/*
 * Copyright (c) 2005-2008 Nominet UK (www.nic.uk)
 * All rights reserved.
 * Contributors: Ben Laurie, Rachel Willmer. The Contributors have asserted
 * their moral rights under the UK Copyright Design and Patents Act 1988 to
 * be recorded as the authors of this copyright work.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. 
 * 
 * You may obtain a copy of the License at 
 *     http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * 
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/** \file
 */

#include <openssl/cast.h>

#include <openpgpsdk/armour.h>
#include <openpgpsdk/create.h>
#include <openpgpsdk/keyring.h>
#include <openpgpsdk/memory.h>
#include <openpgpsdk/random.h>
#include <openpgpsdk/readerwriter.h>
#include "keyring_local.h"
#include <openpgpsdk/packet.h>
#include <openpgpsdk/util.h>
#include <openpgpsdk/std_print.h>
#include <string.h>
#include <assert.h>
#include <fcntl.h>
#ifndef WIN32
#include <unistd.h>
#endif
#include <openpgpsdk/opsdir.h>

#include <openpgpsdk/writer.h>
#include <openpgpsdk/final.h>

static int debug=0;

/** 
 * \ingroup Core_Create
 * \param length
 * \param type
 * \param info
 * \return ops_true if OK, otherwise ops_false
 */

ops_boolean_t ops_write_ss_header(unsigned length,ops_content_tag_t type,
				  ops_create_info_t *info)
    {
    return ops_write_length(length,info)
	&& ops_write_scalar(type-OPS_PTAG_SIGNATURE_SUBPACKET_BASE,1,info);
    }

/* XXX: the general idea of _fast_ is that it doesn't copy stuff
 * the safe (i.e. non _fast_) version will, and so will also need to
 * be freed. */

/**
 * \ingroup Core_Create
 *
 * ops_fast_create_user_id() sets id->user_id to the given user_id.
 * This is fast because it is only copying a char*. However, if user_id
 * is changed or freed in the future, this could have injurious results.
 * \param id
 * \param user_id
 */

void ops_fast_create_user_id(ops_user_id_t *id,unsigned char *user_id)
    {
    id->user_id=user_id;
    }

/**
 * \ingroup Core_WritePackets
 * \brief Writes a User Id packet
 * \param id
 * \param info
 * \return ops_true if OK, otherwise ops_false
 */
ops_boolean_t ops_write_struct_user_id(ops_user_id_t *id,
				       ops_create_info_t *info)
    {
    return ops_write_ptag(OPS_PTAG_CT_USER_ID,info)
	&& ops_write_length(strlen((char *)id->user_id),info)
	&& ops_write(id->user_id,strlen((char *)id->user_id),info);
    }

/**
 * \ingroup Core_WritePackets
 * \brief Write a User Id packet.
 * \param user_id
 * \param info
 *
 * \return return value from ops_write_struct_user_id()
 */
ops_boolean_t ops_write_user_id(const unsigned char *user_id,
				ops_create_info_t *info)
    {
    ops_user_id_t id;

    id.user_id=(unsigned char *)user_id;
    return ops_write_struct_user_id(&id,info);
    }

/**
\ingroup Core_MPI
*/
static unsigned mpi_length(const BIGNUM *bn)
{
	return 2+(BN_num_bits(bn)+7)/8;
}

static unsigned public_key_length(const ops_public_key_t *key)
{
	switch(key->algorithm)
	{
		case OPS_PKA_RSA: return mpi_length(key->key.rsa.n)
										+mpi_length(key->key.rsa.e);

		case OPS_PKA_DSA: return mpi_length(key->key.dsa.p)
										+mpi_length(key->key.dsa.q)
										+mpi_length(key->key.dsa.g)
										+mpi_length(key->key.dsa.y);
		case OPS_PKA_ELGAMAL:
								return mpi_length(key->key.elgamal.p)
										+mpi_length(key->key.elgamal.g)
										+mpi_length(key->key.elgamal.y) ;

		default:
			fprintf(stderr,"Bad algorithm type in key: %d\n",key->algorithm) ;
			assert(!"unknown key algorithm");
	}
	/* not reached */
	return 0;
}

static unsigned secret_key_length(const ops_secret_key_t *key)
{
	int l;

	switch(key->public_key.algorithm)
	{
		case OPS_PKA_RSA: l=mpi_length(key->key.rsa.d)
								 +mpi_length(key->key.rsa.p)
								 +mpi_length(key->key.rsa.q)
								 +mpi_length(key->key.rsa.u);
			break ;

		case OPS_PKA_DSA: l=mpi_length(key->key.dsa.x);
			break;

		default:
			assert(!"unknown key algorithm");
	}

	return l+public_key_length(&key->public_key);
}

/** 
 * \ingroup Core_Create
 * \param key
 * \param time
 * \param n
 * \param e
*/
void ops_fast_create_rsa_public_key(ops_public_key_t *key,time_t time,
				    BIGNUM *n,BIGNUM *e)
    {
    key->version=4;
    key->creation_time=time;
    key->algorithm=OPS_PKA_RSA;
    key->key.rsa.n=n;
    key->key.rsa.e=e;
    }

