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aes-internal.h
pgp-encode.c 9.36 KiB
/* pgp.c
*
* PGP related functions.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001, 2002 Niels Möller
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "pgp.h"
#include "base64.h"
#include "buffer.h"
#include "macros.h"
#include "rsa.h"
int
pgp_put_uint32(struct nettle_buffer *buffer, uint32_t i)
{
uint8_t *p = nettle_buffer_space(buffer, 4);
if (!p)
return 0;
WRITE_UINT32(p, i);
return 1;
}
int
pgp_put_uint16(struct nettle_buffer *buffer, unsigned i)
{
uint8_t *p = nettle_buffer_space(buffer, 2);
if (!p)
return 0;
WRITE_UINT16(p, i);
return 1;
}
int
pgp_put_mpi(struct nettle_buffer *buffer, const mpz_t x)
{
unsigned bits = mpz_sizeinbase(x, 2);
unsigned octets = (bits + 7) / 8;
uint8_t *p;
/* FIXME: What's the correct representation of zero? */
if (!pgp_put_uint16(buffer, bits))
return 0;
p = nettle_buffer_space(buffer, octets);
if (!p)
return 0;
nettle_mpz_get_str_256(octets, p, x);
return 1;
}
int
pgp_put_string(struct nettle_buffer *buffer,
unsigned length,
const uint8_t *s)
{
return nettle_buffer_write(buffer, length, s);
}
#if 0
static unsigned
length_field(unsigned length)
{
if (length < PGP_LENGTH_TWO_OCTET)
return 1;
else if (length < PGP_LENGTH_FOUR_OCTETS)
return 2;
else return 4;
}
#endif
/* bodyLen = ((1st_octet - 192) << 8) + (2nd_octet) + 192
* ==> bodyLen - 192 + 192 << 8 = (1st_octet << 8) + (2nd_octet)
*/
#define LENGTH_TWO_OFFSET (192 * 255)
int
pgp_put_length(struct nettle_buffer *buffer,
unsigned length)
{
if (length < PGP_LENGTH_TWO_OCTETS)
return NETTLE_BUFFER_PUTC(buffer, length);
else if (length < PGP_LENGTH_FOUR_OCTETS)
return pgp_put_uint16(buffer, length + LENGTH_TWO_OFFSET);
else
return NETTLE_BUFFER_PUTC(buffer, 0xff) && pgp_put_uint32(buffer, length);
}
/* Uses the "new" packet format */
int
pgp_put_header(struct nettle_buffer *buffer,
unsigned tag, unsigned length)
{
assert(tag < 0x40);
return (NETTLE_BUFFER_PUTC(buffer, 0xC0 | tag)
&& pgp_put_length(buffer, length));
}
/* FIXME: Should we abort or return error if the length and the field
* size don't match? */
void
pgp_put_header_length(struct nettle_buffer *buffer,
/* start of the header */
unsigned start, unsigned field_size)
{
unsigned length;
switch (field_size)
{
case 1:
length = buffer->size - (start + 2);
assert(length < PGP_LENGTH_TWO_OCTETS);
buffer->contents[start + 1] = length;
break;
case 2:
length = buffer->size - (start + 3);
assert(length < PGP_LENGTH_FOUR_OCTETS
&& length >= PGP_LENGTH_TWO_OCTETS);
WRITE_UINT16(buffer->contents + start + 1, length + LENGTH_TWO_OFFSET);
break;
case 4:
length = buffer->size - (start + 5);
WRITE_UINT32(buffer->contents + start + 2, length);
break;
default:
abort();
}
}
int
pgp_put_userid(struct nettle_buffer *buffer,
unsigned length,
const uint8_t *name)
{
return (pgp_put_header(buffer, PGP_TAG_USERID, length)
&& pgp_put_string(buffer, length, name));
}
unsigned
pgp_sub_packet_start(struct nettle_buffer *buffer)
{
return nettle_buffer_space(buffer, 2) ? buffer->size : 0;
}
int
pgp_put_sub_packet(struct nettle_buffer *buffer,
unsigned type,
unsigned length,
const uint8_t *data)
{
return (pgp_put_length(buffer, length + 1)
&& NETTLE_BUFFER_PUTC(buffer, type)
&& pgp_put_string(buffer, length, data));
}
void
pgp_sub_packet_end(struct nettle_buffer *buffer, unsigned start)
{
unsigned length;
assert(start >= 2);
assert(start <= buffer->size);
length = buffer->size - start;
WRITE_UINT32(buffer->contents + start - 2, length);
}
int
pgp_put_public_rsa_key(struct nettle_buffer *buffer,
const struct rsa_public_key *pub,
time_t timestamp)
{
/* Public key packet, version 4 */
unsigned start; unsigned length;
/* Size of packet is 16 + the size of e and n */
length = (4 * 4
+ nettle_mpz_sizeinbase_256_u(pub->n)
+ nettle_mpz_sizeinbase_256_u(pub->e));
if (!pgp_put_header(buffer, PGP_TAG_PUBLIC_KEY, length))
return 0;
start = buffer->size;
