include/openssl/digest.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_DIGEST_H
 #define OPENSSL_HEADER_DIGEST_H

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

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


 // Digest functions.
 //
 // An EVP_MD abstracts the details of a specific hash function allowing code to
 // deal with the concept of a "hash function" without needing to know exactly
 // which hash function it is.


 // Hash algorithms.
 //
 // The following functions return `EVP_MD` objects that implement the named hash
 // function.

 OPENSSL_EXPORT const EVP_MD *EVP_md4(void);
 OPENSSL_EXPORT const EVP_MD *EVP_md5(void);
 OPENSSL_EXPORT const EVP_MD *EVP_sha1(void);
 OPENSSL_EXPORT const EVP_MD *EVP_sha224(void);
 OPENSSL_EXPORT const EVP_MD *EVP_sha256(void);
 OPENSSL_EXPORT const EVP_MD *EVP_sha384(void);
 OPENSSL_EXPORT const EVP_MD *EVP_sha512(void);
 OPENSSL_EXPORT const EVP_MD *EVP_sha512_256(void);
 OPENSSL_EXPORT const EVP_MD *EVP_blake2b256(void);

 // EVP_md5_sha1 is a TLS-specific `EVP_MD` which computes the concatenation of
 // MD5 and SHA-1, as used in TLS 1.1 and below.
 OPENSSL_EXPORT const EVP_MD *EVP_md5_sha1(void);

 // EVP_get_digestbynid returns an `EVP_MD` for the given NID, or NULL if no
 // such digest is known.
 OPENSSL_EXPORT const EVP_MD *EVP_get_digestbynid(int nid);

 // EVP_get_digestbyobj returns an `EVP_MD` for the given `ASN1_OBJECT`, or NULL
 // if no such digest is known.
 OPENSSL_EXPORT const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *obj);


 // Digest contexts.
 //
 // An EVP_MD_CTX represents the state of a specific digest operation in
 // progress.

 // EVP_MD_CTX_init initialises an, already allocated, `EVP_MD_CTX`. This is the
 // same as setting the structure to zero.
 OPENSSL_EXPORT void EVP_MD_CTX_init(EVP_MD_CTX *ctx);

 // EVP_MD_CTX_new allocates and initialises a fresh `EVP_MD_CTX` and returns
 // it, or NULL on allocation failure. The caller must use `EVP_MD_CTX_free` to
 // release the resulting object.
 OPENSSL_EXPORT EVP_MD_CTX *EVP_MD_CTX_new(void);

 // EVP_MD_CTX_cleanup frees any resources owned by `ctx` and resets it to a
 // freshly initialised state. It does not free `ctx` itself. It returns one.
 OPENSSL_EXPORT int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx);

 // EVP_MD_CTX_cleanse zeros the digest state in `ctx` and then performs the
 // actions of `EVP_MD_CTX_cleanup`. Note that some `EVP_MD_CTX` objects contain
 // more than just a digest (e.g. those resulting from `EVP_DigestSignInit`) but
 // this function does not zero out more than just the digest state even in that
 // case.
 OPENSSL_EXPORT void EVP_MD_CTX_cleanse(EVP_MD_CTX *ctx);

 // EVP_MD_CTX_free calls `EVP_MD_CTX_cleanup` and then frees `ctx` itself.
 OPENSSL_EXPORT void EVP_MD_CTX_free(EVP_MD_CTX *ctx);

 // EVP_MD_CTX_copy_ex sets `out`, which must already be initialised, to be a
 // copy of `in`. It returns one on success and zero on allocation failure.
 OPENSSL_EXPORT int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);

 // EVP_MD_CTX_move sets `out`, which must already be initialised, to the hash
 // state in `in`. `in` is mutated and left in an empty state.
 OPENSSL_EXPORT void EVP_MD_CTX_move(EVP_MD_CTX *out, EVP_MD_CTX *in);

 // EVP_MD_CTX_reset calls `EVP_MD_CTX_cleanup` followed by `EVP_MD_CTX_init`. It
 // returns one.
 OPENSSL_EXPORT int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);


 // Digest operations.

