EVP_PKEY_NEW(3)

NAME
EVP_PKEY_new, EVP_PKEY_up_ref, EVP_PKEY_free, EVP_PKEY_new_raw_private_key, EVP_PKEY_new_raw_public_key, EVP_PKEY_new_CMAC_key, EVP_PKEY_new_mac_key, EVP_PKEY_get_raw_private_key, EVP_PKEY_get_raw_public_key - public/private key allocation and raw key handling functions

SYNOPSIS
 #include <openssl/evp.h>

 EVP_PKEY *EVP_PKEY_new(void);
 int EVP_PKEY_up_ref(EVP_PKEY *key);
 void EVP_PKEY_free(EVP_PKEY *key);

 EVP_PKEY *EVP_PKEY_new_raw_private_key(int type, ENGINE *e,
                                        const unsigned char *key, size_t keylen);
 EVP_PKEY *EVP_PKEY_new_raw_public_key(int type, ENGINE *e,
                                       const unsigned char *key, size_t keylen);
 EVP_PKEY *EVP_PKEY_new_CMAC_key(ENGINE *e, const unsigned char *priv,
                                 size_t len, const EVP_CIPHER *cipher);
 EVP_PKEY *EVP_PKEY_new_mac_key(int type, ENGINE *e, const unsigned char *key,
                                int keylen);

 int EVP_PKEY_get_raw_private_key(const EVP_PKEY *pkey, unsigned char *priv,
                                  size_t *len);
 int EVP_PKEY_get_raw_public_key(const EVP_PKEY *pkey, unsigned char *pub,
                                 size_t *len);

DESCRIPTION
The EVP_PKEY_new() function allocates an empty EVP_PKEY structure which is used by OpenSSL to store public and private keys. The reference count is set to 1.

EVP_PKEY_up_ref() increments the reference count of key.

EVP_PKEY_free() decrements the reference count of key and, if the reference count is zero, frees it up. If key is NULL, nothing is done.

EVP_PKEY_new_raw_private_key() allocates a new EVP_PKEY. If e is non-NULL then the new EVP_PKEY structure is associated with the engine e. The type argument indicates what kind of key this is. The value should be a NID for a public key algorithm that supports raw private keys, i.e. one of EVP_PKEY_HMAC, EVP_PKEY_POLY1305, EVP_PKEY_SIPHASH, EVP_PKEY_X25519, EVP_PKEY_ED25519, EVP_PKEY_X448 or EVP_PKEY_ED448. key points to the raw private key data for this EVP_PKEY which should be of length keylen. The length should be appropriate for the type of the key. The public key data will be automatically derived from the given private key data (if appropriate for the algorithm type).

EVP_PKEY_new_raw_public_key() works in the same way as EVP_PKEY_new_raw_private_key() except that key points to the raw public key data. The EVP_PKEY structure will be initialised without any private key information. Algorithm types that support raw public keys are EVP_PKEY_X25519, EVP_PKEY_ED25519, EVP_PKEY_X448 or EVP_PKEY_ED448.

EVP_PKEY_new_CMAC_key() works in the same way as EVP_PKEY_new_raw_private_key() except it is only for the EVP_PKEY_CMAC algorithm type. In addition to the raw private key data, it also takes a cipher algorithm to be used during creation of a CMAC in the cipher argument. The cipher should be a standard encryption only cipher. For example AEAD and XTS ciphers should not be used.

EVP_PKEY_new_mac_key() works in the same way as EVP_PKEY_new_raw_private_key(). New applications should use EVP_PKEY_new_raw_private_key() instead.

EVP_PKEY_get_raw_private_key() fills the buffer provided by priv with raw private key data. The size of the priv buffer should be in *len on entry to the function, and on exit *len is updated with the number of bytes actually written. If the buffer priv is NULL then *len is populated with the number of bytes required to hold the key. The calling application is responsible for ensuring that the buffer is large enough to receive the private key data. This function only works for algorithms that support raw private keys. Currently this is: EVP_PKEY_HMAC, EVP_PKEY_POLY1305, EVP_PKEY_SIPHASH, EVP_PKEY_X25519, EVP_PKEY_ED25519, EVP_PKEY_X448 or EVP_PKEY_ED448.

EVP_PKEY_get_raw_public_key() fills the buffer provided by pub with raw public key data. The size of the pub buffer should be in *len on entry to the function, and on exit *len is updated with the number of bytes actually written. If the buffer pub is NULL then *len is populated with the number of bytes required to hold the key. The calling application is responsible for ensuring that the buffer is large enough to receive the public key data. This function only works for algorithms that support raw public keys. Currently this is: EVP_PKEY_X25519, EVP_PKEY_ED25519, EVP_PKEY_X448 or EVP_PKEY_ED448.

NOTES
The EVP_PKEY structure is used by various OpenSSL functions which require a general private key without reference to any particular algorithm.

The structure returned by EVP_PKEY_new() is empty. To add a private or public key to this empty structure use the appropriate functions described in EVP_PKEY_set1_RSA(3), EVP_PKEY_set1_DSA, EVP_PKEY_set1_DH or EVP_PKEY_set1_EC_KEY.

RETURN VALUES
EVP_PKEY_new(), EVP_PKEY_new_raw_private_key(), EVP_PKEY_new_raw_public_key(), EVP_PKEY_new_CMAC_key() and EVP_PKEY_new_mac_key() return either the newly allocated EVP_PKEY structure or NULL if an error occurred.

EVP_PKEY_up_ref(), EVP_PKEY_get_raw_private_key() and EVP_PKEY_get_raw_public_key() return 1 for success and 0 for failure.

SEE ALSO
EVP_PKEY_set1_RSA(3), EVP_PKEY_set1_DSA, EVP_PKEY_set1_DH or EVP_PKEY_set1_EC_KEY

HISTORY
The EVP_PKEY_new() and EVP_PKEY_free() functions exist in all versions of OpenSSL.

The EVP_PKEY_up_ref() function was added in OpenSSL 1.1.0.

The EVP_PKEY_new_raw_private_key(), EVP_PKEY_new_raw_public_key(), EVP_PKEY_new_CMAC_key(), EVP_PKEY_new_raw_private_key() and EVP_PKEY_get_raw_public_key() functions were added in OpenSSL 1.1.1.

COPYRIGHT
Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.