if (! (pgp_put_header(buffer, PGP_TAG_PUBLIC_KEY,
/* Assume that we need two octets */
PGP_LENGTH_TWO_OCTETS)
&& pgp_put_uint32(buffer, 4) /* Version */
&& pgp_put_uint32(buffer, timestamp)/* Time stamp */
&& pgp_put_uint32(buffer, PGP_RSA) /* Algorithm */
&& pgp_put_mpi(buffer, pub->n)
&& pgp_put_mpi(buffer, pub->e)) )
return 0;
assert(buffer->size == start + length);
return 1;
}
int
pgp_put_rsa_sha1_signature(struct nettle_buffer *buffer,
const struct rsa_private_key *key,
const uint8_t *keyid,
unsigned type,
struct sha1_ctx *hash)
{
unsigned signature_start = buffer->size;
unsigned hash_end;
unsigned sub_packet_start;
uint8_t trailer[6];
uint8_t digest16[2];
mpz_t s;
/* Signature packet. The packet could reasonably be both smaller and
* larger than 192, so for simplicity we use the 4 octet header
* form. */
if (! (pgp_put_header(buffer, PGP_TAG_SIGNATURE, PGP_LENGTH_FOUR_OCTETS)
&& NETTLE_BUFFER_PUTC(buffer, 4) /* Version */
&& NETTLE_BUFFER_PUTC(buffer, type)
/* Could also be PGP_RSA_SIGN */
&& NETTLE_BUFFER_PUTC(buffer, PGP_RSA)
&& NETTLE_BUFFER_PUTC(buffer, PGP_SHA1)
&& pgp_put_uint16(buffer, 0))) /* Hashed subpacket length */
return 0;
hash_end = buffer->size;
sha1_update(hash,
hash_end - signature_start,
buffer->contents + signature_start);
trailer[0] = 4; trailer[1] = 0xff;
WRITE_UINT32(trailer + 2, buffer->size - signature_start);
sha1_update(hash, sizeof(trailer), trailer);
{
struct sha1_ctx hcopy = *hash;
uint8_t *p = nettle_buffer_space(buffer, 2);
if (!p)
return 0;
sha1_digest(&hcopy, 2, p);
}
/* One "sub-packet" field with the issuer keyid */
sub_packet_start = pgp_sub_packet_start(buffer);
if (!sub_packet_start)
return 0;
if (pgp_put_sub_packet(buffer, PGP_SUBPACKET_ISSUER_KEY_ID, 8, keyid))
{
pgp_sub_packet_end(buffer, sub_packet_start);
return 0;
}
mpz_init(s);
if (!(rsa_sha1_sign(key, hash, s)
&& pgp_put_mpi(buffer, s)))
{
mpz_clear(s);
return 0;
}
mpz_clear(s);
pgp_put_header_length(buffer, signature_start, 4);
return 1;
}
#define CRC24_INIT 0x0b704ceL
#define CRC24_POLY 0x1864cfbL
uint32_t
pgp_crc24(unsigned length, const uint8_t *data)
{
uint32_t crc = CRC24_INIT;
unsigned i;
for (i = 0; i<length; i++)
{
unsigned j;
crc ^= ((unsigned) (data[i]) << 16);
for (j = 0; j<8; j++)
{
crc <<= 1;
if (crc & 0x1000000)
crc ^= CRC24_POLY;
}
}
assert(crc < 0x1000000);
return crc;
}
#define WRITE(buffer, s) (nettle_buffer_write(buffer, strlen((s)), (s)))
/* 15 base 64 groups data per line */
#define BINARY_PER_LINE 45
#define TEXT_PER_LINE BASE64_ENCODE_LENGTH(BINARY_PER_LINE)
int
pgp_armor(struct nettle_buffer *buffer,
const char *tag,
unsigned length,
const uint8_t *data)
{
struct base64_encode_ctx ctx;
unsigned crc = pgp_crc24(length, data);
base64_encode_init(&ctx);
if (! (WRITE(buffer, "BEGIN PGP ")
&& WRITE(buffer, tag)
&& WRITE(buffer, "\nComment: Nettle\n\n")))
return 0;
for (;
length >= BINARY_PER_LINE;
length -= BINARY_PER_LINE, data += BINARY_PER_LINE)
{
unsigned done;
uint8_t *p
= nettle_buffer_space(buffer, TEXT_PER_LINE);
if (!p)
return 0;
done = base64_encode_update(&ctx, p, BINARY_PER_LINE, data);
assert(done <= TEXT_PER_LINE);
/* FIXME: Create some official way to do this */
buffer->size -= (TEXT_PER_LINE - done);
if (!NETTLE_BUFFER_PUTC(buffer, '\n'))
return 0;
}
if (length)
{
unsigned text_size = BASE64_ENCODE_LENGTH(length)
+ BASE64_ENCODE_FINAL_LENGTH;
unsigned done;
uint8_t *p
= nettle_buffer_space(buffer, text_size);
if (!p)
return 0;
done = base64_encode_update(&ctx, p, length, data);
done += base64_encode_final(&ctx, p + done);
/* FIXME: Create some official way to do this */
buffer->size -= (text_size - done);
if (!NETTLE_BUFFER_PUTC(buffer, '\n'))
return 0;
}
/* Checksum */
if (!NETTLE_BUFFER_PUTC(buffer, '='))
return 0;
{
uint8_t *p = nettle_buffer_space(buffer, 4);
if (!p)
return 0;
base64_encode_group(p, crc);
}
return (WRITE(buffer, "\nBEGIN PGP ")
&& WRITE(buffer, tag)
&& NETTLE_BUFFER_PUTC(buffer, '\n'));
}