зеркало из https://github.com/github/putty.git
405 строки
8.7 KiB
C
405 строки
8.7 KiB
C
/*
|
|
* RSA implementation just sufficient for ssh client-side
|
|
* initialisation step
|
|
*
|
|
* Rewritten for more speed by Joris van Rantwijk, Jun 1999.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
#include "ssh.h"
|
|
|
|
typedef unsigned short *Bignum;
|
|
|
|
static unsigned short Zero[1] = { 0 };
|
|
|
|
#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
|
|
|
|
static Bignum newbn(int length) {
|
|
Bignum b = malloc((length+1)*sizeof(unsigned short));
|
|
if (!b)
|
|
abort(); /* FIXME */
|
|
b[0] = length;
|
|
return b;
|
|
}
|
|
|
|
static void freebn(Bignum b) {
|
|
free(b);
|
|
}
|
|
|
|
/*
|
|
* Compute c = a * b.
|
|
* Input is in the first len words of a and b.
|
|
* Result is returned in the first 2*len words of c.
|
|
*/
|
|
static void bigmul(unsigned short *a, unsigned short *b, unsigned short *c,
|
|
int len)
|
|
{
|
|
int i, j;
|
|
unsigned long ai, t;
|
|
|
|
for (j = len - 1; j >= 0; j--)
|
|
c[j+len] = 0;
|
|
|
|
for (i = len - 1; i >= 0; i--) {
|
|
ai = a[i];
|
|
t = 0;
|
|
for (j = len - 1; j >= 0; j--) {
|
|
t += ai * (unsigned long) b[j];
|
|
t += (unsigned long) c[i+j+1];
|
|
c[i+j+1] = (unsigned short)t;
|
|
t = t >> 16;
|
|
}
|
|
c[i] = (unsigned short)t;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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).
|
|
* The MSW of m MUST have its high bit set.
|
|
*/
|
|
static void bigmod(unsigned short *a, unsigned short *m, int len)
|
|
{
|
|
unsigned short m0, m1;
|
|
unsigned int h;
|
|
int i, k;
|
|
|
|
/* Special case for len == 1 */
|
|
if (len == 1) {
|
|
a[1] = (((long) a[0] << 16) + a[1]) % m[0];
|
|
a[0] = 0;
|
|
return;
|
|
}
|
|
|
|
m0 = m[0];
|
|
m1 = m[1];
|
|
|
|
for (i = 0; i <= len; i++) {
|
|
unsigned long t;
|
|
unsigned int q, r, c;
|
|
|
|
if (i == 0) {
|
|
h = 0;
|
|
} else {
|
|
h = a[i-1];
|
|
a[i-1] = 0;
|
|
}
|
|
|
|
/* Find q = h:a[i] / m0 */
|
|
t = ((unsigned long) h << 16) + a[i];
|
|
q = t / m0;
|
|
r = t % m0;
|
|
|
|
/* Refine our estimate of q by looking at
|
|
h:a[i]:a[i+1] / m0:m1 */
|
|
t = (long) m1 * (long) q;
|
|
if (t > ((unsigned long) r << 16) + a[i+1]) {
|
|
q--;
|
|
t -= m1;
|
|
r = (r + m0) & 0xffff; /* overflow? */
|
|
if (r >= (unsigned long)m0 &&
|
|
t > ((unsigned long) r << 16) + a[i+1])
|
|
q--;
|
|
}
|
|
|
|
/* Substract q * m from a[i...] */
|
|
c = 0;
|
|
for (k = len - 1; k >= 0; k--) {
|
|
t = (long) q * (long) m[k];
|
|
t += c;
|
|
c = t >> 16;
|
|
if ((unsigned short) t > a[i+k]) c++;
|
|
a[i+k] -= (unsigned short) t;
|
|
}
|
|
|
|
/* Add back m in case of borrow */
|
|
if (c != h) {
|
|
t = 0;
|
|
for (k = len - 1; k >= 0; k--) {
|
|
t += m[k];
|
|
t += a[i+k];
|
|
a[i+k] = (unsigned short)t;
|
|
t = t >> 16;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Compute (base ^ exp) % mod.
