#include <openssl/evp.h> EVP_PKEY *d2i_PKCS8PrivateKey_bio(BIO *bp, EVP_PKEY **x, pem_password_cb *cb, void *u); EVP_PKEY *d2i_PKCS8PrivateKey_fp(FILE *fp, EVP_PKEY **x, pem_password_cb *cb, void *u); int i2d_PKCS8PrivateKey_bio(BIO *bp, EVP_PKEY *x, const EVP_CIPHER *enc, char *kstr, int klen, pem_password_cb *cb, void *u); int i2d_PKCS8PrivateKey_fp(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc, char *kstr, int klen, pem_password_cb *cb, void *u); int i2d_PKCS8PrivateKey_nid_bio(BIO *bp, EVP_PKEY *x, int nid, char *kstr, int klen, pem_password_cb *cb, void *u); int i2d_PKCS8PrivateKey_nid_fp(FILE *fp, EVP_PKEY *x, int nid, char *kstr, int klen, pem_password_cb *cb, void *u);
Other than the use of DER as opposed to PEM these functions are identical to the corresponding PEM function as described in the pem(3) manual page.
These functions are currently the only way to store encrypted private keys using DER format.
Currently all the functions use BIOs or FILE pointers, there are no functions which work directly on memory: this can be readily worked around by converting the buffers to memory BIOs, see BIO_s_mem(3) for details.