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mpicoder.c
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/* mpicoder.c - Coder for the external representation of MPIs
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
* 2008 Free Software Foundation, Inc.
* Copyright (C) 2013 g10 Code GmbH
*
* This file is part of Libgcrypt.
*
* Libgcrypt 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.
*
* Libgcrypt 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 this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include
<config.h>
#include
<stdio.h>
#include
<string.h>
#include
<stdlib.h>
#include
"mpi-internal.h"
#include
"g10lib.h"
#define MAX_EXTERN_MPI_BITS 16384
/* Helper used to scan PGP style MPIs. Returns NULL on failure. */
static
gcry_mpi_t
mpi_read_from_buffer
(
const
unsigned
char
*
buffer
,
unsigned
*
ret_nread
,
int
secure
)
{
int
i
,
j
;
unsigned
int
nbits
,
nbytes
,
nlimbs
,
nread
=
0
;
mpi_limb_t
a
;
gcry_mpi_t
val
=
MPI_NULL
;
if
(
*
ret_nread
<
2
)
goto
leave
;
nbits
=
buffer
[
0
]
<<
8
|
buffer
[
1
];
if
(
nbits
>
MAX_EXTERN_MPI_BITS
)
{
/* log_debug ("mpi too large (%u bits)\n", nbits); */
goto
leave
;
}
buffer
+=
2
;
nread
=
2
;
nbytes
=
(
nbits
+
7
)
/
8
;
nlimbs
=
(
nbytes
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
;
val
=
secure
?
mpi_alloc_secure
(
nlimbs
)
:
mpi_alloc
(
nlimbs
);
i
=
BYTES_PER_MPI_LIMB
-
nbytes
%
BYTES_PER_MPI_LIMB
;
i
%=
BYTES_PER_MPI_LIMB
;
j
=
val
->
nlimbs
=
nlimbs
;
val
->
sign
=
0
;
for
(
;
j
>
0
;
j
--
)
{
a
=
0
;
for
(;
i
<
BYTES_PER_MPI_LIMB
;
i
++
)
{
if
(
++
nread
>
*
ret_nread
)
{
/* log_debug ("mpi larger than buffer"); */
mpi_free
(
val
);
val
=
NULL
;
goto
leave
;
}
a
<<=
8
;
a
|=
*
buffer
++
;
}
i
=
0
;
val
->
d
[
j
-1
]
=
a
;
}
leave
:
*
ret_nread
=
nread
;
return
val
;
}
/****************
* Fill the mpi VAL from the hex string in STR.
*/
static
int
mpi_fromstr
(
gcry_mpi_t
val
,
const
char
*
str
)
{
int
sign
=
0
;
int
prepend_zero
=
0
;
int
i
,
j
,
c
,
c1
,
c2
;
unsigned
int
nbits
,
nbytes
,
nlimbs
;
mpi_limb_t
a
;
if
(
*
str
==
'-'
)
{
sign
=
1
;
str
++
;
}
/* Skip optional hex prefix. */
if
(
*
str
==
'0'
&&
str
[
1
]
==
'x'
)
str
+=
2
;
nbits
=
4
*
strlen
(
str
);
if
((
nbits
%
8
))
prepend_zero
=
1
;
nbytes
=
(
nbits
+
7
)
/
8
;
nlimbs
=
(
nbytes
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
;
if
(
val
->
alloced
<
nlimbs
)
mpi_resize
(
val
,
nlimbs
);
i
=
BYTES_PER_MPI_LIMB
-
(
nbytes
%
BYTES_PER_MPI_LIMB
);
i
%=
BYTES_PER_MPI_LIMB
;
j
=
val
->
nlimbs
=
nlimbs
;
val
->
sign
=
sign
;
for
(;
j
>
0
;
j
--
)
{
a
=
0
;
for
(;
i
<
BYTES_PER_MPI_LIMB
;
i
++
)
{
if
(
prepend_zero
)
{
c1
=
'0'
;
prepend_zero
=
0
;
}
else
c1
=
*
str
++
;
if
(
!
c1
)
{
mpi_clear
(
val
);
return
1
;
/* Error. */
}
c2
=
*
str
++
;
if
(
!
