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gnupg/cipher/md.c

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/* md.c - message digest dispatcher
* Copyright (C) 1998,1999 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "g10lib.h"
#include "cipher.h"
#include "dynload.h"
#include "rmd.h"
struct md_digest_list_s;
/* this structure is put right after the GCRY_MD_HD buffer, so that
* only one memory block is needed. */
struct gcry_md_context {
int magic;
int secure;
FILE *debug;
int finalized;
struct md_digest_list_s *list;
byte *macpads;
};
#define CTX_MAGIC_NORMAL 0x11071961
#define CTX_MAGIC_SECURE 0x16917011
static const char * digest_algo_to_string( int algo );
static int check_digest_algo( int algo );
static GCRY_MD_HD md_open( int algo, int secure, int hmac );
static int md_enable( GCRY_MD_HD hd, int algo );
static GCRY_MD_HD md_copy( GCRY_MD_HD a );
static void md_close(GCRY_MD_HD a);
static void md_write( GCRY_MD_HD a, byte *inbuf, size_t inlen);
static void md_final(GCRY_MD_HD a);
static byte *md_read( GCRY_MD_HD a, int algo );
static int md_get_algo( GCRY_MD_HD a );
static int md_digest_length( int algo );
static const byte *md_asn_oid( int algo, size_t *asnlen, size_t *mdlen );
static void md_start_debug( GCRY_MD_HD a, const char *suffix );
static void md_stop_debug( GCRY_MD_HD a );
/****************
* This structure is used for the list of available algorithms
* and for the list of algorithms in GCRY_MD_HD.
*/
struct md_digest_list_s {
struct md_digest_list_s *next;
const char *name;
int algo;
byte *asnoid;
int asnlen;
int mdlen;
void (*init)( void *c );
void (*write)( void *c, byte *buf, size_t nbytes );
void (*final)( void *c );
byte *(*read)( void *c );
size_t contextsize; /* allocate this amount of context */
PROPERLY_ALIGNED_TYPE context;
};
static struct md_digest_list_s *digest_list;
static struct md_digest_list_s *
new_list_item( int algo,
const char *(*get_info)( int, size_t*,byte**, int*, int*,
void (**)(void*),
void (**)(void*,byte*,size_t),
void (**)(void*),byte *(**)(void*)) )
{
struct md_digest_list_s *r;
r = g10_xcalloc( 1, sizeof *r );
r->algo = algo,
r->name = (*get_info)( algo, &r->contextsize,
&r->asnoid, &r->asnlen, &r->mdlen,
&r->init, &r->write, &r->final, &r->read );
if( !r->name ) {
g10_free(r);
r = NULL;
}
return r;
}
/****************
* Try to load the modules with the requeste algorithm
* and return true if new modules are available
* If req_alog is -1 try to load all digest algorithms.
*/
static int
load_digest_module( int req_algo )
{
static int initialized = 0;
static u32 checked_algos[256/32];
static int checked_all = 0;
struct md_digest_list_s *r;
void *context = NULL;
int algo;
int any = 0;
const char *(*get_info)( int, size_t*,byte**, int*, int*,
void (**)(void*),
void (**)(void*,byte*,size_t),
void (**)(void*),byte *(**)(void*));
if( !initialized ) {
cipher_modules_constructor();
initialized = 1;
}
algo = req_algo;
if( algo > 255 || !algo )
return 0; /* algorithm number too high (does not fit into out bitmap)*/
if( checked_all )
return 0; /* already called with -1 */
if( algo < 0 )
checked_all = 1;
else if( (checked_algos[algo/32] & (1 << (algo%32))) )
return 0; /* already checked and not found */
else
checked_algos[algo/32] |= (1 << (algo%32));
while( enum_gnupgext_digests( &context, &algo, &get_info ) ) {
if( req_algo != -1 && algo != req_algo )
continue;
for(r=digest_list; r; r = r->next )
if( r->algo == algo )
break;
if( r ) {
log_info("skipping digest %d: already loaded\n", algo );
continue;
}
r = new_list_item( algo, get_info );
if( ! r ) {
log_info("skipping digest %d: no name\n", algo );
continue;
}
/* put it into the list */
if( g10_log_verbosity( 2 ) )
log_info("loaded digest %d\n", algo);
r->next = digest_list;
digest_list = r;
any = 1;
if( req_algo != -1 )
break;
}
enum_gnupgext_digests( &context, NULL, NULL );
return any;
}
/****************
* Map a string to the digest algo
*/
int
gcry_md_map_name( const char *string )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next )
if( !stricmp( r->name, string ) )
return r->algo;
} while( !r && load_digest_module(-1) );
return 0;
}
/****************
* Map a digest algo to a string
*/
static const char *
digest_algo_to_string( int algo )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next )
if( r->algo == algo )
return r->name;
} while( !r && load_digest_module( algo ) );
return NULL;
}
/****************
* This function simply returns the name of the algorithm or some constant
* string when there is no algo. It will never return NULL.
