OpenPKG Specs: gcrypt/idea.c@b12dc513f7b7 (annotated)

gcrypt/idea.c@b12dc513f7b7 (annotated)

gcrypt/idea.c

Fri, 03 Aug 2012 15:56:30 +0200

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Fri, 03 Aug 2012 15:56:30 +0200
changeset 459: b12dc513f7b7
permissions: -rw-r--r--

Use upstream man pages to avoid local help2man failures, likely due to
shell capability assumptions or cross platform environment variance.
The upstream man pages are probably better formatted anyway.

 #include <config.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h> /* for memcmp() */
 #include <assert.h>
 #include "types.h"  /* for byte and u32 typedefs */
 #include "g10lib.h"
 #include "cipher.h"
 /* configuration stuff */
 #ifdef __alpha__
   #define SIZEOF_UNSIGNED_LONG 8
 #else
   #define SIZEOF_UNSIGNED_LONG 4
 #endif
 #if defined(__mc68000__) || defined (__sparc__) || defined (__PPC__) \
     || (defined(__mips__) && (defined(MIPSEB) || defined (__MIPSEB__)) ) \
     || defined(__powerpc__) \
     || defined(__hpux__) /* should be replaced by the Macro for the PA */
   #define BIG_ENDIAN_HOST 1
 #else
   #define LITTLE_ENDIAN_HOST 1
 #endif
 #ifndef DIM
   #define DIM(v) (sizeof(v)/sizeof((v)[0]))
   #define DIMof(type,member)   DIM(((type *)0)->member)
 #endif
 /* imports */
 void g10_log_fatal( const char *fmt, ... );
 /* local stuff */
 #define FNCCAST_SETKEY(f)  ((int(*)(void*, byte*, unsigned))(f))
 #define FNCCAST_CRYPT(f)   ((void(*)(void*, byte*, byte*))(f))
 #define IDEA_KEYSIZE 16
 #define IDEA_BLOCKSIZE 8
 #define IDEA_ROUNDS 8
 #define IDEA_KEYLEN (6*IDEA_ROUNDS+4)
 typedef struct {
     u16 ek[IDEA_KEYLEN];
     u16 dk[IDEA_KEYLEN];
     int have_dk;
 } IDEA_context;
 static u16
 mul_inv( u16 x )
 {
     u16 t0, t1;
     u16 q, y;
     if( x < 2 )
 	return x;
     t1 = 0x10001L / x;
     y =  0x10001L % x;
     if( y == 1 )
 	return (1-t1) & 0xffff;
     t0 = 1;
     do {
 	q = x / y;
 	x = x % y;
 	t0 += q * t1;
 	if( x == 1 )
 	    return t0;
 	q = y / x;
 	y = y % x;
 	t1 += q * t0;
     } while( y != 1 );
     return (1-t1) & 0xffff;
 }
 static void
 cipher( byte *outbuf, const byte *inbuf, u16 *key )
 {
     u16 x1, x2, x3,x4, s2, s3;
     u16 *in, *out;
     int r = IDEA_ROUNDS;
   #define MUL(x,y) \
 	do {u16 _t16; u32 _t32; 		    \
 	    if( (_t16 = (y)) ) {		    \
 		if( (x = (x)&0xffff) ) {	    \
 		    _t32 = (u32)x * _t16;	    \
 		    x = _t32 & 0xffff;		    \
 		    _t16 = _t32 >> 16;		    \
 		    x = ((x)-_t16) + (x<_t16?1:0);  \
 		}				    \
 		else {				    \
 		    x = 1 - _t16;		    \
 		}				    \
 	    }					    \
 	    else {				    \
 		x = 1 - x;			    \
 	    }					    \
 	} while(0)
     in = (u16*)inbuf;
     x1 = *in++;
     x2 = *in++;
     x3 = *in++;
     x4 = *in;
   #ifdef LITTLE_ENDIAN_HOST
     x1 = (x1>>8) | (x1<<8);
     x2 = (x2>>8) | (x2<<8);
     x3 = (x3>>8) | (x3<<8);
     x4 = (x4>>8) | (x4<<8);
   #endif
     do {
 	MUL(x1, *key++);
 	x2 += *key++;
 	x3 += *key++;
 	MUL(x4, *key++ );
 	s3 = x3;
 	x3 ^= x1;
