smime.c   [plain text]

/* smime.c */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 */
/* ====================================================================
 * Copyright (c) 1999-2004 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

/* S/MIME utility function */

#include <stdio.h>
#include <string.h>
#include "apps.h"
#include <openssl/crypto.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#include <openssl/x509_vfy.h>
#include <openssl/x509v3.h>

#undef PROG
#define PROG smime_main
static int save_certs(char *signerfile, STACK_OF(X509) *signers);
static int smime_cb(int ok, X509_STORE_CTX *ctx);

#define SMIME_OP	0x10
#define SMIME_ENCRYPT	(1 | SMIME_OP)
#define SMIME_DECRYPT	2
#define SMIME_SIGN	(3 | SMIME_OP)
#define SMIME_VERIFY	4
#define SMIME_PK7OUT	5

int MAIN(int, char **);

int MAIN(int argc, char **argv)
	{
	ENGINE *e = NULL;
	int operation = 0;
	int ret = 0;
	char **args;
	const char *inmode = "r", *outmode = "w";
	char *infile = NULL, *outfile = NULL;
	char *signerfile = NULL, *recipfile = NULL;
	char *certfile = NULL, *keyfile = NULL, *contfile=NULL;
	const EVP_CIPHER *cipher = NULL;
	PKCS7 *p7 = NULL;
	X509_STORE *store = NULL;
	X509 *cert = NULL, *recip = NULL, *signer = NULL;
	EVP_PKEY *key = NULL;
	STACK_OF(X509) *encerts = NULL, *other = NULL;
	BIO *in = NULL, *out = NULL, *indata = NULL;
	int badarg = 0;
	int flags = PKCS7_DETACHED;
	char *to = NULL, *from = NULL, *subject = NULL;
	char *CAfile = NULL, *CApath = NULL;
	char *passargin = NULL, *passin = NULL;
	char *inrand = NULL;
	int need_rand = 0;
	int informat = FORMAT_SMIME, outformat = FORMAT_SMIME;
        int keyform = FORMAT_PEM;
#ifndef OPENSSL_NO_ENGINE
	char *engine=NULL;
#endif

	X509_VERIFY_PARAM *vpm = NULL;

	args = argv + 1;
	ret = 1;

	apps_startup();

	if (bio_err == NULL)
		{
		if ((bio_err = BIO_new(BIO_s_file())) != NULL)
			BIO_set_fp(bio_err, stderr, BIO_NOCLOSE|BIO_FP_TEXT);
		}

	if (!load_config(bio_err, NULL))
		goto end;

