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RSA key authentication in ssh1 works; SSH2 is nearly there

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[originally from svn r572]
This commit is contained in:
Simon Tatham
2000-09-07 16:33:49 +00:00
parent 0f1e449189
commit d9af8f4b90
12 changed files with 1109 additions and 373 deletions
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171
sshbn.c
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@ -6,36 +6,17 @@
#include <stdlib.h>
#include <string.h>
#include <stdio.h> /* FIXME */
#include <stdarg.h> /* FIXME */
#include <windows.h> /* FIXME */
#include "putty.h" /* FIXME */
#include "ssh.h"
static unsigned short Zero[1] = { 0 };
unsigned short bnZero[1] = { 0 };
unsigned short bnOne[2] = { 1, 1 };
#if defined TESTMODE || defined RSADEBUG
#ifndef DLVL
#define DLVL 10000
#endif
#define debug(x) bndebug(#x,x)
static int level = 0;
static void bndebug(char *name, Bignum b) {
int i;
int w = 50-level-strlen(name)-5*b[0];
if (level >= DLVL)
return;
if (w < 0) w = 0;
dprintf("%*s%s%*s", level, "", name, w, "");
for (i=b[0]; i>0; i--)
dprintf(" %04x", b[i]);
dprintf("\n");
}
#define dmsg(x) do {if(level<DLVL){dprintf("%*s",level,"");printf x;}} while(0)
#define enter(x) do { dmsg(x); level += 4; } while(0)
#define leave(x) do { level -= 4; dmsg(x); } while(0)
#else
#define debug(x)
#define dmsg(x)
#define enter(x)
#define leave(x)
#endif
Bignum Zero = bnZero, One = bnOne;
Bignum newbn(int length) {
Bignum b = malloc((length+1)*sizeof(unsigned short));
@ -46,6 +27,14 @@ Bignum newbn(int length) {
return b;
}
Bignum copybn(Bignum orig) {
Bignum b = malloc((orig[0]+1)*sizeof(unsigned short));
if (!b)
abort(); /* FIXME */
memcpy(b, orig, (orig[0]+1)*sizeof(*b));
return b;
}
void freebn(Bignum b) {
/*
* Burn the evidence, just in case.
@ -83,11 +72,13 @@ static void bigmul(unsigned short *a, unsigned short *b, unsigned short *c,
/*
* Compute a = a % m.
* Input in first 2*len words of a and first len words of m.
* Output in first 2*len words of a (of which first len words will be zero).
* Input in first len2 words of a and first len words of m.
* Output in first len2 words of a
* (of which first len2-len words will be zero).
* The MSW of m MUST have its high bit set.
*/
static void bigmod(unsigned short *a, unsigned short *m, int len)
static void bigmod(unsigned short *a, unsigned short *m,
int len, int len2)
{
unsigned short m0, m1;
unsigned int h;
@ -103,7 +94,7 @@ static void bigmod(unsigned short *a, unsigned short *m, int len)
m0 = m[0];
m1 = m[1];
for (i = 0; i <= len; i++) {
for (i = 0; i <= len2-len; i++) {
unsigned long t;
unsigned int q, r, c;
@ -204,10 +195,10 @@ void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result)
while (i < exp[0]) {
while (j >= 0) {
bigmul(a + mlen, a + mlen, b, mlen);
bigmod(b, m, mlen);
bigmod(b, m, mlen, mlen*2);
if ((exp[exp[0] - i] & (1 << j)) != 0) {
bigmul(b + mlen, n, a, mlen);
bigmod(a, m, mlen);
bigmod(a, m, mlen, mlen*2);
} else {
unsigned short *t;
t = a; a = b; b = t;
@ -222,7 +213,7 @@ void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result)
for (i = mlen - 1; i < 2*mlen - 1; i++)
a[i] = (a[i] << mshift) | (a[i+1] >> (16-mshift));
a[2*mlen-1] = a[2*mlen-1] << mshift;
bigmod(a, m, mlen);
bigmod(a, m, mlen, mlen*2);
for (i = 2*mlen - 1; i >= mlen; i--)
a[i] = (a[i] >> mshift) | (a[i-1] << (16-mshift));
}
@ -237,3 +228,115 @@ void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result)
for (i = 0; i < mlen; i++) m[i] = 0; free(m);
for (i = 0; i < mlen; i++) n[i] = 0; free(n);
}
/*
* Compute (p * q) % mod.