 // EVP_DigestInit_ex configures `ctx`, which must already have been
 // initialised, for a fresh hashing operation using `type`. It returns one on
 // success and zero on allocation failure.
 OPENSSL_EXPORT int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type,
                                      ENGINE *engine);

 // EVP_DigestInit acts like `EVP_DigestInit_ex` except that `ctx` is
 // initialised before use.
 OPENSSL_EXPORT int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);

 // EVP_DigestUpdate hashes `len` bytes from `data` into the hashing operation
 // in `ctx`. It returns one.
 OPENSSL_EXPORT int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *data,
                                     size_t len);

 // EVP_MAX_MD_SIZE is the largest digest size supported, in bytes.
 // Functions that output a digest generally require the buffer have
 // at least this much space.
 #define EVP_MAX_MD_SIZE 64  // SHA-512 is the longest so far.

 // EVP_MAX_MD_BLOCK_SIZE is the largest digest block size supported, in
 // bytes.
 #define EVP_MAX_MD_BLOCK_SIZE 128  // SHA-512 is the longest so far.

 // EVP_DigestFinal_ex finishes the digest in `ctx` and writes the output to
 // `md_out`. `EVP_MD_CTX_size` bytes are written, which is at most
 // `EVP_MAX_MD_SIZE`. If `out_size` is not NULL then `*out_size` is set to the
 // number of bytes written. It returns one. After this call, the hash cannot be
 // updated or finished again until `EVP_DigestInit_ex` is called to start
 // another hashing operation.
 OPENSSL_EXPORT int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, uint8_t *md_out,
                                       unsigned int *out_size);

 // EVP_DigestFinal acts like `EVP_DigestFinal_ex` except that
 // `EVP_MD_CTX_cleanup` is called on `ctx` before returning.
 OPENSSL_EXPORT int EVP_DigestFinal(EVP_MD_CTX *ctx, uint8_t *md_out,
                                    unsigned int *out_size);

 // EVP_Digest performs a complete hashing operation in one call. It hashes `len`
 // bytes from `data` and writes the digest to `md_out`. `EVP_MD_CTX_size` bytes
 // are written, which is at most `EVP_MAX_MD_SIZE`. If `out_size` is not NULL
 // then `*out_size` is set to the number of bytes written. It returns one on
 // success and zero otherwise.
 OPENSSL_EXPORT int EVP_Digest(const void *data, size_t len, uint8_t *md_out,
                               unsigned int *md_out_size, const EVP_MD *type,
                               ENGINE *impl);


 // Digest function accessors.
 //
 // These functions allow code to learn details about an abstract hash
 // function.

 // EVP_MD_type returns a NID identifying `md`. (For example, `NID_sha256`.)
 OPENSSL_EXPORT int EVP_MD_type(const EVP_MD *md);

 // EVP_MD_flags returns the flags for `md`, which is a set of `EVP_MD_FLAG_*`
 // values, ORed together.
 OPENSSL_EXPORT uint32_t EVP_MD_flags(const EVP_MD *md);

 // EVP_MD_size returns the digest size of `md`, in bytes.
 OPENSSL_EXPORT size_t EVP_MD_size(const EVP_MD *md);

 // EVP_MD_block_size returns the native block-size of `md`, in bytes.
 OPENSSL_EXPORT size_t EVP_MD_block_size(const EVP_MD *md);

 // EVP_MD_FLAG_DIGALGID_ABSENT indicates that the parameter type in an X.509
 // DigestAlgorithmIdentifier representing this digest function should be
 // undefined rather than NULL.
 #define EVP_MD_FLAG_DIGALGID_ABSENT 2

 // EVP_MD_FLAG_XOF indicates that the digest is an extensible-output function
 // (XOF). This flag is defined for compatibility and will never be set in any
 // `EVP_MD` in BoringSSL.
 #define EVP_MD_FLAG_XOF 4


 // Digest operation accessors.

 // EVP_MD_CTX_get0_md returns the underlying digest function, or NULL if one has
 // not been set.
 OPENSSL_EXPORT const EVP_MD *EVP_MD_CTX_get0_md(const EVP_MD_CTX *ctx);

 // EVP_MD_CTX_md returns the underlying digest function, or NULL if one has not
 // been set. (This is the same as `EVP_MD_CTX_get0_md` but OpenSSL has
 // deprecated this spelling.)
 OPENSSL_EXPORT const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);

 // EVP_MD_CTX_size returns the digest size of `ctx`, in bytes. It
 // will crash if a digest hasn't been set on `ctx`.
 OPENSSL_EXPORT size_t EVP_MD_CTX_size(const EVP_MD_CTX *ctx);

 // EVP_MD_CTX_block_size returns the block size of the digest function used by
 // `ctx`, in bytes. It will crash if a digest hasn't been set on `ctx`.
 OPENSSL_EXPORT size_t EVP_MD_CTX_block_size(const EVP_MD_CTX *ctx);

