OpenWrt – Rev 4
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/*
* Copyright (c) 1997-1999 The Stanford SRP Authentication Project
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL STANFORD BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF
* THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* In addition, the following conditions apply:
*
* 1. Any software that incorporates the SRP authentication technology
* must display the following acknowlegment:
* "This product uses the 'Secure Remote Password' cryptographic
* authentication system developed by Tom Wu (tjw@CS.Stanford.EDU)."
*
* 2. Any software that incorporates all or part of the SRP distribution
* itself must also display the following acknowledgment:
* "This product includes software developed by Tom Wu and Eugene
* Jhong for the SRP Distribution (http://srp.stanford.edu/srp/)."
*
* 3. Redistributions in source or binary form must retain an intact copy
* of this copyright notice and list of conditions.
*/
#include <stdio.h>
#include "t_defines.h"
#include "t_pwd.h"
#include "t_read.h"
#include "bn.h"
#include "bn_lcl.h"
#include "bn_prime.h"
#define TABLE_SIZE 32
static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont);
/*
* This is the safe prime generation logic.
* To generate a safe prime p (where p = 2q+1 and q is prime), we start
* with a random odd q that is one bit shorter than the desired length
* of p. We use a simple 30-element sieve to filter the values of q
* and consider only those that are 11, 23, or 29 (mod 30). (If q were
* anything else, either q or p would be divisible by 2, 3, or 5).
* For the values of q that are left, we apply the following tests in
* this order:
*
* trial divide q
* let p = 2q + 1
* trial divide p
* apply Fermat test to q (2^q == 2 (mod q))
* apply Fermat test to p (2^p == 2 (mod p))
* apply real probablistic primality test to q
* apply real probablistic primality test to p
*
* A number that passes all these tests is considered a safe prime for
* our purposes. The tests are ordered this way for efficiency; the
* slower tests are run rarely if ever at all.
*/
static int
trialdiv(x)
const BigInteger x;
{
static int primes[] = { /* All odd primes < 256 */
3, 5, 7, 11, 13, 17, 19, 23, 29,
31, 37, 41, 43, 47, 53, 59, 61, 67,
71, 73, 79, 83, 89, 97, 101, 103,
107, 109, 113, 127, 131, 137, 139, 149, 151,
157, 163, 167, 173, 179, 181, 191, 193, 197,
199, 211, 223, 227, 229, 233, 239, 241, 251
};
static int nprimes = sizeof(primes) / sizeof(int);
int i;
for(i = 0; i < nprimes; ++i) {
if(BigIntegerModInt(x, primes[i]) == 0)
return primes[i];
}
return 1;
}
/* x + sieve30[x%30] == 11, 23, or 29 (mod 30) */
static int sieve30[] =
{ 11, 10, 9, 8, 7, 6, 5, 4, 3, 2,
1, 12, 11, 10, 9, 8, 7, 6, 5, 4,
3, 2, 1, 6, 5, 4, 3, 2, 1, 12
};
/* Find a Sophie-Germain prime between "lo" and "hi". NOTE: this is not