c2
)
{
mpi_clear
(
val
);
return
1
;
/* Error. */
}
if
(
c1
>=
'0'
&&
c1
<=
'9'
)
c
=
c1
-
'0'
;
else
if
(
c1
>=
'a'
&&
c1
<=
'f'
)
c
=
c1
-
'a'
+
10
;
else
if
(
c1
>=
'A'
&&
c1
<=
'F'
)
c
=
c1
-
'A'
+
10
;
else
{
mpi_clear
(
val
);
return
1
;
/* Error. */
}
c
<<=
4
;
if
(
c2
>=
'0'
&&
c2
<=
'9'
)
c
|=
c2
-
'0'
;
else
if
(
c2
>=
'a'
&&
c2
<=
'f'
)
c
|=
c2
-
'a'
+
10
;
else
if
(
c2
>=
'A'
&&
c2
<=
'F'
)
c
|=
c2
-
'A'
+
10
;
else
{
mpi_clear
(
val
);
return
1
;
/* Error. */
}
a
<<=
8
;
a
|=
c
;
}
i
=
0
;
val
->
d
[
j
-1
]
=
a
;
}
return
0
;
/* Okay. */
}
/* Return an allocated buffer with the MPI (msb first). NBYTES
receives the length of this buffer. If FILL_LE is not 0, the
returned value is stored as little endian and right padded with
zeroes so that the returned buffer has at least FILL_LE bytes.
Caller must free the return string. This function returns an
allocated buffer with NBYTES set to zero if the value of A is zero.
If sign is not NULL, it will be set to the sign of the A. On error
NULL is returned and ERRNO set appropriately. */
static
unsigned
char
*
do_get_buffer
(
gcry_mpi_t
a
,
unsigned
int
fill_le
,
unsigned
int
*
nbytes
,
int
*
sign
,
int
force_secure
)
{
unsigned
char
*
p
,
*
buffer
;
unsigned
int
length
,
tmp
;
mpi_limb_t
alimb
;
int
i
;
size_t
n
;
if
(
sign
)
*
sign
=
a
->
sign
;
*
nbytes
=
a
->
nlimbs
*
BYTES_PER_MPI_LIMB
;
n
=
*
nbytes
?
*
nbytes
:
1
;
/* Allocate at least one byte. */
if
(
n
<
fill_le
)
n
=
fill_le
;
p
=
buffer
=
(
force_secure
||
mpi_is_secure
(
a
))
?
gcry_malloc_secure
(
n
)
:
gcry_malloc
(
n
);
if
(
!
buffer
)
return
NULL
;
for
(
i
=
a
->
nlimbs
-1
;
i
>=
0
;
i
--
)
{
alimb
=
a
->
d
[
i
];
#if BYTES_PER_MPI_LIMB == 4
*
p
++
=
alimb
>>
24
;
*
p
++
=
alimb
>>
16
;
*
p
++
=
alimb
>>
8
;
*
p
++
=
alimb
;
#elif BYTES_PER_MPI_LIMB == 8
*
p
++
=
alimb
>>
56
;
*
p
++
=
alimb
>>
48
;
*
p
++
=
alimb
>>
40
;
*
p
++
=
alimb
>>
32
;
*
p
++
=
alimb
>>
24
;
*
p
++
=
alimb
>>
16
;
*
p
++
=
alimb
>>
8
;
*
p
++
=
alimb
;
#else
# error please implement for this limb size.
#endif
}
if
(
fill_le
)
{
length
=
*
nbytes
;
/* Reverse buffer and pad with zeroes. */
for
(
i
=
0
;
i
<
length
/
2
;
i
++
)
{
tmp
=
buffer
[
i
];
buffer
[
i
]
=
buffer
[
length
-1
-
i
];
buffer
[
length
-1
-
i
]
=
tmp
;
}
/* Pad with zeroes. */
for
(
p
=
buffer
+
length
;
length
<
fill_le
;
length
++
)
*
p
++
=
0
;
*
nbytes
=
length
;
return
buffer
;
}
/* This is sub-optimal but we need to do the shift operation because
the caller has to free the returned buffer. */
for
(
p
=
buffer
;
*
nbytes
&&
!*
p
;
p
++
,
--*
nbytes
)
;
if
(
p
!=
buffer
)
memmove
(
buffer
,
p
,
*
nbytes
);
return
buffer
;
}
byte
*
_gcry_mpi_get_buffer
(
gcry_mpi_t
a
,
unsigned
int
fill_le
,
unsigned
int
*
r_nbytes
,
int
*
sign
)
{
return
do_get_buffer
(
a
,
fill_le
,
r_nbytes
,
sign
,
0
);
}
byte
*
_gcry_mpi_get_secure_buffer
(
gcry_mpi_t
a
,
unsigned
int
fill_le
,
unsigned
int
*
r_nbytes
,
int
*
sign
)
{
return
do_get_buffer
(
a
,
fill_le
,
r_nbytes
,
sign
,
1
);
}
/*
* Use the NBYTES at BUFFER_ARG to update A. Set the sign of a to
* SIGN.
