include/openssl/evp.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.] */

#ifndef OPENSSL_HEADER_EVP_H
#define OPENSSL_HEADER_EVP_H

#include <openssl/base.h>

#include <openssl/thread.h>

// OpenSSL included digest and cipher functions in this header so we include
// them for users that still expect that.
//
// TODO(fork): clean up callers so that they include what they use.
#include <openssl/aead.h>
#include <openssl/base64.h>
#include <openssl/cipher.h>
#include <openssl/digest.h>
#include <openssl/nid.h>

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


// EVP abstracts over public/private key algorithms.


// Public key objects.

// EVP_PKEY_new creates a new, empty public-key object and returns it or NULL
// on allocation failure.
OPENSSL_EXPORT EVP_PKEY *EVP_PKEY_new(void);

// EVP_PKEY_free frees all data referenced by |pkey| and then frees |pkey|
// itself.
OPENSSL_EXPORT void EVP_PKEY_free(EVP_PKEY *pkey);

// EVP_PKEY_up_ref increments the reference count of |pkey| and returns one.
OPENSSL_EXPORT int EVP_PKEY_up_ref(EVP_PKEY *pkey);

// EVP_PKEY_is_opaque returns one if |pkey| is opaque. Opaque keys are backed by
// custom implementations which do not expose key material and parameters. It is
// an error to attempt to duplicate, export, or compare an opaque key.
OPENSSL_EXPORT int EVP_PKEY_is_opaque(const EVP_PKEY *pkey);

// EVP_PKEY_cmp compares |a| and |b| and returns one if they are equal, zero if
// not and a negative number on error.
//
// WARNING: this differs from the traditional return value of a "cmp"
// function.
OPENSSL_EXPORT int EVP_PKEY_cmp(const EVP_PKEY *a, const EVP_PKEY *b);

// EVP_PKEY_copy_parameters sets the parameters of |to| to equal the parameters
// of |from|. It returns one on success and zero on error.
OPENSSL_EXPORT int EVP_PKEY_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from);

// EVP_PKEY_missing_parameters returns one if |pkey| is missing needed
// parameters or zero if not, or if the algorithm doesn't take parameters.
OPENSSL_EXPORT int EVP_PKEY_missing_parameters(const EVP_PKEY *pkey);

// EVP_PKEY_size returns the maximum size, in bytes, of a signature signed by
// |pkey|. For an RSA key, this returns the number of bytes needed to represent
// the modulus. For an EC key, this returns the maximum size of a DER-encoded
// ECDSA signature.
OPENSSL_EXPORT int EVP_PKEY_size(const EVP_PKEY *pkey);

// EVP_PKEY_bits returns the "size", in bits, of |pkey|. For an RSA key, this
// returns the bit length of the modulus. For an EC key, this returns the bit
// length of the group order.
OPENSSL_EXPORT int EVP_PKEY_bits(EVP_PKEY *pkey);

// EVP_PKEY_id returns the type of |pkey|, which is one of the |EVP_PKEY_*|
// values.
OPENSSL_EXPORT int EVP_PKEY_id(const EVP_PKEY *pkey);

// EVP_PKEY_type returns |nid| if |nid| is a known key type and |NID_undef|
// otherwise.
OPENSSL_EXPORT int EVP_PKEY_type(int nid);


// Getting and setting concrete public key types.
//
// The following functions get and set the underlying public key in an
// |EVP_PKEY| object. The |set1| functions take an additional reference to the
// underlying key and return one on success or zero on error. The |assign|
// functions adopt the caller's reference. The |get1| functions return a fresh
// reference to the underlying object or NULL if |pkey| is not of the correct
// type. The |get0| functions behave the same but return a non-owning
// pointer.

OPENSSL_EXPORT int EVP_PKEY_set1_RSA(EVP_PKEY *pkey, RSA *key);
OPENSSL_EXPORT int EVP_PKEY_assign_RSA(EVP_PKEY *pkey, RSA *key);
OPENSSL_EXPORT RSA *EVP_PKEY_get0_RSA(EVP_PKEY *pkey);
OPENSSL_EXPORT RSA *EVP_PKEY_get1_RSA(EVP_PKEY *pkey);

OPENSSL_EXPORT int EVP_PKEY_set1_DSA(EVP_PKEY *pkey, DSA *key);
OPENSSL_EXPORT int EVP_PKEY_assign_DSA(EVP_PKEY *pkey, DSA *key);
OPENSSL_EXPORT DSA *EVP_PKEY_get0_DSA(EVP_PKEY *pkey);
OPENSSL_EXPORT DSA *EVP_PKEY_get1_DSA(EVP_PKEY *pkey);

