/* S/MIME signing example: 2 signers */
#include <openssl/pem.h>
#include <openssl/cms.h>
#include <openssl/err.h>

int main(int argc, char **argv)
	{
	BIO *in = NULL, *out = NULL, *tbio = NULL;
	X509 *scert = NULL, *scert2 = NULL;
	EVP_PKEY *skey = NULL, *skey2 = NULL;
	CMS_ContentInfo *cms = NULL;
	int ret = 1;

	OpenSSL_add_all_algorithms();
	ERR_load_crypto_strings();

	tbio = BIO_new_file("signer.pem", "r");

	if (!tbio)
		goto err;

	scert = PEM_read_bio_X509(tbio, NULL, 0, NULL);

	BIO_reset(tbio);

	skey = PEM_read_bio_PrivateKey(tbio, NULL, 0, NULL);

	BIO_free(tbio);

	tbio = BIO_new_file("signer2.pem", "r");

	if (!tbio)
		goto err;

	scert2 = PEM_read_bio_X509(tbio, NULL, 0, NULL);

	BIO_reset(tbio);

	skey2 = PEM_read_bio_PrivateKey(tbio, NULL, 0, NULL);

	if (!scert2 || !skey2)
		goto err;

	in = BIO_new_file("sign.txt", "r");

	if (!in)
		goto err;

	cms = CMS_sign(NULL, NULL, NULL, in, CMS_STREAM|CMS_PARTIAL);

	if (!cms)
		goto err;

	/* Add each signer in turn */

	if (!CMS_add1_signer(cms, scert, skey, NULL, 0))
		goto err;

	if (!CMS_add1_signer(cms, scert2, skey2, NULL, 0))
		goto err;

	out = BIO_new_file("smout.txt", "w");
	if (!out)
		goto err;

	/* NB: content included and finalized by SMIME_write_CMS */

	if (!SMIME_write_CMS(out, cms, in, CMS_STREAM))
		goto err;

	ret = 0;

	err:

	if (ret)
		{
		fprintf(stderr, "Error Signing Data\n");
		ERR_print_errors_fp(stderr);
		}

	if (cms)
		CMS_ContentInfo_free(cms);

	if (scert)
		X509_free(scert);
	if (skey)
		EVP_PKEY_free(skey);

	if (scert2)
		X509_free(scert2);
	if (skey)
		EVP_PKEY_free(skey2);

	if (in)
		BIO_free(in);
	if (out)
		BIO_free(out);
	if (tbio)
		BIO_free(tbio);

	return ret;

	}