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-rw-r--r--crypto/bn/bn_exp.c510
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diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
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+/* crypto/bn/bn_exp.c */
+/* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com)
+ * All rights reserved.
+ *
+ * This package is an SSL implementation written
+ * by Eric Young (eay@cryptsoft.com).
+ * The implementation was written so as to conform with Netscapes SSL.
+ *
+ * This library is free for commercial and non-commercial use as long as
+ * the following conditions are aheared to. The following conditions
+ * apply to all code found in this distribution, be it the RC4, RSA,
+ * lhash, DES, etc., code; not just the SSL code. The SSL documentation
+ * included with this distribution is covered by the same copyright terms
+ * except that the holder is Tim Hudson (tjh@cryptsoft.com).
+ *
+ * Copyright remains Eric Young's, and as such any Copyright notices in
+ * the code are not to be removed.
+ * If this package is used in a product, Eric Young should be given attribution
+ * as the author of the parts of the library used.
+ * This can be in the form of a textual message at program startup or
+ * in documentation (online or textual) provided with the package.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * "This product includes cryptographic software written by
+ * Eric Young (eay@cryptsoft.com)"
+ * The word 'cryptographic' can be left out if the rouines from the library
+ * being used are not cryptographic related :-).
+ * 4. If you include any Windows specific code (or a derivative thereof) from
+ * the apps directory (application code) you must include an acknowledgement:
+ * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * The licence and distribution terms for any publically available version or
+ * derivative of this code cannot be changed. i.e. this code cannot simply be
+ * copied and put under another distribution licence
+ * [including the GNU Public Licence.]
+ */
+
+#include <stdio.h>
+#include "cryptlib.h"
+#include "bn_lcl.h"
+
+/* slow but works */
+int BN_mod_mul(ret, a, b, m, ctx)
+BIGNUM *ret;
+BIGNUM *a;
+BIGNUM *b;
+BIGNUM *m;
+BN_CTX *ctx;
+ {
+ BIGNUM *t;
+ int r=0;
+
+ t=ctx->bn[ctx->tos++];
+ if (a == b)
+ { if (!BN_sqr(t,a,ctx)) goto err; }
+ else
+ { if (!BN_mul(t,a,b)) goto err; }
+ if (!BN_mod(ret,t,m,ctx)) goto err;
+ r=1;
+err:
+ ctx->tos--;
+ return(r);
+ }
+
+#if 0
+/* this one works - simple but works */
+int BN_mod_exp(r,a,p,m,ctx)
+BIGNUM *r,*a,*p,*m;
+BN_CTX *ctx;
+ {
+ int i,bits,ret=0;
+ BIGNUM *v,*tmp;
+
+ v=ctx->bn[ctx->tos++];
+ tmp=ctx->bn[ctx->tos++];
+
+ if (BN_copy(v,a) == NULL) goto err;
+ bits=BN_num_bits(p);
+
+ if (BN_is_odd(p))
