mirror of
https://github.com/rvtr/TwlIPL.git
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60f18e5554
git-svn-id: file:///Users/lillianskinner/Downloads/platinum/twl/TwlIPL/trunk@1 b08762b0-b915-fc4b-9d8c-17b2551a87ff
122 lines
2.7 KiB
C
122 lines
2.7 KiB
C
/* $Id$ */
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/*
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* Copyright (C) 1998-2002 RSA Security Inc. All rights reserved.
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*
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* This work contains proprietary information of RSA Security.
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* Distribution is limited to authorized licensees of RSA
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* Security. Any unauthorized reproduction, distribution or
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* modification of this work is strictly prohibited.
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*
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*/
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#include "bn_lcl.h"
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int BN_MONT_CTX_set_word(mont,mod,ctx)
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BN_MONT_CTX *mont;
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BIGNUM *mod;
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BN_CTX *ctx;
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{
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BIGNUM Ri,*R;
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#if 1
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BN_ULONG tmod,rr;
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#else
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BN_ULONG buf[2];
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BIGNUM tmod;
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#endif
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bn_check_top(mod);
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if (mod->top == 0) return(0);
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R= &(mont->RR); /* grab RR as a temp */
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if (BN_copy(&(mont->N),mod) == NULL) /* Set N */
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return(0);
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BN_init(&Ri);
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mont->use_word=1;
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/* EAY is this number of words to shift, or the number to shift to end up
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* with a '1' in the next word?
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* for 8 bit words, is 0x01ab == 1 or 2
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*/
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mont->riw=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2;
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if (!BN_zero(R)) return(0);
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/* We are now setting a number which is larger than our current
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* one after we do the shift
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*/
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if (!BN_set_bit(R,BN_BITS2))
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goto err;
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#if 0
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tmod.d=buf;
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tmod.top=1;
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tmod.max=mod->max;
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tmod.neg=mod->neg;
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buf[0]=mod->d[0]&BN_MASK2;
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buf[1]=0;
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if ((BN_mod_inverse(&Ri,R,&tmod,ctx)) == NULL)
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goto err;
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#else
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tmod=mod->d[0];
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rr=BN_mod_inverse_word(tmod);
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if (!BN_set_word(&Ri,rr))
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goto err;
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#endif
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/* R*Ri */
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if (!BN_lshift(&Ri,&Ri,BN_BITS2))
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goto err;
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if (!BN_is_zero(&Ri))
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(void)BN_sub_word(&Ri,1);
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else
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{
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/* This is not common..., 1 in BN_MASK2,
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* It happens when buf[0] was == 1. So for 8 bit,
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* this is 1/256, 16bit, 1 in 2^16 etc.
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*/
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if (!BN_set_word(&Ri,BN_MASK2))
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goto err;
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}
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#if 0
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BN_div(&Ri,NULL,&Ri,&tmod,ctx);
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//BN_div_word(&Ri,tmod);
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mont->n0=Ri.d[0];
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#else
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#if 0
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{
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BN_ULONG h,l;
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h=l=0;
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if (Ri.top >= 2) h=Ri.d[1];
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if (Ri.top >= 1) l=Ri.d[0];
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mont->n0=bn_div_words(h,l,tmod);
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}
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#endif
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mont->n0=bn_div_words(
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(Ri.top >= 2)?Ri.d[1]:0,
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(Ri.top >= 1)?Ri.d[0]:0,
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tmod);
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#endif
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/* mod->top=z; */
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/* setup RR for conversions */
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(void)BN_zero(&(mont->RR));
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if (!BN_set_bit(&(mont->RR),mont->riw*2*BN_BITS2))
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goto err;
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(void)BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx);
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bn_zexpand(&(mont->RR),mont->riw);
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#if 0
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bn_zexpand(&(mont->Ni),mont->riw); /*This is not used? */
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#endif
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err:
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BN_free(&Ri);
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return(1);
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}
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