a "safe prime", but the smaller prime. Take 2q+1 to get the safe prime. */
static void
sophie_germain(q, lo, hi)
BigInteger q; /* assumed initialized */
const BigInteger lo;
const BigInteger hi;
{
BigInteger m, p, r;
char parambuf[MAXPARAMLEN];
int foundprime = 0;
int i, mod30;
m = BigIntegerFromInt(0);
BigIntegerSub(m, hi, lo);
i = (BigIntegerBitLen(m) + 7) / 8;
t_random(parambuf, i);
r = BigIntegerFromBytes(parambuf, i);
BigIntegerMod(r, r, m);
BigIntegerAdd(q, r, lo);
if(BigIntegerModInt(q, 2) == 0)
BigIntegerAddInt(q, q, 1); /* make q odd */
mod30 = BigIntegerModInt(q, 30); /* mod30 = q % 30 */
BigIntegerFree(m);
m = BigIntegerFromInt(2); /* m = 2 */
p = BigIntegerFromInt(0);
while(BigIntegerCmp(q, hi) < 0) {
if(trialdiv(q) < 2) {
BigIntegerMulInt(p, q, 2); /* p = 2 * q */
BigIntegerAddInt(p, p, 1); /* p += 1 */
if(trialdiv(p) < 2) {
BigIntegerModExp(r, m, q, q); /* r = 2^q % q */
if(BigIntegerCmpInt(r, 2) == 0) { /* if(r == 2) */
BigIntegerModExp(r, m, p, p); /* r = 2^p % p */
if(BigIntegerCmpInt(r, 2) == 0) { /* if(r == 2) */
if(BigIntegerCheckPrime(q) && BigIntegerCheckPrime(p)) {
++foundprime;
break;
}
}
}
}
}
i = sieve30[mod30];
BigIntegerAddInt(q, q, i); /* q += i */
mod30 = (mod30 + i) % 30;
}
/* should wrap around on failure */
if(!foundprime) {
fprintf(stderr, "Prime generation failed!\n");
exit(1);
}
BigIntegerFree(r);
BigIntegerFree(m);
BigIntegerFree(p);
}
_TYPE( struct t_confent * )
t_makeconfent(tc, nsize)
struct t_conf * tc;
int nsize;
{
BigInteger n, g, q, t, u;
t = BigIntegerFromInt(0);
u = BigIntegerFromInt(1); /* u = 1 */
BigIntegerLShift(t, u, nsize - 2); /* t = 2^(nsize-2) */
BigIntegerMulInt(u, t, 2); /* u = 2^(nsize-1) */
q = BigIntegerFromInt(0);
sophie_germain(q, t, u);
n = BigIntegerFromInt(0);
BigIntegerMulInt(n, q, 2);
BigIntegerAddInt(n, n, 1);
/* Look for a generator mod n */
g = BigIntegerFromInt(2);
while(1) {
BigIntegerModExp(t, g, q, n); /* t = g^q % n */
if(BigIntegerCmpInt(t, 1) == 0) /* if(t == 1) */
BigIntegerAddInt(g, g, 1); /* ++g */
else
break;
}
BigIntegerFree(t);
BigIntegerFree(u);
BigIntegerFree(q);
tc->tcbuf.modulus.data = tc->modbuf;
tc->tcbuf.modulus.len = BigIntegerToBytes(n, tc->tcbuf.modulus.data);
BigIntegerFree(n);
tc->tcbuf.generator.data = tc->genbuf;
tc->tcbuf.generator.len = BigIntegerToBytes(g, tc->tcbuf.generator.data);
BigIntegerFree(g);
tc->tcbuf.index = 1;
return &tc->tcbuf;
}
_TYPE( struct t_confent * )
t_makeconfent_c(tc, nsize)
struct t_conf * tc;
int nsize;
{
BigInteger g, n, p, q, j, k, t, u;
int psize, qsize;
psize = nsize / 2;
qsize = nsize - psize;
t = BigIntegerFromInt(1); /* t = 1 */
u = BigIntegerFromInt(0);
BigIntegerLShift(u, t, psize - 3); /* u = t*2^(psize-3) = 2^(psize-3) */
BigIntegerMulInt(t, u, 3); /* t = 3*u = 1.5*2^(psize-2) */
BigIntegerAdd(u, u, t); /* u += t [u = 2^(psize-1)] */