+ { if (BN_copy(r,a) == NULL) goto err; }
+ else { if (BN_one(r)) goto err; }
+
+ for (i=1; i<bits; i++)
+ {
+ if (!BN_sqr(tmp,v,ctx)) goto err;
+ if (!BN_mod(v,tmp,m,ctx)) goto err;
+ if (BN_is_bit_set(p,i))
+ {
+ if (!BN_mul(tmp,r,v)) goto err;
+ if (!BN_mod(r,tmp,m,ctx)) goto err;
+ }
+ }
+ ret=1;
+err:
+ ctx->tos-=2;
+ return(ret);
+ }
+
+#endif
+
+int BN_mod_exp(r,a,p,m,ctx)
+BIGNUM *r;
+BIGNUM *a;
+BIGNUM *p;
+BIGNUM *m;
+BN_CTX *ctx;
+ {
+ int ret;
+
+#ifdef MONT_MUL_MOD
+ /* I have finally been able to take out this pre-condition of
+ * the top bit being set. It was caused by an error in BN_div
+ * with negatives. There was also another problem when for a^b%m
+ * a >= m. eay 07-May-97 */
+/* if ((m->d[m->top-1]&BN_TBIT) && BN_is_odd(m)) */
+
+ if (BN_is_odd(m))
+ { ret=BN_mod_exp_mont(r,a,p,m,ctx); }
+ else
+#endif
+#ifdef RECP_MUL_MOD
+ { ret=BN_mod_exp_recp(r,a,p,m,ctx); }
+#else
+ { ret=BN_mod_exp_simple(r,a,p,m,ctx); }
+#endif
+
+ return(ret);
+ }
+
+/* #ifdef RECP_MUL_MOD */
+int BN_mod_exp_recp(r,a,p,m,ctx)
+BIGNUM *r;
+BIGNUM *a;
+BIGNUM *p;
+BIGNUM *m;
+BN_CTX *ctx;
+ {
+ int nb,i,j,bits,ret=0,wstart,wend,window,wvalue;
+ int start=1;
+ BIGNUM *d,*aa;
+ BIGNUM *val[16];
+
+ d=ctx->bn[ctx->tos++];
+ aa=ctx->bn[ctx->tos++];
+ bits=BN_num_bits(p);
+
+ if (bits == 0)
+ {
+ BN_one(r);
+ return(1);
+ }
+ nb=BN_reciprocal(d,m,ctx);
+ if (nb == -1) goto err;
+
+ val[0]=BN_new();
+ if (!BN_mod(val[0],a,m,ctx)) goto err; /* 1 */
+ if (!BN_mod_mul_reciprocal(aa,val[0],val[0],m,d,nb,ctx))
+ goto err; /* 2 */
+
+ if (bits <= 17) /* This is probably 3 or 0x10001, so just do singles */
+ window=1;
+ else if (bits >= 256)
+ window=5; /* max size of window */
+ else if (bits >= 128)
+ window=4;
+ else
+ window=3;
+
+ j=1<<(window-1);
+ for (i=1; i<j; i++)
+ {
+ val[i]=BN_new();
+ if (!BN_mod_mul_reciprocal(val[i],val[i-1],aa,m,d,nb,ctx))
+ goto err;
+ }
+ for (; i<16; i++)
+ val[i]=NULL;
+
+ start=1; /* This is used to avoid multiplication etc
+ * when there is only the value '1' in the
+ * buffer. */
+ wvalue=0; /* The 'value' of the window */
+ wstart=bits-1; /* The top bit of the window */
+ wend=0; /* The bottom bit of the window */
+
+ if (!BN_one(r)) goto err;
+
+ for (;;)
+ {
+ if (BN_is_bit_set(p,wstart) == 0)
+ {
+ if (!start)
+ if (!BN_mod_mul_reciprocal(r,r,r,m,d,nb,ctx))
+ goto err;
+ if (wstart == 0) break;
+ wstart--;
+ continue;
+ }
+ /* We now have wstart on a 'set' bit, we now need to work out
+ * how bit a window to do. To do this we need to scan
+ * forward until the last set bit before the end of the
+ * window */
+ j=wstart;
+ wvalue=1;
+ wend=0;
+ for (i=1; i<window; i++)
+ {
+ if (wstart-i < 0) break;
+ if (BN_is_bit_set(p,wstart-i))
+ {
+ wvalue<<=(i-wend);
+ wvalue|=1;
+ wend=i;
+ }
+ }
+
+ /* wend is the size of the current window */