OPENSSL_EXPORT int EVP_PKEY_set1_EC_KEY(EVP_PKEY *pkey, EC_KEY *key);
OPENSSL_EXPORT int EVP_PKEY_assign_EC_KEY(EVP_PKEY *pkey, EC_KEY *key);
OPENSSL_EXPORT EC_KEY *EVP_PKEY_get0_EC_KEY(EVP_PKEY *pkey);
OPENSSL_EXPORT EC_KEY *EVP_PKEY_get1_EC_KEY(EVP_PKEY *pkey);

// EVP_PKEY_new_ed25519_public returns a newly allocated |EVP_PKEY| wrapping an
// Ed25519 public key, or NULL on allocation error.
OPENSSL_EXPORT EVP_PKEY *EVP_PKEY_new_ed25519_public(
    const uint8_t public_key[32]);

// EVP_PKEY_new_ed25519_private returns a newly allocated |EVP_PKEY| wrapping an
// Ed25519 private key, or NULL on allocation error.
OPENSSL_EXPORT EVP_PKEY *EVP_PKEY_new_ed25519_private(
    const uint8_t private_key[64]);

#define EVP_PKEY_NONE NID_undef
#define EVP_PKEY_RSA NID_rsaEncryption
#define EVP_PKEY_DSA NID_dsa
#define EVP_PKEY_EC NID_X9_62_id_ecPublicKey
#define EVP_PKEY_ED25519 NID_ED25519

// EVP_PKEY_assign sets the underlying key of |pkey| to |key|, which must be of
// the given type. The |type| argument should be one of the |EVP_PKEY_*|
// values.
OPENSSL_EXPORT int EVP_PKEY_assign(EVP_PKEY *pkey, int type, void *key);

// EVP_PKEY_set_type sets the type of |pkey| to |type|, which should be one of
// the |EVP_PKEY_*| values. It returns one if successful or zero otherwise. If
// |pkey| is NULL, it simply reports whether the type is known.
OPENSSL_EXPORT int EVP_PKEY_set_type(EVP_PKEY *pkey, int type);

// EVP_PKEY_cmp_parameters compares the parameters of |a| and |b|. It returns
// one if they match, zero if not, or a negative number of on error.
//
// WARNING: the return value differs from the usual return value convention.
OPENSSL_EXPORT int EVP_PKEY_cmp_parameters(const EVP_PKEY *a,
                                           const EVP_PKEY *b);


// ASN.1 functions

// EVP_parse_public_key decodes a DER-encoded SubjectPublicKeyInfo structure
// (RFC 5280) from |cbs| and advances |cbs|. It returns a newly-allocated
// |EVP_PKEY| or NULL on error.
//
// The caller must check the type of the parsed public key to ensure it is
// suitable and validate other desired key properties such as RSA modulus size
// or EC curve.
OPENSSL_EXPORT EVP_PKEY *EVP_parse_public_key(CBS *cbs);

// EVP_marshal_public_key marshals |key| as a DER-encoded SubjectPublicKeyInfo
// structure (RFC 5280) and appends the result to |cbb|. It returns one on
// success and zero on error.
OPENSSL_EXPORT int EVP_marshal_public_key(CBB *cbb, const EVP_PKEY *key);

// EVP_parse_private_key decodes a DER-encoded PrivateKeyInfo structure (RFC
// 5208) from |cbs| and advances |cbs|. It returns a newly-allocated |EVP_PKEY|
// or NULL on error.
//
// The caller must check the type of the parsed private key to ensure it is
// suitable and validate other desired key properties such as RSA modulus size
// or EC curve.
//
// A PrivateKeyInfo ends with an optional set of attributes. These are not
// processed and so this function will silently ignore any trailing data in the
// structure.
OPENSSL_EXPORT EVP_PKEY *EVP_parse_private_key(CBS *cbs);

// EVP_marshal_private_key marshals |key| as a DER-encoded PrivateKeyInfo
// structure (RFC 5208) and appends the result to |cbb|. It returns one on
// success and zero on error.
OPENSSL_EXPORT int EVP_marshal_private_key(CBB *cbb, const EVP_PKEY *key);

// EVP_set_buggy_rsa_parser configures whether |RSA_parse_public_key_buggy| is
// used by |EVP_parse_public_key|. By default, it is not used.
OPENSSL_EXPORT void EVP_set_buggy_rsa_parser(int buggy);


// Signing

// EVP_DigestSignInit sets up |ctx| for a signing operation with |type| and
// |pkey|. The |ctx| argument must have been initialised with
// |EVP_MD_CTX_init|. If |pctx| is not NULL, the |EVP_PKEY_CTX| of the signing
// operation will be written to |*pctx|; this can be used to set alternative
// signing options.
//
// For single-shot signing algorithms which do not use a pre-hash, such as
// Ed25519, |type| should be NULL. The |EVP_MD_CTX| itself is unused but is
// present so the API is uniform. See |EVP_DigestSign|.
//
// It returns one on success, or zero on error.
OPENSSL_EXPORT int EVP_DigestSignInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
                                      const EVP_MD *type, ENGINE *e,
                                      EVP_PKEY *pkey);

