/*
* RSA implementation just sufficient for ssh client-side
* initialisation step
+ *
+ * Rewritten for more speed by Joris van Rantwijk, Jun 1999.
*/
-/*#include <windows.h>
-#define RSADEBUG
-#define DLVL 2
-#include "stel.h"*/
-
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <assert.h>
#include "ssh.h"
+#include "misc.h"
-typedef unsigned short *Bignum;
+#define GET_32BIT(cp) \
+ (((unsigned long)(unsigned char)(cp)[0] << 24) | \
+ ((unsigned long)(unsigned char)(cp)[1] << 16) | \
+ ((unsigned long)(unsigned char)(cp)[2] << 8) | \
+ ((unsigned long)(unsigned char)(cp)[3]))
-static unsigned short Zero[1] = { 0 };
+#define PUT_32BIT(cp, value) { \
+ (cp)[0] = (unsigned char)((value) >> 24); \
+ (cp)[1] = (unsigned char)((value) >> 16); \
+ (cp)[2] = (unsigned char)((value) >> 8); \
+ (cp)[3] = (unsigned char)(value); }
-#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 makekey(unsigned char *data, struct RSAKey *result,
+ unsigned char **keystr, int order)
+{
+ unsigned char *p = data;
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;
+
+ 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;
}
-static void freebn(Bignum b) {
- free(b);
+int makeprivate(unsigned char *data, struct RSAKey *result)
+{
+ return ssh1_read_bignum(data, &result->private_exponent);
}
-static int msb(Bignum r) {
+void rsaencrypt(unsigned char *data, int length, struct RSAKey *key)
+{
+ Bignum b1, b2;
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;
+ unsigned char *p;
- return j;
-}
+ memmove(data + key->bytes - length, data, length);
+ data[0] = 0;
+ data[1] = 2;
-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;
+ for (i = 2; i < key->bytes - length - 1; i++) {
+ do {
+ data[i] = random_byte();
+ } while (data[i] == 0);
}
+ data[key->bytes - length - 1] = 0;
- debug(result);
- leave(("<add\n"));
-}
+ b1 = bignum_from_bytes(data, key->bytes);
-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;
+ b2 = modpow(b1, key->exponent, key->modulus);
+
+ p = data;
+ for (i = key->bytes; i--;) {
+ *p++ = bignum_byte(b2, i);
}
- debug(result);
- leave(("<sub\n"));
+ freebn(b1);
+ freebn(b2);
}
-static int ge(Bignum r1, Bignum r2) {
- int i;
+Bignum rsadecrypt(Bignum input, struct RSAKey *key)
+{
+ Bignum ret;
+ ret = modpow(input, key->private_exponent, key->modulus);
+ return ret;
+}
- 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--;
- }
+int rsastr_len(struct RSAKey *key)
+{
+ Bignum md, ex;
+ int mdlen, exlen;
- dmsg(("equal\n"));
- leave(("<ge\n"));
- return 1; /* r1 = r2 */
+ md = key->modulus;
+ ex = key->exponent;
+ mdlen = (bignum_bitcount(md) + 15) / 16;
+ exlen = (bignum_bitcount(ex) + 15) / 16;
+ return 4 * (mdlen + exlen) + 20;
}
-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);
- }
+void rsastr_fmt(char *str, struct RSAKey *key)
+{
+ Bignum md, ex;
+ int len = 0, i, nibbles;
+ static const char hex[] = "0123456789abcdef";
- freebn(temp);
- freebn(tmp2);
+ md = key->modulus;
+ ex = key->exponent;
- debug(result);
- leave(("<modmult\n"));
-}
+ len += sprintf(str + len, "0x");
-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);
- }
+ nibbles = (3 + 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");
- freebn(temp);
- freebn(tmp2);
+ nibbles = (3 + 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];
- debug(result);
- leave(("<modpow\n"));
+ str[len] = '\0';
}
-int makekey(unsigned char *data, struct RSAKey *result,
- unsigned char **keystr) {
- unsigned char *p = data;
- Bignum bn[2];
- int i, j;
- int w, b;
+/*
+ * 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 ", 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';
+ }
+}
- result->bits = 0;
- for (i=0; i<4; i++)
- result->bits = (result->bits << 8) + *p++;
+/*
+ * Verify that the public data in an RSA key matches the private
+ * data. We also check the private data itself: we ensure that p >
+ * q and that iqmp really is the inverse of q mod p.
