#include <stdlib.h>
#include <string.h>
+#define BIGNUM_INTERNAL
+typedef unsigned short *Bignum;
+
#include "ssh.h"
unsigned short bnZero[1] = { 0 };
Bignum Zero = bnZero, One = bnOne;
-Bignum newbn(int length) {
+static Bignum newbn(int length) {
Bignum b = smalloc((length+1)*sizeof(unsigned short));
if (!b)
abort(); /* FIXME */
return b;
}
+void bn_restore_invariant(Bignum b) {
+ while (b[0] > 1 && b[b[0]] == 0) b[0]--;
+}
+
Bignum copybn(Bignum orig) {
Bignum b = smalloc((orig[0]+1)*sizeof(unsigned short));
if (!b)
sfree(b);
}
+Bignum bn_power_2(int n) {
+ Bignum ret = newbn((n+15)/16);
+ bignum_set_bit(ret, n, 1);
+ return ret;
+}
+
/*
* Compute c = a * b.
* Input is in the first len words of a and b.
bn[i]--;
}
+Bignum bignum_from_bytes(unsigned char *data, int nbytes) {
+ Bignum result;
+ int w, i;
+
+ w = (nbytes+1)/2; /* bytes -> words */
+
+ result = newbn(w);
+ for (i=1; i<=w; i++)
+ result[i] = 0;
+ for (i=nbytes; i-- ;) {
+ unsigned char byte = *data++;
+ if (i & 1)
+ result[1+i/2] |= byte<<8;
+ else
+ result[1+i/2] |= byte;
+ }
+
+ while (result[0] > 1 && result[result[0]] == 0) result[0]--;
+ return result;
+}
+
/*
* 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 */
if (!result) /* just return length */
return b + 2;
- bn = newbn(w);
+ *result = bignum_from_bytes(p, b);
- 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;
+ return p + b - data;
}
/*
*/
int ssh1_bignum_bitcount(Bignum bn) {
int bitcount = bn[0] * 16 - 1;
-
while (bitcount >= 0 && (bn[bitcount/16+1] >> (bitcount % 16)) == 0)
bitcount--;
return bitcount + 1;
return bigmuladd(a, b, NULL);
}
+/*
+ * Create a bignum which is the bitmask covering another one. That
+ * is, the smallest integer which is >= N and is also one less than
+ * a power of two.
+ */
+Bignum bignum_bitmask(Bignum n) {
+ Bignum ret = copybn(n);
+ int i;
+ unsigned short j;
+
+ i = ret[0];
+ while (n[i] == 0 && i > 0)
+ i--;
+ if (i <= 0)
+ return ret; /* input was zero */
+ j = 1;
+ while (j < n[i])
+ j = 2*j+1;
+ ret[i] = j;
+ while (--i > 0)
+ ret[i] = 0xFFFF;
+ return ret;
+}
+
/*
* Convert a (max 16-bit) short into a bignum.
*/
return (unsigned short) r;
}
-static void diagbn(char *prefix, Bignum md) {
+void diagbn(char *prefix, Bignum md) {
int i, nibbles, morenibbles;
static const char hex[] = "0123456789ABCDEF";
/*
* The prime p used in the key exchange.
*/
-static unsigned short P[] = {
- 64,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x5381, 0xECE6, 0x6651, 0x4928,
- 0x1FE6, 0x7C4B, 0x2411, 0xAE9F, 0x9FA5, 0x5A89, 0x6BFB, 0xEE38,
- 0xB7ED, 0xF406, 0x5CB6, 0x0BFF, 0xED6B, 0xA637, 0x42E9, 0xF44C,
- 0x7EC6, 0x625E, 0xB576, 0xE485, 0xC245, 0x6D51, 0x356D, 0x4FE1,
- 0x1437, 0xF25F, 0x0A6D, 0x302B, 0x431B, 0xCD3A, 0x19B3, 0xEF95,
- 0x04DD, 0x8E34, 0x0879, 0x514A, 0x9B22, 0x3B13, 0xBEA6, 0x020B,
- 0xCC74, 0x8A67, 0x4E08, 0x2902, 0x1CD1, 0x80DC, 0x628B, 0xC4C6,
- 0xC234, 0x2168, 0xDAA2, 0xC90F, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
+static unsigned char P[] = {
+ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
+ 0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
+ 0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
+ 0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
+ 0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
+ 0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
+ 0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
+ 0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
+ 0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
+ 0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
+ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
/*
- * The order q of the group: (p-1)/2.
+ * The generator g = 2.
*/
-static unsigned short Q[] = {
- 64,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x29C0, 0xF673, 0x3328, 0x2494,
- 0x8FF3, 0xBE25, 0x9208, 0xD74F, 0xCFD2, 0xAD44, 0x35FD, 0xF71C,
- 0x5BF6, 0x7A03, 0xAE5B, 0x85FF, 0xF6B5, 0xD31B, 0x2174, 0x7A26,
- 0x3F63, 0x312F, 0xDABB, 0xF242, 0xE122, 0xB6A8, 0x9AB6, 0xA7F0,
- 0x8A1B, 0xF92F, 0x8536, 0x9815, 0x218D, 0xE69D, 0x8CD9, 0xF7CA,
- 0x026E, 0xC71A, 0x043C, 0x28A5, 0xCD91, 0x1D89, 0xDF53, 0x0105,
- 0xE63A, 0x4533, 0x2704, 0x9481, 0x0E68, 0xC06E, 0x3145, 0x6263,
- 0x611A, 0x10B4, 0xED51, 0xE487, 0xFFFF, 0xFFFF, 0xFFFF, 0x7FFF,
-};
+static unsigned char G[] = { 2 };
/*
- * The bitmask covering q (for ease of generation of x).