// EVP_DigestSignUpdate appends |len| bytes from |data| to the data which will
// be signed in |EVP_DigestSignFinal|. It returns one.
//
// This function performs a streaming signing operation and will fail for
// signature algorithms which do not support this. Use |EVP_DigestSign| for a
// single-shot operation.
OPENSSL_EXPORT int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *data,
                                        size_t len);

// EVP_DigestSignFinal signs the data that has been included by one or more
// calls to |EVP_DigestSignUpdate|. If |out_sig| is NULL then |*out_sig_len| is
// set to the maximum number of output bytes. Otherwise, on entry,
// |*out_sig_len| must contain the length of the |out_sig| buffer. If the call
// is successful, the signature is written to |out_sig| and |*out_sig_len| is
// set to its length.
//
// This function performs a streaming signing operation and will fail for
// signature algorithms which do not support this. Use |EVP_DigestSign| for a
// single-shot operation.
//
// It returns one on success, or zero on error.
OPENSSL_EXPORT int EVP_DigestSignFinal(EVP_MD_CTX *ctx, uint8_t *out_sig,
                                       size_t *out_sig_len);

// EVP_DigestSign signs |data_len| bytes from |data| using |ctx|. If |out_sig|
// is NULL then |*out_sig_len| is set to the maximum number of output
// bytes. Otherwise, on entry, |*out_sig_len| must contain the length of the
// |out_sig| buffer. If the call is successful, the signature is written to
// |out_sig| and |*out_sig_len| is set to its length.
//
// It returns one on success and zero on error.
OPENSSL_EXPORT int EVP_DigestSign(EVP_MD_CTX *ctx, uint8_t *out_sig,
                                  size_t *out_sig_len, const uint8_t *data,
                                  size_t data_len);


// Verifying

// EVP_DigestVerifyInit sets up |ctx| for a signature verification operation
// with |type| and |pkey|. The |ctx| argument must have been initialised with
// |EVP_MD_CTX_init|. If |pctx| is not NULL, the |EVP_PKEY_CTX| of the signing
// operation will be written to |*pctx|; this can be used to set alternative
// signing options.
//
// For single-shot signing algorithms which do not use a pre-hash, such as
// Ed25519, |type| should be NULL. The |EVP_MD_CTX| itself is unused but is
// present so the API is uniform. See |EVP_DigestVerify|.
//
// It returns one on success, or zero on error.
OPENSSL_EXPORT int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
                                        const EVP_MD *type, ENGINE *e,
                                        EVP_PKEY *pkey);

// EVP_DigestVerifyUpdate appends |len| bytes from |data| to the data which
// will be verified by |EVP_DigestVerifyFinal|. It returns one.
//
// This function performs streaming signature verification and will fail for
// signature algorithms which do not support this. Use |EVP_PKEY_verify_message|
// for a single-shot verification.
OPENSSL_EXPORT int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *data,
                                          size_t len);

// EVP_DigestVerifyFinal verifies that |sig_len| bytes of |sig| are a valid
// signature for the data that has been included by one or more calls to
// |EVP_DigestVerifyUpdate|. It returns one on success and zero otherwise.
//
// This function performs streaming signature verification and will fail for
// signature algorithms which do not support this. Use |EVP_PKEY_verify_message|
// for a single-shot verification.
OPENSSL_EXPORT int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, const uint8_t *sig,
                                         size_t sig_len);

// EVP_DigestVerify verifies that |sig_len| bytes from |sig| are a valid
// signature for |data|. It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_DigestVerify(EVP_MD_CTX *ctx, const uint8_t *sig,
                                    size_t sig_len, const uint8_t *data,
                                    size_t len);


// Signing (old functions)

// EVP_SignInit_ex configures |ctx|, which must already have been initialised,
// for a fresh signing operation using the hash function |type|. It returns one
// on success and zero otherwise.
//
// (In order to initialise |ctx|, either obtain it initialised with
// |EVP_MD_CTX_create|, or use |EVP_MD_CTX_init|.)
OPENSSL_EXPORT int EVP_SignInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type,
                                   ENGINE *impl);

// EVP_SignInit is a deprecated version of |EVP_SignInit_ex|.
//
// TODO(fork): remove.
OPENSSL_EXPORT int EVP_SignInit(EVP_MD_CTX *ctx, const EVP_MD *type);

// EVP_SignUpdate appends |len| bytes from |data| to the data which will be
// signed in |EVP_SignFinal|.
OPENSSL_EXPORT int EVP_SignUpdate(EVP_MD_CTX *ctx, const void *data,
                                  size_t len);

