d2i_Private_key, d2i_AutoPrivateKey, i2d_PrivateKey - decode and encode functions for reading and saving EVP_PKEY structures.
#include <openssl/evp.h>
EVP_PKEY *d2i_PrivateKey(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);
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_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.
These functions are similar to the d2i_X509() functions, and you should refer to
that page for a detailed description (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_PKC8PrivateKey() 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.
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).
crypto(3), d2i_PKCS8PrivateKey(3)