/*
    ecdsagen.c -- ECDSA key generation and export
    Copyright (C) 2011 Guus Sliepen <guus@tinc-vpn.org>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "system.h"

#include <openssl/pem.h>
#include <openssl/err.h>
#include <openssl/obj_mac.h>

#include "ecdsagen.h"
#include "utils.h"

// Generate ECDSA key

bool ecdsa_generate(ecdsa_t *ecdsa) {
	*ecdsa = EC_KEY_new_by_curve_name(NID_secp521r1);

	if(!EC_KEY_generate_key(*ecdsa)) {
		fprintf(stderr, "Generating EC key failed: %s", ERR_error_string(ERR_get_error(), NULL));
		return false;
	}

	EC_KEY_set_asn1_flag(*ecdsa, OPENSSL_EC_NAMED_CURVE);
	EC_KEY_set_conv_form(*ecdsa, POINT_CONVERSION_COMPRESSED);

	return true;
}

// Write PEM ECDSA keys

bool ecdsa_write_pem_public_key(ecdsa_t *ecdsa, FILE *fp) {
	BIO *out = BIO_new(BIO_s_file());
	BIO_set_fp(out,fp,BIO_NOCLOSE);
	PEM_write_bio_EC_PUBKEY(out, *ecdsa);
	BIO_free(out);
	return true;
}

bool ecdsa_write_pem_private_key(ecdsa_t *ecdsa, FILE *fp) {
	BIO *out = BIO_new(BIO_s_file());
	BIO_set_fp(out,fp,BIO_NOCLOSE);
	PEM_write_bio_ECPrivateKey(out, *ecdsa, NULL, NULL, 0, NULL, NULL);
	BIO_free(out);
	return true;
}

// Convert ECDSA public key to base64 format

char *ecdsa_get_base64_public_key(ecdsa_t *ecdsa) {
	unsigned char *pubkey = NULL;
	int len = i2o_ECPublicKey(*ecdsa, &pubkey);

	char *base64 = malloc(len * 4 / 3 + 5);
	b64encode((char *)pubkey, base64, len);

	free(pubkey);

	return base64;
}