	while (!badarg && *args && *args[0] == '-')
		{
		if (!strcmp (*args, "-encrypt"))
			operation = SMIME_ENCRYPT;
		else if (!strcmp (*args, "-decrypt"))
			operation = SMIME_DECRYPT;
		else if (!strcmp (*args, "-sign"))
			operation = SMIME_SIGN;
		else if (!strcmp (*args, "-verify"))
			operation = SMIME_VERIFY;
		else if (!strcmp (*args, "-pk7out"))
			operation = SMIME_PK7OUT;
#ifndef OPENSSL_NO_DES
		else if (!strcmp (*args, "-des3")) 
				cipher = EVP_des_ede3_cbc();
		else if (!strcmp (*args, "-des")) 
				cipher = EVP_des_cbc();
#endif
#ifndef OPENSSL_NO_SEED
		else if (!strcmp (*args, "-seed")) 
				cipher = EVP_seed_cbc();
#endif
#ifndef OPENSSL_NO_RC2
		else if (!strcmp (*args, "-rc2-40")) 
				cipher = EVP_rc2_40_cbc();
		else if (!strcmp (*args, "-rc2-128")) 
				cipher = EVP_rc2_cbc();
		else if (!strcmp (*args, "-rc2-64")) 
				cipher = EVP_rc2_64_cbc();
#endif
#ifndef OPENSSL_NO_AES
		else if (!strcmp(*args,"-aes128"))
				cipher = EVP_aes_128_cbc();
		else if (!strcmp(*args,"-aes192"))
				cipher = EVP_aes_192_cbc();
		else if (!strcmp(*args,"-aes256"))
				cipher = EVP_aes_256_cbc();
#endif
#ifndef OPENSSL_NO_CAMELLIA
		else if (!strcmp(*args,"-camellia128"))
				cipher = EVP_camellia_128_cbc();
		else if (!strcmp(*args,"-camellia192"))
				cipher = EVP_camellia_192_cbc();
		else if (!strcmp(*args,"-camellia256"))
				cipher = EVP_camellia_256_cbc();
#endif
		else if (!strcmp (*args, "-text")) 
				flags |= PKCS7_TEXT;
		else if (!strcmp (*args, "-nointern")) 
				flags |= PKCS7_NOINTERN;
		else if (!strcmp (*args, "-noverify")) 
				flags |= PKCS7_NOVERIFY;
		else if (!strcmp (*args, "-nochain")) 
				flags |= PKCS7_NOCHAIN;
		else if (!strcmp (*args, "-nocerts")) 
				flags |= PKCS7_NOCERTS;
		else if (!strcmp (*args, "-noattr")) 
				flags |= PKCS7_NOATTR;
		else if (!strcmp (*args, "-nodetach")) 
				flags &= ~PKCS7_DETACHED;
		else if (!strcmp (*args, "-nosmimecap"))
				flags |= PKCS7_NOSMIMECAP;
		else if (!strcmp (*args, "-binary"))
				flags |= PKCS7_BINARY;
		else if (!strcmp (*args, "-nosigs"))
				flags |= PKCS7_NOSIGS;
		else if (!strcmp (*args, "-nooldmime"))
				flags |= PKCS7_NOOLDMIMETYPE;
		else if (!strcmp (*args, "-crlfeol"))
				flags |= PKCS7_CRLFEOL;
		else if (!strcmp(*args,"-rand"))
			{
			if (args[1])
				{
				args++;
				inrand = *args;
				}
			else
				badarg = 1;
			need_rand = 1;
			}
#ifndef OPENSSL_NO_ENGINE
		else if (!strcmp(*args,"-engine"))
			{
			if (args[1])
				{
				args++;
				engine = *args;
				}
			else badarg = 1;
			}
#endif
		else if (!strcmp(*args,"-passin"))
			{
			if (args[1])
				{
				args++;
				passargin = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-to"))
			{
			if (args[1])
				{
				args++;
				to = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-from"))
			{
			if (args[1])
				{
				args++;
				from = *args;
				}
			else badarg = 1;
			}
		else if (!strcmp (*args, "-subject"))
			{
			if (args[1])
				{
				args++;
				subject = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-signer"))
			{
			if (args[1])
				{
				args++;
				signerfile = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-recip"))
			{
			if (args[1])
				{
				args++;
				recipfile = *args;
				}
			else badarg = 1;
			}
		else if (!strcmp (*args, "-inkey"))
			{
			if (args[1])
				{
				args++;
				keyfile = *args;
				}
			else
				badarg = 1;
		}
		else if (!strcmp (*args, "-keyform"))
			{
			if (args[1])
				{
				args++;
				keyform = str2fmt(*args);
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-certfile"))
			{
			if (args[1])
				{
				args++;
				certfile = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-CAfile"))
			{
			if (args[1])
				{
				args++;
				CAfile = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-CApath"))
			{
			if (args[1])
				{
				args++;
				CApath = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-in"))
			{
			if (args[1])
				{
				args++;
				infile = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-inform"))
			{
			if (args[1])
				{
				args++;
				informat = str2fmt(*args);
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-outform"))
			{
			if (args[1])
				{
				args++;
				outformat = str2fmt(*args);
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-out"))
			{
			if (args[1])
				{
				args++;
				outfile = *args;
				}
			else
				badarg = 1;
			}
		else if (!strcmp (*args, "-content"))
			{
			if (args[1])
				{
				args++;
				contfile = *args;
				}
			else
				badarg = 1;
			}
		else if (args_verify(&args, NULL, &badarg, bio_err, &vpm))
			continue;
		else
			badarg = 1;
		args++;
		}


	if (operation == SMIME_SIGN)
		{
		if (!signerfile)
			{
			BIO_printf(bio_err, "No signer certificate specified\n");
			badarg = 1;
			}
		need_rand = 1;
		}
	else if (operation == SMIME_DECRYPT)
		{
		if (!recipfile && !keyfile)
			{
			BIO_printf(bio_err, "No recipient certificate or key specified\n");
			badarg = 1;
			}
		}
	else if (operation == SMIME_ENCRYPT)
		{
		if (!*args)
			{
			BIO_printf(bio_err, "No recipient(s) certificate(s) specified\n");
			badarg = 1;
			}
		need_rand = 1;
		}
	else if (!operation)
		badarg = 1;