j = BigIntegerFromInt(0);
sophie_germain(j, t, u);
k = BigIntegerFromInt(0);
if(qsize != psize) {
BigIntegerFree(t);
t = BigIntegerFromInt(1); /* t = 1 */
BigIntegerLShift(u, t, qsize - 3); /* u = t*2^(qsize-3) = 2^(qsize-3) */
BigIntegerMulInt(t, u, 3); /* t = 3*u = 1.5*2^(qsize-2) */
BigIntegerAdd(u, u, t); /* u += t [u = 2^(qsize-1)] */
}
sophie_germain(k, t, u);
p = BigIntegerFromInt(0);
BigIntegerMulInt(p, j, 2); /* p = 2 * j */
BigIntegerAddInt(p, p, 1); /* p += 1 */
q = BigIntegerFromInt(0);
BigIntegerMulInt(q, k, 2); /* q = 2 * k */
BigIntegerAddInt(q, q, 1); /* q += 1 */
n = BigIntegerFromInt(0);
BigIntegerMul(n, p, q); /* n = p * q */
BigIntegerMul(u, j, k); /* u = j * k */
BigIntegerFree(p);
BigIntegerFree(q);
BigIntegerFree(j);
BigIntegerFree(k);
g = BigIntegerFromInt(2); /* g = 2 */
/* Look for a generator mod n */
while(1) {
BigIntegerModExp(t, g, u, n); /* t = g^u % n */
if(BigIntegerCmpInt(t, 1) == 0)
BigIntegerAddInt(g, g, 1); /* ++g */
else
break;
}
BigIntegerFree(u);
BigIntegerFree(t);
tc->tcbuf.modulus.data = tc->modbuf;
tc->tcbuf.modulus.len = BigIntegerToBytes(n, tc->tcbuf.modulus.data);
BigIntegerFree(n);
tc->tcbuf.generator.data = tc->genbuf;
tc->tcbuf.generator.len = BigIntegerToBytes(g, tc->tcbuf.generator.data);
BigIntegerFree(g);
tc->tcbuf.index = 1;
return &tc->tcbuf;
}
_TYPE( struct t_confent * )
t_newconfent(tc)
struct t_conf * tc;
{
tc->tcbuf.index = 0;
tc->tcbuf.modulus.data = tc->modbuf;
tc->tcbuf.modulus.len = 0;
tc->tcbuf.generator.data = tc->genbuf;
tc->tcbuf.generator.len = 0;
return &tc->tcbuf;
}
_TYPE( void )
t_putconfent(ent, fp)
const struct t_confent * ent;
FILE * fp;
{
char strbuf[MAXB64PARAMLEN];
fprintf(fp, "%d:%s:", ent->index,
t_tob64(strbuf, ent->modulus.data, ent->modulus.len));
fprintf(fp, "%s\n",
t_tob64(strbuf, ent->generator.data, ent->generator.len));
}
int
BigIntegerBitLen(b)
BigInteger b;
{
return BN_num_bits(b);
}
int
BigIntegerCheckPrime(n)
BigInteger n;
{
BN_CTX * ctx = BN_CTX_new();
int rv = BN_is_prime(n, 25, NULL, ctx, NULL);
BN_CTX_free(ctx);
return rv;
}
unsigned int
BigIntegerModInt(d, m)
BigInteger d;
unsigned int m;
{
return BN_mod_word(d, m);
}
void
BigIntegerMod(result, d, m)
BigInteger result, d, m;
{
BN_CTX * ctx = BN_CTX_new();
BN_mod(result, d, m, ctx);
BN_CTX_free(ctx);
}
void
BigIntegerMul(result, m1, m2)
BigInteger result, m1, m2;
{
BN_CTX * ctx = BN_CTX_new();
BN_mul(result, m1, m2, ctx);
BN_CTX_free(ctx);
}
void
BigIntegerLShift(result, x, bits)
BigInteger result, x;
unsigned int bits;
{
BN_lshift(result, x, bits);
}
int BN_is_prime(const BIGNUM *a, int checks, void (*callback)(int,int,void *),
BN_CTX *ctx_passed, void *cb_arg)
{
return BN_is_prime_fasttest(a, checks, callback, ctx_passed, cb_arg, 0);
}
int BN_is_prime_fasttest(const BIGNUM *a, int checks,
void (*callback)(int,int,void *),
