NAME

       d2i_PrivateKey, d2i_PublicKey, d2i_AutoPrivateKey, i2d_PrivateKey, i2d_PublicKey,
       d2i_PrivateKey_bio, d2i_PrivateKey_fp - decode and encode functions for reading and saving
       EVP_PKEY structures

SYNOPSIS

        #include <openssl/evp.h>

        EVP_PKEY *d2i_PrivateKey(int type, EVP_PKEY **a, const unsigned char **pp,
                                 long length);
        EVP_PKEY *d2i_PublicKey(int type, EVP_PKEY **a, const unsigned char **pp,
                                long length);
        EVP_PKEY *d2i_AutoPrivateKey(EVP_PKEY **a, const unsigned char **pp,
                                     long length);
        int i2d_PrivateKey(EVP_PKEY *a, unsigned char **pp);
        int i2d_PublicKey(EVP_PKEY *a, unsigned char **pp);

        EVP_PKEY *d2i_PrivateKey_bio(BIO *bp, EVP_PKEY **a);
        EVP_PKEY *d2i_PrivateKey_fp(FILE *fp, EVP_PKEY **a)

DESCRIPTION

       d2i_PrivateKey() decodes a private key using algorithm type. It attempts to use any key
       specific format or PKCS#8 unencrypted PrivateKeyInfo format. The type parameter should be
       a public key algorithm constant such as EVP_PKEY_RSA. An error occurs if the decoded key
       does not match type.  d2i_PublicKey() does the same for public keys.

       d2i_AutoPrivateKey() is similar to d2i_PrivateKey() except it attempts to automatically
       detect the private key format.

       i2d_PrivateKey() encodes key. It uses a key specific format or, if none is defined for
       that key type, PKCS#8 unencrypted PrivateKeyInfo format.  i2d_PublicKey() does the same
       for public keys.

       These functions are similar to the d2i_X509() functions; see d2i_X509(3).

NOTES

       All these functions use DER format and unencrypted keys. Applications wishing to encrypt
       or decrypt private keys should use other functions such as d2i_PKCS8PrivateKey() instead.

       If the *a is not NULL when calling d2i_PrivateKey() or d2i_AutoPrivateKey() (i.e. an
       existing structure is being reused) and the key format is PKCS#8 then *a will be freed and
       replaced on a successful call.

RETURN VALUES

       d2i_PrivateKey() and d2i_AutoPrivateKey() return a valid EVP_KEY structure or NULL if an
       error occurs. The error code can be obtained by calling ERR_get_error(3).

       i2d_PrivateKey() returns the number of bytes successfully encoded or a negative value if
       an error occurs. The error code can be obtained by calling ERR_get_error(3).

SEE ALSO

       crypto(7), d2i_PKCS8PrivateKey_bio(3)

COPYRIGHT

       Copyright 2017-2018 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>.