	if (badarg)
		{
		BIO_printf (bio_err, "Usage smime [options] cert.pem ...\n");
		BIO_printf (bio_err, "where options are\n");
		BIO_printf (bio_err, "-encrypt       encrypt message\n");
		BIO_printf (bio_err, "-decrypt       decrypt encrypted message\n");
		BIO_printf (bio_err, "-sign          sign message\n");
		BIO_printf (bio_err, "-verify        verify signed message\n");
		BIO_printf (bio_err, "-pk7out        output PKCS#7 structure\n");
#ifndef OPENSSL_NO_DES
		BIO_printf (bio_err, "-des3          encrypt with triple DES\n");
		BIO_printf (bio_err, "-des           encrypt with DES\n");
#endif
#ifndef OPENSSL_NO_SEED
		BIO_printf (bio_err, "-seed          encrypt with SEED\n");
#endif
#ifndef OPENSSL_NO_RC2
		BIO_printf (bio_err, "-rc2-40        encrypt with RC2-40 (default)\n");
		BIO_printf (bio_err, "-rc2-64        encrypt with RC2-64\n");
		BIO_printf (bio_err, "-rc2-128       encrypt with RC2-128\n");
#endif
#ifndef OPENSSL_NO_AES
		BIO_printf (bio_err, "-aes128, -aes192, -aes256\n");
		BIO_printf (bio_err, "               encrypt PEM output with cbc aes\n");
#endif
#ifndef OPENSSL_NO_CAMELLIA
		BIO_printf (bio_err, "-camellia128, -camellia192, -camellia256\n");
		BIO_printf (bio_err, "               encrypt PEM output with cbc camellia\n");
#endif
		BIO_printf (bio_err, "-nointern      don't search certificates in message for signer\n");
		BIO_printf (bio_err, "-nosigs        don't verify message signature\n");
		BIO_printf (bio_err, "-noverify      don't verify signers certificate\n");
		BIO_printf (bio_err, "-nocerts       don't include signers certificate when signing\n");
		BIO_printf (bio_err, "-nodetach      use opaque signing\n");
		BIO_printf (bio_err, "-noattr        don't include any signed attributes\n");
		BIO_printf (bio_err, "-binary        don't translate message to text\n");
		BIO_printf (bio_err, "-certfile file other certificates file\n");
		BIO_printf (bio_err, "-signer file   signer certificate file\n");
		BIO_printf (bio_err, "-recip  file   recipient certificate file for decryption\n");
		BIO_printf (bio_err, "-in file       input file\n");
		BIO_printf (bio_err, "-inform arg    input format SMIME (default), PEM or DER\n");
		BIO_printf (bio_err, "-inkey file    input private key (if not signer or recipient)\n");
		BIO_printf (bio_err, "-keyform arg   input private key format (PEM or ENGINE)\n");
		BIO_printf (bio_err, "-out file      output file\n");
		BIO_printf (bio_err, "-outform arg   output format SMIME (default), PEM or DER\n");
		BIO_printf (bio_err, "-content file  supply or override content for detached signature\n");
		BIO_printf (bio_err, "-to addr       to address\n");
		BIO_printf (bio_err, "-from ad       from address\n");
		BIO_printf (bio_err, "-subject s     subject\n");
		BIO_printf (bio_err, "-text          include or delete text MIME headers\n");
		BIO_printf (bio_err, "-CApath dir    trusted certificates directory\n");
		BIO_printf (bio_err, "-CAfile file   trusted certificates file\n");
		BIO_printf (bio_err, "-crl_check     check revocation status of signer's certificate using CRLs\n");
		BIO_printf (bio_err, "-crl_check_all check revocation status of signer's certificate chain using CRLs\n");
#ifndef OPENSSL_NO_ENGINE
		BIO_printf (bio_err, "-engine e      use engine e, possibly a hardware device.\n");
#endif
		BIO_printf (bio_err, "-passin arg    input file pass phrase source\n");
		BIO_printf(bio_err,  "-rand file%cfile%c...\n", LIST_SEPARATOR_CHAR, LIST_SEPARATOR_CHAR);
		BIO_printf(bio_err,  "               load the file (or the files in the directory) into\n");
		BIO_printf(bio_err,  "               the random number generator\n");
		BIO_printf (bio_err, "cert.pem       recipient certificate(s) for encryption\n");
		goto end;
		}

