WARNING: do not use. This function returns -1 for error, 0 for invalid and 1
	// for valid. However, this is dangerously different to the usual OpenSSL
	// convention and could be a disaster if a user did \|if (DSA_do_verify(...))\|.
	// Because of this, \|DSA_check_signature\| is a safer version of this.
	//
	// TODO(fork): deprecate.
	OPENSSL_EXPORT int DSA_verify(int type, const uint8_t *digest,
	size_t digest_len, const uint8_t *sig,
	size_t sig_len, const DSA *dsa);

	// DSA_check_signature sets \|*out_valid\| to zero. Then it verifies that \|sig\|
	// is a valid, ASN.1 signature, by the public key in \|dsa\|, of the hash in
	// \|digest\|. If so, it sets \|*out_valid\| to one.
	//
	// It returns one if it was able to verify the signature as valid or invalid,
	// and zero on error.
	OPENSSL_EXPORT int DSA_check_signature(int out_valid, const uint8_t digest,
	size_t digest_len, const uint8_t *sig,
	size_t sig_len, const DSA *dsa);

	// DSA_size returns the size, in bytes, of an ASN.1 encoded, DSA signature
	// generated by \|dsa\|. Parameters must already have been setup in \|dsa\|.
	OPENSSL_EXPORT int DSA_size(const DSA *dsa);


	// ASN.1 encoding.

	// DSA_SIG_parse parses a DER-encoded DSA-Sig-Value structure from \|cbs\| and
	// advances \|cbs\|. It returns a newly-allocated \|DSA_SIG\| or NULL on error.
	OPENSSL_EXPORT DSA_SIG DSA_SIG_parse(CBS cbs);

	// DSA_SIG_marshal marshals \|sig\| as a DER-encoded DSA-Sig-Value and appends the
	// result to \|cbb\|. It returns one on success and zero on error.
	OPENSSL_EXPORT int DSA_SIG_marshal(CBB cbb, const DSA_SIG sig);

	// DSA_parse_public_key parses a DER-encoded DSA public key from \|cbs\| and
	// advances \|cbs\|. It returns a newly-allocated \|DSA\| or NULL on error.
	OPENSSL_EXPORT DSA DSA_parse_public_key(CBS cbs);

	// DSA_marshal_public_key marshals \|dsa\| as a DER-encoded DSA public key and
	// appends the result to \|cbb\|. It returns one on success and zero on
	// failure.
	OPENSSL_EXPORT int DSA_marshal_public_key(CBB cbb, const DSA dsa);

	// DSA_parse_private_key parses a DER-encoded DSA private key from \|cbs\| and
	// advances \|cbs\|. It returns a newly-allocated \|DSA\| or NULL on error.
	OPENSSL_EXPORT DSA DSA_parse_private_key(CBS cbs);

	// DSA_marshal_private_key marshals \|dsa\| as a DER-encoded DSA private key and
	// appends the result to \|cbb\|. It returns one on success and zero on
	// failure.
	OPENSSL_EXPORT int DSA_marshal_private_key(CBB cbb, const DSA dsa);

	// DSA_parse_parameters parses a DER-encoded Dss-Parms structure (RFC 3279)
	// from \|cbs\| and advances \|cbs\|. It returns a newly-allocated \|DSA\| or NULL on
	// error.
	OPENSSL_EXPORT DSA DSA_parse_parameters(CBS cbs);

	// DSA_marshal_parameters marshals \|dsa\| as a DER-encoded Dss-Parms structure
	// (RFC 3279) and appends the result to \|cbb\|. It returns one on success and
	// zero on failure.
	OPENSSL_EXPORT int DSA_marshal_parameters(CBB cbb, const DSA dsa);


	// Conversion.

	// DSA_dup_DH returns a \|DH\| constructed from the parameters of \|dsa\|. This is
	// sometimes needed when Diffie-Hellman parameters are stored in the form of
	// DSA parameters. It returns an allocated \|DH\| on success or NULL on error.
	OPENSSL_EXPORT DH DSA_dup_DH(const DSA dsa);


	// ex_data functions.
	//
	// See \|ex_data.h\| for details.

	OPENSSL_EXPORT int DSA_get_ex_new_index(long argl, void *argp,
	CRYPTO_EX_unused *unused,
	CRYPTO_EX_dup *dup_unused,
	CRYPTO_EX_free *free_func);
	OPENSSL_EXPORT int DSA_set_ex_data(DSA dsa, int idx, void arg);
	OPENSSL_EXPORT void DSA_get_ex_data(const DSA dsa, int idx);


	// Deprecated functions.