* Use the macro gcry_md_test_algo() to check whether the algorithm
* is valid.
*/
const char *
gcry_md_algo_name( int algo )
{
const char *s = digest_algo_to_string( algo );
return s? s: "?";
}
static int
check_digest_algo( int algo )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next )
if( r->algo == algo )
return 0;
} while( !r && load_digest_module(algo) );
return GCRYERR_INV_MD_ALGO;
}
/****************
* Open a message digest handle for use with algorithm ALGO.
* More algorithms may be added by md_enable(). The initial algorithm
* may be 0.
*/
static GCRY_MD_HD
md_open( int algo, int secure, int hmac )
{
GCRY_MD_HD hd;
struct gcry_md_context *ctx;
int bufsize = secure? 512 : 1024;
size_t n;
/* Allocate a memory area to hold the caller visible buffer with it's
* control information and the data required by this module. Set the
* context pointer at the beginning to this area.
* We have to use this strange scheme because we want to hide the
* internal data but have a variable sized buffer.
*
* +---+------+---........------+-------------+
* !ctx! bctl ! buffer ! private !
* +---+------+---........------+-------------+
* ! ^
* !---------------------------!
*
* We have to make sture that private is well aligned.
*/
n = sizeof( struct gcry_md_handle ) + bufsize;
n = ((n + sizeof(PROPERLY_ALIGNED_TYPE)-1)
/ sizeof(PROPERLY_ALIGNED_TYPE) ) * sizeof(PROPERLY_ALIGNED_TYPE);
/* allocate and set the Context pointer to the private data */
hd = secure ? g10_malloc_secure( n + sizeof( struct gcry_md_context ) )
: g10_malloc( n + sizeof( struct gcry_md_context ) );
if( !hd ) {
set_lasterr( GCRYERR_NO_MEM );
return NULL;
}
hd->ctx = ctx = (struct gcry_md_context*)( (char*)hd + n );
/* setup the globally visible data (bctl in the diagram)*/
hd->bufsize = n - sizeof( struct gcry_md_handle ) + 1;
hd->bufpos = 0;
/* initialize the private data */
memset( hd->ctx, 0, sizeof *hd->ctx );
ctx->magic = secure ? CTX_MAGIC_SECURE : CTX_MAGIC_NORMAL;
ctx->secure = secure;
if( hmac ) {
ctx->macpads = g10_malloc_secure( 128 );
if( !ctx->macpads ) {
md_close( hd );
set_lasterr( GCRYERR_NO_MEM );
return NULL;
}
}
fast_random_poll(); /* FIXME: should we really do that? */
if( algo && md_enable( hd, algo ) ) {
md_close( hd );
return NULL;
}
return hd;
}
GCRY_MD_HD
gcry_md_open( int algo, unsigned int flags )
{
GCRY_MD_HD hd;
/* fixme: check that algo is available and that only valid
* flag values are used */
hd = md_open( algo, (flags & GCRY_MD_FLAG_SECURE),