+ */
+int rsa_verify(struct RSAKey *key)
+{
+ Bignum n, ed, pm1, qm1;
+ int cmp;
+
+ /* n must equal pq. */
+ n = bigmul(key->p, key->q);
+ cmp = bignum_cmp(n, key->modulus);
+ freebn(n);
+ if (cmp != 0)
+ return 0;
+
+ /* e * d must be congruent to 1, modulo (p-1) and modulo (q-1). */
+ pm1 = copybn(key->p);
+ decbn(pm1);
+ ed = modmul(key->exponent, key->private_exponent, pm1);
+ cmp = bignum_cmp(ed, One);
+ sfree(ed);
+ if (cmp != 0)
+ return 0;
+
+ qm1 = copybn(key->q);
+ decbn(qm1);
+ ed = modmul(key->exponent, key->private_exponent, qm1);
+ cmp = bignum_cmp(ed, One);
+ sfree(ed);
+ if (cmp != 0)
+ return 0;
+
+ /*
+ * Ensure p > q.
+ */
+ if (bignum_cmp(key->p, key->q) <= 0)
+ return 0;
+
+ /*
+ * Ensure iqmp * q is congruent to 1, modulo p.
+ */
+ n = modmul(key->iqmp, key->q, key->p);
+ cmp = bignum_cmp(n, One);
+ sfree(n);
+ if (cmp != 0)
+ return 0;
+
+ return 1;
+}
- for (j=0; j<2; j++) {
+/* Public key blob as used by Pageant: exponent before modulus. */
+unsigned char *rsa_public_blob(struct RSAKey *key, int *len)
+{
+ int length, pos;
+ unsigned char *ret;
- w = 0;
- for (i=0; i<2; i++)
- w = (w << 8) + *p++;
+ length = (ssh1_bignum_length(key->modulus) +
+ ssh1_bignum_length(key->exponent) + 4);
+ ret = smalloc(length);
- result->bytes = b = (w+7)/8; /* bits -> bytes */
- w = (w+15)/16; /* bits -> words */
+ PUT_32BIT(ret, bignum_bitcount(key->modulus));
+ pos = 4;
+ pos += ssh1_write_bignum(ret + pos, key->exponent);
+ pos += ssh1_write_bignum(ret + pos, key->modulus);
- bn[j] = newbn(w);
+ *len = length;
+ return ret;
+}
- if (keystr) *keystr = p; /* point at key string, second time */
+/* Given a public blob, determine its length. */
+int rsa_public_blob_len(void *data)
+{
+ unsigned char *p = (unsigned char *)data;
+ int ret;
- 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;
- }
+ p += 4; /* length word */
+ p += ssh1_read_bignum(p, NULL); /* exponent */
+ p += ssh1_read_bignum(p, NULL); /* modulus */
- debug(bn[j]);
+ return p - (unsigned char *)data;
+}
- }
+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)
+ sfree(key->comment);
+}
- result->exponent = bn[0];
- result->modulus = bn[1];
+/* ----------------------------------------------------------------------
+ * Implementation of the ssh-rsa signing key type.
