/*
* RSA implementation just sufficient for ssh client-side
* initialisation step
- * Modified by Joris, Jun 1999.
+ *
+ * Rewritten for more speed by Joris van Rantwijk, Jun 1999.
*/
-#define JORIS_RSA
-
-/*#include <windows.h>
-#define RSADEBUG
-#define DLVL 2
-#include "stel.h"*/
-
#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
#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);
-}
-
-#ifdef JORIS_RSA
-
-/*
- * 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] = t;
- t = t >> 16;
- }
- c[i] = 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 >= 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] = 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);
-}
-
-#else
-
-static int msb(Bignum r) {
- int i;
- int j;
- unsigned short n;
-
- for (i=r[0]; i>0; i--)
- if (r[i])
- break;
-
- j = (i-1)*16;
- n = r[i];
- if (n & 0xFF00) j += 8, n >>= 8;
- if (n & 0x00F0) j += 4, n >>= 4;
- if (n & 0x000C) j += 2, n >>= 2;
- if (n & 0x0002) j += 1, n >>= 1;
-
- return j;
-}
-
-static void add(Bignum r1, Bignum r2, Bignum result) {
- int i;
- long stuff = 0;
-
- enter((">add\n"));
- debug(r1);
- debug(r2);
-
- for (i = 1 ;; i++) {
- if (i <= r1[0])
- stuff += r1[i];
- if (i <= r2[0])
- stuff += r2[i];
- if (i <= result[0])
- result[i] = stuff & 0xFFFFU;
- if (i > r1[0] && i > r2[0] && i >= result[0])
- break;
- stuff >>= 16;
- }
-
- debug(result);
- leave(("<add\n"));
-}
-
-static void sub(Bignum r1, Bignum r2, Bignum result) {
- int i;
- long stuff = 0;
-
- enter((">sub\n"));
- debug(r1);
- debug(r2);
-
- for (i = 1 ;; i++) {
- if (i <= r1[0])
- stuff += r1[i];
- if (i <= r2[0])
- stuff -= r2[i];
- if (i <= result[0])
- result[i] = stuff & 0xFFFFU;
- if (i > r1[0] && i > r2[0] && i >= result[0])
- break;
- stuff = stuff<0 ? -1 : 0;
- }
-
- debug(result);
- leave(("<sub\n"));
-}
-
-static int ge(Bignum r1, Bignum r2) {
- int i;
-
- enter((">ge\n"));
- debug(r1);
- debug(r2);
-
- if (r1[0] < r2[0])
- i = r2[0];
- else
- i = r1[0];
-
- while (i > 0) {
- unsigned short n1 = (i > r1[0] ? 0 : r1[i]);
- unsigned short n2 = (i > r2[0] ? 0 : r2[i]);
-
- if (n1 > n2) {
- dmsg(("greater\n"));
- leave(("<ge\n"));
- return 1; /* r1 > r2 */
- } else if (n1 < n2) {
- dmsg(("less\n"));
- leave(("<ge\n"));
- return 0; /* r1 < r2 */
- }
-
- i--;
- }
-
- dmsg(("equal\n"));
- leave(("<ge\n"));
- return 1; /* r1 = r2 */
-}
-
-static void modmult(Bignum r1, Bignum r2, Bignum modulus, Bignum result) {
- Bignum temp = newbn(modulus[0]+1);
- Bignum tmp2 = newbn(modulus[0]+1);
- int i;
- int bit, bits, digit, smallbit;
-
- enter((">modmult\n"));
- debug(r1);
- debug(r2);
- debug(modulus);
-
- for (i=1; i<=result[0]; i++)
- result[i] = 0; /* result := 0 */
- for (i=1; i<=temp[0]; i++)
- temp[i] = (i > r2[0] ? 0 : r2[i]); /* temp := r2 */
-
- bits = 1+msb(r1);
-
- for (bit = 0; bit < bits; bit++) {
- digit = 1 + bit / 16;
- smallbit = bit % 16;
-
- debug(temp);
- if (digit <= r1[0] && (r1[digit] & (1<<smallbit))) {
- dmsg(("bit %d\n", bit));
- add(temp, result, tmp2);
- if (ge(tmp2, modulus))
- sub(tmp2, modulus, result);
- else