/* Note that we support v3 keys here because they're needed for
 * for verification - the writer doesn't allow them, though */
static ops_boolean_t write_public_key_body(const ops_public_key_t *key,
					   ops_create_info_t *info)
{
	if(!(ops_write_scalar(key->version,1,info) && ops_write_scalar(key->creation_time,4,info)))
		return ops_false;

	if(key->version != 4 && !ops_write_scalar(key->days_valid,2,info))
		return ops_false;

	if(!ops_write_scalar(key->algorithm,1,info))
		return ops_false;

	switch(key->algorithm)
	{
		case OPS_PKA_DSA:
			return ops_write_mpi(key->key.dsa.p,info)
				&& ops_write_mpi(key->key.dsa.q,info)
				&& ops_write_mpi(key->key.dsa.g,info)
				&& ops_write_mpi(key->key.dsa.y,info);

		case OPS_PKA_RSA:
		case OPS_PKA_RSA_ENCRYPT_ONLY:
		case OPS_PKA_RSA_SIGN_ONLY:
			return ops_write_mpi(key->key.rsa.n,info)
				&& ops_write_mpi(key->key.rsa.e,info);

		case OPS_PKA_ELGAMAL:
			return ops_write_mpi(key->key.elgamal.p,info)
				&& ops_write_mpi(key->key.elgamal.g,info)
				&& ops_write_mpi(key->key.elgamal.y,info);

		default:
			fprintf(stderr, "Unknown algorithm %d\n", key->algorithm);
			assert(0);
			break;
	}

	/* not reached */
	return ops_false;
}

/* Note that we support v3 keys here because they're needed for
 * for verification - the writer doesn't allow them, though */
static ops_boolean_t write_secret_key_body(const ops_secret_key_t *key,
                                           const unsigned char* passphrase,
                                           const size_t pplen,
					   ops_create_info_t *info)
{
	/* RFC4880 Section 5.5.3 Secret-Key Packet Formats */

	ops_crypt_t crypt;
	ops_hash_t hash;
	unsigned char hashed[OPS_SHA1_HASH_SIZE];
	unsigned char session_key[CAST_KEY_LENGTH];
	unsigned int done=0;
	unsigned int i=0;

	if(!write_public_key_body(&key->public_key,info))
		return ops_false;

	assert(key->s2k_usage==OPS_S2KU_ENCRYPTED_AND_HASHED); /* = 254 */
	if(!ops_write_scalar(key->s2k_usage,1,info))
		return ops_false;

	assert(key->algorithm==OPS_SA_CAST5);
	if (!ops_write_scalar(key->algorithm,1,info))
		return ops_false;

	assert(key->s2k_specifier==OPS_S2KS_SIMPLE
			|| key->s2k_specifier==OPS_S2KS_SALTED); // = 1 \todo could also be iterated-and-salted
	if (!ops_write_scalar(key->s2k_specifier,1,info))
		return ops_false;

	assert(key->hash_algorithm==OPS_HASH_SHA1);
	if (!ops_write_scalar(key->hash_algorithm,1,info))
		return ops_false;

	switch(key->s2k_specifier)
	{
		case OPS_S2KS_SIMPLE:
			// nothing more to do
			break;

		case OPS_S2KS_SALTED:
			// 8-octet salt value
			ops_random((void *)&key->salt[0],OPS_SALT_SIZE);
			if (!ops_write(key->salt, OPS_SALT_SIZE, info))
				return ops_false;
			break;

			/* \todo
				case OPS_S2KS_ITERATED_AND_SALTED:
			// 8-octet salt value
			// 1-octet count
			break;
			 */

		default:
			fprintf(stderr,"invalid/unsupported s2k specifier %d\n",
					key->s2k_specifier);
			assert(0);
	}

	if (!ops_write(&key->iv[0],ops_block_size(key->algorithm),info))
		return ops_false;

	/* create the session key for encrypting the algorithm-specific fields */

	switch(key->s2k_specifier)
	{
		case OPS_S2KS_SIMPLE:
		case OPS_S2KS_SALTED:
			// RFC4880: section 3.7.1.1 and 3.7.1.2

			done=0;
			for (i=0; done<CAST_KEY_LENGTH; i++ )
			{
				unsigned int j=0;
				unsigned char zero=0;
				int needed=CAST_KEY_LENGTH-done;
				int use= needed < SHA_DIGEST_LENGTH ? needed : SHA_DIGEST_LENGTH;

				ops_hash_any(&hash, key->hash_algorithm);
				hash.init(&hash);

				// preload if iterating 
				for (j=0; j<i; j++)
				{
					/* 
						Coverity shows a DEADCODE error on this line.
						This is expected since the hardcoded use of
						SHA1 and CAST5 means that it will not used.
						This will change however when other algorithms are
						supported.
					 */
					hash.add(&hash, &zero, 1);
				}

				if (key->s2k_specifier==OPS_S2KS_SALTED)
				{ hash.add(&hash, key->salt, OPS_SALT_SIZE); }

				hash.add(&hash, passphrase, pplen);
				hash.finish(&hash, hashed);

				// if more in hash than is needed by session key, use the
				// leftmost octets
				memcpy(session_key+(i*SHA_DIGEST_LENGTH), hashed, use);
				done += use;
				assert(done<=CAST_KEY_LENGTH);
			}

			break;

