OpenWrt – Rev 1
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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_client.h"
#include "t_sha.h"
_TYPE( struct t_client * )
t_clientopen(u, n, g, s)
const char * u;
struct t_num * n;
struct t_num * g;
struct t_num * s;
{
struct t_client * tc;
unsigned char buf1[SHA_DIGESTSIZE], buf2[SHA_DIGESTSIZE];
SHA1_CTX ctxt;
int i, validated;
struct t_preconf * tpc;
validated = 0;
if(n->len < MIN_MOD_BYTES)
return 0;
for(i = 0; i < t_getprecount(); ++i) {
tpc = t_getpreparam(i);
if(tpc->modulus.len == n->len && tpc->generator.len == g->len &&
memcmp(tpc->modulus.data, n->data, n->len) == 0 &&
memcmp(tpc->generator.data, g->data, g->len) == 0) {
validated = 1; /* Match found, done */
break;
}
}
if(validated == 0)
return 0;
if((tc = malloc(sizeof(struct t_client))) == 0)
return 0;
strncpy(tc->username, u, MAXUSERLEN);
SHA1Init(&tc->hash);
tc->n.len = n->len;
tc->n.data = tc->nbuf;
memcpy(tc->n.data, n->data, tc->n.len);
SHA1Init(&ctxt);
SHA1Update(&ctxt, tc->n.data, tc->n.len);
SHA1Final(buf1, &ctxt);
tc->g.len = g->len;
tc->g.data = tc->gbuf;
memcpy(tc->g.data, g->data, tc->g.len);
SHA1Init(&ctxt);
SHA1Update(&ctxt, tc->g.data, tc->g.len);
SHA1Final(buf2, &ctxt);
for(i = 0; i < sizeof(buf1); ++i)
buf1[i] ^= buf2[i];
SHA1Update(&tc->hash, buf1, sizeof(buf1));
SHA1Init(&ctxt);
SHA1Update(&ctxt, tc->username, strlen(tc->username));
SHA1Final(buf1, &ctxt);
SHA1Update(&tc->hash, buf1, sizeof(buf1));
tc->s.len = s->len;
tc->s.data = tc->sbuf;
memcpy(tc->s.data, s->data, tc->s.len);
SHA1Update(&tc->hash, tc->s.data, tc->s.len);
tc->a.data = tc->abuf;
tc->A.data = tc->Abuf;
tc->p.data = tc->pbuf;
tc->v.data = tc->vbuf;
SHA1Init(&tc->ckhash);
return tc;
}
_TYPE( struct t_num * )
t_clientgenexp(tc)
struct t_client * tc;
{
BigInteger a, A, n, g;
if(tc->n.len < ALEN)
tc->a.len = tc->n.len;
else
tc->a.len = ALEN;
t_random(tc->a.data, tc->a.len);
a = BigIntegerFromBytes(tc->a.data, tc->a.len);
n = BigIntegerFromBytes(tc->n.data, tc->n.len);
g = BigIntegerFromBytes(tc->g.data, tc->g.len);
A = BigIntegerFromInt(0);
BigIntegerModExp(A, g, a, n);
tc->A.len = BigIntegerToBytes(A, tc->A.data);
BigIntegerFree(A);
BigIntegerFree(a);
BigIntegerFree(g);
BigIntegerFree(n);
SHA1Update(&tc->hash, tc->A.data, tc->A.len);
SHA1Update(&tc->ckhash, tc->A.data, tc->A.len);
return &tc->A;
}
_TYPE( void )
t_clientpasswd(tc, password)
struct t_client * tc;
char * password;
{
BigInteger n, g, p, v;
SHA1_CTX ctxt;
unsigned char dig[SHA_DIGESTSIZE];
n = BigIntegerFromBytes(tc->n.data, tc->n.len);
g = BigIntegerFromBytes(tc->g.data, tc->g.len);
SHA1Init(&ctxt);