// EVP_SignFinal signs the data that has been included by one or more calls to
// |EVP_SignUpdate|, using the key |pkey|, and writes it to |sig|. On entry,
// |sig| must point to at least |EVP_PKEY_size(pkey)| bytes of space. The
// actual size of the signature is written to |*out_sig_len|.
//
// It returns one on success and zero otherwise.
//
// It does not modify |ctx|, thus it's possible to continue to use |ctx| in
// order to sign a longer message.
OPENSSL_EXPORT int EVP_SignFinal(const EVP_MD_CTX *ctx, uint8_t *sig,
                                 unsigned int *out_sig_len, EVP_PKEY *pkey);


// Verifying (old functions)

// EVP_VerifyInit_ex configures |ctx|, which must already have been
// initialised, for a fresh signature verification operation using the hash
// function |type|. It returns one on success and zero otherwise.
//
// (In order to initialise |ctx|, either obtain it initialised with
// |EVP_MD_CTX_create|, or use |EVP_MD_CTX_init|.)
OPENSSL_EXPORT int EVP_VerifyInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type,
                                     ENGINE *impl);

// EVP_VerifyInit is a deprecated version of |EVP_VerifyInit_ex|.
//
// TODO(fork): remove.
OPENSSL_EXPORT int EVP_VerifyInit(EVP_MD_CTX *ctx, const EVP_MD *type);

// EVP_VerifyUpdate appends |len| bytes from |data| to the data which will be
// signed in |EVP_VerifyFinal|.
OPENSSL_EXPORT int EVP_VerifyUpdate(EVP_MD_CTX *ctx, const void *data,
                                    size_t len);

// EVP_VerifyFinal verifies that |sig_len| bytes of |sig| are a valid
// signature, by |pkey|, for the data that has been included by one or more
// calls to |EVP_VerifyUpdate|.
//
// It returns one on success and zero otherwise.
//
// It does not modify |ctx|, thus it's possible to continue to use |ctx| in
// order to sign a longer message.
OPENSSL_EXPORT int EVP_VerifyFinal(EVP_MD_CTX *ctx, const uint8_t *sig,
                                   size_t sig_len, EVP_PKEY *pkey);


// Printing

// EVP_PKEY_print_public prints a textual representation of the public key in
// |pkey| to |out|. Returns one on success or zero otherwise.
OPENSSL_EXPORT int EVP_PKEY_print_public(BIO *out, const EVP_PKEY *pkey,
                                         int indent, ASN1_PCTX *pctx);

// EVP_PKEY_print_private prints a textual representation of the private key in
// |pkey| to |out|. Returns one on success or zero otherwise.
OPENSSL_EXPORT int EVP_PKEY_print_private(BIO *out, const EVP_PKEY *pkey,
                                          int indent, ASN1_PCTX *pctx);

// EVP_PKEY_print_params prints a textual representation of the parameters in
// |pkey| to |out|. Returns one on success or zero otherwise.
OPENSSL_EXPORT int EVP_PKEY_print_params(BIO *out, const EVP_PKEY *pkey,
                                         int indent, ASN1_PCTX *pctx);


// Password stretching.
//
// Password stretching functions take a low-entropy password and apply a slow
// function that results in a key suitable for use in symmetric
// cryptography.

// PKCS5_PBKDF2_HMAC computes |iterations| iterations of PBKDF2 of |password|
// and |salt|, using |digest|, and outputs |key_len| bytes to |out_key|. It
// returns one on success and zero on error.
OPENSSL_EXPORT int PKCS5_PBKDF2_HMAC(const char *password, size_t password_len,
                                     const uint8_t *salt, size_t salt_len,
                                     unsigned iterations, const EVP_MD *digest,
                                     size_t key_len, uint8_t *out_key);

// PKCS5_PBKDF2_HMAC_SHA1 is the same as PKCS5_PBKDF2_HMAC, but with |digest|
// fixed to |EVP_sha1|.
OPENSSL_EXPORT int PKCS5_PBKDF2_HMAC_SHA1(const char *password,
                                          size_t password_len,
                                          const uint8_t *salt, size_t salt_len,
                                          unsigned iterations, size_t key_len,
                                          uint8_t *out_key);

// EVP_PBE_scrypt expands |password| into a secret key of length |key_len| using
// scrypt, as described in RFC 7914, and writes the result to |out_key|. It
// returns one on success and zero on error.
//
// |N|, |r|, and |p| are as described in RFC 7914 section 6. They determine the
// cost of the operation. If the memory required exceeds |max_mem|, the
// operation will fail instead. If |max_mem| is zero, a defult limit of 32MiB
// will be used.
OPENSSL_EXPORT int EVP_PBE_scrypt(const char *password, size_t password_len,
                                  const uint8_t *salt, size_t salt_len,
                                  uint64_t N, uint64_t r, uint64_t p,
                                  size_t max_mem, uint8_t *out_key,
                                  size_t key_len);


// Public key contexts.
//
// |EVP_PKEY_CTX| objects hold the context of an operation (e.g. signing or
// encrypting) that uses a public key.