#ifndef OPENSSL_NO_ENGINE
        e = setup_engine(bio_err, engine, 0);
#endif

	if (!app_passwd(bio_err, passargin, NULL, &passin, NULL))
		{
		BIO_printf(bio_err, "Error getting password\n");
		goto end;
		}

	if (need_rand)
		{
		app_RAND_load_file(NULL, bio_err, (inrand != NULL));
		if (inrand != NULL)
			BIO_printf(bio_err,"%ld semi-random bytes loaded\n",
				app_RAND_load_files(inrand));
		}

	ret = 2;

	if (operation != SMIME_SIGN)
		flags &= ~PKCS7_DETACHED;

	if (operation & SMIME_OP)
		{
		if (flags & PKCS7_BINARY)
			inmode = "rb";
		if (outformat == FORMAT_ASN1)
			outmode = "wb";
		}
	else
		{
		if (flags & PKCS7_BINARY)
			outmode = "wb";
		if (informat == FORMAT_ASN1)
			inmode = "rb";
		}

	if (operation == SMIME_ENCRYPT)
		{
		if (!cipher)
			{
#ifndef OPENSSL_NO_RC2			
			cipher = EVP_rc2_40_cbc();
#else
			BIO_printf(bio_err, "No cipher selected\n");
			goto end;
#endif
			}
		encerts = sk_X509_new_null();
		while (*args)
			{
			if (!(cert = load_cert(bio_err,*args,FORMAT_PEM,
				NULL, e, "recipient certificate file")))
				{
#if 0				/* An appropriate message is already printed */
				BIO_printf(bio_err, "Can't read recipient certificate file %s\n", *args);
#endif
				goto end;
				}
			sk_X509_push(encerts, cert);
			cert = NULL;
			args++;
			}
		}

	if (signerfile && (operation == SMIME_SIGN))
		{
		if (!(signer = load_cert(bio_err,signerfile,FORMAT_PEM, NULL,
			e, "signer certificate")))
			{
#if 0			/* An appropri message has already been printed */
			BIO_printf(bio_err, "Can't read signer certificate file %s\n", signerfile);
#endif
			goto end;
			}
		}

	if (certfile)
		{
		if (!(other = load_certs(bio_err,certfile,FORMAT_PEM, NULL,
			e, "certificate file")))
			{
#if 0			/* An appropriate message has already been printed */
			BIO_printf(bio_err, "Can't read certificate file %s\n", certfile);
#endif
			ERR_print_errors(bio_err);
			goto end;
			}
		}

	if (recipfile && (operation == SMIME_DECRYPT))
		{
		if (!(recip = load_cert(bio_err,recipfile,FORMAT_PEM,NULL,
			e, "recipient certificate file")))
			{
#if 0			/* An appropriate message has alrady been printed */
			BIO_printf(bio_err, "Can't read recipient certificate file %s\n", recipfile);
#endif
			ERR_print_errors(bio_err);
			goto end;
			}
		}

	if (operation == SMIME_DECRYPT)
		{
		if (!keyfile)
			keyfile = recipfile;
		}
	else if (operation == SMIME_SIGN)
		{
		if (!keyfile)
			keyfile = signerfile;
		}
	else keyfile = NULL;

	if (keyfile)
		{
		key = load_key(bio_err, keyfile, keyform, 0, passin, e,
			       "signing key file");
		if (!key)
			goto end;
		}

	if (infile)
		{
		if (!(in = BIO_new_file(infile, inmode)))
			{
			BIO_printf (bio_err,
				 "Can't open input file %s\n", infile);
			goto end;
			}
		}
	else
		in = BIO_new_fp(stdin, BIO_NOCLOSE);

	if (outfile)
		{
		if (!(out = BIO_new_file(outfile, outmode)))
			{
			BIO_printf (bio_err,
				 "Can't open output file %s\n", outfile);
			goto end;
			}
		}
	else
		{
		out = BIO_new_fp(stdout, BIO_NOCLOSE);
#ifdef OPENSSL_SYS_VMS
		{
		    BIO *tmpbio = BIO_new(BIO_f_linebuffer());
		    out = BIO_push(tmpbio, out);
		}
#endif
		}

	if (operation == SMIME_VERIFY)
		{
		if (!(store = setup_verify(bio_err, CAfile, CApath)))
			goto end;
		X509_STORE_set_verify_cb_func(store, smime_cb);
		if (vpm)
			X509_STORE_set1_param(store, vpm);
		}


	ret = 3;

