NAME

       d2i_PrivateKey_ex, d2i_PrivateKey, d2i_PublicKey, d2i_KeyParams, d2i_AutoPrivateKey_ex,
       d2i_AutoPrivateKey, i2d_PrivateKey, i2d_PublicKey, i2d_KeyParams, i2d_KeyParams_bio,
       d2i_PrivateKey_ex_bio, d2i_PrivateKey_bio, d2i_PrivateKey_ex_fp, d2i_PrivateKey_fp,
       d2i_KeyParams_bio, i2d_PrivateKey_bio, i2d_PrivateKey_fp - decode and encode functions for
       reading and saving EVP_PKEY structures

SYNOPSIS

        #include <openssl/evp.h>

        EVP_PKEY *d2i_PrivateKey_ex(int type, EVP_PKEY **a, const unsigned char **pp,
                                    long length, OSSL_LIB_CTX *libctx,
                                    const char *propq);
        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_KeyParams(int type, EVP_PKEY **a, const unsigned char **pp,
                                long length);
        EVP_PKEY *d2i_AutoPrivateKey_ex(EVP_PKEY **a, const unsigned char **pp,
                                        long length, OSSL_LIB_CTX *libctx,
                                        const char *propq);
        EVP_PKEY *d2i_AutoPrivateKey(EVP_PKEY **a, const unsigned char **pp,
                                     long length);

        int i2d_PrivateKey(const EVP_PKEY *a, unsigned char **pp);
        int i2d_PublicKey(const EVP_PKEY *a, unsigned char **pp);
        int i2d_KeyParams(const EVP_PKEY *a, unsigned char **pp);
        int i2d_KeyParams_bio(BIO *bp, const EVP_PKEY *pkey);
        EVP_PKEY *d2i_KeyParams_bio(int type, EVP_PKEY **a, BIO *in);

        #include <openssl/x509.h>

        EVP_PKEY *d2i_PrivateKey_ex_bio(BIO *bp, EVP_PKEY **a, OSSL_LIB_CTX *libctx,
                                        const char *propq);
        EVP_PKEY *d2i_PrivateKey_bio(BIO *bp, EVP_PKEY **a);
        EVP_PKEY *d2i_PrivateKey_ex_fp(FILE *fp, EVP_PKEY **a, OSSL_LIB_CTX *libctx,
                                       const char *propq);
        EVP_PKEY *d2i_PrivateKey_fp(FILE *fp, EVP_PKEY **a);

        int i2d_PrivateKey_bio(BIO *bp, const EVP_PKEY *pkey);
        int i2d_PrivateKey_fp(FILE *fp, const EVP_PKEY *pkey);

DESCRIPTION

       d2i_PrivateKey_ex() 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. Some private key decoding implementations may use
       cryptographic algorithms (for example to automatically derive the public key if it is not
       explicitly included in the encoding). In this case the supplied library context libctx and
       property query string propq are used.  If successful and the a parameter is not NULL the
       function assigns the returned EVP_PKEY structure pointer to *a, overwriting any previous
       value.

       d2i_PrivateKey() does the same as d2i_PrivateKey_ex() except that the default library
       context and property query string are used.  d2i_PublicKey() does the same for public
       keys.  d2i_KeyParams() does the same for key parameters.

       The d2i_PrivateKey_ex_bio() and d2i_PrivateKey_bio() functions are similar to
       d2i_PrivateKey_ex() and d2i_PrivateKey() respectively except that they decode the data
       read from the given BIO. The d2i_PrivateKey_ex_fp() and d2i_PrivateKey_fp() functions are
       the same except that they read the data from the given FILE.

       d2i_AutoPrivateKey_ex() and d2i_AutoPrivateKey() are similar to d2i_PrivateKey_ex() and
       d2i_PrivateKey() respectively except that they attempt to automatically detect the private
       key format.

       i2d_PrivateKey() encodes a. 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.  i2d_KeyParams() does the same for key parameters.  These functions are
       similar to the d2i_X509() functions; see d2i_X509(3).  i2d_PrivateKey_bio() and
       i2d_PrivateKey_fp() do the same thing except that they encode to a BIO or FILE
       respectively. Again, these work similarly to the functions described in d2i_X509(3).

NOTES

       All the functions that operate on data in memory update the data pointer *pp after a
       successful operation, just like the other d2i and i2d functions; see d2i_X509(3).

       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.

       To decode a key with type EVP_PKEY_EC, d2i_PublicKey() requires *a to be a non-NULL
       EVP_PKEY structure assigned an EC_KEY structure referencing the proper EC_GROUP.

RETURN VALUES

       The d2i_PrivateKey_ex(), d2i_PrivateKey(), d2i_AutoPrivateKey_ex(), d2i_AutoPrivateKey(),
       d2i_PrivateKey_ex_bio(), d2i_PrivateKey_bio(), d2i_PrivateKey_ex_fp(),
       d2i_PrivateKey_fp(), d2i_PublicKey(), d2i_KeyParams() and d2i_KeyParams_bio() functions
       return a valid EVP_PKEY structure or NULL if an error occurs. The error code can be
       obtained by calling ERR_get_error(3).

       i2d_PrivateKey(), i2d_PublicKey() and i2d_KeyParams() return 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).

       i2d_PrivateKey_bio(), i2d_PrivateKey_fp() and i2d_KeyParams_bio() return 1 if successfully
       encoded or zero if an error occurs.

SEE ALSO

       crypto(7), d2i_PKCS8PrivateKey_bio(3)

HISTORY

       d2i_PrivateKey_ex(), d2i_PrivateKey_ex_bio(), d2i_PrivateKey_ex_fp(), and
       d2i_AutoPrivateKey_ex() were added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.