			/* \todo
				case OPS_S2KS_ITERATED_AND_SALTED:
			// 8-octet salt value
			// 1-octet count
			break;
			 */

		default:
			fprintf(stderr,"invalid/unsupported s2k specifier %d\n",
					key->s2k_specifier);
			assert(0);
	}

	/* use this session key to encrypt */

	ops_crypt_any(&crypt,key->algorithm);
	crypt.set_iv(&crypt, key->iv);
	crypt.set_key(&crypt, session_key);
	ops_encrypt_init(&crypt);

	if (debug)
	{
		unsigned int i=0;
		fprintf(stderr,"\nWRITING:\niv=");
		for (i=0; i<ops_block_size(key->algorithm); i++)
		{
			fprintf(stderr, "%02x ", key->iv[i]);
		}
		fprintf(stderr,"\n");

		fprintf(stderr,"key=");
		for (i=0; i<CAST_KEY_LENGTH; i++)
		{
			fprintf(stderr, "%02x ", session_key[i]);
		}
		fprintf(stderr,"\n");

		//ops_print_secret_key(OPS_PTAG_CT_SECRET_KEY,key);

		fprintf(stderr,"turning encryption on...\n");
	}

	ops_writer_push_encrypt_crypt(info, &crypt);

	switch(key->public_key.algorithm)
	{
		case OPS_PKA_DSA:
			return ops_write_mpi(key->key.dsa.x,info);

		case OPS_PKA_RSA:
		case OPS_PKA_RSA_ENCRYPT_ONLY:
		case OPS_PKA_RSA_SIGN_ONLY:

			if(!ops_write_mpi(key->key.rsa.d,info)
					|| !ops_write_mpi(key->key.rsa.p,info)
					|| !ops_write_mpi(key->key.rsa.q,info)
					|| !ops_write_mpi(key->key.rsa.u,info))
			{
				if (debug)
				{ fprintf(stderr,"4 x mpi not written - problem\n"); }
				return ops_false;
			}

			break;

			//    case OPS_PKA_ELGAMAL:
			//	return ops_write_mpi(key->key.elgamal.x,info);

		default:
			assert(0);
			break;
	}

	if(!ops_write(key->checkhash, OPS_CHECKHASH_SIZE, info))
		return ops_false;

	ops_writer_pop(info);

	free(crypt.encrypt_key) ;
	free(crypt.decrypt_key) ;

	return ops_true;
}


/**
   \ingroup HighLevel_KeyWrite

   \brief Writes a transferable PGP public key to the given output stream.

   \param keydata Key to be written
   \param armoured Flag is set for armoured output
   \param info Output stream

   Example code:
   \code
   void example(const ops_keydata_t* keydata)
   {
   ops_boolean_t armoured=ops_true;
   char* filename="/tmp/testkey.asc";

   int fd;
   ops_boolean_t overwrite=ops_true;
   ops_create_info_t* cinfo;

   fd=ops_setup_file_write(&cinfo, filename, overwrite);
   ops_write_transferable_public_key(keydata,armoured,cinfo);
   ops_teardown_file_write(cinfo,fd);
   }
   \endcode
*/

ops_boolean_t ops_write_transferable_public_key(const ops_keydata_t *keydata,
						ops_boolean_t armoured,
						ops_create_info_t *info)
{
	ops_boolean_t rtn;
	unsigned int i=0,j=0;

	if (armoured)
	{ ops_writer_push_armoured(info, OPS_PGP_PUBLIC_KEY_BLOCK); }

	// public key
	rtn=ops_write_struct_public_key(&keydata->key.skey.public_key,info);
	if (rtn!=ops_true)
		return rtn;

	// TODO: revocation signatures go here

	// user ids and corresponding signatures
	for (i=0; i<keydata->nuids; i++)
	{
		ops_user_id_t* uid=&keydata->uids[i];

		rtn=ops_write_struct_user_id(uid, info);

		if (!rtn)
			return rtn;

		// find signature for this packet if it exists
		for (j=0; j<keydata->nsigs; j++)
		{
			sigpacket_t* sig=&keydata->sigs[i];
			if (!strcmp((char *)sig->userid->user_id, (char *)uid->user_id))
			{
				rtn=ops_write(sig->packet->raw, sig->packet->length, info);
				if (!rtn)
					return !rtn;
			}
		}
	}

	// TODO: user attributes and corresponding signatures

	// subkey packets and corresponding signatures and optional revocation

	if (armoured)
	{ 
		writer_info_finalise(&info->errors, &info->winfo);
		ops_writer_pop(info); 
	}

	return rtn;
}

ops_boolean_t ops_write_transferable_public_key_from_packet_data(const ops_keydata_t *keydata,
						ops_boolean_t armoured,
						ops_create_info_t *info)
{
	ops_boolean_t rtn = ops_true;
	unsigned int i=0;

	if (armoured)
	{ ops_writer_push_armoured(info, OPS_PGP_PUBLIC_KEY_BLOCK); }

	for(i=0;i<keydata->npackets;++i)
		if(!ops_write(keydata->packets[i].raw, keydata->packets[i].length, info))
			return ops_false ;

	if (armoured)
	{ 
		writer_info_finalise(&info->errors, &info->winfo);
		ops_writer_pop(info); 
	}