|
|
* The base MUST be smaller than the modulus.
|
|
* The most significant word of mod MUST be non-zero.
|
|
* We assume that the result array is the same size as the mod array.
|
|
*/
|
|
static void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result)
|
|
{
|
|
unsigned short *a, *b, *n, *m;
|
|
int mshift;
|
|
int 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;
|
|
}
|
|
|
|
/* Allocate n of size mlen, copy base to n */
|
|
n = malloc(mlen * sizeof(unsigned short));
|
|
i = mlen - base[0];
|
|
for (j = 0; j < i; j++) n[j] = 0;
|
|
for (j = 0; j < base[0]; j++) n[i+j] = base[base[0] - j];
|
|
|
|
/* Allocate a and b of size 2*mlen. Set a = 1 */
|
|
a = malloc(2 * mlen * sizeof(unsigned short));
|
|
b = malloc(2 * mlen * sizeof(unsigned short));
|
|
for (i = 0; i < 2*mlen; i++) a[i] = 0;
|
|
a[2*mlen-1] = 1;
|
|
|
|
/* Skip leading zero bits of exp. */
|
|
i = 0; j = 15;
|
|
while (i < exp[0] && (exp[exp[0] - i] & (1 << j)) == 0) {
|
|
j--;
|
|
if (j < 0) { i++; j = 15; }
|
|
}
|
|
|
|
/* Main computation */
|
|
while (i < exp[0]) {
|
|
while (j >= 0) {
|
|
bigmul(a + mlen, a + mlen, b, mlen);
|
|
bigmod(b, m, mlen);
|
|
if ((exp[exp[0] - i] & (1 << j)) != 0) {
|
|
bigmul(b + mlen, n, a, mlen);
|
|
bigmod(a, m, mlen);
|
|
} else {
|
|
unsigned short *t;
|
|
t = a; a = b; b = t;
|
|
}
|
|
j--;
|
|
}
|
|
i++; j = 15;
|
|
}
|
|
|
|
/* Fixup result in case the modulus was shifted */
|
|
if (mshift) {
|
|
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);
|
|
for (i = 2*mlen - 1; i >= 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+mlen];
|
|
|
|
/* Free temporary arrays */
|
|
for (i = 0; i < 2*mlen; i++) a[i] = 0; free(a);
|
|
for (i = 0; i < 2*mlen; i++) b[i] = 0; free(b);
|
|
for (i = 0; i < mlen; i++) m[i] = 0; free(m);
|
|
for (i = 0; i < mlen; i++) n[i] = 0; free(n);
|
|
}
|
|
|
|
int makekey(unsigned char *data, struct RSAKey *result,
|
|
unsigned char **keystr) {
|
|
unsigned char *p = data;
|
|
Bignum bn[2];
|
|
int i, j;
|
|
int w, b;
|
|
|
|
result->bits = 0;
|
|
for (i=0; i<4; i++)
|
|
result->bits = (result->bits << 8) + *p++;
|
|
|
|
for (j=0; j<2; j++) {
|
|
|
|
w = 0;
|
|
for (i=0; i<2; i++)
|
|
w = (w << 8) + *p++;
|
|
|
|
result->bytes = b = (w+7)/8; /* bits -> bytes */
|
|
w = (w+15)/16; /* bits -> words */
|
|
|
|
bn[j] = newbn(w);
|
|
|
|
if (keystr) *keystr = p; /* point at key string, second time */
|
|
|
|
for (i=1; i<=w; i++)
|
|
bn[j][i] = 0;
|
|
for (i=b; i-- ;) {
|
|
unsigned char byte = *p++;
|
|
if (i & 1)
|
|
bn[j][1+i/2] |= byte<<8;
|
|
else
|
|
bn[j][1+i/2] |= byte;
|
|
}
|
|
|
|
debug(bn[j]);
|
|
|
|
}
|