*/
void
_gcry_mpi_set_buffer
(
gcry_mpi_t
a
,
const
void
*
buffer_arg
,
unsigned
int
nbytes
,
int
sign
)
{
const
unsigned
char
*
buffer
=
(
const
unsigned
char
*
)
buffer_arg
;
const
unsigned
char
*
p
;
mpi_limb_t
alimb
;
int
nlimbs
;
int
i
;
if
(
mpi_is_immutable
(
a
))
{
mpi_immutable_failed
();
return
;
}
nlimbs
=
(
nbytes
+
BYTES_PER_MPI_LIMB
-
1
)
/
BYTES_PER_MPI_LIMB
;
RESIZE_IF_NEEDED
(
a
,
nlimbs
);
a
->
sign
=
sign
;
for
(
i
=
0
,
p
=
buffer
+
nbytes
-1
;
p
>=
buffer
+
BYTES_PER_MPI_LIMB
;
)
{
#if BYTES_PER_MPI_LIMB == 4
alimb
=
*
p
--
;
alimb
|=
*
p
--
<<
8
;
alimb
|=
*
p
--
<<
16
;
alimb
|=
*
p
--
<<
24
;
#elif BYTES_PER_MPI_LIMB == 8
alimb
=
(
mpi_limb_t
)
*
p
--
;
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
8
;
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
16
;
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
24
;
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
32
;
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
40
;
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
48
;
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
56
;
#else
# error please implement for this limb size.
#endif
a
->
d
[
i
++
]
=
alimb
;
}
if
(
p
>=
buffer
)
{
#if BYTES_PER_MPI_LIMB == 4
alimb
=
*
p
--
;
if
(
p
>=
buffer
)
alimb
|=
*
p
--
<<
8
;
if
(
p
>=
buffer
)
alimb
|=
*
p
--
<<
16
;
if
(
p
>=
buffer
)
alimb
|=
*
p
--
<<
24
;
#elif BYTES_PER_MPI_LIMB == 8
alimb
=
(
mpi_limb_t
)
*
p
--
;
if
(
p
>=
buffer
)
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
8
;
if
(
p
>=
buffer
)
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
16
;
if
(
p
>=
buffer
)
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
24
;
if
(
p
>=
buffer
)
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
32
;
if
(
p
>=
buffer
)
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
40
;
if
(
p
>=
buffer
)
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
48
;
if
(
p
>=
buffer
)
alimb
|=
(
mpi_limb_t
)
*
p
--
<<
56
;
#else
# error please implement for this limb size.
#endif
a
->
d
[
i
++
]
=
alimb
;
}
a
->
nlimbs
=
i
;
gcry_assert
(
i
==
nlimbs
);
}
static
void
onecompl
(
gcry_mpi_t
a
)
{
mpi_ptr_t
ap
;
mpi_size_t
n
;
unsigned
int
i
;
unsigned
int
nbits
=
mpi_get_nbits
(
a
);
if
(
mpi_is_immutable
(
a
))
{
mpi_immutable_failed
();
return
;
}
mpi_normalize
(
a
);
ap
=
a
->
d
;
n
=
a
->
nlimbs
;
for
(
i
=
0
;
i
<
n
;
i
++
)
ap
[
i
]
^=
(
mpi_limb_t
)(
-1
);
a
->
sign
=
0
;
mpi_clear_highbit
(
a
,
nbits
-1
);
}
/* Perform a two's complement operation on buffer P of size N bytes. */
static
void
twocompl
(
unsigned
char
*
p
,
unsigned
int
n
)
{
int
i
;
for
(
i
=
n
-1
;
i
>=
0
&&
!
