include/openssl/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);

// SHA-3 family of digest functions.
//
// WARNING: Prefer to use SHA-2 (e.g. `EVP_sha256`) over SHA-3. Despite being a
// newer hash function, SHA-3 performs poorly and should only be used when
// necessary for interoperability with existing systems.

OPENSSL_EXPORT const EVP_MD *EVP_sha3_256(void);
OPENSSL_EXPORT const EVP_MD *EVP_sha3_384(void);
OPENSSL_EXPORT const EVP_MD *EVP_sha3_512(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 sets an uninitialized `EVP_MD_CTX` to the zero state. This
// is the same as setting the structure to zero.
//
// This function is used for initializing uninitialized memory in an
// `EVP_MD_CTX`, e.g. if it is declared as a local variable on the stack. This
// function should not be used on objects that have already been initialized.
OPENSSL_EXPORT void EVP_MD_CTX_init(EVP_MD_CTX *ctx);

// EVP_MD_CTX_new returns a newly-allocated `EVP_MD_CTX` in the zero state, 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 the
// zero 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` to be a copy of `in`. It returns one on success
// and zero on allocation failure. `out` must have been previously initialized,
// e.g. with `EVP_MD_CTX_init` or `EVP_MD_CTX_new`.
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`, whose memory must already have been
// initialised (e.g. with `EVP_MD_CTX_init` or `EVP_MD_CTX_new`), for a fresh
// hashing operation using `type`. It returns one on success and zero on
// allocation failure.
//
// This function may be used to reconfigure an `EVP_MD_CTX` that was previously
// used for another operation.
OPENSSL_EXPORT int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type,
                                     ENGINE *engine);

// 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 136  // SHA3-256 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_DigestInit calls `EVP_MD_CTX_init`, followed by `EVP_DigestInit_ex`.
//
// `EVP_MD_CTX_init` is used for initializing uninitialized memory in an
// `EVP_MD_CTX`, e.g. if it is declared as a local variable on the stack. Thus
// this function should not be used on objects that have already been
// initialized.
//
// WARNING: This differs from OpenSSL 1.1.x, where `EVP_DigestInit` and
// `EVP_DigestInit_ex` are largely equivalent. This difference is because
// BoringSSL, like OpenSSL 1.0.x, still supports stack-allocating `EVP_MD_CTX`.
// Implementing the OpenSSL 1.1.x semantics would introduce uninitialized reads
// in those callers.
OPENSSL_EXPORT int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);

// EVP_MD_CTX_copy calls `EVP_MD_CTX_init`, followed by `EVP_MD_CTX_copy_ex`.
//
// `EVP_MD_CTX_init` is used for initializing uninitialized memory in an
// `EVP_MD_CTX`, e.g. if it is declared as a local variable on the stack. Thus
// this function should not be used on objects that have already been
// initialized.
//
// WARNING: This differs from OpenSSL 1.1.x, where `EVP_MD_CTX_copy` and
// |EVP_MD_CTX_copy_ex| are largely equivalent. This difference is because
// BoringSSL, like OpenSSL 1.0.x, still supports stack-allocating `EVP_MD_CTX`.
// Implementing the OpenSSL 1.1.x semantics would introduce uninitialized reads
// in those callers.
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 to 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. SHA3-256 is the largest. Consuming code only uses this
// via the `EVP_MD_CTX` type.
#define EVP_MAX_MD_DATA_SIZE 240

// 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)

BORINGSSL_MAKE_STACK_TRAITS_MOVABLE(EVP_MD_CTX, EVP_MD_CTX_init,
                                    EVP_MD_CTX_cleanup, EVP_MD_CTX_move)
using ScopedEVP_MD_CTX = internal::StackAllocatedMovable<EVP_MD_CTX>;

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