// EVP_PKEY_CTX_new allocates a fresh |EVP_PKEY_CTX| for use with |pkey|. It
// returns the context or NULL on error.
OPENSSL_EXPORT EVP_PKEY_CTX *EVP_PKEY_CTX_new(EVP_PKEY *pkey, ENGINE *e);

// EVP_PKEY_CTX_new_id allocates a fresh |EVP_PKEY_CTX| for a key of type |id|
// (e.g. |EVP_PKEY_HMAC|). This can be used for key generation where
// |EVP_PKEY_CTX_new| can't be used because there isn't an |EVP_PKEY| to pass
// it. It returns the context or NULL on error.
OPENSSL_EXPORT EVP_PKEY_CTX *EVP_PKEY_CTX_new_id(int id, ENGINE *e);

// EVP_PKEY_CTX_free frees |ctx| and the data it owns.
OPENSSL_EXPORT void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx);

// EVP_PKEY_CTX_dup allocates a fresh |EVP_PKEY_CTX| and sets it equal to the
// state of |ctx|. It returns the fresh |EVP_PKEY_CTX| or NULL on error.
OPENSSL_EXPORT EVP_PKEY_CTX *EVP_PKEY_CTX_dup(EVP_PKEY_CTX *ctx);

// EVP_PKEY_CTX_get0_pkey returns the |EVP_PKEY| associated with |ctx|.
OPENSSL_EXPORT EVP_PKEY *EVP_PKEY_CTX_get0_pkey(EVP_PKEY_CTX *ctx);

// EVP_PKEY_sign_init initialises an |EVP_PKEY_CTX| for a signing operation. It
// should be called before |EVP_PKEY_sign|.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);

// EVP_PKEY_sign signs |digest_len| bytes from |digest| using |ctx|. If |sig| is
// NULL, the maximum size of the signature is written to
// |out_sig_len|. Otherwise, |*sig_len| must contain the number of bytes of
// space available at |sig|. If sufficient, the signature will be written to
// |sig| and |*sig_len| updated with the true length.
//
// This function expects a pre-hashed input and will fail for signature
// algorithms which do not support this. Use |EVP_DigestSignInit| to sign an
// unhashed input.
//
// WARNING: Setting |sig| to NULL only gives the maximum size of the
// signature. The actual signature may be smaller.
//
// It returns one on success or zero on error. (Note: this differs from
// OpenSSL, which can also return negative values to indicate an error. )
OPENSSL_EXPORT int EVP_PKEY_sign(EVP_PKEY_CTX *ctx, uint8_t *sig,
                                 size_t *sig_len, const uint8_t *digest,
                                 size_t digest_len);

// EVP_PKEY_verify_init initialises an |EVP_PKEY_CTX| for a signature
// verification operation. It should be called before |EVP_PKEY_verify|.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);

// EVP_PKEY_verify verifies that |sig_len| bytes from |sig| are a valid
// signature for |digest|.
//
// This function expects a pre-hashed input and will fail for signature
// algorithms which do not support this. Use |EVP_DigestVerifyInit| to verify a
// signature given the unhashed input.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_verify(EVP_PKEY_CTX *ctx, const uint8_t *sig,
                                   size_t sig_len, const uint8_t *digest,
                                   size_t digest_len);

// EVP_PKEY_encrypt_init initialises an |EVP_PKEY_CTX| for an encryption
// operation. It should be called before |EVP_PKEY_encrypt|.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_encrypt_init(EVP_PKEY_CTX *ctx);

// EVP_PKEY_encrypt encrypts |in_len| bytes from |in|. If |out| is NULL, the
// maximum size of the ciphertext is written to |out_len|. Otherwise, |*out_len|
// must contain the number of bytes of space available at |out|. If sufficient,
// the ciphertext will be written to |out| and |*out_len| updated with the true
// length.
//
// WARNING: Setting |out| to NULL only gives the maximum size of the
// ciphertext. The actual ciphertext may be smaller.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_encrypt(EVP_PKEY_CTX *ctx, uint8_t *out,
                                    size_t *out_len, const uint8_t *in,
                                    size_t in_len);

// EVP_PKEY_decrypt_init initialises an |EVP_PKEY_CTX| for a decryption
// operation. It should be called before |EVP_PKEY_decrypt|.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_decrypt_init(EVP_PKEY_CTX *ctx);

// EVP_PKEY_decrypt decrypts |in_len| bytes from |in|. If |out| is NULL, the
// maximum size of the plaintext is written to |out_len|. Otherwise, |*out_len|
// must contain the number of bytes of space available at |out|. If sufficient,
// the ciphertext will be written to |out| and |*out_len| updated with the true
// length.
//
// WARNING: Setting |out| to NULL only gives the maximum size of the
// plaintext. The actual plaintext may be smaller.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_decrypt(EVP_PKEY_CTX *ctx, uint8_t *out,
                                    size_t *out_len, const uint8_t *in,
                                    size_t in_len);