(flags & GCRY_MD_FLAG_HMAC) );
return hd;
}
static int
md_enable( GCRY_MD_HD hd, int algo )
{
struct gcry_md_context *h = hd->ctx;
struct md_digest_list_s *r, *ac;
for( ac=h->list; ac; ac = ac->next )
if( ac->algo == algo )
return 0; /* already enabled */
/* find the algorithm */
do {
for(r = digest_list; r; r = r->next )
if( r->algo == algo )
break;
} while( !r && load_digest_module( algo ) );
if( !r ) {
log_debug("md_enable: algorithm %d not available\n", algo );
return set_lasterr( GCRYERR_INV_MD_ALGO );
}
/* and allocate a new list entry */
ac = h->secure? g10_malloc_secure( sizeof *ac + r->contextsize
- sizeof(r->context) )
: g10_malloc( sizeof *ac + r->contextsize
- sizeof(r->context) );
if( !ac )
return set_lasterr( GCRYERR_NO_MEM );
*ac = *r;
ac->next = h->list;
h->list = ac;
/* and init this instance */
(*ac->init)( &ac->context.c );
return 0;
}
int
gcry_md_enable( GCRY_MD_HD hd, int algo )
{
return md_enable( hd, algo );
}
static GCRY_MD_HD
md_copy( GCRY_MD_HD ahd )
{
struct gcry_md_context *a = ahd->ctx;
struct gcry_md_context *b;
GCRY_MD_HD bhd;
struct md_digest_list_s *ar, *br;
size_t n;
if( ahd->bufpos )
md_write( ahd, NULL, 0 );
n = (char*)ahd->ctx - (char*)ahd;
bhd = a->secure ? g10_malloc_secure( n + sizeof( struct gcry_md_context ) )
: g10_malloc( n + sizeof( struct gcry_md_context ) );
if( !bhd ) {
set_lasterr( GCRYERR_NO_MEM );
return NULL;
}
bhd->ctx = b = (struct gcry_md_context*)( (char*)bhd + n );
/* no need to copy the buffer due to the write above */
assert( ahd->bufsize == (n - sizeof( struct gcry_md_handle ) + 1) );
bhd->bufsize = ahd->bufsize;
bhd->bufpos = 0; assert( !ahd->bufpos );
memcpy( b, a, sizeof *a );
b->list = NULL;
b->debug = NULL;
if( a->macpads ) {
b->macpads = g10_malloc_secure( 128 );
memcpy( b->macpads, a->macpads, 128 );
}
/* and now copy the complete list of algorithms */
/* I know that the copied list is reversed, but that doesn't matter */
for( ar=a->list; ar; ar = ar->next ) {
br = a->secure ? g10_xmalloc_secure( sizeof *br + ar->contextsize
- sizeof(ar->context) )
: g10_xmalloc( sizeof *br + ar->contextsize
- sizeof(ar->context) );
memcpy( br, ar, sizeof(*br) + ar->contextsize
- sizeof(ar->context) );
br->next = b->list;
b->list = br;
}
if( a->debug )
md_start_debug( bhd, "unknown" );
return bhd;
}
GCRY_MD_HD
gcry_md_copy( GCRY_MD_HD hd )
{
return md_copy( hd );
}
/****************
* Reset all contexts and discard any buffered stuff. This may be used
* instead of a md_close(); md_open().