	return rtn;
}

ops_boolean_t ops_write_transferable_secret_key_from_packet_data(const ops_keydata_t *keydata,
						ops_boolean_t armoured,
						ops_create_info_t *info)
{
	ops_boolean_t rtn = ops_true;
	unsigned int i=0;

	if(keydata->type != OPS_PTAG_CT_ENCRYPTED_SECRET_KEY)
	{
		fprintf(stderr,"Can only output encrypted secret keys from raw packet data. Current type is %d\n",keydata->type) ;
		return ops_false ;
	}
	if (armoured)
	{ ops_writer_push_armoured(info, OPS_PGP_PRIVATE_KEY_BLOCK); }

	for(i=0;i<keydata->npackets;++i)
		if(!ops_write(keydata->packets[i].raw, keydata->packets[i].length, info))
			return ops_false ;

	if (armoured)
	{ 
		writer_info_finalise(&info->errors, &info->winfo);
		ops_writer_pop(info); 
	}

	return rtn;
}
/**
   \ingroup HighLevel_KeyWrite

   \brief Writes a transferable PGP secret key to the given output stream.

   \param keydata Key to be written
   \param passphrase
   \param pplen
   \param armoured Flag is set for armoured output
   \param info Output stream

   Example code:
   \code
   void example(const ops_keydata_t* keydata)
   {
   const unsigned char* passphrase=NULL;
   const size_t passphraselen=0;
   ops_boolean_t armoured=ops_true;

   int fd;
   char* filename="/tmp/testkey.asc";
   ops_boolean_t overwrite=ops_true;
   ops_create_info_t* cinfo;

   fd=ops_setup_file_write(&cinfo, filename, overwrite);
   ops_write_transferable_secret_key(keydata,passphrase,pplen,armoured,cinfo);
   ops_teardown_file_write(cinfo,fd);
   }
   \endcode
*/

ops_boolean_t ops_write_transferable_secret_key(const ops_keydata_t *keydata, const unsigned char* passphrase, const size_t pplen, ops_boolean_t armoured, ops_create_info_t *info)
    {
    ops_boolean_t rtn;
    unsigned int i=0,j=0;

    if (armoured)
        { ops_writer_push_armoured(info,OPS_PGP_PRIVATE_KEY_BLOCK); }

    // public key
    rtn=ops_write_struct_secret_key(&keydata->key.skey,passphrase,pplen,info);
    if (rtn!=ops_true)
        return rtn;

    // TODO: revocation signatures go here

    // user ids and corresponding signatures
    for (i=0; i<keydata->nuids; i++)
        {
        ops_user_id_t* uid=&keydata->uids[i];

        rtn=ops_write_struct_user_id(uid, info);

        if (!rtn)
            return rtn;

        // find signature for this packet if it exists
        for (j=0; j<keydata->nsigs; j++)
            {
            sigpacket_t* sig=&keydata->sigs[i];
            if (!strcmp((char *)sig->userid->user_id, (char *)uid->user_id))
                {
                rtn=ops_write(sig->packet->raw, sig->packet->length, info);
                if (!rtn)
                    return !rtn;
                }
            }
        }

        // TODO: user attributes and corresponding signatures

        // subkey packets and corresponding signatures and optional revocation

    if (armoured)
        { 
        writer_info_finalise(&info->errors, &info->winfo);
        ops_writer_pop(info); 
        }

    return rtn;
    }

/**
 * \ingroup Core_WritePackets
 * \brief Writes a Public Key packet
 * \param key
 * \param info
 * \return ops_true if OK, otherwise ops_false
 */
ops_boolean_t ops_write_struct_public_key(const ops_public_key_t *key,
					  ops_create_info_t *info)
{
	assert(key->version == 4);

	if(key->algorithm != OPS_PKA_RSA)
	{
		fprintf(stderr,"\nUnhandled key algorithm %d\n",key->algorithm);
		return ops_false ;
	}

	return ops_write_ptag(OPS_PTAG_CT_PUBLIC_KEY,info)
 		 && ops_write_length(1+4+1+public_key_length(key),info)
		 && write_public_key_body(key,info);
}

/**
 * \ingroup Core_WritePackets
 * \brief Writes one RSA public key packet.
 * \param time Creation time
 * \param n RSA public modulus
 * \param e RSA public encryption exponent
 * \param info Writer settings
 *
 * \return ops_true if OK, otherwise ops_false
 */

ops_boolean_t ops_write_rsa_public_key(time_t time,const BIGNUM *n,
				       const BIGNUM *e,
				       ops_create_info_t *info)
    {
    ops_public_key_t key;

    ops_fast_create_rsa_public_key(&key,time,DECONST(BIGNUM,n),
				   DECONST(BIGNUM,e));
    return ops_write_struct_public_key(&key,info);
    }