// EVP_PKEY_verify_recover_init initialises an |EVP_PKEY_CTX| for a public-key
// decryption operation. It should be called before |EVP_PKEY_verify_recover|.
//
// Public-key decryption is a very obscure operation that is only implemented
// by RSA keys. It is effectively a signature verification operation that
// returns the signed message directly. It is almost certainly not what you
// want.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_verify_recover_init(EVP_PKEY_CTX *ctx);

// EVP_PKEY_verify_recover decrypts |sig_len| bytes from |sig|. If |out| is
// NULL, the maximum size of the plaintext is written to |out_len|. Otherwise,
// |*out_len| must contain the number of bytes of space available at |out|. If
// sufficient, the ciphertext will be written to |out| and |*out_len| updated
// with the true length.
//
// WARNING: Setting |out| to NULL only gives the maximum size of the
// plaintext. The actual plaintext may be smaller.
//
// See the warning about this operation in |EVP_PKEY_verify_recover_init|. It
// is probably not what you want.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_verify_recover(EVP_PKEY_CTX *ctx, uint8_t *out,
                                           size_t *out_len, const uint8_t *sig,
                                           size_t siglen);

// EVP_PKEY_derive_init initialises an |EVP_PKEY_CTX| for a key derivation
// operation. It should be called before |EVP_PKEY_derive_set_peer| and
// |EVP_PKEY_derive|.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx);

// EVP_PKEY_derive_set_peer sets the peer's key to be used for key derivation
// by |ctx| to |peer|. It should be called after |EVP_PKEY_derive_init|. (For
// example, this is used to set the peer's key in (EC)DH.) It returns one on
// success and zero on error.
OPENSSL_EXPORT int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX *ctx, EVP_PKEY *peer);

// EVP_PKEY_derive derives a shared key between the two keys configured in
// |ctx|. If |key| is non-NULL then, on entry, |out_key_len| must contain the
// amount of space at |key|. If sufficient then the shared key will be written
// to |key| and |*out_key_len| will be set to the length. If |key| is NULL then
// |out_key_len| will be set to the maximum length.
//
// WARNING: Setting |out| to NULL only gives the maximum size of the key. The
// actual key may be smaller.
//
// It returns one on success and zero on error.
OPENSSL_EXPORT int EVP_PKEY_derive(EVP_PKEY_CTX *ctx, uint8_t *key,
                                   size_t *out_key_len);

// EVP_PKEY_keygen_init initialises an |EVP_PKEY_CTX| for a key generation
// operation. It should be called before |EVP_PKEY_keygen|.
//
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_keygen_init(EVP_PKEY_CTX *ctx);

// EVP_PKEY_keygen performs a key generation operation using the values from
// |ctx| and sets |*ppkey| to a fresh |EVP_PKEY| containing the resulting key.
// It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);


// Generic control functions.

// EVP_PKEY_CTX_set_signature_md sets |md| as the digest to be used in a
// signature operation. It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set_signature_md(EVP_PKEY_CTX *ctx,
                                                 const EVP_MD *md);

// EVP_PKEY_CTX_get_signature_md sets |*out_md| to the digest to be used in a
// signature operation. It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_get_signature_md(EVP_PKEY_CTX *ctx,
                                                 const EVP_MD **out_md);


// RSA specific control functions.

// EVP_PKEY_CTX_set_rsa_padding sets the padding type to use. It should be one
// of the |RSA_*_PADDING| values. Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set_rsa_padding(EVP_PKEY_CTX *ctx, int padding);

// EVP_PKEY_CTX_get_rsa_padding sets |*out_padding| to the current padding
// value, which is one of the |RSA_*_PADDING| values. Returns one on success or
// zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_get_rsa_padding(EVP_PKEY_CTX *ctx,
                                                int *out_padding);

// EVP_PKEY_CTX_set_rsa_pss_saltlen sets the length of the salt in a PSS-padded
// signature. A value of -1 cause the salt to be the same length as the digest
// in the signature. A value of -2 causes the salt to be the maximum length
// that will fit when signing and recovered from the signature when verifying.
// Otherwise the value gives the size of the salt in bytes.
//
// If unsure, use -1.
//
// Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set_rsa_pss_saltlen(EVP_PKEY_CTX *ctx,
                                                    int salt_len);

// EVP_PKEY_CTX_get_rsa_pss_saltlen sets |*out_salt_len| to the salt length of
// a PSS-padded signature. See the documentation for
// |EVP_PKEY_CTX_set_rsa_pss_saltlen| for details of the special values that it
// can take.
//
// Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_get_rsa_pss_saltlen(EVP_PKEY_CTX *ctx,
                                                    int *out_salt_len);