 // EVP_MD_CTX_type returns a NID describing the digest function used by `ctx`.
 // (For example, `NID_sha256`.) It will crash if a digest hasn't been set on
 // `ctx`.
 OPENSSL_EXPORT int EVP_MD_CTX_type(const EVP_MD_CTX *ctx);

 // EVP_MD_CTX_pkey_ctx returns the `EVP_PKEY_CTX` used to configure additional
 // parameters on `ctx` if `ctx` is used for a sign or verify operation with
 // `EVP_DigestSignInit` or `EVP_DigestVerifyInit`. It returns NULL otherwise.
 OPENSSL_EXPORT EVP_PKEY_CTX *EVP_MD_CTX_pkey_ctx(const EVP_MD_CTX *ctx);


 // ASN.1 functions.
 //
 // These functions allow code to parse and serialize AlgorithmIdentifiers for
 // hash functions.

 // EVP_parse_digest_algorithm parses an AlgorithmIdentifier structure containing
 // a hash function OID (for example, 2.16.840.1.101.3.4.2.1 is SHA-256) and
 // advances `cbs`. The parameters field may either be omitted or a NULL. It
 // returns the digest function or NULL on error.
 OPENSSL_EXPORT const EVP_MD *EVP_parse_digest_algorithm(CBS *cbs);

 // EVP_parse_digest_algorithm_nid behaves like `EVP_parse_digest_algorithm`
 // except it returns `NID_undef` on error and some other value on success. This
 // may be used to avoid depending on every digest algorithm in the library.
 OPENSSL_EXPORT int EVP_parse_digest_algorithm_nid(CBS *cbs);

 // EVP_marshal_digest_algorithm marshals `md` as an AlgorithmIdentifier
 // structure and appends the result to `cbb`. It returns one on success and zero
 // on error. It sets the parameters field to NULL. Use
 // `EVP_marshal_digest_algorithm_no_params` to omit the parameters instead.
 //
 // In general, the parameters should be omitted for digest algorithms, but the
 // following specifications require a NULL parameter instead.
 //
 // - Hash algorithms and MGF-1 hash algorithms used in RSASSA-PSS and RSAES-OAEP
 //   (see RFC 4055, Section 2.1)
 // - The hash algorithm in the DigestInfo structure of RSASSA-PKCS1-v1_5 (see
 //   RFC 8017, Appendix A.2.4)
 //
 // Some existing software also uses NULL parameters in other contexts. In
 // practice, digest algorithms are encoded wildly inconsistently.
 OPENSSL_EXPORT int EVP_marshal_digest_algorithm(CBB *cbb, const EVP_MD *md);

 // EVP_marshal_digest_algorithm_no_params behaves like
 // `EVP_marshal_digest_algorithm` but omits the parameters field.
 OPENSSL_EXPORT int EVP_marshal_digest_algorithm_no_params(CBB *cbb,
                                                           const EVP_MD *md);


 // Deprecated functions.

 // EVP_MD_CTX_copy sets `out`, which must /not/ be initialised, to be a copy of
 // `in`. It returns one on success and zero on error.
 OPENSSL_EXPORT int EVP_MD_CTX_copy(EVP_MD_CTX *out, const EVP_MD_CTX *in);

 // EVP_add_digest does nothing and returns one. It exists only for
 // compatibility with OpenSSL.
 OPENSSL_EXPORT int EVP_add_digest(const EVP_MD *digest);

 // EVP_get_digestbyname returns an `EVP_MD` given a human readable name in
 // `name`, or NULL if the name is unknown.
 OPENSSL_EXPORT const EVP_MD *EVP_get_digestbyname(const char *name);

 // EVP_dss1 returns the value of EVP_sha1(). This was provided by OpenSSL to
 // specify the original DSA signatures, which were fixed to use SHA-1. Note,
 // however, that attempting to sign or verify DSA signatures with the EVP
 // interface will always fail.
 OPENSSL_EXPORT const EVP_MD *EVP_dss1(void);

 // EVP_MD_CTX_create calls `EVP_MD_CTX_new`.
 OPENSSL_EXPORT EVP_MD_CTX *EVP_MD_CTX_create(void);

 // EVP_MD_CTX_destroy calls `EVP_MD_CTX_free`.
 OPENSSL_EXPORT void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx);

