gnutls_x509_privkey_export - export the private key
#include <gnutls/x509.h> int gnutls_x509_privkey_export(gnutls_x509_privkey_t key, gnutls_x509_crt_fmt_t format, void * output_data, size_t * output_data_size);
gnutls_x509_privkey_t key Holds the key gnutls_x509_crt_fmt_t format the format of output params. One of PEM or DER. void * output_data will contain a private key PEM or DER encoded size_t * output_data_size holds the size of output_data (and will be replaced by the actual size of parameters)
This function will export the private key to a PKCS1 structure for RSA keys, or an integer sequence for DSA keys. The DSA keys are in the same format with the parameters used by openssl. If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. If the structure is PEM encoded, it will have a header of "BEGIN RSA PRIVATE KEY"..