// EVP_PKEY_CTX_set_rsa_keygen_bits sets the size of the desired RSA modulus,
// in bits, for key generation. Returns one on success or zero on
// error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set_rsa_keygen_bits(EVP_PKEY_CTX *ctx,
                                                    int bits);

// EVP_PKEY_CTX_set_rsa_keygen_pubexp sets |e| as the public exponent for key
// generation. Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx,
                                                      BIGNUM *e);

// EVP_PKEY_CTX_set_rsa_oaep_md sets |md| as the digest used in OAEP padding.
// Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set_rsa_oaep_md(EVP_PKEY_CTX *ctx,
                                                const EVP_MD *md);

// EVP_PKEY_CTX_get_rsa_oaep_md sets |*out_md| to the digest function used in
// OAEP padding. Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_get_rsa_oaep_md(EVP_PKEY_CTX *ctx,
                                                const EVP_MD **out_md);

// EVP_PKEY_CTX_set_rsa_mgf1_md sets |md| as the digest used in MGF1. Returns
// one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set_rsa_mgf1_md(EVP_PKEY_CTX *ctx,
                                                const EVP_MD *md);

// EVP_PKEY_CTX_get_rsa_mgf1_md sets |*out_md| to the digest function used in
// MGF1. Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_get_rsa_mgf1_md(EVP_PKEY_CTX *ctx,
                                                const EVP_MD **out_md);

// EVP_PKEY_CTX_set0_rsa_oaep_label sets |label_len| bytes from |label| as the
// label used in OAEP. DANGER: On success, this call takes ownership of |label|
// and will call |OPENSSL_free| on it when |ctx| is destroyed.
//
// Returns one on success or zero on error.
OPENSSL_EXPORT int EVP_PKEY_CTX_set0_rsa_oaep_label(EVP_PKEY_CTX *ctx,
                                                    uint8_t *label,
                                                    size_t label_len);

// EVP_PKEY_CTX_get0_rsa_oaep_label sets |*out_label| to point to the internal
// buffer containing the OAEP label (which may be NULL) and returns the length
// of the label or a negative value on error.
//
// WARNING: the return value differs from the usual return value convention.
OPENSSL_EXPORT int EVP_PKEY_CTX_get0_rsa_oaep_label(EVP_PKEY_CTX *ctx,
                                                    const uint8_t **out_label);


// Deprecated functions.

// EVP_PKEY_DH is defined for compatibility, but it is impossible to create an
// |EVP_PKEY| of that type.
#define EVP_PKEY_DH NID_dhKeyAgreement

// EVP_PKEY_RSA2 was historically an alternate form for RSA public keys (OID
// 2.5.8.1.1), but is no longer accepted.
#define EVP_PKEY_RSA2 NID_rsa

// OpenSSL_add_all_algorithms does nothing.
OPENSSL_EXPORT void OpenSSL_add_all_algorithms(void);

// OPENSSL_add_all_algorithms_conf does nothing.
OPENSSL_EXPORT void OPENSSL_add_all_algorithms_conf(void);

// OpenSSL_add_all_ciphers does nothing.
OPENSSL_EXPORT void OpenSSL_add_all_ciphers(void);

// OpenSSL_add_all_digests does nothing.
OPENSSL_EXPORT void OpenSSL_add_all_digests(void);

// EVP_cleanup does nothing.
OPENSSL_EXPORT void EVP_cleanup(void);

OPENSSL_EXPORT void EVP_CIPHER_do_all_sorted(
    void (*callback)(const EVP_CIPHER *cipher, const char *name,
                     const char *unused, void *arg),
    void *arg);

OPENSSL_EXPORT void EVP_MD_do_all_sorted(void (*callback)(const EVP_MD *cipher,
                                                          const char *name,
                                                          const char *unused,
                                                          void *arg),
                                         void *arg);

// i2d_PrivateKey marshals a private key from |key| to an ASN.1, DER
// structure. If |outp| is not NULL then the result is written to |*outp| and
// |*outp| is advanced just past the output. It returns the number of bytes in
// the result, whether written or not, or a negative value on error.
//
// RSA keys are serialized as a DER-encoded RSAPublicKey (RFC 3447) structure.
// EC keys are serialized as a DER-encoded ECPrivateKey (RFC 5915) structure.
//
// Use |RSA_marshal_private_key| or |EC_marshal_private_key| instead.
OPENSSL_EXPORT int i2d_PrivateKey(const EVP_PKEY *key, uint8_t **outp);

// i2d_PublicKey marshals a public key from |key| to a type-specific format.
// If |outp| is not NULL then the result is written to |*outp| and
// |*outp| is advanced just past the output. It returns the number of bytes in
// the result, whether written or not, or a negative value on error.
//
// RSA keys are serialized as a DER-encoded RSAPublicKey (RFC 3447) structure.
// EC keys are serialized as an EC point per SEC 1.
//
// Use |RSA_marshal_public_key| or |EC_POINT_point2cbb| instead.
OPENSSL_EXPORT int i2d_PublicKey(EVP_PKEY *key, uint8_t **outp);

