diff options
Diffstat (limited to 'libgcrypt-1.4.6/mpi/mpicoder.c')
| -rw-r--r-- | libgcrypt-1.4.6/mpi/mpicoder.c | 1503 |
1 files changed, 752 insertions, 751 deletions
diff --git a/libgcrypt-1.4.6/mpi/mpicoder.c b/libgcrypt-1.4.6/mpi/mpicoder.c index b2d542c..8f0c76f 100644 --- a/libgcrypt-1.4.6/mpi/mpicoder.c +++ b/libgcrypt-1.4.6/mpi/mpicoder.c @@ -1,751 +1,752 @@ -/* mpicoder.c - Coder for the external representation of MPIs
- * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
- * 2008 Free Software Foundation, Inc.
- *
- * 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. */
-}
-
-
-/* Dump the value of A in a format suitable for debugging to
- Libgcrypt's logging stream. Note that one leading space but no
- trailing space or linefeed will be printed. It is okay to pass
- NULL for A. */
-void
-gcry_mpi_dump (const gcry_mpi_t a)
-{
- int i;
-
- log_printf (" ");
- if (!a)
- log_printf ("[MPI_NULL]");
- else
- {
- if (a->sign)
- log_printf ( "-");
-#if BYTES_PER_MPI_LIMB == 2
-# define X "4"
-#elif BYTES_PER_MPI_LIMB == 4
-# define X "8"
-#elif BYTES_PER_MPI_LIMB == 8
-# define X "16"
-#elif BYTES_PER_MPI_LIMB == 16
-# define X "32"
-#else
-# error please define the format here
-#endif
- for (i=a->nlimbs; i > 0 ; i-- )
- {
- log_printf (i != a->nlimbs? "%0" X "lX":"%lX", (ulong)a->d[i-1]);
- }
-#undef X
- if (!a->nlimbs)
- log_printf ("0");
- }
-}
-
-/* Convience function used internally. */
-void
-_gcry_log_mpidump (const char *text, gcry_mpi_t a)
-{
- log_printf ("%s:", text);
- gcry_mpi_dump (a);
- log_printf ("\n");
-}
-
-
-/* Return an allocated buffer with the MPI (msb first). NBYTES
- receives the length of this buffer. 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 *nbytes, int *sign, int force_secure)
-{
- unsigned char *p, *buffer;
- 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. */
- 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
- }
-
- /* This is sub-optimal but we need to do the shift operation because
- the caller has to free the returned buffer. */
- for (p=buffer; !*p && *nbytes; p++, --*nbytes)
- ;
- if (p != buffer)
- memmove (buffer,p, *nbytes);
- return buffer;
-}
-
-
-byte *
-_gcry_mpi_get_buffer (gcry_mpi_t a, unsigned int *nbytes, int *sign)
-{
- return do_get_buffer (a, nbytes, sign, 0);
-}
-
-byte *
-_gcry_mpi_get_secure_buffer (gcry_mpi_t a, unsigned *nbytes, int *sign)
-{
- return do_get_buffer (a, 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;
-
- 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);
-}
-
-
-/* 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_error_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)
- {
- a->sign = !!(*s & 0x80);
- if (a->sign)
- {
- /* FIXME: we have to convert from 2compl to magnitude format */
- mpi_free (a);
- return gcry_error (GPG_ERR_INTERNAL);
- }
- else
- _gcry_mpi_set_buffer (a, s, len, 0);
- }
- if (ret_mpi)
- {
- mpi_normalize ( a );
- *ret_mpi = a;
- }
- else
- mpi_free(a);
- 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);
- 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 : gcry_error (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 gcry_error (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 gcry_error (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)
- {
- a->sign = !!(*s & 0x80);
- if (a->sign)
- {
- /* FIXME: we have to convert from 2compl to magnitude format */
- mpi_free(a);
- return gcry_error (GPG_ERR_INTERNAL);
- }
- else
- _gcry_mpi_set_buffer( a, s, n, 0 );
- }
- 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 gcry_error (GPG_ERR_INV_ARG);
-
- a = secure? mpi_alloc_secure (0) : mpi_alloc(0);
- if (mpi_fromstr (a, (const char *)buffer))
- {
- mpi_free (a);
- return gcry_error (GPG_ERR_INV_OBJ);
- }
- if (ret_mpi)
- {
- mpi_normalize ( a );
- *ret_mpi = a;
- }
- else
- mpi_free(a);
- return 0;
- }
- else
- return gcry_error (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_error_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;
-
- if (!nwritten)
- nwritten = &dummy_nwritten;
-
- len = buflen;
- *nwritten = 0;
- if (format == GCRYMPI_FMT_STD)
- {
- unsigned char *tmp;
- int extra = 0;
- unsigned int n;
-
- if (a->sign)
- return gcry_error (GPG_ERR_INTERNAL); /* Can't handle it yet. */
-
- tmp = _gcry_mpi_get_buffer (a, &n, NULL);
- if (!tmp)
- return gpg_error_from_syserror ();