- add(tmp2, Zero, result);
- debug(result);
- }
-
- add(temp, temp, tmp2);
- if (ge(tmp2, modulus))
- sub(tmp2, modulus, temp);
- else
- add(tmp2, Zero, temp);
- }
-
- freebn(temp);
- freebn(tmp2);
-
- debug(result);
- leave(("<modmult\n"));
-}
-
-static void modpow(Bignum r1, Bignum r2, Bignum modulus, Bignum result) {
- Bignum temp = newbn(modulus[0]+1);
- Bignum tmp2 = newbn(modulus[0]+1);
- int i;
- int bit, bits, digit, smallbit;
-
- enter((">modpow\n"));
- debug(r1);
- debug(r2);
- debug(modulus);
-
- for (i=1; i<=result[0]; i++)
- result[i] = (i==1); /* result := 1 */
- for (i=1; i<=temp[0]; i++)
- temp[i] = (i > r1[0] ? 0 : r1[i]); /* temp := r1 */
-
- bits = 1+msb(r2);
-
- for (bit = 0; bit < bits; bit++) {
- digit = 1 + bit / 16;
- smallbit = bit % 16;
-
- debug(temp);
- if (digit <= r2[0] && (r2[digit] & (1<<smallbit))) {
- dmsg(("bit %d\n", bit));
- modmult(temp, result, modulus, tmp2);
- add(tmp2, Zero, result);
- debug(result);
- }
-
- modmult(temp, temp, modulus, tmp2);
- add(tmp2, Zero, temp);
- }
-
- freebn(temp);
- freebn(tmp2);
-
- debug(result);
- leave(("<modpow\n"));
-}
-
-#endif
+#include "ssh.h"
int makekey(unsigned char *data, struct RSAKey *result,
- unsigned char **keystr) {
+ unsigned char **keystr, int order) {
unsigned char *p = data;
- Bignum bn[2];
- int i, j;
- int w, b;
+ int i;
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 */
+ /*
+ * order=0 means exponent then modulus (the keys sent by the
+ * server). order=1 means modulus then exponent (the keys
+ * stored in a keyfile).
+ */
- for (i=1; i<=w; i++)
- bn[j][i] = 0;
- for (i=0; i<b; i++) {
- unsigned char byte = *p++;
- if ((b-i) & 1)
- bn[j][w-i/2] |= byte;
- else
- bn[j][w-i/2] |= byte<<8;
- }
-
- debug(bn[j]);
-
- }
-
- result->exponent = bn[0];
- result->modulus = bn[1];
+ if (order == 0)
+ p += ssh1_read_bignum(p, &result->exponent);
+ result->bytes = (((p[0] << 8) + p[1]) + 7) / 8;
+ if (keystr) *keystr = p+2;
+ p += ssh1_read_bignum(p, &result->modulus);
+ if (order == 1)
+ p += ssh1_read_bignum(p, &result->exponent);
return p - data;
}
+int makeprivate(unsigned char *data, struct RSAKey *result) {
+ return ssh1_read_bignum(data, &result->private_exponent);
+}
+
void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) {
Bignum b1, b2;
int w, i;
p = data;
for (i=1; i<=w; i++)
b1[i] = 0;
- for (i=0; i<key->bytes; i++) {
+ for (i=key->bytes; i-- ;) {
unsigned char byte = *p++;
- if ((key->bytes-i) & 1)
- b1[w-i/2] |= byte;
+ if (i & 1)
+ b1[1+i/2] |= byte<<8;
else
- b1[w-i/2] |= byte<<8;
+ b1[1+i/2] |= byte;
}
debug(b1);
debug(b2);
p = data;
- for (i=0; i<key->bytes; i++) {
+ for (i=key->bytes; i-- ;) {
unsigned char b;
if (i & 1)
- b = b2[w-i/2] & 0xFF;
+ b = b2[1+i/2] >> 8;
else
- b = b2[w-i/2] >> 8;
+ b = b2[1+i/2] & 0xFF;
*p++ = b;
}
freebn(b2);
}
+Bignum rsadecrypt(Bignum input, struct RSAKey *key) {
+ Bignum ret;
+ ret = newbn(key->modulus[0]);
+ modpow(input, key->private_exponent, key->modulus, ret);
+ return ret;
+}
+
int rsastr_len(struct RSAKey *key) {
Bignum md, ex;
projects / u / mdw / putty / blobdiff