BN_CTX *ctx_passed, void *cb_arg,
int do_trial_division)
{
int i, j, ret = -1;
int k;
BN_CTX *ctx = NULL;
BIGNUM *A1, *A1_odd, *check; /* taken from ctx */
BN_MONT_CTX *mont = NULL;
const BIGNUM *A = NULL;
if (checks == BN_prime_checks)
checks = BN_prime_checks_for_size(BN_num_bits(a));
/* first look for small factors */
if (!BN_is_odd(a))
return(0);
if (do_trial_division)
{
for (i = 1; i < NUMPRIMES; i++)
if (BN_mod_word(a, primes[i]) == 0)
return 0;
if (callback != NULL) callback(1, -1, cb_arg);
}
if (ctx_passed != NULL)
ctx = ctx_passed;
else
if ((ctx=BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
/* A := abs(a) */
if (a->neg)
{
BIGNUM *t;
if ((t = BN_CTX_get(ctx)) == NULL) goto err;
BN_copy(t, a);
t->neg = 0;
A = t;
}
else
A = a;
A1 = BN_CTX_get(ctx);
A1_odd = BN_CTX_get(ctx);
check = BN_CTX_get(ctx);
if (check == NULL) goto err;
/* compute A1 := A - 1 */
if (!BN_copy(A1, A))
goto err;
if (!BN_sub_word(A1, 1))
goto err;
if (BN_is_zero(A1))
{
ret = 0;
goto err;
}
/* write A1 as A1_odd * 2^k */
k = 1;
while (!BN_is_bit_set(A1, k))
k++;
if (!BN_rshift(A1_odd, A1, k))
goto err;
/* Montgomery setup for computations mod A */
mont = BN_MONT_CTX_new();
if (mont == NULL)
goto err;
if (!BN_MONT_CTX_set(mont, A, ctx))
goto err;
for (i = 0; i < checks; i++)
{
if (!BN_pseudo_rand(check, BN_num_bits(A1), 0, 0))
goto err;
if (BN_cmp(check, A1) >= 0)
if (!BN_sub(check, check, A1))
goto err;
if (!BN_add_word(check, 1))
goto err;
/* now 1 <= check < A */
j = witness(check, A, A1, A1_odd, k, ctx, mont);
if (j == -1) goto err;
if (j)
{
ret=0;
goto err;
}
if (callback != NULL) callback(1,i,cb_arg);
}
ret=1;
err:
if (ctx != NULL)
{
BN_CTX_end(ctx);
if (ctx_passed == NULL)
BN_CTX_free(ctx);
}
if (mont != NULL)
BN_MONT_CTX_free(mont);
return(ret);
}
static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont)
{
if (!BN_mod_exp_mont(w, w, a1_odd, a, ctx, mont)) /* w := w^a1_odd mod a */
return -1;
if (BN_is_one(w))
return 0; /* probably prime */
if (BN_cmp(w, a1) == 0)
return 0; /* w == -1 (mod a), 'a' is probably prime */
while (--k)
{
if (!BN_mod_mul(w, w, w, a, ctx)) /* w := w^2 mod a */
return -1;
if (BN_is_one(w))
return 1; /* 'a' is composite, otherwise a previous 'w' would
* have been == -1 (mod 'a') */
if (BN_cmp(w, a1) == 0)
return 0; /* w == -1 (mod a), 'a' is probably prime */
}
/* If we get here, 'w' is the (a-1)/2-th power of the original 'w',
* and it is neither -1 nor +1 -- so 'a' cannot be prime */
return 1;
}
int BN_mod_exp_mont(BIGNUM *rr, BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
{
int i,j,bits,ret=0,wstart,wend,window,wvalue;
int start=1,ts=0;
BIGNUM *d,*r;
BIGNUM *aa;
BIGNUM val[TABLE_SIZE];
BN_MONT_CTX *mont=NULL;
bn_check_top(a);
bn_check_top(p);
bn_check_top(m);
if (!(m->d[0] & 1))
{
return(0);
}
bits=BN_num_bits(p);
if (bits == 0)
{
BN_one(rr);