- if (n && (*tmp & 0x80))
- {
- n++;
- extra=1;
- }
-
- if (buffer && n > len)
- {
- /* The provided buffer is too short. */
- gcry_free (tmp);
- return gcry_error (GPG_ERR_TOO_SHORT);
- }
- if (buffer)
- {
- unsigned char *s = buffer;
-
- if (extra)
- *s++ = 0;
- 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 gcry_error (GPG_ERR_TOO_SHORT);
- if (buffer)
- {
- unsigned char *tmp;
-
- tmp = _gcry_mpi_get_buffer (a, &n, NULL);
- if (!tmp)
- return gpg_error_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( a->sign )
- return gcry_error (GPG_ERR_INV_ARG);
-
- if (buffer && n+2 > len)
- return gcry_error (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, &n, NULL);
- if (!tmp)
- return gpg_error_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;
-
- if (a->sign)
- return gcry_error (GPG_ERR_INTERNAL); /* Can't handle it yet. */
-
- tmp = _gcry_mpi_get_buffer (a, &n, NULL);
- if (!tmp)
- return gpg_error_from_syserror ();
- if (n && (*tmp & 0x80))
- {
- n++;
- extra=1;
- }
-
- if (buffer && n+4 > len)
- {
- gcry_free(tmp);
- return gcry_error (GPG_ERR_TOO_SHORT);
- }
-
- if (buffer)
- {
- unsigned char *s = buffer;
-
- *s++ = n >> 24;
- *s++ = n >> 16;
- *s++ = n >> 8;
- *s++ = n;
- if (extra)
- *s++ = 0;
-
- 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, &n, NULL);
- if (!tmp)
- return gpg_error_from_syserror ();
- if (!n || (*tmp & 0x80))
- extra = 2;
-
- if (buffer && 2*n + extra + !!a->sign + 1 > len)
- {
- gcry_free(tmp);
- return gcry_error (GPG_ERR_TOO_SHORT);
- }
- if (buffer)
- {
- unsigned char *s = buffer;
-
- if (a->sign)
- *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 + !!a->sign + 1;
- }
- gcry_free (tmp);
- return 0;
- }
- else
- return gcry_error (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_error_t
-gcry_mpi_aprint (enum gcry_mpi_format format,
- unsigned char **buffer, size_t *nwritten,
- struct gcry_mpi *a)
-{
- size_t n;
- gcry_error_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) : gcry_malloc (n);
- if (!*buffer)
- return gpg_error_from_syserror ();
- rc = gcry_mpi_print( format, *buffer, n, &n, a );
- if (rc)
- {
- gcry_free(*buffer);
- *buffer = NULL;
- }
- else if (nwritten)
- *nwritten = n;
- return rc;
-}
-
+/* mpicoder.c - Coder for the external representation of MPIs + * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 + * 2008 Free Software Foundation, Inc. + * + * 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; + } + else if( !nbits ) + { +/* log_debug ("an mpi of size 0 is not allowed\n"); */ + 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. */ +} + + +/* Dump the value of A in a format suitable for debugging to + Libgcrypt's logging stream. Note that one leading space but no + trailing space or linefeed will be printed. It is okay to pass + NULL for A. */ +void +gcry_mpi_dump (const gcry_mpi_t a) +{ + int i; + + log_printf (" "); + if (!a) + log_printf ("[MPI_NULL]"); + else + { + if (a->sign) + log_printf ( "-"); +#if BYTES_PER_MPI_LIMB == 2 +# define X "4" +#elif BYTES_PER_MPI_LIMB == 4 +# define X "8" +#elif BYTES_PER_MPI_LIMB == 8 +# define X "16" +#elif BYTES_PER_MPI_LIMB == 16 +# define X "32" +#else +# error please define the format here +#endif + for (i=a->nlimbs; i > 0 ; i-- ) + { + log_printf (i != a->nlimbs? "%0" X "lX":"%lX", (ulong)a->d[i-1]); + } +#undef X + if (!a->nlimbs) + log_printf ("0"); + } +} + +/* Convience function used internally. */ +void +_gcry_log_mpidump (const char *text, gcry_mpi_t a) +{ + log_printf ("%s:", text); + gcry_mpi_dump (a); + log_printf ("\n"); +} + + +/* Return an allocated buffer with the MPI (msb first). NBYTES + receives the length of this buffer. 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 *nbytes, int *sign, int force_secure) +{ + unsigned char *p, *buffer; + 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. */ + 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 + } + + /* This is sub-optimal but we need to do the shift operation because + the caller has to free the returned buffer. */ + for (p=buffer; !