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

 // Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #ifndef OPENSSL_HEADER_DSA_H
 #define OPENSSL_HEADER_DSA_H

 #include <openssl/base.h>   // IWYU pragma: export

 #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.

 // OPENSSL_DSA_MAX_MODULUS_BITS is the maximum supported DSA group modulus, in
 // bits.
 #define OPENSSL_DSA_MAX_MODULUS_BITS 8192

 // 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 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// https://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#ifndef OPENSSL_HEADER_DSA_H
	#define OPENSSL_HEADER_DSA_H

	#include <openssl/base.h> // IWYU pragma: export

	#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.

	// OPENSSL_DSA_MAX_MODULUS_BITS is the maximum supported DSA group modulus, in
	// bits.
	#define OPENSSL_DSA_MAX_MODULUS_BITS 8192

	// 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