// d2i_PrivateKey parses an ASN.1, DER-encoded, private key from |len| bytes at
// |*inp|. If |out| is not NULL then, on exit, a pointer to the result is in
// |*out|. Note that, even if |*out| is already non-NULL on entry, it will not
// be written to. Rather, a fresh |EVP_PKEY| is allocated and the previous one
// is freed. On successful exit, |*inp| is advanced past the DER structure. It
// returns the result or NULL on error.
//
// This function tries to detect one of several formats. Instead, use
// |EVP_parse_private_key| for a PrivateKeyInfo, |RSA_parse_private_key| for an
// RSAPrivateKey, and |EC_parse_private_key| for an ECPrivateKey.
OPENSSL_EXPORT EVP_PKEY *d2i_PrivateKey(int type, EVP_PKEY **out,
                                        const uint8_t **inp, long len);

// d2i_AutoPrivateKey acts the same as |d2i_PrivateKey|, but detects the type
// of the private key.
//
// This function tries to detect one of several formats. Instead, use
// |EVP_parse_private_key| for a PrivateKeyInfo, |RSA_parse_private_key| for an
// RSAPrivateKey, and |EC_parse_private_key| for an ECPrivateKey.
OPENSSL_EXPORT EVP_PKEY *d2i_AutoPrivateKey(EVP_PKEY **out, const uint8_t **inp,
                                            long len);

// EVP_PKEY_get0_DH returns NULL.
OPENSSL_EXPORT DH *EVP_PKEY_get0_DH(EVP_PKEY *pkey);


// Private structures.

struct evp_pkey_st {
  CRYPTO_refcount_t references;

  // type contains one of the EVP_PKEY_* values or NID_undef and determines
  // which element (if any) of the |pkey| union is valid.
  int type;

  union {
    void *ptr;
    RSA *rsa;
    DSA *dsa;
    DH *dh;
    EC_KEY *ec;
  } pkey;

  // ameth contains a pointer to a method table that contains many ASN.1
  // methods for the key type.
  const EVP_PKEY_ASN1_METHOD *ameth;
} /* EVP_PKEY */;


#if defined(__cplusplus)
}  // extern C

extern "C++" {
namespace bssl {

BORINGSSL_MAKE_DELETER(EVP_PKEY, EVP_PKEY_free)
BORINGSSL_MAKE_DELETER(EVP_PKEY_CTX, EVP_PKEY_CTX_free)

}  // namespace bssl

}  // extern C++

#endif

#define EVP_R_BUFFER_TOO_SMALL 100
#define EVP_R_COMMAND_NOT_SUPPORTED 101
#define EVP_R_DECODE_ERROR 102
#define EVP_R_DIFFERENT_KEY_TYPES 103
#define EVP_R_DIFFERENT_PARAMETERS 104
#define EVP_R_ENCODE_ERROR 105
#define EVP_R_EXPECTING_AN_EC_KEY_KEY 106
#define EVP_R_EXPECTING_AN_RSA_KEY 107
#define EVP_R_EXPECTING_A_DSA_KEY 108
#define EVP_R_ILLEGAL_OR_UNSUPPORTED_PADDING_MODE 109
#define EVP_R_INVALID_DIGEST_LENGTH 110
#define EVP_R_INVALID_DIGEST_TYPE 111
#define EVP_R_INVALID_KEYBITS 112
#define EVP_R_INVALID_MGF1_MD 113
#define EVP_R_INVALID_OPERATION 114
#define EVP_R_INVALID_PADDING_MODE 115
#define EVP_R_INVALID_PSS_SALTLEN 116
#define EVP_R_KEYS_NOT_SET 117
#define EVP_R_MISSING_PARAMETERS 118
#define EVP_R_NO_DEFAULT_DIGEST 119
#define EVP_R_NO_KEY_SET 120
#define EVP_R_NO_MDC2_SUPPORT 121
#define EVP_R_NO_NID_FOR_CURVE 122
#define EVP_R_NO_OPERATION_SET 123
#define EVP_R_NO_PARAMETERS_SET 124
#define EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE 125
#define EVP_R_OPERATON_NOT_INITIALIZED 126
#define EVP_R_UNKNOWN_PUBLIC_KEY_TYPE 127
#define EVP_R_UNSUPPORTED_ALGORITHM 128
#define EVP_R_UNSUPPORTED_PUBLIC_KEY_TYPE 129
#define EVP_R_NOT_A_PRIVATE_KEY 130
#define EVP_R_INVALID_SIGNATURE 131
#define EVP_R_MEMORY_LIMIT_EXCEEDED 132
#define EVP_R_INVALID_PARAMETERS 133

#endif  // OPENSSL_HEADER_EVP_H