 // EVP_DigestFinalXOF returns zero and adds an error to the error queue.
 // BoringSSL does not support any XOF digests.
 OPENSSL_EXPORT int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, uint8_t *out,
                                       size_t len);

 // EVP_MD_meth_get_flags calls `EVP_MD_flags`.
 OPENSSL_EXPORT uint32_t EVP_MD_meth_get_flags(const EVP_MD *md);

 // EVP_MD_CTX_set_flags does nothing.
 OPENSSL_EXPORT void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);

 // EVP_MD_CTX_FLAG_NON_FIPS_ALLOW is meaningless. In OpenSSL it permits non-FIPS
 // algorithms in FIPS mode. But BoringSSL FIPS mode doesn't prohibit algorithms
 // (it's up the the caller to use the FIPS module in a fashion compliant with
 // their needs). Thus this exists only to allow code to compile.
 #define EVP_MD_CTX_FLAG_NON_FIPS_ALLOW 0

 // EVP_MD_nid calls `EVP_MD_type`.
 OPENSSL_EXPORT int EVP_MD_nid(const EVP_MD *md);

 // EVP_MD_fetch behaves like `EVP_get_digestbyname`. `libctx` and `propq` are
 // ignored. Although it returns a non-const pointer, `EVP_MD`s in BoringSSL are
 // static and do not need to be freed.
 OPENSSL_EXPORT EVP_MD *EVP_MD_fetch(OSSL_LIB_CTX *libctx, const char *name,
                                     const char *propq);

 // EVP_MD_up_ref returns one. `EVP_MD`s in BoringSSL are static.
 OPENSSL_EXPORT int EVP_MD_up_ref(EVP_MD *md);

 // EVP_MD_free does nothing. `EVP_MD`s in BoringSSL are static.
 OPENSSL_EXPORT void EVP_MD_free(EVP_MD *md);

 // EVP_Q_digest behaves like `EVP_Digest` but specifies the digest by a string
 // `name`. `libctx` and `propq` are ignored.
 OPENSSL_EXPORT int EVP_Q_digest(OSSL_LIB_CTX *libctx, const char *name,
                                 const char *propq, const void *in,
                                 size_t in_len, uint8_t *out, size_t *out_len);

 // Internal constants and structures (hidden).

 struct evp_md_pctx_ops;

 // EVP_MAX_MD_DATA_SIZE is a private constant which specifies the size of the
 // largest digest state. SHA-512 and BLAKE2b are joint-largest. Consuming code
 // only uses this via the `EVP_MD_CTX` type.
 #define EVP_MAX_MD_DATA_SIZE 208

 // env_md_ctx_st is typoed ("evp" -> "env"), but the typo comes from OpenSSL
 // and some consumers forward-declare these structures so we're leaving it
 // alone.
 struct env_md_ctx_st {
   // md_data contains the hash-specific context.
   union {
     uint8_t md_data[EVP_MAX_MD_DATA_SIZE];
     uint64_t alignment;
   };

   // digest is the underlying digest function, or NULL if not set.
   const EVP_MD *digest;

   // pctx is an opaque (at this layer) pointer to additional context that
   // EVP_PKEY functions may store in this object.
   EVP_PKEY_CTX *pctx;

   // pctx_ops, if not NULL, points to a vtable that contains functions to
   // manipulate `pctx`.
   const struct evp_md_pctx_ops *pctx_ops;
 } /* EVP_MD_CTX */;


 #if defined(__cplusplus)
 }  // extern C

 #if !defined(BORINGSSL_NO_CXX)
 extern "C++" {

 BSSL_NAMESPACE_BEGIN

 BORINGSSL_MAKE_DELETER(EVP_MD_CTX, EVP_MD_CTX_free)

 using ScopedEVP_MD_CTX =
     internal::StackAllocatedMovable<EVP_MD_CTX, int, EVP_MD_CTX_init,
                                     EVP_MD_CTX_cleanup, EVP_MD_CTX_move>;

 BSSL_NAMESPACE_END

 }  // extern C++
 #endif

 #endif

 #define DIGEST_R_INPUT_NOT_INITIALIZED 100
 #define DIGEST_R_DECODE_ERROR 101
 #define DIGEST_R_UNKNOWN_HASH 102

 #endif  // OPENSSL_HEADER_DIGEST_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_DIGEST_H
	#define OPENSSL_HEADER_DIGEST_H

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

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


	// Digest functions.
	//
	// An EVP_MD abstracts the details of a specific hash function allowing code to
	// deal with the concept of a "hash function" without needing to know exactly
	// which hash function it is.