+ */
- return p - data;
+static void getstring(char **data, int *datalen, char **p, int *length)
+{
+ *p = NULL;
+ if (*datalen < 4)
+ return;
+ *length = GET_32BIT(*data);
+ *datalen -= 4;
+ *data += 4;
+ if (*datalen < *length)
+ return;
+ *p = *data;
+ *data += *length;
+ *datalen -= *length;
+}
+static Bignum getmp(char **data, int *datalen)
+{
+ char *p;
+ int length;
+ Bignum b;
+
+ getstring(data, datalen, &p, &length);
+ if (!p)
+ return NULL;
+ b = bignum_from_bytes(p, length);
+ return b;
}
-void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) {
- Bignum b1, b2;
- int w, i;
- unsigned char *p;
+static void *rsa2_newkey(char *data, int len)
+{
+ char *p;
+ int slen;
+ struct RSAKey *rsa;
- debug(key->exponent);
+ rsa = smalloc(sizeof(struct RSAKey));
+ if (!rsa)
+ return NULL;
+ getstring(&data, &len, &p, &slen);
- 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);
+ if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) {
+ sfree(rsa);
+ return NULL;
}
- data[key->bytes-length-1] = 0;
+ rsa->exponent = getmp(&data, &len);
+ rsa->modulus = getmp(&data, &len);
+ rsa->private_exponent = NULL;
+ rsa->comment = NULL;
- w = (key->bytes+1)/2;
+ return rsa;
+}
- b1 = newbn(w);
- b2 = newbn(w);
+static void rsa2_freekey(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ freersakey(rsa);
+ sfree(rsa);
+}
- p = data;
- for (i=1; i<=w; i++)
- b1[i] = 0;
- for (i=0; i<key->bytes; i++) {
- unsigned char byte = *p++;
- if ((key->bytes-i) & 1)
- b1[w-i/2] |= byte;
- else
- b1[w-i/2] |= byte<<8;
- }
+static char *rsa2_fmtkey(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ char *p;
+ int len;
- debug(b1);
+ len = rsastr_len(rsa);
+ p = smalloc(len);
+ rsastr_fmt(p, rsa);
+ return p;
+}
- modpow(b1, key->exponent, key->modulus, b2);
+static unsigned char *rsa2_public_blob(void *key, int *len)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ int elen, mlen, bloblen;
+ int i;
+ unsigned char *blob, *p;
+
+ elen = (bignum_bitcount(rsa->exponent) + 8) / 8;
+ mlen = (bignum_bitcount(rsa->modulus) + 8) / 8;
+
+ /*
+ * string "ssh-rsa", mpint exp, mpint mod. Total 19+elen+mlen.
+ * (three length fields, 12+7=19).
+ */
+ bloblen = 19 + elen + mlen;
+ blob = smalloc(bloblen);
+ p = blob;
+ PUT_32BIT(p, 7);
+ p += 4;
+ memcpy(p, "ssh-rsa", 7);
+ p += 7;
+ PUT_32BIT(p, elen);
+ p += 4;
+ for (i = elen; i--;)
+ *p++ = bignum_byte(rsa->exponent, i);
+ PUT_32BIT(p, mlen);
+ p += 4;
+ for (i = mlen; i--;)
+ *p++ = bignum_byte(rsa->modulus, i);
+ assert(p == blob + bloblen);
+ *len = bloblen;
+ return blob;
+}
- debug(b2);
+static unsigned char *rsa2_private_blob(void *key, int *len)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ int dlen, plen, qlen, ulen, bloblen;
+ int i;
+ unsigned char *blob, *p;
+
+ dlen = (bignum_bitcount(rsa->private_exponent) + 8) / 8;
+ plen = (bignum_bitcount(rsa->p) + 8) / 8;
+ qlen = (bignum_bitcount(rsa->q) + 8) / 8;
+ ulen = (bignum_bitcount(rsa->iqmp) + 8) / 8;
+
+ /*
+ * mpint private_exp, mpint p, mpint q, mpint iqmp. Total 16 +
+ * sum of lengths.