/**
 * \ingroup Core_Create
 * \param out
 * \param key
 * \param make_packet
 */

void ops_build_public_key(ops_memory_t *out,const ops_public_key_t *key,
			  ops_boolean_t make_packet)
    {
    ops_create_info_t *info;

    info=ops_create_info_new();

    ops_memory_init(out,128);
    ops_writer_set_memory(info,out);

    write_public_key_body(key,info);

    if(make_packet)
	ops_memory_make_packet(out,OPS_PTAG_CT_PUBLIC_KEY);

    ops_create_info_delete(info);
    }

/**
 * \ingroup Core_Create
 *
 * Create an RSA secret key structure. If a parameter is marked as
 * [OPTIONAL], then it can be omitted and will be calculated from
 * other parameters - or, in the case of e, will default to 0x10001.
 *
 * Parameters are _not_ copied, so will be freed if the structure is
 * freed.
 *
 * \param key The key structure to be initialised.
 * \param time
 * \param d The RSA parameter d (=e^-1 mod (p-1)(q-1)) [OPTIONAL]
 * \param p The RSA parameter p
 * \param q The RSA parameter q (q > p)
 * \param u The RSA parameter u (=p^-1 mod q) [OPTIONAL]
 * \param n The RSA public parameter n (=p*q) [OPTIONAL]
 * \param e The RSA public parameter e */

void ops_fast_create_rsa_secret_key(ops_secret_key_t *key,time_t time,
				    BIGNUM *d,BIGNUM *p,BIGNUM *q,BIGNUM *u,
				    BIGNUM *n,BIGNUM *e)
    {
    ops_fast_create_rsa_public_key(&key->public_key,time,n,e);

    // XXX: calculate optionals
    key->key.rsa.d=d;
    key->key.rsa.p=p;
    key->key.rsa.q=q;
    key->key.rsa.u=u;

    key->s2k_usage=OPS_S2KU_NONE;

    // XXX: sanity check and add errors...
    }

/**
 * \ingroup Core_WritePackets
 * \brief Writes a Secret Key packet.
 * \param key The secret key
 * \param passphrase The passphrase
 * \param pplen Length of passphrase
 * \param info
 * \return ops_true if OK; else ops_false
 */
ops_boolean_t ops_write_struct_secret_key(const ops_secret_key_t *key,
                                          const unsigned char* passphrase,
                                          const size_t pplen,
					  ops_create_info_t *info)
    {
    int length=0;

    assert(key->public_key.version == 4);

    // Ref: RFC4880 Section 5.5.3

    // public_key, excluding MPIs
    length += 1+4+1+1;

    // s2k usage
    length+=1;

    switch (key->s2k_usage)
        {
    case OPS_S2KU_NONE:
        // nothing to add
        break;

    case OPS_S2KU_ENCRYPTED_AND_HASHED: // 254
    case OPS_S2KU_ENCRYPTED: // 255

        // Ref: RFC4880 Section 3.7
        length+=1; // s2k_specifier

        switch(key->s2k_specifier)
            {
        case OPS_S2KS_SIMPLE:
            length+=1; // hash algorithm
            break;

        case OPS_S2KS_SALTED:
            length+=1+8; // hash algorithm + salt
            break;

        case OPS_S2KS_ITERATED_AND_SALTED:
            length+=1+8+1; // hash algorithm, salt + count
            break;

        default:
            assert(0);
            }
        break;

    default:
        assert(0);
        }

    // IV
    if (key->s2k_usage != 0)
        {
        length += ops_block_size(key->algorithm);
        }

    // checksum or hash
    switch (key->s2k_usage)
        {
    case 0:
    case 255:
        length += 2;
        break;

    case 254:
        length += 20;
        break;

    default:
        assert(0);
        }

    // secret key and public key MPIs
    length += secret_key_length(key);

    return ops_write_ptag(OPS_PTAG_CT_SECRET_KEY,info)
        //	&& ops_write_length(1+4+1+1+secret_key_length(key)+2,info)
        && ops_write_length(length,info)
        && write_secret_key_body(key,passphrase,pplen,info);
    }

/**
 * \ingroup InternalAPI
 *
 * \brief Initialise a temporary info structure that can be used for
 * writing to a writer's parent.
 *
 * This is used by writers who want to use the various ops_write functions
 * in order to write to the parent writer.
 * Example code:
 * \code
 *   ops_boolean_t writer(const unsigned char *src,
 *                        unsigned length,
 *                        ops_error_t **errors,
 *                        ops_writer_info_t *winfo) {
 *     ops_create_info_t parent;
 *     ops_prepare_parent_info(&parent, winfo, errors);
 *
 *     // The ptag will be written to the parent writer
 *     ops_write_ptag(OPS_PTAG_CT_LITERAL_DATA, &parent);
 *
 *     // The data is written to the parent. This line is
       // equivalent to:
 *     //   ops_stacked_write(src, length, errors, winfo);
 *     ops_boolean_t result = ops_write(src, length, info);
 *     ops_move_errors(&parent_info, errors);
 *     return result;
 * \endcode
 *
 * \note It is the responsiblity of the caller to assign space for the parent
 * structure, typically on the stack. IOn order to report errors correctly,
 * use ops_move_errors() after the write operation.
 *
 * \see ops_move_errors
 */
void ops_prepare_parent_info(ops_create_info_t *parent_info,
                             ops_writer_info_t *winfo)
    {
    parent_info->winfo = *winfo->next;
    parent_info->errors = NULL;
    }

/**
 * \ingroup Core_Create
 *
 * \brief Create a new ops_create_info_t structure.
 *
 * \return the new structure.
 * \note It is the responsiblity of the caller to call ops_create_info_delete().
 * \sa ops_create_info_delete()
 */
ops_create_info_t *ops_create_info_new(void)
    { return ops_mallocz(sizeof(ops_create_info_t)); }