*/
void
gcry_md_reset( GCRY_MD_HD a )
{
struct md_digest_list_s *r;
a->bufpos = a->ctx->finalized = 0;
for( r=a->ctx->list; r; r = r->next ) {
memset( r->context.c, 0, r->contextsize );
(*r->init)( &r->context.c );
}
if( a->ctx->macpads ) {
md_write( a, a->ctx->macpads, 64 ); /* inner pad */
}
}
static void
md_close(GCRY_MD_HD a)
{
struct md_digest_list_s *r, *r2;
if( !a )
return;
if( a->ctx->debug )
md_stop_debug(a);
for(r=a->ctx->list; r; r = r2 ) {
r2 = r->next;
g10_free(r);
}
g10_free(a->ctx->macpads);
g10_free(a);
}
void
gcry_md_close( GCRY_MD_HD hd )
{
md_close( hd );
}
static void
md_write( GCRY_MD_HD a, byte *inbuf, size_t inlen)
{
struct md_digest_list_s *r;
if( a->ctx->debug ) {
if( a->bufpos && fwrite(a->buf, a->bufpos, 1, a->ctx->debug ) != 1 )
BUG();
if( inlen && fwrite(inbuf, inlen, 1, a->ctx->debug ) != 1 )
BUG();
}
for(r=a->ctx->list; r; r = r->next ) {
if( a->bufpos )
(*r->write)( &r->context.c, a->buf, a->bufpos );
(*r->write)( &r->context.c, inbuf, inlen );
}
a->bufpos = 0;
}
void
gcry_md_write( GCRY_MD_HD hd, const byte *inbuf, size_t inlen)
{
md_write( hd, (byte*)inbuf, inlen );
}
static void
md_final(GCRY_MD_HD a)
{
struct md_digest_list_s *r;
if( a->ctx->finalized )
return;
if( a->bufpos )
md_write( a, NULL, 0 );
for(r=a->ctx->list; r; r = r->next ) {
(*r->final)( &r->context.c );
}
a->ctx->finalized = 1;
if( a->ctx->macpads ) { /* finish the hmac */
int algo = md_get_algo( a );
byte *p = md_read( a, algo );
size_t dlen = md_digest_length(algo);
GCRY_MD_HD om = md_open( algo, a->ctx->secure, 0 );
if( !om )
g10_fatal_error( gcry_errno(), NULL );
md_write( om, a->ctx->macpads+64, 64 );
md_write( om, p, dlen );
md_final( om );
/* replace our digest with the mac (they have the same size) */
memcpy( p, md_read( om, algo ), dlen );
md_close( om );
}
}
static int
prepare_macpads( GCRY_MD_HD hd, byte *key, size_t keylen)
{
int i;
int algo = md_get_algo( hd );
byte *helpkey = NULL;
byte *ipad, *opad;
if( !algo )
return GCRYERR_INV_MD_ALGO; /* i.e. no algo enabled */
if( keylen > 64 ) {
helpkey = g10_malloc_secure( md_digest_length( algo ) );
if( !helpkey )
return GCRYERR_NO_MEM;
gcry_md_hash_buffer( algo, helpkey, key, keylen );
key = helpkey;
keylen = md_digest_length( algo );
assert( keylen <= 64 );
}
memset( hd->ctx->macpads, 0, 128 );
ipad = hd->ctx->macpads;
opad = hd->ctx->macpads+64;
memcpy( ipad, key, keylen );
memcpy( opad, key, keylen );
for(i=0; i < 64; i++ ) {
ipad[i] ^= 0x36;
opad[i] ^= 0x5c;
}
g10_free( helpkey );
return 0;
}
int
gcry_md_ctl( GCRY_MD_HD hd, int cmd, byte *buffer, size_t buflen)
{
int rc = 0;
if( cmd == GCRYCTL_FINALIZE )
md_final( hd );
else if( cmd == GCRYCTL_SET_KEY ) {
rc = gcry_md_setkey ( hd, buffer, buflen );
}
else if( cmd == GCRYCTL_START_DUMP ) {
md_start_debug( hd, buffer );
}
else if( cmd == GCRYCTL_STOP_DUMP ) {
md_stop_debug( hd );
}
else
rc = GCRYERR_INV_OP;
return set_lasterr( rc );
}
int
gcry_md_setkey( GCRY_MD_HD hd, const char *key, size_t keylen )
{
int rc = 0;
if( !(hd->ctx->macpads ) )
rc = GCRYERR_CONFLICT;
else if ( !(rc = prepare_macpads( hd, key, keylen )) )
gcry_md_reset( hd );
return rc;
}
/****************
* if ALGO is null get the digest for the used algo (which should be only one)
*/
static byte *
md_read( GCRY_MD_HD a, int algo )
{
struct md_digest_list_s *r;
if( !algo ) { /* return the first algorithm */
if( (r=a->ctx->list) ) {
if( r->next )
log_debug("more than algorithm in md_read(0)\n");
return (*r->read)( &r->context.c );
}
}
else {
for(r=a->ctx->list; r; r = r->next )
if( r->algo == algo )
return (*r->read)( &r->context.c );
}
BUG();
return NULL;
}
/****************
* Read out the complete digest, this function implictly finalizes
* the hash.