*p && *nbytes; p++, --*nbytes) + ; + if (p != buffer) + memmove (buffer,p, *nbytes); + return buffer; +} + + +byte * +_gcry_mpi_get_buffer (gcry_mpi_t a, unsigned int *nbytes, int *sign) +{ + return do_get_buffer (a, nbytes, sign, 0); +} + +byte * +_gcry_mpi_get_secure_buffer (gcry_mpi_t a, unsigned *nbytes, int *sign) +{ + return do_get_buffer (a, 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; + + 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); +} + + +/* 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_error_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) + { + a->sign = !!(*s & 0x80); + if (a->sign) + { + /* FIXME: we have to convert from 2compl to magnitude format */ + mpi_free (a); + return gcry_error (GPG_ERR_INTERNAL); + } + else + _gcry_mpi_set_buffer (a, s, len, 0); + } + if (ret_mpi) + { + mpi_normalize ( a ); + *ret_mpi = a; + } + else + mpi_free(a); + 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); + 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 : gcry_error (GPG_ERR_INV_OBJ); + } + else if (format == GCRYMPI_FMT_SSH) + { + const unsigned char *s = buffer; + size_t n; + + if (len && len < 4) + return gcry_error (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 gcry_error (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) + { + a->sign = !!(*s & 0x80); + if (a->sign) + { + /* FIXME: we have to convert from 2compl to magnitude format */ + mpi_free(a); + return gcry_error (GPG_ERR_INTERNAL); + } + else + _gcry_mpi_set_buffer( a, s, n, 0 ); + } + 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 gcry_error (GPG_ERR_INV_ARG); + + a = secure? mpi_alloc_secure (0) : mpi_alloc(0); + if (mpi_fromstr (a, (const char *)buffer)) + { + mpi_free (a); + return gcry_error (GPG_ERR_INV_OBJ); + } + if (ret_mpi) + { + mpi_normalize ( a ); + *ret_mpi = a; + } + else + mpi_free(a); + return 0; + } + else + return gcry_error (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_error_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; + + if (!nwritten) + nwritten = &dummy_nwritten; + + len = buflen; + *nwritten = 0; + if (format == GCRYMPI_FMT_STD) + { + unsigned char *tmp; + int extra = 0; + unsigned int n; + + if (a->sign) + return gcry_error (GPG_ERR_INTERNAL); /* Can't handle it yet. */ + + tmp = _gcry_mpi_get_buffer (a, &n, NULL); + if (!tmp) + return gpg_error_from_syserror (); + if (n && (*tmp & 0x80)) + { + n++; + extra=1; + } + + if (buffer && n > len) + { + /* The provided buffer is too short. */ + gcry_free (tmp); + return gcry_error (GPG_ERR_TOO_SHORT); + } + if (buffer) + { + unsigned char *s = buffer; + + if (extra) + *s++ = 0; + 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 gcry_error (GPG_ERR_TOO_SHORT); + if (buffer) + { + unsigned char *tmp; + + tmp = _gcry_mpi_get_buffer (a, &n, NULL); + if (!tmp) + return gpg_error_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( a->sign ) + return gcry_error (GPG_ERR_INV_ARG); + + if (buffer && n+2 > len) + return gcry_error (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, &n, NULL); + if (!tmp) + return gpg_error_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; + + if (a->sign) + return gcry_error (GPG_ERR_INTERNAL); /* Can't handle it yet. */ + + tmp = _gcry_mpi_get_buffer (a, &n, NULL); + if (!tmp) + return gpg_error_from_syserror (); + if (n && (*tmp & 0x80)) + { + n++; + extra=1; + } + + if (buffer && n+4 > len) + { + gcry_free(tmp); + return gcry_error (GPG_ERR_TOO_SHORT); + } + + if (buffer) + { + unsigned char *s = buffer; + + *s++ = n >> 24; + *s++ = n >> 16; + *s++ = n >> 8; + *s++ = n; + if (extra) + *s++ = 0; + + 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, &n, NULL); + if (!tmp) + return gpg_error_from_syserror (); + if (!n || (*tmp & 0x80)) + extra = 2; + + if (buffer && 2*n + extra + !!a->sign + 1 > len) + { + gcry_free(tmp); + return gcry_error (GPG_ERR_TOO_SHORT); + } + if (buffer) + { + unsigned char *s = buffer; + + if (a->sign) + *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 + !!a->sign + 1; + } + gcry_free (tmp); + return 0; + } + else + return gcry_error (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_error_t +gcry_mpi_aprint (enum gcry_mpi_format format, + unsigned char **buffer, size_t *nwritten, + struct gcry_mpi *a) +{ + size_t n; + gcry_error_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) : gcry_malloc (n); + if (!*buffer) + return gpg_error_from_syserror (); + rc = gcry_mpi_print( format, *buffer, n, &n, a ); + if (rc) + { + gcry_free(*buffer); + *buffer = NULL; + } + else if (nwritten) + *nwritten = n; + return rc; +} + |