/**
 * \ingroup Core_Create
 * \brief Delete an ops_create_info_t strucut and associated resources.
 *
 * Delete an ops_create_info_t structure. If a writer is active, then
 * that is also deleted.
 *
 * \param info the structure to be deleted.
 */
void ops_create_info_delete(ops_create_info_t *info)
    {
    writer_info_delete(&info->winfo);
    free(info);
    }

/** 
 \ingroup Core_Create
 \brief Calculate the checksum for a session key
 \param session_key Session Key to use
 \param cs Checksum to be written
 \return ops_true if OK; else ops_false
*/
ops_boolean_t ops_calc_session_key_checksum(ops_pk_session_key_t *session_key,
					    unsigned char cs[2])
    {
    unsigned int i=0;
    unsigned long checksum=0;

    if (!ops_is_sa_supported(session_key->symmetric_algorithm))
        return ops_false;

    for (i=0; i<ops_key_size(session_key->symmetric_algorithm); i++)
        {
        checksum+=session_key->key[i];
        }
    checksum = checksum % 65536;

    cs[0]=checksum >> 8;
    cs[1]=checksum & 0xFF;

    return ops_true;
    //    fprintf(stderr,"\nm buf checksum: ");
    //    fprintf(stderr," %2x",cs[0]);
    //    fprintf(stderr," %2x\n",cs[1]);
    }    

static ops_boolean_t create_unencoded_m_buf(ops_pk_session_key_t *session_key,
					    unsigned char *m_buf)
    {
    int i=0;
    //    unsigned long checksum=0;

    // m_buf is the buffer which will be encoded in PKCS#1 block
    // encoding to form the "m" value used in the 
    // Public Key Encrypted Session Key Packet
    // as defined in RFC Section 5.1 "Public-Key Encrypted Session Key Packet"

    m_buf[0]=session_key->symmetric_algorithm;

    assert(session_key->symmetric_algorithm == OPS_SA_CAST5);
    for (i=0; i<CAST_KEY_LENGTH; i++)
        {
        m_buf[1+i]=session_key->key[i];
        }

    return(ops_calc_session_key_checksum(session_key, m_buf+1+CAST_KEY_LENGTH));
    }

/** 
\ingroup Core_Create
\brief implementation of EME-PKCS1-v1_5-ENCODE, as defined in OpenPGP RFC
\param M
\param mLen
\param pkey
\param EM
\return ops_true if OK; else ops_false
*/
ops_boolean_t encode_m_buf(const unsigned char *M, size_t mLen,
                           const ops_public_key_t *pkey,
                           unsigned char* EM
)
    {
    unsigned int k;
    unsigned i;

    // implementation of EME-PKCS1-v1_5-ENCODE, as defined in OpenPGP RFC
    
    if(pkey->algorithm != OPS_PKA_RSA)
	 {
		 fprintf(stderr,"\nUnhandled key algorithm %d\n",pkey->algorithm);
		 return ops_false ;
	 }

    k=BN_num_bytes(pkey->key.rsa.n);
    assert(mLen <= k-11);
    if (mLen > k-11)
        {
        fprintf(stderr,"message too long\n");
        return ops_false;
        }

    // these two bytes defined by RFC
    EM[0]=0x00;
    EM[1]=0x02;

    // add non-zero random bytes of length k - mLen -3
    for(i=2 ; i < k-mLen-1 ; ++i)
        do
            ops_random(EM+i, 1);
        while(EM[i] == 0);

    assert (i >= 8+2);

    EM[i++]=0;

    memcpy(EM+i, M, mLen);
    

    if (debug)
        {
        unsigned int i=0;
        fprintf(stderr,"Encoded Message: \n");
        for (i=0; i<mLen; i++)
            fprintf(stderr,"%2x ", EM[i]);
        fprintf(stderr,"\n");
        }

    return ops_true;
    }

/**
 \ingroup Core_Create
\brief Creates an ops_pk_session_key_t struct from keydata
\param key Keydata to use
\return ops_pk_session_key_t struct
\note It is the caller's responsiblity to free the returned pointer. Before freeing,
      the key must be cleared by calling ops_pk_session_key_free()
\note Currently hard-coded to use CAST5
\note Currently hard-coded to use RSA
*/
ops_pk_session_key_t *ops_create_pk_session_key(const ops_keydata_t *key)
    {
    /*
     * Creates a random session key and encrypts it for the given key
     *
     * Session Key is for use with a SK algo, 
     * can be any, we're hardcoding CAST5 for now
     *
     * Encryption used is PK, 
     * can be any, we're hardcoding RSA for now
     */

    const ops_public_key_t* pub_key=ops_get_public_key_from_data(key);
#define SZ_UNENCODED_M_BUF CAST_KEY_LENGTH+1+2
    unsigned char unencoded_m_buf[SZ_UNENCODED_M_BUF];

    const size_t sz_encoded_m_buf=BN_num_bytes(pub_key->key.rsa.n);
    unsigned char* encoded_m_buf = ops_mallocz(sz_encoded_m_buf);

    ops_pk_session_key_t *session_key=ops_mallocz(sizeof *session_key);

    assert(key->type == OPS_PTAG_CT_PUBLIC_KEY);
    session_key->version=OPS_PKSK_V3;
    memcpy(session_key->key_id, key->key_id, sizeof session_key->key_id);

    if (debug)
        {
        unsigned int i=0;
        fprintf(stderr,"Encrypting for RSA key id : ");
        for (i=0; i<sizeof session_key->key_id; i++)
            fprintf(stderr,"%2x ", key->key_id[i]);
        fprintf(stderr,"\n");
        }

    assert(key->key.pkey.algorithm == OPS_PKA_RSA);
    session_key->algorithm=key->key.pkey.algorithm;