*/
byte *
gcry_md_read( GCRY_MD_HD hd, int algo )
{
gcry_md_ctl( hd, GCRYCTL_FINALIZE, NULL, 0 );
return md_read( hd, algo);
}
/****************
* This function combines md_final and md_read but keeps the context
* intact. This function can be used to calculate intermediate
* digests. The digest is copied into buffer and the digestlength is
* returned. If buffer is NULL only the needed size for buffer is returned.
* buflen gives the max size of buffer. If the buffer is too shourt to
* hold the complete digest, the buffer is filled with as many bytes are
* possible and this value is returned.
*/
#if 0
static int
md_digest( GCRY_MD_HD a, int algo, byte *buffer, int buflen )
{
struct md_digest_list_s *r = NULL;
char *context;
char *digest;
if( a->bufpos )
md_write( a, NULL, 0 );
if( !algo ) { /* return digest for the first algorithm */
if( (r=a->ctx->list) && r->next )
log_debug("more than algorithm in md_digest(0)\n");
}
else {
for(r=a->ctx->list; r; r = r->next )
if( r->algo == algo )
break;
}
if( !r )
BUG();
if( !buffer )
return r->mdlen;
/* I don't want to change the interface, so I simply work on a copy
* of the context (extra overhead - should be fixed)*/
context = a->ctx->secure ? g10_xmalloc_secure( r->contextsize )
: g10_xmalloc( r->contextsize );
memcpy( context, r->context.c, r->contextsize );
(*r->final)( context );
digest = (*r->read)( context );
if( buflen > r->mdlen )
buflen = r->mdlen;
memcpy( buffer, digest, buflen );
g10_free(context);
return buflen;
}
#endif
/****************
* Read out an intermediate digest.
*/
int
gcry_md_get( GCRY_MD_HD hd, int algo, byte *buffer, int buflen )
{
/*md_digest ... */
return GCRYERR_INTERNAL;
}
/****************
* Shortcut function to hash a buffer with a given algo. The only supported
* algorithm is RIPE-MD. The supplied digest buffer must be large enough
* to store the resulting hash. No error is returned, the function will
* abort on an invalid algo. DISABLED_ALGOS are ignored here.
*/
void
gcry_md_hash_buffer( int algo, char *digest, const char *buffer, size_t length)
{
if( algo == GCRY_MD_RMD160 )
rmd160_hash_buffer( digest, buffer, length );
else { /* for the others we do not have a fast function, so
* we use the normal functions to do it */
GCRY_MD_HD h = md_open( algo, 0, 0 );
if( !h )
BUG(); /* algo not available */
md_write( h, (byte*)buffer, length );
md_final( h );
memcpy( digest, md_read( h, algo ), md_digest_length( algo ) );
}
}
static int
md_get_algo( GCRY_MD_HD a )
{
struct md_digest_list_s *r;
if( (r=a->ctx->list) ) {
if( r->next )
log_error("WARNING: more than algorithm in md_get_algo()\n");
return r->algo;
}
return 0;
}
int
gcry_md_get_algo( GCRY_MD_HD hd )
{
return md_get_algo( hd ); /* fixme: we need error handling */
}
/****************
* Return the length of the digest
*/
static int
md_digest_length( int algo )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next ) {
if( r->algo == algo )
return r->mdlen;
}
} while( !r && load_digest_module( algo ) );
return 0;
}
/****************
* Return the length of the digest in bytes.
* This function will return 0 in case of errors.