	// Hash algorithms.
	//
	// The following functions return `EVP_MD` objects that implement the named hash
	// function.

	OPENSSL_EXPORT const EVP_MD *EVP_md4(void);
	OPENSSL_EXPORT const EVP_MD *EVP_md5(void);
	OPENSSL_EXPORT const EVP_MD *EVP_sha1(void);
	OPENSSL_EXPORT const EVP_MD *EVP_sha224(void);
	OPENSSL_EXPORT const EVP_MD *EVP_sha256(void);
	OPENSSL_EXPORT const EVP_MD *EVP_sha384(void);
	OPENSSL_EXPORT const EVP_MD *EVP_sha512(void);
	OPENSSL_EXPORT const EVP_MD *EVP_sha512_256(void);
	OPENSSL_EXPORT const EVP_MD *EVP_blake2b256(void);

	// EVP_md5_sha1 is a TLS-specific `EVP_MD` which computes the concatenation of
	// MD5 and SHA-1, as used in TLS 1.1 and below.
	OPENSSL_EXPORT const EVP_MD *EVP_md5_sha1(void);

	// EVP_get_digestbynid returns an `EVP_MD` for the given NID, or NULL if no
	// such digest is known.
	OPENSSL_EXPORT const EVP_MD *EVP_get_digestbynid(int nid);

	// EVP_get_digestbyobj returns an `EVP_MD` for the given `ASN1_OBJECT`, or NULL
	// if no such digest is known.
	OPENSSL_EXPORT const EVP_MD EVP_get_digestbyobj(const ASN1_OBJECT obj);


	// Digest contexts.
	//
	// An EVP_MD_CTX represents the state of a specific digest operation in
	// progress.

	// EVP_MD_CTX_init initialises an, already allocated, `EVP_MD_CTX`. This is the
	// same as setting the structure to zero.
	OPENSSL_EXPORT void EVP_MD_CTX_init(EVP_MD_CTX *ctx);

	// EVP_MD_CTX_new allocates and initialises a fresh `EVP_MD_CTX` and returns
	// it, or NULL on allocation failure. The caller must use `EVP_MD_CTX_free` to
	// release the resulting object.
	OPENSSL_EXPORT EVP_MD_CTX *EVP_MD_CTX_new(void);

	// EVP_MD_CTX_cleanup frees any resources owned by `ctx` and resets it to a
	// freshly initialised state. It does not free `ctx` itself. It returns one.
	OPENSSL_EXPORT int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx);

	// EVP_MD_CTX_cleanse zeros the digest state in `ctx` and then performs the
	// actions of `EVP_MD_CTX_cleanup`. Note that some `EVP_MD_CTX` objects contain
	// more than just a digest (e.g. those resulting from `EVP_DigestSignInit`) but
	// this function does not zero out more than just the digest state even in that
	// case.
	OPENSSL_EXPORT void EVP_MD_CTX_cleanse(EVP_MD_CTX *ctx);

	// EVP_MD_CTX_free calls `EVP_MD_CTX_cleanup` and then frees `ctx` itself.
	OPENSSL_EXPORT void EVP_MD_CTX_free(EVP_MD_CTX *ctx);

	// EVP_MD_CTX_copy_ex sets `out`, which must already be initialised, to be a
	// copy of `in`. It returns one on success and zero on allocation failure.
	OPENSSL_EXPORT int EVP_MD_CTX_copy_ex(EVP_MD_CTX out, const EVP_MD_CTX in);

	// EVP_MD_CTX_move sets `out`, which must already be initialised, to the hash
	// state in `in`. `in` is mutated and left in an empty state.
	OPENSSL_EXPORT void EVP_MD_CTX_move(EVP_MD_CTX out, EVP_MD_CTX in);

	// EVP_MD_CTX_reset calls `EVP_MD_CTX_cleanup` followed by `EVP_MD_CTX_init`. It
	// returns one.
	OPENSSL_EXPORT int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);


	// Digest operations.