p
[
i
];
i
--
)
;
if
(
i
>=
0
)
{
if
((
p
[
i
]
&
0x01
))
p
[
i
]
=
(((
p
[
i
]
^
0xfe
)
|
0x01
)
&
0xff
);
else
if
((
p
[
i
]
&
0x02
))
p
[
i
]
=
(((
p
[
i
]
^
0xfc
)
|
0x02
)
&
0xfe
);
else
if
((
p
[
i
]
&
0x04
))
p
[
i
]
=
(((
p
[
i
]
^
0xf8
)
|
0x04
)
&
0xfc
);
else
if
((
p
[
i
]
&
0x08
))
p
[
i
]
=
(((
p
[
i
]
^
0xf0
)
|
0x08
)
&
0xf8
);
else
if
((
p
[
i
]
&
0x10
))
p
[
i
]
=
(((
p
[
i
]
^
0xe0
)
|
0x10
)
&
0xf0
);
else
if
((
p
[
i
]
&
0x20
))
p
[
i
]
=
(((
p
[
i
]
^
0xc0
)
|
0x20
)
&
0xe0
);
else
if
((
p
[
i
]
&
0x40
))
p
[
i
]
=
(((
p
[
i
]
^
0x80
)
|
0x40
)
&
0xc0
);
else
p
[
i
]
=
0x80
;
for
(
i
--
;
i
>=
0
;
i
--
)
p
[
i
]
^=
0xff
;
}
}
/* Convert the external representation of an integer stored in BUFFER
with a length of BUFLEN into a newly create MPI returned in
RET_MPI. If NBYTES is not NULL, it will receive the number of
bytes actually scanned after a successful operation. */
gcry_err_code_t
_gcry_mpi_scan
(
struct
gcry_mpi
**
ret_mpi
,
enum
gcry_mpi_format
format
,
const
void
*
buffer_arg
,
size_t
buflen
,
size_t
*
nscanned
)
{
const
unsigned
char
*
buffer
=
(
const
unsigned
char
*
)
buffer_arg
;
struct
gcry_mpi
*
a
=
NULL
;
unsigned
int
len
;
int
secure
=
(
buffer
&&
gcry_is_secure
(
buffer
));
if
(
format
==
GCRYMPI_FMT_SSH
)
len
=
0
;
else
len
=
buflen
;
if
(
format
==
GCRYMPI_FMT_STD
)
{
const
unsigned
char
*
s
=
buffer
;
a
=
secure
?
mpi_alloc_secure
((
len
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
)
:
mpi_alloc
((
len
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
);
if
(
len
)
{
_gcry_mpi_set_buffer
(
a
,
s
,
len
,
0
);
a
->
sign
=
!!
(
*
s
&
0x80
);
if
(
a
->
sign
)
{
onecompl
(
a
);
mpi_add_ui
(
a
,
a
,
1
);
a
->
sign
=
1
;
}
}
if
(
ret_mpi
)
{
mpi_normalize
(
a
);
*
ret_mpi
=
a
;
}
else
mpi_free
(
a
);
if
(
nscanned
)
*
nscanned
=
len
;
return
0
;
}
else
if
(
format
==
GCRYMPI_FMT_USG
)
{
a
=
secure
?
mpi_alloc_secure
((
len
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
)
:
mpi_alloc
((
len
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
);
if
(
len
)
_gcry_mpi_set_buffer
(
a
,
buffer
,
len
,
0
);
if
(
ret_mpi
)
{
mpi_normalize
(
a
);
*
ret_mpi
=
a
;
}
else
mpi_free
(
a
);
if
(
nscanned
)
*
nscanned
=
len
;
return
0
;
}
else
if
(
format
==
GCRYMPI_FMT_PGP
)
{
a
=
mpi_read_from_buffer
(
buffer
,
&
len
,
secure
);
if
(
nscanned
)
*
nscanned
=
len
;
if
(
ret_mpi
&&
a
)
{
mpi_normalize
(
a
);
*
ret_mpi
=
a
;
}
else
if
(
a
)
{
mpi_free
(
a
);
a
=
NULL
;
}
return
a
?
