EVP_PKEY *b2i_PVK_bio(BIO *in, pem_password_cb *cb, void *u);
int i2b_PVK_bio(BIO *out, EVP_PKEY *pk, int enclevel,
pem_password_cb *cb, void *u);
EVP_PKEY *b2i_PVK_bio(BIO *in, pem_password_cb *cb, void *u);
int i2b_PVK_bio(BIO *out, EVP_PKEY *pk, int enclevel,
pem_password_cb *cb, void *u);