	// EVP_DigestInit_ex configures `ctx`, which must already have been
	// initialised, for a fresh hashing operation using `type`. It returns one on
	// success and zero on allocation failure.
	OPENSSL_EXPORT int EVP_DigestInit_ex(EVP_MD_CTX ctx, const EVP_MD type,
	ENGINE *engine);

	// EVP_DigestInit acts like `EVP_DigestInit_ex` except that `ctx` is
	// initialised before use.
	OPENSSL_EXPORT int EVP_DigestInit(EVP_MD_CTX ctx, const EVP_MD type);

	// EVP_DigestUpdate hashes `len` bytes from `data` into the hashing operation
	// in `ctx`. It returns one.
	OPENSSL_EXPORT int EVP_DigestUpdate(EVP_MD_CTX ctx, const void data,
	size_t len);

	// EVP_MAX_MD_SIZE is the largest digest size supported, in bytes.
	// Functions that output a digest generally require the buffer have
	// at least this much space.
	#define EVP_MAX_MD_SIZE 64 // SHA-512 is the longest so far.

	// EVP_MAX_MD_BLOCK_SIZE is the largest digest block size supported, in
	// bytes.
	#define EVP_MAX_MD_BLOCK_SIZE 128 // SHA-512 is the longest so far.

	// EVP_DigestFinal_ex finishes the digest in `ctx` and writes the output to
	// `md_out`. `EVP_MD_CTX_size` bytes are written, which is at most
	// `EVP_MAX_MD_SIZE`. If `out_size` is not NULL then `*out_size` is set to the
	// number of bytes written. It returns one. After this call, the hash cannot be
	// updated or finished again until `EVP_DigestInit_ex` is called to start
	// another hashing operation.
	OPENSSL_EXPORT int EVP_DigestFinal_ex(EVP_MD_CTX ctx, uint8_t md_out,
	unsigned int *out_size);

	// EVP_DigestFinal acts like `EVP_DigestFinal_ex` except that
	// `EVP_MD_CTX_cleanup` is called on `ctx` before returning.
	OPENSSL_EXPORT int EVP_DigestFinal(EVP_MD_CTX ctx, uint8_t md_out,
	unsigned int *out_size);

	// EVP_Digest performs a complete hashing operation in one call. It hashes `len`
	// bytes from `data` and writes the digest to `md_out`. `EVP_MD_CTX_size` bytes
	// are written, which is at most `EVP_MAX_MD_SIZE`. If `out_size` is not NULL
	// then `*out_size` is set to the number of bytes written. It returns one on
	// success and zero otherwise.
	OPENSSL_EXPORT int EVP_Digest(const void data, size_t len, uint8_t md_out,
	unsigned int md_out_size, const EVP_MD type,
	ENGINE *impl);


	// Digest function accessors.
	//
	// These functions allow code to learn details about an abstract hash
	// function.

	// EVP_MD_type returns a NID identifying `md`. (For example, `NID_sha256`.)
	OPENSSL_EXPORT int EVP_MD_type(const EVP_MD *md);

	// EVP_MD_flags returns the flags for `md`, which is a set of `EVP_MD_FLAG_*`
	// values, ORed together.
	OPENSSL_EXPORT uint32_t EVP_MD_flags(const EVP_MD *md);

	// EVP_MD_size returns the digest size of `md`, in bytes.
	OPENSSL_EXPORT size_t EVP_MD_size(const EVP_MD *md);

	// EVP_MD_block_size returns the native block-size of `md`, in bytes.
	OPENSSL_EXPORT size_t EVP_MD_block_size(const EVP_MD *md);

	// EVP_MD_FLAG_DIGALGID_ABSENT indicates that the parameter type in an X.509
	// DigestAlgorithmIdentifier representing this digest function should be
	// undefined rather than NULL.
	#define EVP_MD_FLAG_DIGALGID_ABSENT 2

	// EVP_MD_FLAG_XOF indicates that the digest is an extensible-output function
	// (XOF). This flag is defined for compatibility and will never be set in any
	// `EVP_MD` in BoringSSL.
	#define EVP_MD_FLAG_XOF 4


	// Digest operation accessors.

	// EVP_MD_CTX_get0_md returns the underlying digest function, or NULL if one has
	// not been set.
	OPENSSL_EXPORT const EVP_MD EVP_MD_CTX_get0_md(const EVP_MD_CTX ctx);

	// EVP_MD_CTX_md returns the underlying digest function, or NULL if one has not
	// been set. (This is the same as `EVP_MD_CTX_get0_md` but OpenSSL has
	// deprecated this spelling.)
	OPENSSL_EXPORT const EVP_MD EVP_MD_CTX_md(const EVP_MD_CTX ctx);

	// EVP_MD_CTX_size returns the digest size of `ctx`, in bytes. It
	// will crash if a digest hasn't been set on `ctx`.
	OPENSSL_EXPORT size_t EVP_MD_CTX_size(const EVP_MD_CTX *ctx);