* The most significant word of mod MUST be non-zero.
* We assume that the result array is the same size as the mod array.
*/
void modmul(Bignum p, Bignum q, Bignum mod, Bignum result)
{
unsigned short *a, *n, *m, *o;
int mshift;
int pqlen, mlen, i, j;
/* Allocate m of size mlen, copy mod to m */
/* We use big endian internally */
mlen = mod[0];
m = malloc(mlen * sizeof(unsigned short));
for (j = 0; j < mlen; j++) m[j] = mod[mod[0] - j];
/* Shift m left to make msb bit set */
for (mshift = 0; mshift < 15; mshift++)
if ((m[0] << mshift) & 0x8000) break;
if (mshift) {
for (i = 0; i < mlen - 1; i++)
m[i] = (m[i] << mshift) | (m[i+1] >> (16-mshift));
m[mlen-1] = m[mlen-1] << mshift;
}
pqlen = (p[0] > q[0] ? p[0] : q[0]);
/* Allocate n of size pqlen, copy p to n */
n = malloc(pqlen * sizeof(unsigned short));
i = pqlen - p[0];
for (j = 0; j < i; j++) n[j] = 0;
for (j = 0; j < p[0]; j++) n[i+j] = p[p[0] - j];
/* Allocate o of size pqlen, copy q to o */
o = malloc(pqlen * sizeof(unsigned short));
i = pqlen - q[0];
for (j = 0; j < i; j++) o[j] = 0;
for (j = 0; j < q[0]; j++) o[i+j] = q[q[0] - j];
/* Allocate a of size 2*pqlen for result */
a = malloc(2 * pqlen * sizeof(unsigned short));
/* Main computation */
bigmul(n, o, a, pqlen);
bigmod(a, m, mlen, 2*pqlen);
/* Fixup result in case the modulus was shifted */
if (mshift) {
for (i = 2*pqlen - mlen - 1; i < 2*pqlen - 1; i++)
a[i] = (a[i] << mshift) | (a[i+1] >> (16-mshift));
a[2*pqlen-1] = a[2*pqlen-1] << mshift;
bigmod(a, m, mlen, pqlen*2);
for (i = 2*pqlen - 1; i >= 2*pqlen - mlen; i--)
a[i] = (a[i] >> mshift) | (a[i-1] << (16-mshift));
}
/* Copy result to buffer */
for (i = 0; i < mlen; i++)
result[result[0] - i] = a[i+2*pqlen-mlen];
/* Free temporary arrays */
for (i = 0; i < 2*pqlen; i++) a[i] = 0; free(a);
for (i = 0; i < mlen; i++) m[i] = 0; free(m);
for (i = 0; i < pqlen; i++) n[i] = 0; free(n);
for (i = 0; i < pqlen; i++) o[i] = 0; free(o);
}
/*
* Decrement a number.
*/
void decbn(Bignum bn) {
int i = 1;
while (i < bn[0] && bn[i] == 0)
bn[i++] = 0xFFFF;
bn[i]--;
}
/*
* Read an ssh1-format bignum from a data buffer. Return the number
* of bytes consumed.
*/
int ssh1_read_bignum(unsigned char *data, Bignum *result) {
unsigned char *p = data;
Bignum bn;
int i;
int w, b;
w = 0;
for (i=0; i<2; i++)
w = (w << 8) + *p++;
b = (w+7)/8; /* bits -> bytes */
w = (w+15)/16; /* bits -> words */
bn = newbn(w);
for (i=1; i<=w; i++)
bn[i] = 0;
for (i=b; i-- ;) {
unsigned char byte = *p++;
if (i & 1)
bn[1+i/2] |= byte<<8;
else
bn[1+i/2] |= byte;
}
*result = bn;
return p - data;
}