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/*
* pgp-pubenc.c
* Encrypt session key with public key.
*
* Copyright (c) 2005 Marko Kreen
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS 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 AUTHOR OR 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.
*
* contrib/pgcrypto/pgp-pubenc.c
*/
#include "postgres.h"
#include "pgp.h"
#include "px.h"
/*
* padded msg: 02 || non-zero pad bytes || 00 || msg
*/
static int
pad_eme_pkcs1_v15(uint8 *data, int data_len, int res_len, uint8 **res_p)
{
uint8 *buf,
*p;
int pad_len = res_len - 2 - data_len;
if (pad_len < 8)
return PXE_BUG;
buf = px_alloc(res_len);
buf[0] = 0x02;
if (!pg_strong_random(buf + 1, pad_len))
{
px_free(buf);
return PXE_NO_RANDOM;
}
/* pad must not contain zero bytes */
p = buf + 1;
while (p < buf + 1 + pad_len)
{
if (*p == 0)
{
if (!pg_strong_random(p, 1))
{
px_memset(buf, 0, res_len);
px_free(buf);
return PXE_NO_RANDOM;
}
}
if (*p != 0)
p++;
}
buf[pad_len + 1] = 0;
memcpy(buf + pad_len + 2, data, data_len);
*res_p = buf;
return 0;
}
static int
create_secmsg(PGP_Context *ctx, PGP_MPI **msg_p, int full_bytes)
{
uint8 *secmsg;
int res,
i;
unsigned cksum = 0;
int klen = ctx->sess_key_len;
uint8 *padded = NULL;
PGP_MPI *m = NULL;
/* calc checksum */
for (i = 0; i < klen; i++)
cksum += ctx->sess_key[i];
/*
* create "secret message"
*/
secmsg = px_alloc(klen + 3);
secmsg[0] = ctx->cipher_algo;
memcpy(secmsg + 1, ctx->sess_key, klen);
secmsg[klen + 1] = (cksum >> 8) & 0xFF;
secmsg[klen + 2] = cksum & 0xFF;
/*
* now create a large integer of it
*/
res = pad_eme_pkcs1_v15(secmsg, klen + 3, full_bytes, &padded);
if (res >= 0)
{
/* first byte will be 0x02 */
int full_bits = full_bytes * 8 - 6;
res = pgp_mpi_create(padded, full_bits, &m);
}
if (padded)
{
px_memset(padded, 0, full_bytes);
px_free(padded);
}
px_memset(secmsg, 0, klen + 3);
px_free(secmsg);
if (res >= 0)
*msg_p = m;
return res;
}
static int
encrypt_and_write_elgamal(PGP_Context *ctx, PGP_PubKey *pk, PushFilter *pkt)
{
int res;
PGP_MPI *m = NULL,
*c1 = NULL,
*c2 = NULL;
/* create padded msg */
res = create_secmsg(ctx, &m, pk->pub.elg.p->bytes - 1);
if (res < 0)
goto err;
/* encrypt it */
res = pgp_elgamal_encrypt(pk, m, &c1, &c2);
if (res < 0)
goto err;
/* write out */
res = pgp_mpi_write(pkt, c1);
if (res < 0)
goto err;
res = pgp_mpi_write(pkt, c2);
err:
pgp_mpi_free(m);
pgp_mpi_free(c1);
pgp_mpi_free(c2);
return res;
}
static int
encrypt_and_write_rsa(PGP_Context *ctx, PGP_PubKey *pk, PushFilter *pkt)
{
int res;
PGP_MPI *m = NULL,
*c = NULL;
/* create padded msg */
res = create_secmsg(ctx, &m, pk->pub.rsa.n->bytes - 1);
if (res < 0)
goto err;
/* encrypt it */
res = pgp_rsa_encrypt(pk, m, &c);
if (res < 0)
goto err;
/* write out */
res = pgp_mpi_write(pkt, c);
err:
pgp_mpi_free(m);
pgp_mpi_free(c);
return res;
}
int
pgp_write_pubenc_sesskey(PGP_Context *ctx, PushFilter *dst)
{
int res;
PGP_PubKey *pk = ctx->pub_key;
uint8 ver = 3;
PushFilter *pkt = NULL;
uint8 algo;
if (pk == NULL)
{
px_debug("no pubkey?\n");
return PXE_BUG;
}
algo = pk->algo;
/*
* now write packet
*/
res = pgp_create_pkt_writer(dst, PGP_PKT_PUBENCRYPTED_SESSKEY, &pkt);
if (res < 0)
goto err;
res = pushf_write(pkt, &ver, 1);
if (res < 0)
goto err;
res = pushf_write(pkt, pk->key_id, 8);
if (res < 0)
goto err;
res = pushf_write(pkt, &algo, 1);
if (res < 0)
goto err;
switch (algo)
{
case PGP_PUB_ELG_ENCRYPT:
res = encrypt_and_write_elgamal(ctx, pk, pkt);
break;
case PGP_PUB_RSA_ENCRYPT:
case PGP_PUB_RSA_ENCRYPT_SIGN:
res = encrypt_and_write_rsa(ctx, pk, pkt);
break;
}
if (res < 0)
goto err;
/*
* done, signal packet end
*/
res = pushf_flush(pkt);
err:
if (pkt)
pushf_free(pkt);
return res;
}
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