|
|
|
result->exponent = bn[0];
|
|
result->modulus = bn[1];
|
|
|
|
return p - data;
|
|
}
|
|
|
|
void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) {
|
|
Bignum b1, b2;
|
|
int w, i;
|
|
unsigned char *p;
|
|
|
|
debug(key->exponent);
|
|
|
|
memmove(data+key->bytes-length, data, length);
|
|
data[0] = 0;
|
|
data[1] = 2;
|
|
|
|
for (i = 2; i < key->bytes-length-1; i++) {
|
|
do {
|
|
data[i] = random_byte();
|
|
} while (data[i] == 0);
|
|
}
|
|
data[key->bytes-length-1] = 0;
|
|
|
|
w = (key->bytes+1)/2;
|
|
|
|
b1 = newbn(w);
|
|
b2 = newbn(w);
|
|
|
|
p = data;
|
|
for (i=1; i<=w; i++)
|
|
b1[i] = 0;
|
|
for (i=key->bytes; i-- ;) {
|
|
unsigned char byte = *p++;
|
|
if (i & 1)
|
|
b1[1+i/2] |= byte<<8;
|
|
else
|
|
b1[1+i/2] |= byte;
|
|
}
|
|
|
|
debug(b1);
|
|
|
|
modpow(b1, key->exponent, key->modulus, b2);
|
|
|
|
debug(b2);
|
|
|
|
p = data;
|
|
for (i=key->bytes; i-- ;) {
|
|
unsigned char b;
|
|
if (i & 1)
|
|
b = b2[1+i/2] >> 8;
|
|
else
|
|
b = b2[1+i/2] & 0xFF;
|
|
*p++ = b;
|
|
}
|
|
|
|
freebn(b1);
|
|
freebn(b2);
|
|
}
|
|
|
|
int rsastr_len(struct RSAKey *key) {
|
|
Bignum md, ex;
|
|
|
|
md = key->modulus;
|
|
ex = key->exponent;
|
|
return 4 * (ex[0]+md[0]) + 10;
|
|
}
|
|
|
|
void rsastr_fmt(char *str, struct RSAKey *key) {
|
|
Bignum md, ex;
|
|
int len = 0, i;
|
|
|
|
md = key->modulus;
|
|
ex = key->exponent;
|
|
|
|
for (i=1; i<=ex[0]; i++) {
|
|
sprintf(str+len, "%04x", ex[i]);
|
|
len += strlen(str+len);
|
|
}
|
|
str[len++] = '/';
|
|
for (i=1; i<=md[0]; i++) {
|
|
sprintf(str+len, "%04x", md[i]);
|
|
len += strlen(str+len);
|
|
}
|
|
str[len] = '\0';
|
|
}
|
|
|
|
#ifdef TESTMODE
|
|
|
|
#ifndef NODDY
|
|
#define p1 10007
|
|
#define p2 10069
|
|
#define p3 10177
|
|
#else
|
|
#define p1 3
|
|
#define p2 7
|
|
#define p3 13
|
|
#endif
|
|
|
|
unsigned short P1[2] = { 1, p1 };
|
|
unsigned short P2[2] = { 1, p2 };
|
|
unsigned short P3[2] = { 1, p3 };
|
|
unsigned short bigmod[5] = { 4, 0, 0, 0, 32768U };
|
|
unsigned short mod[5] = { 4, 0, 0, 0, 0 };
|
|
unsigned short a[5] = { 4, 0, 0, 0, 0 };
|
|
unsigned short b[5] = { 4, 0, 0, 0, 0 };
|
|
unsigned short c[5] = { 4, 0, 0, 0, 0 };
|
|
unsigned short One[2] = { 1, 1 };
|
|
unsigned short Two[2] = { 1, 2 };
|
|
|
|
int main(void) {
|
|
modmult(P1, P2, bigmod, a); debug(a);
|
|
modmult(a, P3, bigmod, mod); debug(mod);
|
|
|
|
sub(P1, One, a); debug(a);
|
|
sub(P2, One, b); debug(b);
|
|
modmult(a, b, bigmod, c); debug(c);
|
|
sub(P3, One, a); debug(a);
|
|
modmult(a, c, bigmod, b); debug(b);
|
|
|
|
modpow(Two, b, mod, a); debug(a);
|
|
|
|
return 0;
|
|
}
|
|
|
|
#endif
|