OpenSSL ASN1 Revision
=====================

This document describes some of the issues relating to the new ASN1 code.

Previous OpenSSL ASN1 problems
=============================

OK why did the OpenSSL ASN1 code need revising in the first place? Well
there are lots of reasons some of which are included below...

1. The code is difficult to read and write. For every single ASN1 structure
(e.g. SEQUENCE) four functions need to be written for new, free, encode and
decode operations. This is a very painful and error prone operation. Very few
people have ever written any OpenSSL ASN1 and those that have usually wish
they hadn't.

2. Partly because of 1. the code is bloated and takes up a disproportionate
amount of space. The SEQUENCE encoder is particularly bad: it essentially
contains two copies of the same operation, one to compute the SEQUENCE length
and the other to encode it.

3. The code is memory based: that is it expects to be able to read the whole
structure from memory. This is fine for small structures but if you have a
(say) 1Gb PKCS#7 signedData structure it isn't such a good idea...

4. The code for the ASN1 IMPLICIT tag is evil. It is handled by temporarily
changing the tag to the expected one, attempting to read it, then changing it
back again. This means that decode buffers have to be writable even though they
are ultimately unchanged. This gets in the way of constification.

5. The handling of EXPLICIT isn't much better. It adds a chunk of code into 
the decoder and encoder for every EXPLICIT tag.

6. APPLICATION and PRIVATE tags aren't even supported at all.

7. Even IMPLICIT isn't complete: there is no support for implicitly tagged
types that are not OPTIONAL.

8. Much of the code assumes that a tag will fit in a single octet. This is
only true if the tag is 30 or less (mercifully tags over 30 are rare).

9. The ASN1 CHOICE type has to be largely handled manually, there aren't any
macros that properly support it.

10. Encoders have no concept of OPTIONAL and have no error checking. If the
passed structure contains a NULL in a mandatory field it will not be encoded,
resulting in an invalid structure.

11. It is tricky to add ASN1 encoders and decoders to external applications.

Template model
==============

One of the major problems with revision is the sheer volume of the ASN1 code.
Attempts to change (for example) the IMPLICIT behaviour would result in a
modification of *every* single decode function. 

I decided to adopt a template based approach. I'm using the term 'template'
in a manner similar to SNACC templates: it has nothing to do with C++
templates.

A template is a description of an ASN1 module as several constant C structures.
It describes in a machine readable way exactly how the ASN1 structure should
behave. If this template contains enough detail then it is possible to write
versions of new, free, encode, decode (and possibly others operations) that
operate on templates.

Instead of having to write code to handle each operation only a single
template needs to be written. If new operations are needed (such as a 'print'
operation) only a single new template based function needs to be written 
which will then automatically handle all existing templates.

Plans for revision
==================

The revision will consist of the following steps. Other 
/* pkcs8.c */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project 1999-2004.
 */
/* ====================================================================
 * Copyright (c) 1999 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).
 *
 */
#include <stdio.h>
#include <string.h>
#include "apps.h"
#include <openssl/pem.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/pkcs12.h>

#define PROG pkcs8_main

int MAIN(int, char **);

int MAIN(int argc, char **argv)
	{
	ENGINE *e = NULL;
	char **args, *infile = NULL, *outfile = NULL;
	char *passargin = NULL, *passargout = NULL;
	BIO *in = NULL, *out = NULL;
	int topk8 = 0;
	int pbe_nid = -1;
	const EVP_CIPHER *cipher = NULL;
	int iter = PKCS12_DEFAULT_ITER;
	int informat, outformat;
	int p8_broken = PKCS8_OK;
	int nocrypt = 0;
	X509_SIG *p8 = NULL;
	PKCS8_PRIV_KEY_INFO *p8inf = NULL;
	EVP_PKEY *pkey=NULL;
	char pass[50], *passin = NULL, *passout = NULL, *p8pass = NULL;
	int badarg = 0;
	int ret = 1;
#ifndef OPENSSL_NO_ENGINE
	char *engine=NULL;
#endif

	if (bio_err == NULL) bio_err = BIO_new_fp (stderr, BIO_NOCLOSE);