    // \todo allow user to specify other algorithm
    session_key->symmetric_algorithm=OPS_SA_CAST5;
    ops_random(session_key->key, CAST_KEY_LENGTH);

    if (debug)
        {
        unsigned int i=0;
        fprintf(stderr,"CAST5 session key created (len=%d):\n ",
		CAST_KEY_LENGTH);
        for (i=0; i<CAST_KEY_LENGTH; i++)
            fprintf(stderr,"%2x ", session_key->key[i]);
        fprintf(stderr,"\n");
        }

    if (create_unencoded_m_buf(session_key, &unencoded_m_buf[0])==ops_false)
        {
        free(encoded_m_buf);
        return NULL;
        }

    if (debug)
        {
        unsigned int i=0;
        printf("unencoded m buf:\n");
        for (i=0; i<SZ_UNENCODED_M_BUF; i++)
            printf("%2x ", unencoded_m_buf[i]);
        printf("\n");
        }
    encode_m_buf(&unencoded_m_buf[0], SZ_UNENCODED_M_BUF, pub_key,
		 &encoded_m_buf[0]);
    
    // and encrypt it
    if(!ops_rsa_encrypt_mpi(encoded_m_buf, sz_encoded_m_buf, pub_key,
			    &session_key->parameters))
        {
        free (encoded_m_buf);
        return NULL;
        }

    free(encoded_m_buf);
    return session_key;
    }

/**
\ingroup Core_WritePackets
\brief Writes Public Key Session Key packet
\param info Write settings
\param pksk Public Key Session Key to write out
\return ops_true if OK; else ops_false
*/
ops_boolean_t ops_write_pk_session_key(ops_create_info_t *info,
				       ops_pk_session_key_t *pksk)
    {
    assert(pksk);
    assert(pksk->algorithm == OPS_PKA_RSA);

    return ops_write_ptag(OPS_PTAG_CT_PK_SESSION_KEY, info)
	&& ops_write_length(1 + 8 + 1
			    + BN_num_bytes(pksk->parameters.rsa.encrypted_m)
			    + 2, info)
	&& ops_write_scalar(pksk->version, 1, info)
	&& ops_write(pksk->key_id, 8, info)
	&& ops_write_scalar(pksk->algorithm, 1, info)
	&& ops_write_mpi(pksk->parameters.rsa.encrypted_m, info)
        //??	&& ops_write_scalar(0, 2, info);
        ;
    }

/**
\ingroup Core_WritePackets
\brief Writes MDC packet
\param hashed Hash for MDC
\param info Write settings
\return ops_true if OK; else ops_false
*/

ops_boolean_t ops_write_mdc(const unsigned char *hashed,
                            ops_create_info_t* info)
    {
    // write it out
    return ops_write_ptag(OPS_PTAG_CT_MDC, info)
        && ops_write_length(OPS_SHA1_HASH_SIZE,info)
        && ops_write(hashed, OPS_SHA1_HASH_SIZE, info);
    }

/**
\ingroup Core_WritePackets
\brief Writes Literal Data packet from buffer
\param data Buffer to write out
\param maxlen Max length of buffer
\param type Literal Data Type
\param info Write settings
\return ops_true if OK; else ops_false
*/
ops_boolean_t ops_write_literal_data_from_buf(const unsigned char *data, 
                                     const int maxlen, 
                                     const ops_literal_data_type_t type,
                                     ops_create_info_t *info)
    {
    /*
     * RFC4880 does not specify a meaning for filename or date.
     * It is implementation-dependent.
     * We will not implement them.
     */
    // \todo do we need to check text data for <cr><lf> line endings ?
    return ops_write_ptag(OPS_PTAG_CT_LITERAL_DATA, info)
        && ops_write_length(1+1+4+maxlen,info)
        && ops_write_scalar(type, 1, info)
        && ops_write_scalar(0, 1, info)
        && ops_write_scalar(0, 4, info)
        && ops_write(data, maxlen, info);
    }

/**
\ingroup Core_WritePackets
\brief Writes Literal Data packet from contents of file
\param filename Name of file to read from
\param type Literal Data Type
\param info Write settings
\return ops_true if OK; else ops_false
*/

ops_boolean_t
ops_write_literal_data_from_file(const char *filename, 
				 const ops_literal_data_type_t type,
				 ops_create_info_t *info)
    {
    size_t initial_size=1024;
    int fd=0;
    ops_boolean_t rtn;
    unsigned char buf[1024];
    ops_memory_t* mem=NULL;
    size_t len=0;

    fd=ops_open(filename,O_RDONLY | O_BINARY, 0);

    if (fd < 0)
        return ops_false;

    mem=ops_memory_new();
    ops_memory_init(mem,initial_size);
    for (;;)
        {
        ssize_t n=0;
        n=read(fd,buf,1024);
        if (!n)
            break;
        if (n == -1)
        {
            close(fd);
            ops_memory_free(mem);
            return ops_false;
        }
        ops_memory_add(mem, &buf[0], n);
        }
    close(fd);    