*/
unsigned int
gcry_md_get_algo_dlen( int algo )
{
/* we do some very quick checks here */
switch( algo )
{
case GCRY_MD_MD5: return 16;
case GCRY_MD_SHA1:
case GCRY_MD_RMD160: return 20;
default: {
int len = md_digest_length( algo );
if( !len )
set_lasterr( GCRYERR_INV_MD_ALGO );
return 0;
}
}
}
/* Hmmm: add a mode to enumerate the OIDs
* to make g10/sig-check.c more portable */
static const byte *
md_asn_oid( int algo, size_t *asnlen, size_t *mdlen )
{
struct md_digest_list_s *r;
do {
for(r = digest_list; r; r = r->next ) {
if( r->algo == algo ) {
if( asnlen )
*asnlen = r->asnlen;
if( mdlen )
*mdlen = r->mdlen;
return r->asnoid;
}
}
} while( !r && load_digest_module( algo ) );
log_bug("no asn for md algo %d\n", algo);
return NULL;
}
/****************
* Return information about the given cipher algorithm
* WHAT select the kind of information returned:
* GCRYCTL_TEST_ALGO:
* Returns 0 when the specified algorithm is available for use.
* buffer and nbytes must be zero.
* GCRYCTL_GET_ASNOID:
* Return the ASNOID of the algorithm in buffer. if buffer is NULL, only
* the required length is returned.
*
* On error the value -1 is returned and the error reason may be
* retrieved by gcry_errno().
* Note: Because this function is in most caes used to return an
* integer value, we can make it easier for the caller to just look at
* the return value. The caller will in all cases consult the value
* and thereby detecting whether a error occured or not (i.e. while checking
* the block size)
*/
int
gcry_md_algo_info( int algo, int what, void *buffer, size_t *nbytes)
{
switch( what ) {
case GCRYCTL_TEST_ALGO:
if( buffer || nbytes ) {
set_lasterr( GCRYERR_INV_ARG );
return -1;
}
if( check_digest_algo( algo ) ) {
set_lasterr( GCRYERR_INV_MD_ALGO );
return -1;
}
break;
case GCRYCTL_GET_ASNOID: {
size_t asnlen;
const char *asn = md_asn_oid( algo, &asnlen, NULL );
if( buffer && *nbytes >= asnlen ) {
memcpy( buffer, asn, asnlen );
*nbytes = asnlen;
return 0;
}
if( !buffer && nbytes ) {
*nbytes = asnlen;
return 0;
}
set_lasterr( buffer ? GCRYERR_TOO_SHORT : GCRYERR_INV_ARG );
return -1;
}
break;
default:
set_lasterr( GCRYERR_INV_OP );
return -1;
}
return 0;
}
static void
md_start_debug( GCRY_MD_HD md, const char *suffix )
{
static int idx=0;
char buf[25];
if( md->ctx->debug ) {
log_debug("Oops: md debug already started\n");
return;
}
idx++;
sprintf(buf, "dbgmd-%05d.%.10s", idx, suffix );
md->ctx->debug = fopen(buf, "w");
if( !md->ctx->debug )
log_debug("md debug: can't open %s\n", buf );
}
static void
md_stop_debug( GCRY_MD_HD md )
{
if( md->ctx->debug ) {
if( md->bufpos )
md_write( md, NULL, 0 );
fclose(md->ctx->debug);
md->ctx->debug = NULL;
}
#ifdef HAVE_U64_TYPEDEF
{ /* a kludge to pull in the __muldi3 for Solaris */
volatile u32 a = (u32)(ulong)md;
volatile u64 b = 42;
volatile u64 c;
c = a * b;
}
#endif
}
/****************
* Return information about the digest handle.
* GCRYCTL_IS_SECURE:
* Returns 1 when the handle works on secured memory
* otherwise 0 is returned. There is no error return.
*/
int
gcry_md_info( GCRY_MD_HD h, int cmd, void *buffer, size_t *nbytes)
{
switch( cmd ) {
case GCRYCTL_IS_SECURE:
return h->ctx->secure;
default:
set_lasterr( GCRYERR_INV_OP );
return -1;
}
return 0;
}
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