0
:
GPG_ERR_INV_OBJ
;
}
else
if
(
format
==
GCRYMPI_FMT_SSH
)
{
const
unsigned
char
*
s
=
buffer
;
size_t
n
;
/* This test is not strictly necessary and an assert (!len)
would be sufficient. We keep this test in case we later
allow the BUFLEN argument to act as a sanitiy check. Same
below. */
if
(
len
&&
len
<
4
)
return
GPG_ERR_TOO_SHORT
;
n
=
(
s
[
0
]
<<
24
|
s
[
1
]
<<
16
|
s
[
2
]
<<
8
|
s
[
3
]);
s
+=
4
;
if
(
len
)
len
-=
4
;
if
(
len
&&
n
>
len
)
return
GPG_ERR_TOO_LARGE
;
a
=
secure
?
mpi_alloc_secure
((
n
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
)
:
mpi_alloc
((
n
+
BYTES_PER_MPI_LIMB
-1
)
/
BYTES_PER_MPI_LIMB
);
if
(
n
)
{
_gcry_mpi_set_buffer
(
a
,
s
,
n
,
0
);
a
->
sign
=
!!
(
*
s
&
0x80
);
if
(
a
->
sign
)
{
onecompl
(
a
);
mpi_add_ui
(
a
,
a
,
1
);
a
->
sign
=
1
;
}
}
if
(
nscanned
)
*
nscanned
=
n
+
4
;
if
(
ret_mpi
)
{
mpi_normalize
(
a
);
*
ret_mpi
=
a
;
}
else
mpi_free
(
a
);
return
0
;
}
else
if
(
format
==
GCRYMPI_FMT_HEX
)
{
/* We can only handle C strings for now. */
if
(
buflen
)
return
GPG_ERR_INV_ARG
;
a
=
secure
?
mpi_alloc_secure
(
0
)
:
mpi_alloc
(
0
);
if
(
mpi_fromstr
(
a
,
(
const
char
*
)
buffer
))
{
mpi_free
(
a
);
return
GPG_ERR_INV_OBJ
;
}
if
(
ret_mpi
)
{
mpi_normalize
(
a
);
*
ret_mpi
=
a
;
}
else
mpi_free
(
a
);
if
(
nscanned
)
*
nscanned
=
strlen
((
const
char
*
)
buffer
);
return
0
;
}
else
return
GPG_ERR_INV_ARG
;
}
/* Convert the big integer A into the external representation
described by FORMAT and store it in the provided BUFFER which has
been allocated by the user with a size of BUFLEN bytes. NWRITTEN
receives the actual length of the external representation unless it
has been passed as NULL. BUFFER may be NULL to query the required
length. */
gcry_err_code_t
_gcry_mpi_print
(
enum
gcry_mpi_format
format
,
unsigned
char
*
buffer
,
size_t
buflen
,
size_t
*
nwritten
,
struct
gcry_mpi
*
a
)
{
unsigned
int
nbits
=
mpi_get_nbits
(
a
);
size_t
len
;
size_t
dummy_nwritten
;
int
negative
;
if
(
!
nwritten
)
nwritten
=
&
dummy_nwritten
;
/* Libgcrypt does no always care to set clear the sign if the value
is 0. For printing this is a bit of a surprise, in particular
because if some of the formats don't support negative numbers but
should be able to print a zero. Thus we need this extra test
for a negative number. */
if
(
a
->
sign
&&
_gcry_mpi_cmp_ui
(
a
,
0
))
negative
=
1
;
else
negative
=
0
;
len
=
buflen
;
*
nwritten
=
0
;
if
(
format
==
GCRYMPI_FMT_STD
)
{
unsigned
char
*
tmp
;
int
extra
=
0
;
unsigned
int
n
;
tmp
=
_gcry_mpi_get_buffer
(
a
,
0
,
&
n
,
NULL
);
if
(
!
tmp
)
return
gpg_err_code_from_syserror
();
if
(
negative
)
{
twocompl
(
tmp
,
n
);
if
(
!
(
*
tmp
&
0x80
))
{
/* Need to extend the sign. */
n
++
;
extra
=
2
;
}
}
else
if
(
n
&&
(
*
tmp
&
0x80
))
{
/* Positive but the high bit of the returned buffer is set.