	if (operation == SMIME_ENCRYPT)
		p7 = PKCS7_encrypt(encerts, in, cipher, flags);
	else if (operation == SMIME_SIGN)
		{
		/* If detached data and SMIME output enable partial
		 * signing.
		 */
		if ((flags & PKCS7_DETACHED) && (outformat == FORMAT_SMIME))
			flags |= PKCS7_STREAM;
		p7 = PKCS7_sign(signer, key, other, in, flags);
		}
	else
		{
		if (informat == FORMAT_SMIME) 
			p7 = SMIME_read_PKCS7(in, &indata);
		else if (informat == FORMAT_PEM) 
			p7 = PEM_read_bio_PKCS7(in, NULL, NULL, NULL);
		else if (informat == FORMAT_ASN1) 
			p7 = d2i_PKCS7_bio(in, NULL);
		else
			{
			BIO_printf(bio_err, "Bad input format for PKCS#7 file\n");
			goto end;
			}

		if (!p7)
			{
			BIO_printf(bio_err, "Error reading S/MIME message\n");
			goto end;
			}
		if (contfile)
			{
			BIO_free(indata);
			if (!(indata = BIO_new_file(contfile, "rb")))
				{
				BIO_printf(bio_err, "Can't read content file %s\n", contfile);
				goto end;
				}
			}
		}

	if (!p7)
		{
		BIO_printf(bio_err, "Error creating PKCS#7 structure\n");
		goto end;
		}

	ret = 4;
	if (operation == SMIME_DECRYPT)
		{
		if (!PKCS7_decrypt(p7, key, recip, out, flags))
			{
			BIO_printf(bio_err, "Error decrypting PKCS#7 structure\n");
			goto end;
			}
		}
	else if (operation == SMIME_VERIFY)
		{
		STACK_OF(X509) *signers;
		if (PKCS7_verify(p7, other, store, indata, out, flags))
			BIO_printf(bio_err, "Verification successful\n");
		else
			{
			BIO_printf(bio_err, "Verification failure\n");
			goto end;
			}
		signers = PKCS7_get0_signers(p7, other, flags);
		if (!save_certs(signerfile, signers))
			{
			BIO_printf(bio_err, "Error writing signers to %s\n",
								signerfile);
			ret = 5;
			goto end;
			}
		sk_X509_free(signers);
		}
	else if (operation == SMIME_PK7OUT)
		PEM_write_bio_PKCS7(out, p7);
	else
		{
		if (to)
			BIO_printf(out, "To: %s\n", to);
		if (from)
			BIO_printf(out, "From: %s\n", from);
		if (subject)
			BIO_printf(out, "Subject: %s\n", subject);
		if (outformat == FORMAT_SMIME) 
			SMIME_write_PKCS7(out, p7, in, flags);
		else if (outformat == FORMAT_PEM) 
			PEM_write_bio_PKCS7(out,p7);
		else if (outformat == FORMAT_ASN1) 
			i2d_PKCS7_bio(out,p7);
		else
			{
			BIO_printf(bio_err, "Bad output format for PKCS#7 file\n");
			goto end;
			}
		}
	ret = 0;
end:
	if (need_rand)
		app_RAND_write_file(NULL, bio_err);
	if (ret) ERR_print_errors(bio_err);
	sk_X509_pop_free(encerts, X509_free);
	sk_X509_pop_free(other, X509_free);
	if (vpm)
		X509_VERIFY_PARAM_free(vpm);
	X509_STORE_free(store);
	X509_free(cert);
	X509_free(recip);
	X509_free(signer);
	EVP_PKEY_free(key);
	PKCS7_free(p7);
	BIO_free(in);
	BIO_free(indata);
	BIO_free_all(out);
	if (passin) OPENSSL_free(passin);
	return (ret);
}

static int save_certs(char *signerfile, STACK_OF(X509) *signers)
	{
	int i;
	BIO *tmp;
	if (!signerfile)
		return 1;
	tmp = BIO_new_file(signerfile, "w");
	if (!tmp) return 0;
	for(i = 0; i < sk_X509_num(signers); i++)
		PEM_write_bio_X509(tmp, sk_X509_value(signers, i));
	BIO_free(tmp);
	return 1;
	}
	

/* Minimal callback just to output policy info (if any) */

static int smime_cb(int ok, X509_STORE_CTX *ctx)
	{
	int error;

	error = X509_STORE_CTX_get_error(ctx);

	if ((error != X509_V_ERR_NO_EXPLICIT_POLICY)
		&& ((error != X509_V_OK) || (ok != 2)))
		return ok;

	policies_print(NULL, ctx);

	return ok;

	}