X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/7ef88f13fc063395e27705265a9db76a853be8f3..d5859615f641e5bbd853cd42aafd4fa577da17eb:/sshrsa.c

diff --git a/sshrsa.c b/sshrsa.c
index bac360fe..d39f8462 100644
--- a/sshrsa.c
+++ b/sshrsa.c
@@ -1,496 +1,56 @@
 /*
  * 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
-#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);
-}
-
-#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
 
 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;
-
-    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=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]);
-
-    }
+    int i;
 
-    result->exponent = bn[0];
-    result->modulus = bn[1];
+    if (result) {
+        result->bits = 0;
+        for (i=0; i<4; i++)
+            result->bits = (result->bits << 8) + *p++;
+    } else
+        p += 4;
+
+    /*
+     * order=0 means exponent then modulus (the keys sent by the
+     * server). order=1 means modulus then exponent (the keys
+     * stored in a keyfile).
+     */
+
+    if (order == 0)
+        p += ssh1_read_bignum(p, result ? &result->exponent : NULL);
+    if (result)
+        result->bytes = (((p[0] << 8) + p[1]) + 7) / 8;
+    if (keystr) *keystr = p+2;
+    p += ssh1_read_bignum(p, result ? &result->modulus : NULL);
+    if (order == 1)
+        p += ssh1_read_bignum(p, result ? &result->exponent : NULL);
 
     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;
     unsigned char *p;
 
-    debug(key->exponent);
-
     memmove(data+key->bytes-length, data, length);
     data[0] = 0;
     data[1] = 2;
@@ -510,27 +70,23 @@ void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) {
     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);
-
     modpow(b1, key->exponent, key->modulus, b2);
 
-    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;
     }
 
@@ -538,69 +94,82 @@ void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) {
     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;
 
     md = key->modulus;
     ex = key->exponent;
-    return 4 * (ex[0]+md[0]) + 10;
+    return 4 * (ex[0]+md[0]) + 20;
 }
 
 void rsastr_fmt(char *str, struct RSAKey *key) {
     Bignum md, ex;
-    int len = 0, i;
+    int len = 0, i, nibbles;
+    static const char hex[] = "0123456789abcdef";
 
     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);
-    }
+    len += sprintf(str+len, "0x");
+
+    nibbles = (3 + ssh1_bignum_bitcount(ex))/4; if (nibbles<1) nibbles=1;
+    for (i=nibbles; i-- ;)
+        str[len++] = hex[(bignum_byte(ex, i/2) >> (4*(i%2))) & 0xF];
+
+    len += sprintf(str+len, ",0x");
+
+    nibbles = (3 + ssh1_bignum_bitcount(md))/4; if (nibbles<1) nibbles=1;
+    for (i=nibbles; i-- ;)
+        str[len++] = hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF];
+
     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;
+/*
+ * Generate a fingerprint string for the key. Compatible with the
+ * OpenSSH fingerprint code.
+ */
+void rsa_fingerprint(char *str, int len, struct RSAKey *key) {
+    struct MD5Context md5c;
+    unsigned char digest[16];
+    char buffer[16*3+40];
+    int numlen, slen, i;
+
+    MD5Init(&md5c);
+    numlen = ssh1_bignum_length(key->modulus) - 2;
+    for (i = numlen; i-- ;) {
+        unsigned char c = bignum_byte(key->modulus, i);
+        MD5Update(&md5c, &c, 1);
+    }
+    numlen = ssh1_bignum_length(key->exponent) - 2;
+    for (i = numlen; i-- ;) {
+        unsigned char c = bignum_byte(key->exponent, i);
+        MD5Update(&md5c, &c, 1);
+    }
+    MD5Final(digest, &md5c);
+
+    sprintf(buffer, "%d ", ssh1_bignum_bitcount(key->modulus));
+    for (i = 0; i < 16; i++)
+        sprintf(buffer+strlen(buffer), "%s%02x", i?":":"", digest[i]);
+    strncpy(str, buffer, len); str[len-1] = '\0';
+    slen = strlen(str);
+    if (key->comment && slen < len-1) {
+        str[slen] = ' ';
+        strncpy(str+slen+1, key->comment, len-slen-1);
+        str[len-1] = '\0';
+    }
 }
 
-#endif
+void freersakey(struct RSAKey *key) {
+    if (key->modulus) freebn(key->modulus);
+    if (key->exponent) freebn(key->exponent);
+    if (key->private_exponent) freebn(key->private_exponent);
+    if (key->comment) free(key->comment);
+}