+ */
+ bloblen = 16 + dlen + plen + qlen + ulen;
+ blob = smalloc(bloblen);
+ p = blob;
+ PUT_32BIT(p, dlen);
+ p += 4;
+ for (i = dlen; i--;)
+ *p++ = bignum_byte(rsa->private_exponent, i);
+ PUT_32BIT(p, plen);
+ p += 4;
+ for (i = plen; i--;)
+ *p++ = bignum_byte(rsa->p, i);
+ PUT_32BIT(p, qlen);
+ p += 4;
+ for (i = qlen; i--;)
+ *p++ = bignum_byte(rsa->q, i);
+ PUT_32BIT(p, ulen);
+ p += 4;
+ for (i = ulen; i--;)
+ *p++ = bignum_byte(rsa->iqmp, i);
+ assert(p == blob + bloblen);
+ *len = bloblen;
+ return blob;
+}
- p = data;
- for (i=0; i<key->bytes; i++) {
- unsigned char b;
- if (i & 1)
- b = b2[w-i/2] & 0xFF;
- else
- b = b2[w-i/2] >> 8;
- *p++ = b;
+static void *rsa2_createkey(unsigned char *pub_blob, int pub_len,
+ unsigned char *priv_blob, int priv_len)
+{
+ struct RSAKey *rsa;
+ char *pb = (char *) priv_blob;
+
+ rsa = rsa2_newkey((char *) pub_blob, pub_len);
+ rsa->private_exponent = getmp(&pb, &priv_len);
+ rsa->p = getmp(&pb, &priv_len);
+ rsa->q = getmp(&pb, &priv_len);
+ rsa->iqmp = getmp(&pb, &priv_len);
+
+ if (!rsa_verify(rsa)) {
+ rsa2_freekey(rsa);
+ return NULL;
}
- freebn(b1);
- freebn(b2);
+ return rsa;
}
-int rsastr_len(struct RSAKey *key) {
- Bignum md, ex;
+static void *rsa2_openssh_createkey(unsigned char **blob, int *len)
+{
+ char **b = (char **) blob;
+ struct RSAKey *rsa;
+
+ rsa = smalloc(sizeof(struct RSAKey));
+ if (!rsa)
+ return NULL;
+ rsa->comment = NULL;
+
+ rsa->modulus = getmp(b, len);
+ rsa->exponent = getmp(b, len);
+ rsa->private_exponent = getmp(b, len);
+ rsa->iqmp = getmp(b, len);
+ rsa->p = getmp(b, len);
+ rsa->q = getmp(b, len);
+
+ if (!rsa->modulus || !rsa->exponent || !rsa->private_exponent ||
+ !rsa->iqmp || !rsa->p || !rsa->q) {
+ sfree(rsa->modulus);
+ sfree(rsa->exponent);
+ sfree(rsa->private_exponent);
+ sfree(rsa->iqmp);
+ sfree(rsa->p);
+ sfree(rsa->q);
+ sfree(rsa);
+ return NULL;
+ }
- md = key->modulus;
- ex = key->exponent;
- return 4 * (ex[0]+md[0]) + 10;
+ return rsa;
}
-void rsastr_fmt(char *str, struct RSAKey *key) {
- Bignum md, ex;
- int len = 0, i;
+static int rsa2_openssh_fmtkey(void *key, unsigned char *blob, int len)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ int bloblen, i;
+
+ bloblen =
+ ssh2_bignum_length(rsa->modulus) +
+ ssh2_bignum_length(rsa->exponent) +
+ ssh2_bignum_length(rsa->private_exponent) +
+ ssh2_bignum_length(rsa->iqmp) +
+ ssh2_bignum_length(rsa->p) + ssh2_bignum_length(rsa->q);
+
+ if (bloblen > len)
+ return bloblen;
+
+ bloblen = 0;
+#define ENC(x) \
+ PUT_32BIT(blob+bloblen, ssh2_bignum_length((x))-4); bloblen += 4; \
+ for (i = ssh2_bignum_length((x))-4; i-- ;) blob[bloblen++]=bignum_byte((x),i);
+ ENC(rsa->modulus);
+ ENC(rsa->exponent);
+ ENC(rsa->private_exponent);
+ ENC(rsa->iqmp);
+ ENC(rsa->p);
+ ENC(rsa->q);
+
+ return bloblen;
+}
- md = key->modulus;
- ex = key->exponent;
+static char *rsa2_fingerprint(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ struct MD5Context md5c;