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

	informat=FORMAT_PEM;
	outformat=FORMAT_PEM;

	ERR_load_crypto_strings();
	OpenSSL_add_all_algorithms();
	args = argv + 1;
	while (!badarg && *args && *args[0] == '-')
		{
		if (!strcmp(*args,"-v2"))
			{
			if (args[1])
				{
				args++;
				cipher=EVP_get_cipherbyname(*args);
				if (!cipher)
					{
					BIO_printf(bio_err,
						 "Unknown cipher %s\n", *args);
					badarg = 1;
					}
				}
			else
				badarg = 1;
			}
		else if (!strcmp(*args,"-v1"))
			{
			if (args[1])
				{
				args++;
				pbe_nid=OBJ_txt2nid(*args);
				if (pbe_nid == NID_undef)
					{
					BIO_printf(bio_err,
						 "Unknown PBE algorithm %s\n", *args);
					badarg = 1;
					}
				}
			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, "-topk8"))
			topk8 = 1;
		else if (!strcmp (*args, "-noiter"))
			iter = 1;
		else if (!strcmp (*args, "-nocrypt"))
			nocrypt = 1;
		else if (!strcmp (*args, "-nooct"))
			p8_broken = PKCS8_NO_OCTET;
		else if (!strcmp (*args, "-nsdb"))
			p8_broken = PKCS8_NS_DB;
		else if (!strcmp (*args, "-embed"))
			p8_broken = PKCS8_EMBEDDED_PARAM;
		else if (!strcmp(*args,"-passin"))
			{
			if (!args[1]) goto bad;
			passargin= *(++args);
			}
		else if (!strcmp(*args,"-passout"))
			{
			if (!args[1]) goto bad;
			passargout= *(++args);
			}
#ifndef OPENSSL_NO_ENGINE
		else if (strcmp(*args,"-engine") == 0)
			{
			if (!args[1]) goto bad;
			engine= *(++args);
			}
#endif
		else if (!strcmp (*args, "-in"))
			{
			if (args[1])
				{
				args++;
				infile = *args;
				}
			else badarg = 1;
			}
		else if (!strcmp (*args, "-out"))
			{
			if (args[1])
				{
				args++;
				outfile = *args;
				}
			else badarg = 1;
			}
		else badarg = 1;
		args++;
		}

	if (badarg)
		{
		bad:
		BIO_printf(bio_err, "Usage pkcs8 [options]\n");
		BIO_printf(bio_err, "where options are\n");
		BIO_printf(bio_err, "-in file        input file\n");
		BIO_printf(bio_err, "-inform X       input format (DER or PEM)\n");
		BIO_printf(bio_err, "-passin arg     input file pass phrase source\n");
		BIO_printf(bio_err, "-outform X      output format (DER or PEM)\n");
		BIO_printf(bio_err, "-out file       output file\n");
		BIO_printf(bio_err, "-passout arg    output file pass phrase source\n");
		BIO_printf(bio_err, "-topk8          output PKCS8 file\n");
		BIO_printf(bio_err, "-nooct          use (nonstandard) no octet format\n");
		BIO_printf(bio_err, "-embed          use (nonstandard) embedded DSA parameters format\n");
		BIO_printf(bio_err, "-nsdb           use (nonstandard) DSA Netscape DB format\n");
		BIO_printf(bio_err, "-noiter         use 1 as iteration count\n");
		BIO_printf(bio_err, "-nocrypt        use or expect unencrypted private key\n");
		BIO_printf(bio_err, "-v2 alg         use PKCS#5 v2.0 and cipher \"alg\"\n");
		BIO_printf(bio_err, "-v1 obj         use PKCS#5 v1.5 and cipher \"alg\"\n");
#ifndef OPENSSL_NO_ENGINE
		BIO_printf(bio_err," -engine e       use engine e, possibly a hardware device.\n");
#endif
		goto end;
		}

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

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

	if ((pbe_nid == -1) && !cipher)
		pbe_nid = NID_pbeWithMD5AndDES_CBC;

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