 	MUL(x3, *key++);
 	s2 = x2;
 	x2 ^=x4;
 	x2 += x3;
 	MUL(x2, *key++);
 	x3 += x2;
 	x1 ^= x2;
 	x4 ^= x3;
 	x2 ^= s3;
 	x3 ^= s2;
     } while( --r );
     MUL(x1, *key++);
     x3 += *key++;
     x2 += *key++;
     MUL(x4, *key);
     out = (u16*)outbuf;
   #ifdef LITTLE_ENDIAN_HOST
     *out++ = (x1>>8) | (x1<<8);
     *out++ = (x3>>8) | (x3<<8);
     *out++ = (x2>>8) | (x2<<8);
     *out   = (x4>>8) | (x4<<8);
   #else
     *out++ = x1;
     *out++ = x3;
     *out++ = x2;
     *out   = x4;
   #endif
   #undef MUL
 }
 static void
 expand_key( const byte *userkey, u16 *ek )
 {
     int i,j;
     for(j=0; j < 8; j++ ) {
 	ek[j] = (*userkey << 8) + userkey[1];
 	userkey += 2;
     }
     for(i=0; j < IDEA_KEYLEN; j++ ) {
 	i++;
 	ek[i+7] = ek[i&7] << 9 | ek[(i+1)&7] >> 7;
 	ek += i & 8;
 	i &= 7;
     }
 }
 static void
 invert_key( u16 *ek, u16 dk[IDEA_KEYLEN] )
 {
     int i;
     u16 t1, t2, t3;
     u16 temp[IDEA_KEYLEN];
     u16 *p = temp + IDEA_KEYLEN;
     t1 = mul_inv( *ek++ );
     t2 = -*ek++;
     t3 = -*ek++;
     *--p = mul_inv( *ek++ );
     *--p = t3;
     *--p = t2;
     *--p = t1;
     for(i=0; i < IDEA_ROUNDS-1; i++ ) {
 	t1 = *ek++;
 	*--p = *ek++;
 	*--p = t1;
 	t1 = mul_inv( *ek++ );
 	t2 = -*ek++;
 	t3 = -*ek++;
 	*--p = mul_inv( *ek++ );
 	*--p = t2;
 	*--p = t3;
 	*--p = t1;
     }
     t1 = *ek++;
     *--p = *ek++;
     *--p = t1;
     t1 = mul_inv( *ek++ );
     t2 = -*ek++;
     t3 = -*ek++;
     *--p = mul_inv( *ek++ );
     *--p = t3;
     *--p = t2;
     *--p = t1;
     memcpy(dk, temp, sizeof(temp) );
     memset(temp, 0, sizeof(temp) );  /* burn temp */
 }
 static int
 do_idea_setkey( IDEA_context *c, const byte *key, unsigned int keylen )
 {
     assert(keylen == 16);
     c->have_dk = 0;
     expand_key( key, c->ek );
     invert_key( c->ek, c->dk );
     return 0;
 }
 static gcry_err_code_t
 idea_setkey (void *context, const byte *key, unsigned int keylen)
 {
   IDEA_context *ctx = context;
   int rc = do_idea_setkey (ctx, key, keylen);
   _gcry_burn_stack (23+6*sizeof(void*));
   return rc;
 }
 static void
 do_idea_encrypt( IDEA_context *c, byte *outbuf, const byte *inbuf )
 {
     cipher( outbuf, inbuf, c->ek );
 }
 static void
 idea_encrypt (void *context, byte *out, const byte *in)
 {
   IDEA_context *ctx = context;
   do_idea_encrypt (ctx, out, in);
   _gcry_burn_stack (24+3*sizeof (void*));
 }
 static void
 do_idea_decrypt( IDEA_context *c, byte *outbuf, const byte *inbuf )
 {
     if( !c->have_dk ) {
        c->have_dk = 1;
        invert_key( c->ek, c->dk );
     }
     cipher( outbuf, inbuf, c->dk );
 }
 static void
 idea_decrypt (void *context, byte *out, const byte *in)
 {
   IDEA_context *ctx = context;
   do_idea_decrypt (ctx, out, in);
   _gcry_burn_stack (24+3*sizeof (void*));
 }
 gcry_cipher_spec_t _gcry_cipher_spec_idea =
 {
     "IDEA", NULL, NULL, IDEA_BLOCKSIZE, 128, sizeof (IDEA_context),
     idea_setkey, idea_encrypt, idea_decrypt,
 };

OpenPKG Specs / annotate

gcrypt/idea.c@b12dc513f7b7 (annotated)

gcrypt/idea.c