+ j=wend+1;
+ /* add the 'bytes above' */
+ if (!start)
+ for (i=0; i<j; i++)
+ {
+ if (!BN_mod_mul_reciprocal(r,r,r,m,d,nb,ctx))
+ goto err;
+ }
+
+ /* wvalue will be an odd number < 2^window */
+ if (!BN_mod_mul_reciprocal(r,r,val[wvalue>>1],m,d,nb,ctx))
+ goto err;
+
+ /* move the 'window' down further */
+ wstart-=wend+1;
+ wvalue=0;
+ start=0;
+ if (wstart < 0) break;
+ }
+ ret=1;
+err:
+ ctx->tos-=2;
+ for (i=0; i<16; i++)
+ if (val[i] != NULL) BN_clear_free(val[i]);
+ return(ret);
+ }
+/* #endif */
+
+/* #ifdef MONT_MUL_MOD */
+int BN_mod_exp_mont(r,a,p,m,ctx)
+BIGNUM *r;
+BIGNUM *a;
+BIGNUM *p;
+BIGNUM *m;
+BN_CTX *ctx;
+ {
+ int i,j,bits,ret=0,wstart,wend,window,wvalue;
+ int start=1;
+ BIGNUM *d,*aa;
+ BIGNUM *val[16];
+ BN_MONT_CTX *mont=NULL;
+
+ if (!(m->d[0] & 1))
+ {
+ BNerr(BN_F_BN_MOD_EXP_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
+ return(0);
+ }
+ d=ctx->bn[ctx->tos++];
+ bits=BN_num_bits(p);
+ if (bits == 0)
+ {
+ BN_one(r);
+ return(1);
+ }
+
+ /* If this is not done, things will break in the montgomery
+ * part */
+
+ if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
+ if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
+
+ val[0]=BN_new();
+ if (BN_ucmp(a,m) >= 0)
+ {
+ BN_mod(val[0],a,m,ctx);
+ aa=val[0];
+ }
+ else
+ aa=a;
+ if (!BN_to_montgomery(val[0],aa,mont,ctx)) goto err; /* 1 */
+ if (!BN_mod_mul_montgomery(d,val[0],val[0],mont,ctx)) goto err; /* 2 */
+
+ if (bits <= 17) /* This is probably 3 or 0x10001, so just do singles */
+ window=1;
+ else if (bits >= 256)
+ window=5; /* max size of window */
+ else if (bits >= 128)
+ window=4;
+ else
+ window=3;
+
+ j=1<<(window-1);
+ for (i=1; i<j; i++)
+ {
+ val[i]=BN_new();
+ if (!BN_mod_mul_montgomery(val[i],val[i-1],d,mont,ctx))
+ goto err;
+ }
+ for (; i<16; i++)
+ val[i]=NULL;
+
+ start=1; /* This is used to avoid multiplication etc
+ * when there is only the value '1' in the
+ * buffer. */
+ wvalue=0; /* The 'value' of the window */
+ wstart=bits-1; /* The top bit of the window */
+ wend=0; /* The bottom bit of the window */
+
+ if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
+ for (;;)
+ {
+ if (BN_is_bit_set(p,wstart) == 0)
+ {
+ if (!start)
+ if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
+ goto err;
+ if (wstart == 0) break;
+ wstart--;
+ continue;
+ }
+ /* We now have wstart on a 'set' bit, we now need to work out
+ * how bit a window to do. To do this we need to scan
+ * forward until the last set bit before the end of the
+ * window */
+ j=wstart;
+ wvalue=1;
+ wend=0;
+ for (i=1; i<window; i++)
+ {
+ if (wstart-i < 0) break;
+ if (BN_is_bit_set(p,wstart-i))
+ {
+ wvalue<<=(i-wend);
+ wvalue|=1;
+ wend=i;
+ }
+ }
+
+ /* wend is the size of the current window */
+ j=wend+1;
+ /* add the 'bytes above' */