    // \todo do we need to check text data for <cr><lf> line endings ?
    len=ops_memory_get_length(mem);
    rtn=ops_write_ptag(OPS_PTAG_CT_LITERAL_DATA, info)
        && ops_write_length(1+1+4+len,info)
        && ops_write_scalar(type, 1, info)
        && ops_write_scalar(0, 1, info) // filename
        && ops_write_scalar(0, 4, info) // date
        && ops_write(ops_memory_get_data(mem), len, info);

    ops_memory_free(mem);
    return rtn;
    }

/**
   \ingroup HighLevel_General

   \brief Reads contents of file into new ops_memory_t struct.

   \param filename Filename to read from
   \param errnum Pointer to error
   \return new ops_memory_t pointer containing the contents of the file
   
   \note If there was an error opening the file or reading from it,
   errnum is set to the cause

   \note It is the caller's responsibility to call ops_memory_free(mem)
*/

ops_memory_t* ops_write_mem_from_file(const char *filename, int* errnum)
    {
    size_t initial_size=1024;
    int fd=0;
    unsigned char buf[1024];
    ops_memory_t* mem=NULL;

    *errnum=0;

    fd=ops_open(filename,O_RDONLY | O_BINARY, 0);

    if (fd < 0)
        {
        *errnum=errno;
        return ops_false;
        }

    mem=ops_memory_new();
    ops_memory_init(mem,initial_size);
    for (;;)
        {
        ssize_t n=0;
        n=read(fd,buf,1024);
        if (n<0)
            {
            *errnum=errno;
            break;
            }
        if (!n)
            break;
        ops_memory_add(mem, &buf[0], n);
        }
    close(fd);    
    return mem;
    }

/**
   \ingroup HighLevel_General

   \brief Reads contents of buffer into file

   \param filename Filename to write to
   \param buf Buffer to write to file
   \param len Size of buffer
   \param overwrite Flag to set whether to overwrite an existing file
   \return 1 if OK; 0 if error
*/

int ops_write_file_from_buf(const char *filename, const char* buf,
			    const size_t len, const ops_boolean_t overwrite)
    {
    int fd=0;
    size_t n=0;
    int flags=0;

    flags=O_WRONLY | O_CREAT;
    if (overwrite==ops_true)
        flags |= O_TRUNC;
    else
        flags |= O_EXCL;

    flags |= O_BINARY;

    fd=ops_open(filename,flags, 0600);
    if (fd < 0)
        {
        perror(NULL); 
        return 0;
        }

    n=write(fd,buf,len);
    if (n!=len)
        return 0;

    if(!close(fd))
        return 1;

    return 0;
    }

/**
\ingroup Core_WritePackets
\brief Write Symmetrically Encrypted packet
\param data Data to encrypt
\param len Length of data
\param info Write settings
\return ops_true if OK; else ops_false
\note Hard-coded to use AES256
*/
ops_boolean_t ops_write_symmetrically_encrypted_data(const unsigned char *data, 
                                                     const int len, 
                                                     ops_create_info_t *info)
    {
    int done=0;
    ops_crypt_t crypt_info;
    int encrypted_sz=0;// size of encrypted data
    unsigned char *encrypted=NULL; // buffer to write encrypted data to
    
    // \todo assume AES256 for now
    ops_crypt_any(&crypt_info, OPS_SA_AES_256);
    ops_encrypt_init(&crypt_info);

    encrypted_sz=len+crypt_info.blocksize+2;
    encrypted=ops_mallocz(encrypted_sz);

    done=ops_encrypt_se(&crypt_info, encrypted, data, len);
    assert(done==len);
    //    printf("len=%d, done: %d\n", len, done);

    return ops_write_ptag(OPS_PTAG_CT_SE_DATA, info)
        && ops_write_length(1+encrypted_sz,info)
        && ops_write(data, len, info);
    }

/**
\ingroup Core_WritePackets
\brief Write a One Pass Signature packet
\param skey Secret Key to use
\param hash_alg Hash Algorithm to use
\param sig_type Signature type
\param info Write settings
\return ops_true if OK; else ops_false
*/
ops_boolean_t ops_write_one_pass_sig(const ops_secret_key_t* skey,
                                     const ops_hash_algorithm_t hash_alg,
                                     const ops_sig_type_t sig_type,
                                     ops_create_info_t* info)
    {
    unsigned char keyid[OPS_KEY_ID_SIZE];
    if (debug)
        fprintf(stderr, "calling ops_keyid in write_one_pass_sig: "
		"this calls sha1_init\n");
    ops_keyid(keyid,&skey->public_key);

    return ops_write_ptag(OPS_PTAG_CT_ONE_PASS_SIGNATURE, info)
        && ops_write_length(1+1+1+1+8+1, info)
        && ops_write_scalar (3, 1, info) // version
        && ops_write_scalar (sig_type, 1, info)
        && ops_write_scalar (hash_alg, 1, info)
        && ops_write_scalar (skey->public_key.algorithm,  1, info)
        && ops_write(keyid, 8, info)
        && ops_write_scalar (1, 1, info);
    }

// EOF