Thus we need to print an extra leading 0x00 so that the
output is interpreted as a positive number. */
n
++
;
extra
=
1
;
}
if
(
buffer
&&
n
>
len
)
{
/* The provided buffer is too short. */
gcry_free
(
tmp
);
return
GPG_ERR_TOO_SHORT
;
}
if
(
buffer
)
{
unsigned
char
*
s
=
buffer
;
if
(
extra
==
1
)
*
s
++
=
0
;
else
if
(
extra
)
*
s
++
=
0xff
;
memcpy
(
s
,
tmp
,
n
-!!
extra
);
}
gcry_free
(
tmp
);
*
nwritten
=
n
;
return
0
;
}
else
if
(
format
==
GCRYMPI_FMT_USG
)
{
unsigned
int
n
=
(
nbits
+
7
)
/
8
;
/* Note: We ignore the sign for this format. */
/* FIXME: for performance reasons we should put this into
mpi_aprint because we can then use the buffer directly. */
if
(
buffer
&&
n
>
len
)
return
GPG_ERR_TOO_SHORT
;
if
(
buffer
)
{
unsigned
char
*
tmp
;
tmp
=
_gcry_mpi_get_buffer
(
a
,
0
,
&
n
,
NULL
);
if
(
!
tmp
)
return
gpg_err_code_from_syserror
();
memcpy
(
buffer
,
tmp
,
n
);
gcry_free
(
tmp
);
}
*
nwritten
=
n
;
return
0
;
}
else
if
(
format
==
GCRYMPI_FMT_PGP
)
{
unsigned
int
n
=
(
nbits
+
7
)
/
8
;
/* The PGP format can only handle unsigned integers. */
if
(
negative
)
return
GPG_ERR_INV_ARG
;
if
(
buffer
&&
n
+
2
>
len
)
return
GPG_ERR_TOO_SHORT
;
if
(
buffer
)
{
unsigned
char
*
tmp
;
unsigned
char
*
s
=
buffer
;
s
[
0
]
=
nbits
>>
8
;
s
[
1
]
=
nbits
;
tmp
=
_gcry_mpi_get_buffer
(
a
,
0
,
&
n
,
NULL
);
if
(
!
tmp
)
return
gpg_err_code_from_syserror
();
memcpy
(
s
+
2
,
tmp
,
n
);
gcry_free
(
tmp
);
}
*
nwritten
=
n
+
2
;
return
0
;
}
else
if
(
format
==
GCRYMPI_FMT_SSH
)
{
unsigned
char
*
tmp
;
int
extra
=
0
;
unsigned
int
n
;
tmp
=
_gcry_mpi_get_buffer
(
a
,
0
,
&
n
,
NULL
);
if
(
!
tmp
)
return
gpg_err_code_from_syserror
();
if
(
negative
)
{
twocompl
(
tmp
,
n
);
if
(
!
(
*
tmp
&
0x80
))
{
/* Need to extend the sign. */
n
++
;
extra
=
2
;
}
}
else
if
(
n
&&
(
*
tmp
&
0x80
))
{
n
++
;
extra
=
1
;
}
if
(
buffer
&&
n
+
4
>
len
)
{
gcry_free
(
tmp
);
return
GPG_ERR_TOO_SHORT
;
}
if
(
buffer
)
{
unsigned
char
*
s
=
buffer
;
*
s
++
=
n
>>
24
;
*
s
++
=
n
>>
16
;
*
s
++
=
n
>>
8
;
*
s
++
=
n
;
if
(
extra
==
1
)
*
s
++
=
0
;
else
if
(
extra
)
*
s
++
=
0xff
;
memcpy
(
s
,
tmp
,
n
-!!
extra
);
}
gcry_free
(
tmp
);
*
nwritten
=
4
+
n
;
return
0
;
}
else
if
(
format
==
GCRYMPI_FMT_HEX
)
{
unsigned
char
*
tmp
;
int
i
;
int
extra
=
0
;
unsigned
int
n
=
0
;
tmp
=
_gcry_mpi_get_buffer
(
a
,
0
,
&
n
,
NULL
);
if
(
!
tmp
)
return
gpg_err_code_from_syserror
();
if
(
!
n
||
(
*
tmp
&
0x80
))
extra
=
2
;
if
(
buffer
&&
2
*
n
+
extra
+
negative
+
1
>
len
)
{
gcry_free
(
tmp
);
return
GPG_ERR_TOO_SHORT
;
}
if
(
buffer
)
{
unsigned
char
*
s
=
buffer
;
if
(
negative
)
*
s
++
=
'-'
;
if
(
extra
)
{
*
s
++
=
'0'
;
*
s
++
=
'0'
;
}
for
(
i
=
0
;
i
<
n
;
i
++
)
{
unsigned
int
c
=
tmp
[
i
];
*
s
++
=
(
c
>>
4
)
<
10
?