	// d2i_DSA_SIG parses a DER-encoded DSA-Sig-Value structure from \|len\| bytes at
	// \|*inp\|, as described in \|d2i_SAMPLE\|.
	//
	// Use \|DSA_SIG_parse\| instead.
	OPENSSL_EXPORT DSA_SIG d2i_DSA_SIG(DSA_SIG out_sig, const uint8_t *inp,
	long len);

	// i2d_DSA_SIG marshals \|in\| to a DER-encoded DSA-Sig-Value structure, as
	// described in \|i2d_SAMPLE\|.
	//
	// Use \|DSA_SIG_marshal\| instead.
	OPENSSL_EXPORT int i2d_DSA_SIG(const DSA_SIG in, uint8_t *outp);

	// d2i_DSAPublicKey parses a DER-encoded DSA public key from \|len\| bytes at
	// \|*inp\|, as described in \|d2i_SAMPLE\|.
	//
	// Use \|DSA_parse_public_key\| instead.
	OPENSSL_EXPORT DSA d2i_DSAPublicKey(DSA out, const uint8_t *inp, long len);

	// i2d_DSAPublicKey marshals \|in\| as a DER-encoded DSA public key, as described
	// in \|i2d_SAMPLE\|.
	//
	// Use \|DSA_marshal_public_key\| instead.
	OPENSSL_EXPORT int i2d_DSAPublicKey(const DSA in, uint8_t *outp);

	// d2i_DSAPrivateKey parses a DER-encoded DSA private key from \|len\| bytes at
	// \|*inp\|, as described in \|d2i_SAMPLE\|.
	//
	// Use \|DSA_parse_private_key\| instead.
	OPENSSL_EXPORT DSA d2i_DSAPrivateKey(DSA out, const uint8_t *inp, long len);

	// i2d_DSAPrivateKey marshals \|in\| as a DER-encoded DSA private key, as
	// described in \|i2d_SAMPLE\|.
	//
	// Use \|DSA_marshal_private_key\| instead.
	OPENSSL_EXPORT int i2d_DSAPrivateKey(const DSA in, uint8_t *outp);

	// d2i_DSAparams parses a DER-encoded Dss-Parms structure (RFC 3279) from \|len\|
	// bytes at \|*inp\|, as described in \|d2i_SAMPLE\|.
	//
	// Use \|DSA_parse_parameters\| instead.
	OPENSSL_EXPORT DSA d2i_DSAparams(DSA out, const uint8_t *inp, long len);

	// i2d_DSAparams marshals \|in\|'s parameters as a DER-encoded Dss-Parms structure
	// (RFC 3279), as described in \|i2d_SAMPLE\|.
	//
	// Use \|DSA_marshal_parameters\| instead.
	OPENSSL_EXPORT int i2d_DSAparams(const DSA in, uint8_t *outp);

	// DSA_generate_parameters is a deprecated version of
	// \|DSA_generate_parameters_ex\| that creates and returns a \|DSA*\|. Don't use
	// it.
	OPENSSL_EXPORT DSA DSA_generate_parameters(int bits, unsigned char seed,
	int seed_len, int *counter_ret,
	unsigned long *h_ret,
	void (callback)(int, int, void ),
	void *cb_arg);


	#if defined(__cplusplus)
	} // extern C

	extern "C++" {

	BSSL_NAMESPACE_BEGIN

	BORINGSSL_MAKE_DELETER(DSA, DSA_free)
	BORINGSSL_MAKE_UP_REF(DSA, DSA_up_ref)
	BORINGSSL_MAKE_DELETER(DSA_SIG, DSA_SIG_free)

	BSSL_NAMESPACE_END

	} // extern C++

	#endif

	#define DSA_R_BAD_Q_VALUE 100
	#define DSA_R_MISSING_PARAMETERS 101
	#define DSA_R_MODULUS_TOO_LARGE 102
	#define DSA_R_NEED_NEW_SETUP_VALUES 103
	#define DSA_R_BAD_VERSION 104
	#define DSA_R_DECODE_ERROR 105
	#define DSA_R_ENCODE_ERROR 106
	#define DSA_R_INVALID_PARAMETERS 107
	#define DSA_R_TOO_MANY_ITERATIONS 108

	#endif // OPENSSL_HEADER_DSA_H