	// EVP_MD_CTX_block_size returns the block size of the digest function used by
	// `ctx`, in bytes. It will crash if a digest hasn't been set on `ctx`.
	OPENSSL_EXPORT size_t EVP_MD_CTX_block_size(const EVP_MD_CTX *ctx);

	// EVP_MD_CTX_type returns a NID describing the digest function used by `ctx`.
	// (For example, `NID_sha256`.) It will crash if a digest hasn't been set on
	// `ctx`.
	OPENSSL_EXPORT int EVP_MD_CTX_type(const EVP_MD_CTX *ctx);

	// EVP_MD_CTX_pkey_ctx returns the `EVP_PKEY_CTX` used to configure additional
	// parameters on `ctx` if `ctx` is used for a sign or verify operation with
	// `EVP_DigestSignInit` or `EVP_DigestVerifyInit`. It returns NULL otherwise.
	OPENSSL_EXPORT EVP_PKEY_CTX EVP_MD_CTX_pkey_ctx(const EVP_MD_CTX ctx);


	// ASN.1 functions.
	//
	// These functions allow code to parse and serialize AlgorithmIdentifiers for
	// hash functions.

	// EVP_parse_digest_algorithm parses an AlgorithmIdentifier structure containing
	// a hash function OID (for example, 2.16.840.1.101.3.4.2.1 is SHA-256) and
	// advances `cbs`. The parameters field may either be omitted or a NULL. It
	// returns the digest function or NULL on error.
	OPENSSL_EXPORT const EVP_MD EVP_parse_digest_algorithm(CBS cbs);

	// EVP_parse_digest_algorithm_nid behaves like `EVP_parse_digest_algorithm`
	// except it returns `NID_undef` on error and some other value on success. This
	// may be used to avoid depending on every digest algorithm in the library.
	OPENSSL_EXPORT int EVP_parse_digest_algorithm_nid(CBS *cbs);

	// EVP_marshal_digest_algorithm marshals `md` as an AlgorithmIdentifier
	// structure and appends the result to `cbb`. It returns one on success and zero
	// on error. It sets the parameters field to NULL. Use
	// `EVP_marshal_digest_algorithm_no_params` to omit the parameters instead.
	//
	// In general, the parameters should be omitted for digest algorithms, but the
	// following specifications require a NULL parameter instead.
	//
	// - Hash algorithms and MGF-1 hash algorithms used in RSASSA-PSS and RSAES-OAEP
	// (see RFC 4055, Section 2.1)
	// - The hash algorithm in the DigestInfo structure of RSASSA-PKCS1-v1_5 (see
	// RFC 8017, Appendix A.2.4)
	//
	// Some existing software also uses NULL parameters in other contexts. In
	// practice, digest algorithms are encoded wildly inconsistently.
	OPENSSL_EXPORT int EVP_marshal_digest_algorithm(CBB cbb, const EVP_MD md);

	// EVP_marshal_digest_algorithm_no_params behaves like
	// `EVP_marshal_digest_algorithm` but omits the parameters field.
	OPENSSL_EXPORT int EVP_marshal_digest_algorithm_no_params(CBB *cbb,
	const EVP_MD *md);


	// Deprecated functions.

	// EVP_MD_CTX_copy sets `out`, which must /not/ be initialised, to be a copy of
	// `in`. It returns one on success and zero on error.
	OPENSSL_EXPORT int EVP_MD_CTX_copy(EVP_MD_CTX out, const EVP_MD_CTX in);

	// EVP_add_digest does nothing and returns one. It exists only for
	// compatibility with OpenSSL.
	OPENSSL_EXPORT int EVP_add_digest(const EVP_MD *digest);

	// EVP_get_digestbyname returns an `EVP_MD` given a human readable name in
	// `name`, or NULL if the name is unknown.
	OPENSSL_EXPORT const EVP_MD EVP_get_digestbyname(const char name);

	// EVP_dss1 returns the value of EVP_sha1(). This was provided by OpenSSL to
	// specify the original DSA signatures, which were fixed to use SHA-1. Note,
	// however, that attempting to sign or verify DSA signatures with the EVP
	// interface will always fail.
	OPENSSL_EXPORT const EVP_MD *EVP_dss1(void);

	// EVP_MD_CTX_create calls `EVP_MD_CTX_new`.
	OPENSSL_EXPORT EVP_MD_CTX *EVP_MD_CTX_create(void);