'0'
+
(
c
>>
4
)
:
'A'
+
(
c
>>
4
)
-10
;
c
&=
15
;
*
s
++
=
c
<
10
?
'0'
+
c
:
'A'
+
c
-10
;
}
*
s
++
=
0
;
*
nwritten
=
s
-
buffer
;
}
else
{
*
nwritten
=
2
*
n
+
extra
+
negative
+
1
;
}
gcry_free
(
tmp
);
return
0
;
}
else
return
GPG_ERR_INV_ARG
;
}
/*
* Like gcry_mpi_print but this function allocates the buffer itself.
* The caller has to supply the address of a pointer. NWRITTEN may be
* NULL.
*/
gcry_err_code_t
_gcry_mpi_aprint
(
enum
gcry_mpi_format
format
,
unsigned
char
**
buffer
,
size_t
*
nwritten
,
struct
gcry_mpi
*
a
)
{
size_t
n
;
gcry_err_code_t
rc
;
*
buffer
=
NULL
;
rc
=
_gcry_mpi_print
(
format
,
NULL
,
0
,
&
n
,
a
);
if
(
rc
)
return
rc
;
*
buffer
=
mpi_is_secure
(
a
)
?
gcry_malloc_secure
(
n
?
n
:
1
)
:
gcry_malloc
(
n
?
n
:
1
);
if
(
!*
buffer
)
return
gpg_err_code_from_syserror
();
/* If the returned buffer will have a length of 0, we nevertheless
allocated 1 byte (malloc needs it anyway) and store a 0. */
if
(
!
n
)
**
buffer
=
0
;
rc
=
_gcry_mpi_print
(
format
,
*
buffer
,
n
,
&
n
,
a
);
if
(
rc
)
{
gcry_free
(
*
buffer
);
*
buffer
=
NULL
;
}
else
if
(
nwritten
)
*
nwritten
=
n
;
return
rc
;
}
/* Turn VALUE into an octet string and store it in an allocated buffer
at R_FRAME or - if R_RAME is NULL - copy it into the caller
provided buffer SPACE; either SPACE or R_FRAME may be used. If
SPACE if not NULL, the caller must provide a buffer of at least
NBYTES. If the resulting octet string is shorter than NBYTES pad
it to the left with zeroes. If VALUE does not fit into NBYTES
return an error code. */
gpg_err_code_t
_gcry_mpi_to_octet_string
(
unsigned
char
**
r_frame
,
void
*
space
,
gcry_mpi_t
value
,
size_t
nbytes
)
{
gpg_err_code_t
rc
;
size_t
nframe
,
noff
,
n
;
unsigned
char
*
frame
;
if
(
!
r_frame
==
!
space
)
return
GPG_ERR_INV_ARG
;
/* Only one may be used. */
if
(
r_frame
)
*
r_frame
=
NULL
;
rc
=
_gcry_mpi_print
(
GCRYMPI_FMT_USG
,
NULL
,
0
,
&
nframe
,
value
);
if
(
rc
)
return
rc
;
if
(
nframe
>
nbytes
)
return
GPG_ERR_TOO_LARGE
;
/* Value too long to fit into NBYTES. */
noff
=
(
nframe
<
nbytes
)
?
nbytes
-
nframe
:
0
;
n
=
nframe
+
noff
;
if
(
space
)
frame
=
space
;
else
{
frame
=
mpi_is_secure
(
value
)
?
gcry_malloc_secure
(
n
)
:
gcry_malloc
(
n
);
if
(
!
frame
)
{
rc
=
gpg_err_code_from_syserror
();
return
rc
;
}
}
if
(
noff
)
memset
(
frame
,
0
,
noff
);
nframe
+=
noff
;
rc
=
_gcry_mpi_print
(
GCRYMPI_FMT_USG
,
frame
+
noff
,
nframe
-
noff
,
NULL
,
value
);
if
(
rc
)
{
gcry_free
(
frame
);
return
rc
;
}
if
(
r_frame
)
*
r_frame
=
frame
;
return
0
;
}
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Mime Type
text/x-c
Expires
Mon, Dec 23, 5:34 PM (2 h, 23 m)
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Storage Handle
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