return(1);
}
BN_CTX_start(ctx);
d = BN_CTX_get(ctx);
r = BN_CTX_get(ctx);
if (d == NULL || r == NULL) goto err;
/* If this is not done, things will break in the montgomery
* part */
if (in_mont != NULL)
mont=in_mont;
else
{
if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
}
BN_init(&val[0]);
ts=1;
if (BN_ucmp(a,m) >= 0)
{
if (!BN_mod(&(val[0]),a,m,ctx))
goto err;
aa= &(val[0]);
}
else
aa=a;
if (!BN_to_montgomery(&(val[0]),aa,mont,ctx)) goto err; /* 1 */
window = BN_window_bits_for_exponent_size(bits);
if (window > 1)
{
if (!BN_mod_mul_montgomery(d,&(val[0]),&(val[0]),mont,ctx)) goto err; /* 2 */
j=1<<(window-1);
for (i=1; i<j; i++)
{
BN_init(&(val[i]));
if (!BN_mod_mul_montgomery(&(val[i]),&(val[i-1]),d,mont,ctx))
goto err;
}
ts=i;
}
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;
}
if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;
ret=1;
err:
if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
BN_CTX_end(ctx);
for (i=0; i<ts; i++)
BN_clear_free(&(val[i]));
return(ret);
}
BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
{
#ifndef BN_LLONG
BN_ULONG ret=0;
#else
BN_ULLONG ret=0;
#endif
int i;
w&=BN_MASK2;
for (i=a->top-1; i>=0; i--)
{
#ifndef BN_LLONG
ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%w;
ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%w;
#else
ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])%
(BN_ULLONG)w);
#endif
}
return((BN_ULONG)ret);
}
static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
{
unsigned char *buf=NULL;
int ret=0,bit,bytes,mask;
if (bits == 0)
{
BN_zero(rnd);
return 1;
}
bytes=(bits+7)/8;
bit=(bits-1)%8;
mask=0xff<<bit;
buf=(unsigned char *)malloc(bytes);
if (buf == NULL)
{
goto err;
}
/* make a random number and set the top and bottom bits */
/* this ignores the pseudorand flag */
t_random(buf, bytes);
if (top)
{
if (bit == 0)
{
buf[0]=1;
buf[1]|=0x80;
}
else
{
buf[0]|=(3<<(bit-1));
buf[0]&= ~(mask<<1);
}
}
else
{
buf[0]|=(1<<bit);
buf[0]&= ~(mask<<1);
}
if (bottom) /* set bottom bits to whatever odd is */
buf[bytes-1]|=1;
if (!BN_bin2bn(buf,bytes,rnd)) goto err;
ret=1;
err:
if (buf != NULL)
{
memset(buf,0,bytes);
free(buf);
}
return(ret);
}
/* BN_pseudo_rand is the same as BN_rand, now. */
int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
{
return bnrand(1, rnd, bits, top, bottom);
}
#define MONT_WORD /* use the faster word-based algorithm */
int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
BN_MONT_CTX *mont, BN_CTX *ctx)
{
BIGNUM *tmp,*tmp2;
int ret=0;
BN_CTX_start(ctx);
tmp = BN_CTX_get(ctx);
tmp2 = BN_CTX_get(ctx);
if (tmp == NULL || tmp2 == NULL) goto err;
bn_check_top(tmp);
bn_check_top(tmp2);
if (a == b)
{
if (!BN_sqr(tmp,a,ctx)) goto err;
}
else
{
if (!BN_mul(tmp,a,b,ctx)) goto err;
}
/* reduce from aRR to aR */
if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