SHA1Update(&ctxt, tc->username, strlen(tc->username));
SHA1Update(&ctxt, ":", 1);
SHA1Update(&ctxt, password, strlen(password));
SHA1Final(dig, &ctxt);
SHA1Init(&ctxt);
SHA1Update(&ctxt, tc->s.data, tc->s.len);
SHA1Update(&ctxt, dig, sizeof(dig));
SHA1Final(dig, &ctxt);
p = BigIntegerFromBytes(dig, sizeof(dig));
v = BigIntegerFromInt(0);
BigIntegerModExp(v, g, p, n);
tc->p.len = BigIntegerToBytes(p, tc->p.data);
BigIntegerFree(p);
tc->v.len = BigIntegerToBytes(v, tc->v.data);
BigIntegerFree(v);
}
_TYPE( unsigned char * )
t_clientgetkey(tc, serverval)
struct t_client * tc;
struct t_num * serverval;
{
BigInteger n, B, v, p, a, sum, S;
unsigned char sbuf[MAXPARAMLEN];
unsigned char dig[SHA_DIGESTSIZE];
unsigned slen;
unsigned int u;
SHA1_CTX ctxt;
SHA1Init(&ctxt);
SHA1Update(&ctxt, serverval->data, serverval->len);
SHA1Final(dig, &ctxt);
u = (dig[0] << 24) | (dig[1] << 16) | (dig[2] << 8) | dig[3];
if(u == 0)
return NULL;
SHA1Update(&tc->hash, serverval->data, serverval->len);
B = BigIntegerFromBytes(serverval->data, serverval->len);
n = BigIntegerFromBytes(tc->n.data, tc->n.len);
if(BigIntegerCmp(B, n) >= 0 || BigIntegerCmpInt(B, 0) == 0) {
BigIntegerFree(B);
BigIntegerFree(n);
return NULL;
}
v = BigIntegerFromBytes(tc->v.data, tc->v.len);
if(BigIntegerCmp(B, v) < 0)
BigIntegerAdd(B, B, n);
BigIntegerSub(B, B, v);
BigIntegerFree(v);
a = BigIntegerFromBytes(tc->a.data, tc->a.len);
p = BigIntegerFromBytes(tc->p.data, tc->p.len);
sum = BigIntegerFromInt(0);
BigIntegerMulInt(sum, p, u);
BigIntegerAdd(sum, sum, a);
BigIntegerFree(p);
BigIntegerFree(a);
S = BigIntegerFromInt(0);
BigIntegerModExp(S, B, sum, n);
slen = BigIntegerToBytes(S, sbuf);
BigIntegerFree(S);
BigIntegerFree(sum);
BigIntegerFree(B);
BigIntegerFree(n);
t_sessionkey(tc->session_key, sbuf, slen);
memset(sbuf, 0, slen);
SHA1Update(&tc->hash, tc->session_key, sizeof(tc->session_key));
SHA1Final(tc->session_response, &tc->hash);
SHA1Update(&tc->ckhash, tc->session_response, sizeof(tc->session_response));
SHA1Update(&tc->ckhash, tc->session_key, sizeof(tc->session_key));
return tc->session_key;
}
_TYPE( int )
t_clientverify(tc, resp)
struct t_client * tc;
unsigned char * resp;
{
unsigned char expected[SHA_DIGESTSIZE];
SHA1Final(expected, &tc->ckhash);
return memcmp(expected, resp, sizeof(expected));
}
_TYPE( unsigned char * )
t_clientresponse(tc)
struct t_client * tc;
{
return tc->session_response;
}
_TYPE( void )
t_clientclose(tc)
struct t_client * tc;
{
memset(tc->abuf, 0, sizeof(tc->abuf));
memset(tc->pbuf, 0, sizeof(tc->pbuf));
memset(tc->vbuf, 0, sizeof(tc->vbuf));
memset(tc->session_key, 0, sizeof(tc->session_key));
free(tc);
}