X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/3709bfe9981af43e3cd491c37d300b57e5b26d50..7af9fa7f957710190d184d85e43bf917f71f84a9:/sshbn.c

diff --git a/sshbn.c b/sshbn.c
index aea5a82b..2fd98f91 100644
--- a/sshbn.c
+++ b/sshbn.c
@@ -6,6 +6,14 @@
 #include <stdlib.h>
 #include <string.h>
 
+#if 0 // use PuTTY main debugging for diagbn()
+#include <windows.h>
+#include "putty.h"
+#define debugprint debug
+#else
+#define debugprint(x) printf x
+#endif
+
 #define BIGNUM_INTERNAL
 typedef unsigned short *Bignum;
 
@@ -60,7 +68,7 @@ void freebn(Bignum b) {
 }
 
 Bignum bn_power_2(int n) {
-    Bignum ret = newbn((n+15)/16);
+    Bignum ret = newbn(n/16+1);
     bignum_set_bit(ret, n, 1);
     return ret;
 }
@@ -289,7 +297,7 @@ Bignum modmul(Bignum p, Bignum q, Bignum mod)
 {
     unsigned short *a, *n, *m, *o;
     int mshift;
-    int pqlen, mlen, i, j;
+    int pqlen, mlen, rlen, i, j;
     Bignum result;
 
     /* Allocate m of size mlen, copy mod to m */
@@ -339,9 +347,10 @@ Bignum modmul(Bignum p, Bignum q, Bignum mod)
     }
 
     /* Copy result to buffer */
-    result = newbn(mod[0]);
-    for (i = 0; i < mlen; i++)
-	result[result[0] - i] = a[i+2*pqlen-mlen];
+    rlen = (mlen < pqlen*2 ? mlen : pqlen*2);
+    result = newbn(rlen);
+    for (i = 0; i < rlen; i++)
+	result[result[0] - i] = a[i+2*pqlen-rlen];
     while (result[0] > 1 && result[result[0]] == 0) result[0]--;
 
     /* Free temporary arrays */
@@ -469,7 +478,7 @@ int ssh1_read_bignum(unsigned char *data, Bignum *result) {
 /*
  * Return the bit count of a bignum, for ssh1 encoding.
  */
-int ssh1_bignum_bitcount(Bignum bn) {
+int bignum_bitcount(Bignum bn) {
     int bitcount = bn[0] * 16 - 1;
     while (bitcount >= 0 && (bn[bitcount/16+1] >> (bitcount % 16)) == 0)
         bitcount--;
@@ -480,7 +489,14 @@ int ssh1_bignum_bitcount(Bignum bn) {
  * Return the byte length of a bignum when ssh1 encoded.
  */
 int ssh1_bignum_length(Bignum bn) {
-    return 2 + (ssh1_bignum_bitcount(bn)+7)/8;
+    return 2 + (bignum_bitcount(bn)+7)/8;
+}
+
+/*
+ * Return the byte length of a bignum when ssh2 encoded.
+ */
+int ssh2_bignum_length(Bignum bn) {
+    return 4 + (bignum_bitcount(bn)+8)/8;
 }
 
 /*
@@ -529,7 +545,7 @@ int ssh1_write_bignum(void *data, Bignum bn) {
     unsigned char *p = data;
     int len = ssh1_bignum_length(bn);
     int i;
-    int bitc = ssh1_bignum_bitcount(bn);
+    int bitc = bignum_bitcount(bn);
 
     *p++ = (bitc >> 8) & 0xFF;
     *p++ = (bitc     ) & 0xFF;
@@ -562,7 +578,7 @@ Bignum bignum_rshift(Bignum a, int shift) {
     int i, shiftw, shiftb, shiftbb, bits;
     unsigned short ai, ai1;
 
-    bits = ssh1_bignum_bitcount(a) - shift;
+    bits = bignum_bitcount(a) - shift;
     ret = newbn((bits+15)/16);
 
     if (ret) {
@@ -713,15 +729,15 @@ void diagbn(char *prefix, Bignum md) {
     int i, nibbles, morenibbles;
     static const char hex[] = "0123456789ABCDEF";
 
-    printf("%s0x", prefix ? prefix : "");
+    debugprint(("%s0x", prefix ? prefix : ""));
 
-    nibbles = (3 + ssh1_bignum_bitcount(md))/4; if (nibbles<1) nibbles=1;
+    nibbles = (3 + bignum_bitcount(md))/4; if (nibbles<1) nibbles=1;
     morenibbles = 4*md[0] - nibbles;
-    for (i=0; i<morenibbles; i++) putchar('-');
+    for (i=0; i<morenibbles; i++) debugprint(("-"));
     for (i=nibbles; i-- ;)
-        putchar(hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF]);
+        debugprint(("%c",hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF]));
 
-    if (prefix) putchar('\n');
+    if (prefix) debugprint(("\n"));
 }
 
 /*
@@ -826,7 +842,7 @@ char *bignum_decimal(Bignum x) {
      * Therefore if we multiply the bit count by 28/93, rounding
      * up, we will have enough digits.
      */
-    i = ssh1_bignum_bitcount(x);
+    i = bignum_bitcount(x);
     ndigits = (28*i + 92)/93;          /* multiply by 28/93 and round up */
     ndigits++;                         /* allow for trailing \0 */
     ret = smalloc(ndigits);