ret=1;
err:
BN_CTX_end(ctx);
return(ret);
}
int BN_from_montgomery(BIGNUM *ret, BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx)
{
int retn=0;
#ifdef MONT_WORD
BIGNUM *n,*r;
BN_ULONG *ap,*np,*rp,n0,v,*nrp;
int al,nl,max,i,x,ri;
BN_CTX_start(ctx);
if ((r = BN_CTX_get(ctx)) == NULL) goto err;
if (!BN_copy(r,a)) goto err;
n= &(mont->N);
ap=a->d;
/* mont->ri is the size of mont->N in bits (rounded up
to the word size) */
al=ri=mont->ri/BN_BITS2;
nl=n->top;
if ((al == 0) || (nl == 0)) { r->top=0; return(1); }
max=(nl+al+1); /* allow for overflow (no?) XXX */
if (bn_wexpand(r,max) == NULL) goto err;
if (bn_wexpand(ret,max) == NULL) goto err;
r->neg=a->neg^n->neg;
np=n->d;
rp=r->d;
nrp= &(r->d[nl]);
/* clear the top words of T */
#if 1
for (i=r->top; i<max; i++) /* memset? XXX */
r->d[i]=0;
#else
memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
#endif
r->top=max;
n0=mont->n0;
#ifdef BN_COUNT
printf("word BN_from_montgomery %d * %d\n",nl,nl);
#endif
for (i=0; i<nl; i++)
{
#ifdef __TANDEM
{
long long t1;
long long t2;
long long t3;
t1 = rp[0] * (n0 & 0177777);
t2 = 037777600000l;
t2 = n0 & t2;
t3 = rp[0] & 0177777;
t2 = (t3 * t2) & BN_MASK2;
t1 = t1 + t2;
v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
}
#else
v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
#endif
nrp++;
rp++;
if (((nrp[-1]+=v)&BN_MASK2) >= v)
continue;
else
{
if (((++nrp[0])&BN_MASK2) != 0) continue;
if (((++nrp[1])&BN_MASK2) != 0) continue;
for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
}
}
bn_fix_top(r);
/* mont->ri will be a multiple of the word size */
#if 0
BN_rshift(ret,r,mont->ri);
#else
ret->neg = r->neg;
x=ri;
rp=ret->d;
ap= &(r->d[x]);
if (r->top < x)
al=0;
else
al=r->top-x;
ret->top=al;
al-=4;
for (i=0; i<al; i+=4)
{
BN_ULONG t1,t2,t3,t4;
t1=ap[i+0];
t2=ap[i+1];
t3=ap[i+2];
t4=ap[i+3];
rp[i+0]=t1;
rp[i+1]=t2;
rp[i+2]=t3;
rp[i+3]=t4;
}
al+=4;
for (; i<al; i++)
rp[i]=ap[i];
#endif
#else /* !MONT_WORD */
BIGNUM *t1,*t2;
BN_CTX_start(ctx);
t1 = BN_CTX_get(ctx);
t2 = BN_CTX_get(ctx);
if (t1 == NULL || t2 == NULL) goto err;
if (!BN_copy(t1,a)) goto err;
BN_mask_bits(t1,mont->ri);
if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
BN_mask_bits(t2,mont->ri);
if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
if (!BN_add(t2,a,t1)) goto err;
BN_rshift(ret,t2,mont->ri);
#endif /* MONT_WORD */
if (BN_ucmp(ret, &(mont->N)) >= 0)
{
BN_usub(ret,ret,&(mont->N));
}
retn=1;
err:
BN_CTX_end(ctx);
return(retn);
}
void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
{
ctx->ri=0;
BN_init(&(ctx->RR));
BN_init(&(ctx->N));
BN_init(&(ctx->Ni));
ctx->flags=0;
}
BN_MONT_CTX *BN_MONT_CTX_new(void)
{
BN_MONT_CTX *ret;
if ((ret=(BN_MONT_CTX *)malloc(sizeof(BN_MONT_CTX))) == NULL)
return(NULL);
BN_MONT_CTX_init(ret);
ret->flags=BN_FLG_MALLOCED;
return(ret);
}
void BN_MONT_CTX_free(BN_MONT_CTX *mont)