+ * Variables.
*/
-static unsigned short Qmask[] = {
- 64,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
- 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x7FFF,
-};
+static Bignum x, e, p, q, qmask, g;
+static int need_to_free_pg;
/*
- * The generator g = 2.
+ * Common DH initialisation.
*/
-static unsigned short G[] = { 1, 2 };
+static void dh_init(void) {
+ q = bignum_rshift(p, 1);
+ qmask = bignum_bitmask(q);
+}
/*
- * Variables.
+ * Initialise DH for the standard group1.
*/
-static Bignum x, e;
+void dh_setup_group1(void) {
+ p = bignum_from_bytes(P, sizeof(P));
+ g = bignum_from_bytes(G, sizeof(G));
+ dh_init();
+}
+
+/*
+ * Clean up.
+ */
+void dh_cleanup(void) {
+ freebn(p);
+ freebn(g);
+ freebn(q);
+ freebn(qmask);
+}
/*
* DH stage 1: invent a number x between 1 and q, and compute e =
Bignum dh_create_e(void) {
int i;
- x = newbn(Q[0]);
+ int nbytes;
+ unsigned char *buf;
+
+ nbytes = ssh1_bignum_length(qmask);
+ buf = smalloc(nbytes);
do {
/*
* Create a potential x, by ANDing a string of random bytes
- * with Qmask.
+ * with qmask.
*/
- for (i = 1; i <= x[0]; i++)
- x[i] = ((random_byte() << 8) + random_byte()) & Qmask[i];
- } while (bignum_cmp(x, One) <= 0 || bignum_cmp(x, Q) >= 0);
+ if (x) freebn(x);
+ ssh1_write_bignum(buf, qmask);
+ for (i = 2; i < nbytes; i++)
+ buf[i] &= random_byte();
+ ssh1_read_bignum(buf, &x);
+ } while (bignum_cmp(x, One) <= 0 || bignum_cmp(x, q) >= 0);
/*
* Done. Now compute e = g^x mod p.
*/
- e = modpow(G, x, P);
+ e = modpow(g, x, p);
return e;
}
* DH stage 2: given a number f, compute K = f^x mod p.
*/
Bignum dh_find_K(Bignum f) {
- return modpow(f, x, P);
+ return modpow(f, x, p);
}
(cp)[3] = (unsigned char)(value); }
#if 0
-/*
- * Condition this section in for debugging of DSS.
- */
-static void diagbn(char *prefix, Bignum md) {
- int i, nibbles, morenibbles;
- static const char hex[] = "0123456789ABCDEF";
-
- printf("%s0x", prefix ? prefix : "");
-
- nibbles = (3 + ssh1_bignum_bitcount(md))/4; if (nibbles<1) nibbles=1;
- morenibbles = 4*md[0] - nibbles;
- for (i=0; i<morenibbles; i++) putchar('-');
- for (i=nibbles; i-- ;)
- putchar(hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF]);
-
- if (prefix) putchar('\n');
-}
#define DEBUG_DSS
#else
#define diagbn(x,y)
}
static Bignum getmp(char **data, int *datalen) {
char *p;
- int i, j, length;
+ int length;
Bignum b;
getstring(data, datalen, &p, &length);
return NULL;
if (p[0] & 0x80)
return NULL; /* negative mp */
- b = newbn((length+1)/2);
- for (i = 0; i < length; i++) {
- j = length - 1 - i;
- if (j & 1)
- b[j/2+1] |= ((unsigned char)p[i]) << 8;
- else
- b[j/2+1] |= ((unsigned char)p[i]);
- }
- while (b[0] > 1 && b[b[0]] == 0) b[0]--;
+ b = bignum_from_bytes(p, length);
return b;
}
static Bignum get160(char **data, int *datalen) {
- char *p;
- int i, j, length;
Bignum b;
- p = *data;
+ b = bignum_from_bytes(*data, 20);
*data += 20; *datalen -= 20;
- length = 20;
- while (length > 0 && !p[0])
- p++, length--;
- b = newbn((length+1)/2);
- for (i = 0; i < length; i++) {
- j = length - 1 - i;
- if (j & 1)
- b[j/2+1] |= ((unsigned char)p[i]) << 8;
- else
- b[j/2+1] |= ((unsigned char)p[i]);
- }
return b;
}
if (!dss->p)
return NULL;
len = 8 + 4 + 1; /* 4 x "0x", punctuation, \0 */
- len += 4 * (dss->p[0] + dss->q[0] + dss->g[0] + dss->y[0]); /* digits */
+ len += 4 * (ssh1_bignum_bitcount(dss->p)+15)/16;
+ len += 4 * (ssh1_bignum_bitcount(dss->q)+15)/16;
+ len += 4 * (ssh1_bignum_bitcount(dss->g)+15)/16;
+ len += 4 * (ssh1_bignum_bitcount(dss->y)+15)/16;
p = smalloc(len);
if (!p) return NULL;
int i;
printf("sig:");
for (i=0;i<siglen;i++)
- printf(" %02xf", (unsigned char)(sig[i]));
+ printf(" %02x", (unsigned char)(sig[i]));
printf("\n");
}
#endif