+ if (!start)
+ for (i=0; i<j; i++)
+ {
+ if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
+ goto err;
+ }
+
+ /* wvalue will be an odd number < 2^window */
+ if (!BN_mod_mul_montgomery(r,r,val[wvalue>>1],mont,ctx))
+ goto err;
+
+ /* move the 'window' down further */
+ wstart-=wend+1;
+ wvalue=0;
+ start=0;
+ if (wstart < 0) break;
+ }
+ BN_from_montgomery(r,r,mont,ctx);
+ ret=1;
+err:
+ if (mont != NULL) BN_MONT_CTX_free(mont);
+ ctx->tos--;
+ for (i=0; i<16; i++)
+ if (val[i] != NULL) BN_clear_free(val[i]);
+ return(ret);
+ }
+/* #endif */
+
+/* The old fallback, simple version :-) */
+int BN_mod_exp_simple(r,a,p,m,ctx)
+BIGNUM *r;
+BIGNUM *a;
+BIGNUM *p;
+BIGNUM *m;
+BN_CTX *ctx;
+ {
+ int i,j,bits,ret=0,wstart,wend,window,wvalue;
+ int start=1;
+ BIGNUM *d;
+ BIGNUM *val[16];
+
+ d=ctx->bn[ctx->tos++];
+ bits=BN_num_bits(p);
+
+ if (bits == 0)
+ {
+ BN_one(r);
+ return(1);
+ }
+
+ val[0]=BN_new();
+ if (!BN_mod(val[0],a,m,ctx)) goto err; /* 1 */
+ if (!BN_mod_mul(d,val[0],val[0],m,ctx))
+ goto err; /* 2 */
+
+ if (bits <= 17) /* This is probably 3 or 0x10001, so just do singles */
+ window=1;
+ else if (bits >= 256)
+ window=5; /* max size of window */
+ else if (bits >= 128)
+ window=4;
+ else
+ window=3;
+
+ j=1<<(window-1);
+ for (i=1; i<j; i++)
+ {
+ val[i]=BN_new();
+ if (!BN_mod_mul(val[i],val[i-1],d,m,ctx))
+ goto err;
+ }
+ for (; i<16; i++)
+ val[i]=NULL;
+
+ start=1; /* This is used to avoid multiplication etc
+ * when there is only the value '1' in the
+ * buffer. */
+ wvalue=0; /* The 'value' of the window */
+ wstart=bits-1; /* The top bit of the window */
+ wend=0; /* The bottom bit of the window */
+
+ if (!BN_one(r)) goto err;
+
+ for (;;)
+ {
+ if (BN_is_bit_set(p,wstart) == 0)
+ {
+ if (!start)
+ if (!BN_mod_mul(r,r,r,m,ctx))
+ goto err;
+ if (wstart == 0) break;
+ wstart--;
+ continue;
+ }
+ /* We now have wstart on a 'set' bit, we now need to work out
+ * how bit a window to do. To do this we need to scan
+ * forward until the last set bit before the end of the
+ * window */
+ j=wstart;
+ wvalue=1;
+ wend=0;
+ for (i=1; i<window; i++)
+ {
+ if (wstart-i < 0) break;
+ if (BN_is_bit_set(p,wstart-i))
+ {
+ wvalue<<=(i-wend);
+ wvalue|=1;
+ wend=i;
+ }
+ }
+
+ /* wend is the size of the current window */
+ j=wend+1;
+ /* add the 'bytes above' */
+ if (!start)
+ for (i=0; i<j; i++)
+ {
+ if (!BN_mod_mul(r,r,r,m,ctx))
+ goto err;
+ }
+
+ /* wvalue will be an odd number < 2^window */
+ if (!BN_mod_mul(r,r,val[wvalue>>1],m,ctx))
+ goto err;
+
+ /* move the 'window' down further */
+ wstart-=wend+1;
+ wvalue=0;
+ start=0;
+ if (wstart < 0) break;
+ }
+ ret=1;
+err:
+ ctx->tos--;
+ for (i=0; i<16; i++)
+ if (val[i] != NULL) BN_clear_free(val[i]);
+ return(ret);
+ }
+
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