{
if(mont == NULL)
return;
BN_free(&(mont->RR));
BN_free(&(mont->N));
BN_free(&(mont->Ni));
if (mont->flags & BN_FLG_MALLOCED)
free(mont);
}
int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
{
BIGNUM Ri,*R;
BN_init(&Ri);
R= &(mont->RR); /* grab RR as a temp */
BN_copy(&(mont->N),mod); /* Set N */
#ifdef MONT_WORD
{
BIGNUM tmod;
BN_ULONG buf[2];
mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
BN_zero(R);
BN_set_bit(R,BN_BITS2); /* R */
buf[0]=mod->d[0]; /* tmod = N mod word size */
buf[1]=0;
tmod.d=buf;
tmod.top=1;
tmod.dmax=2;
tmod.neg=mod->neg;
/* Ri = R^-1 mod N*/
if ((BN_mod_inverse(&Ri,R,&tmod,ctx)) == NULL)
goto err;
BN_lshift(&Ri,&Ri,BN_BITS2); /* R*Ri */
if (!BN_is_zero(&Ri))
BN_sub_word(&Ri,1);
else /* if N mod word size == 1 */
BN_set_word(&Ri,BN_MASK2); /* Ri-- (mod word size) */
BN_div(&Ri,NULL,&Ri,&tmod,ctx); /* Ni = (R*Ri-1)/N,
* keep only least significant word: */
mont->n0=Ri.d[0];
BN_free(&Ri);
}
#else /* !MONT_WORD */
{ /* bignum version */
mont->ri=BN_num_bits(mod);
BN_zero(R);
BN_set_bit(R,mont->ri); /* R = 2^ri */
/* Ri = R^-1 mod N*/
if ((BN_mod_inverse(&Ri,R,mod,ctx)) == NULL)
goto err;
BN_lshift(&Ri,&Ri,mont->ri); /* R*Ri */
BN_sub_word(&Ri,1);
/* Ni = (R*Ri-1) / N */
BN_div(&(mont->Ni),NULL,&Ri,mod,ctx);
BN_free(&Ri);
}
#endif
/* setup RR for conversions */
BN_zero(&(mont->RR));
BN_set_bit(&(mont->RR),mont->ri*2);
BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx);
return(1);
err:
return(0);
}
BIGNUM *BN_value_one(void)
{
static BN_ULONG data_one=1L;
static BIGNUM const_one={&data_one,1,1,0};
return(&const_one);
}
/* solves ax == 1 (mod n) */
BIGNUM *BN_mod_inverse(BIGNUM *in, BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
{
BIGNUM *A,*B,*X,*Y,*M,*D,*R=NULL;
BIGNUM *T,*ret=NULL;
int sign;
bn_check_top(a);
bn_check_top(n);
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
B = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
D = BN_CTX_get(ctx);
M = BN_CTX_get(ctx);
Y = BN_CTX_get(ctx);
if (Y == NULL) goto err;
if (in == NULL)
R=BN_new();
else
R=in;
if (R == NULL) goto err;
BN_zero(X);
BN_one(Y);
if (BN_copy(A,a) == NULL) goto err;
if (BN_copy(B,n) == NULL) goto err;
sign=1;
while (!BN_is_zero(B))
{
if (!BN_div(D,M,A,B,ctx)) goto err;
T=A;
A=B;
B=M;
/* T has a struct, M does not */
if (!BN_mul(T,D,X,ctx)) goto err;
if (!BN_add(T,T,Y)) goto err;
M=Y;
Y=X;
X=T;
sign= -sign;
}
if (sign < 0)
{
if (!BN_sub(Y,n,Y)) goto err;
}
if (BN_is_one(A))
{ if (!BN_mod(R,Y,n,ctx)) goto err; }
else
{
goto err;
}
ret=R;
err:
if ((ret == NULL) && (in == NULL)) BN_free(R);
BN_CTX_end(ctx);
return(ret);
}
int BN_set_bit(BIGNUM *a, int n)
{
int i,j,k;
i=n/BN_BITS2;
j=n%BN_BITS2;
if (a->top <= i)
{
if (bn_wexpand(a,i+1) == NULL) return(0);
for(k=a->top; k<i+1; k++)
a->d[k]=0;
a->top=i+1;
}
a->d[i]|=(((BN_ULONG)1)<<j);
return(1);
}