	// EVP_MD_CTX_destroy calls `EVP_MD_CTX_free`.
	OPENSSL_EXPORT void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx);

	// EVP_DigestFinalXOF returns zero and adds an error to the error queue.
	// BoringSSL does not support any XOF digests.
	OPENSSL_EXPORT int EVP_DigestFinalXOF(EVP_MD_CTX ctx, uint8_t out,
	size_t len);

	// EVP_MD_meth_get_flags calls `EVP_MD_flags`.
	OPENSSL_EXPORT uint32_t EVP_MD_meth_get_flags(const EVP_MD *md);

	// EVP_MD_CTX_set_flags does nothing.
	OPENSSL_EXPORT void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);

	// EVP_MD_CTX_FLAG_NON_FIPS_ALLOW is meaningless. In OpenSSL it permits non-FIPS
	// algorithms in FIPS mode. But BoringSSL FIPS mode doesn't prohibit algorithms
	// (it's up the the caller to use the FIPS module in a fashion compliant with
	// their needs). Thus this exists only to allow code to compile.
	#define EVP_MD_CTX_FLAG_NON_FIPS_ALLOW 0

	// EVP_MD_nid calls `EVP_MD_type`.
	OPENSSL_EXPORT int EVP_MD_nid(const EVP_MD *md);

	// EVP_MD_fetch behaves like `EVP_get_digestbyname`. `libctx` and `propq` are
	// ignored. Although it returns a non-const pointer, `EVP_MD`s in BoringSSL are
	// static and do not need to be freed.
	OPENSSL_EXPORT EVP_MD EVP_MD_fetch(OSSL_LIB_CTX libctx, const char *name,
	const char *propq);

	// EVP_MD_up_ref returns one. `EVP_MD`s in BoringSSL are static.
	OPENSSL_EXPORT int EVP_MD_up_ref(EVP_MD *md);

	// EVP_MD_free does nothing. `EVP_MD`s in BoringSSL are static.
	OPENSSL_EXPORT void EVP_MD_free(EVP_MD *md);

	// EVP_Q_digest behaves like `EVP_Digest` but specifies the digest by a string
	// `name`. `libctx` and `propq` are ignored.
	OPENSSL_EXPORT int EVP_Q_digest(OSSL_LIB_CTX libctx, const char name,
	const char propq, const void in,
	size_t in_len, uint8_t out, size_t out_len);

	// Internal constants and structures (hidden).

	struct evp_md_pctx_ops;

	// EVP_MAX_MD_DATA_SIZE is a private constant which specifies the size of the
	// largest digest state. SHA-512 and BLAKE2b are joint-largest. Consuming code
	// only uses this via the `EVP_MD_CTX` type.
	#define EVP_MAX_MD_DATA_SIZE 208

	// env_md_ctx_st is typoed ("evp" -> "env"), but the typo comes from OpenSSL
	// and some consumers forward-declare these structures so we're leaving it
	// alone.
	struct env_md_ctx_st {
	// md_data contains the hash-specific context.
	union {
	uint8_t md_data[EVP_MAX_MD_DATA_SIZE];
	uint64_t alignment;
	};

	// digest is the underlying digest function, or NULL if not set.
	const EVP_MD *digest;

	// pctx is an opaque (at this layer) pointer to additional context that
	// EVP_PKEY functions may store in this object.
	EVP_PKEY_CTX *pctx;

	// pctx_ops, if not NULL, points to a vtable that contains functions to
	// manipulate `pctx`.
	const struct evp_md_pctx_ops *pctx_ops;
	} /* EVP_MD_CTX */;


	#if defined(__cplusplus)
	} // extern C

	#if !defined(BORINGSSL_NO_CXX)
	extern "C++" {

	BSSL_NAMESPACE_BEGIN

	BORINGSSL_MAKE_DELETER(EVP_MD_CTX, EVP_MD_CTX_free)

	using ScopedEVP_MD_CTX =
	internal::StackAllocatedMovable<EVP_MD_CTX, int, EVP_MD_CTX_init,
	EVP_MD_CTX_cleanup, EVP_MD_CTX_move>;

	BSSL_NAMESPACE_END

	} // extern C++
	#endif

	#endif

	#define DIGEST_R_INPUT_NOT_INITIALIZED 100
	#define DIGEST_R_DECODE_ERROR 101
	#define DIGEST_R_UNKNOWN_HASH 102

	#endif // OPENSSL_HEADER_DIGEST_H