+ unsigned char digest[16], lenbuf[4];
+ char buffer[16 * 3 + 40];
+ char *ret;
+ int numlen, i;
+
+ MD5Init(&md5c);
+ MD5Update(&md5c, "\0\0\0\7ssh-rsa", 11);
+
+#define ADD_BIGNUM(bignum) \
+ numlen = (bignum_bitcount(bignum)+8)/8; \
+ PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \
+ for (i = numlen; i-- ;) { \
+ unsigned char c = bignum_byte(bignum, i); \
+ MD5Update(&md5c, &c, 1); \
+ }
+ ADD_BIGNUM(rsa->exponent);
+ ADD_BIGNUM(rsa->modulus);
+#undef ADD_BIGNUM
+
+ MD5Final(digest, &md5c);
+
+ sprintf(buffer, "ssh-rsa %d ", bignum_bitcount(rsa->modulus));
+ for (i = 0; i < 16; i++)
+ sprintf(buffer + strlen(buffer), "%s%02x", i ? ":" : "",
+ digest[i]);
+ ret = smalloc(strlen(buffer) + 1);
+ if (ret)
+ strcpy(ret, buffer);
+ return ret;
+}
- for (i=1; i<=ex[0]; i++) {
- sprintf(str+len, "%04x", ex[i]);
- len += strlen(str+len);
+/*
+ * This is the magic ASN.1/DER prefix that goes in the decoded
+ * signature, between the string of FFs and the actual SHA hash
+ * value. The meaning of it is:
+ *
+ * 00 -- this marks the end of the FFs; not part of the ASN.1 bit itself
+ *
+ * 30 21 -- a constructed SEQUENCE of length 0x21
+ * 30 09 -- a constructed sub-SEQUENCE of length 9
+ * 06 05 -- an object identifier, length 5
+ * 2B 0E 03 02 1A -- object id { 1 3 14 3 2 26 }
+ * (the 1,3 comes from 0x2B = 43 = 40*1+3)
+ * 05 00 -- NULL
+ * 04 14 -- a primitive OCTET STRING of length 0x14
+ * [0x14 bytes of hash data follows]
+ *
+ * The object id in the middle there is listed as `id-sha1' in
+ * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1d2.asn (the
+ * ASN module for PKCS #1) and its expanded form is as follows:
+ *
+ * id-sha1 OBJECT IDENTIFIER ::= {
+ * iso(1) identified-organization(3) oiw(14) secsig(3)
+ * algorithms(2) 26 }
+ */
+static unsigned char asn1_weird_stuff[] = {
+ 0x00, 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B,
+ 0x0E, 0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14,
+};
+
+#define ASN1_LEN ( (int) sizeof(asn1_weird_stuff) )
+
+static int rsa2_verifysig(void *key, char *sig, int siglen,
+ char *data, int datalen)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ Bignum in, out;
+ char *p;
+ int slen;
+ int bytes, i, j, ret;
+ unsigned char hash[20];
+
+ getstring(&sig, &siglen, &p, &slen);
+ if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) {
+ return 0;
}
- str[len++] = '/';
- for (i=1; i<=md[0]; i++) {
- sprintf(str+len, "%04x", md[i]);
- len += strlen(str+len);
+ in = getmp(&sig, &siglen);
+ out = modpow(in, rsa->exponent, rsa->modulus);
+ freebn(in);
+
+ ret = 1;
+
+ bytes = bignum_bitcount(rsa->modulus) / 8;
+ /* Top (partial) byte should be zero. */
+ if (bignum_byte(out, bytes - 1) != 0)
+ ret = 0;
+ /* First whole byte should be 1. */
+ if (bignum_byte(out, bytes - 2) != 1)
+ ret = 0;
+ /* Most of the rest should be FF. */
+ for (i = bytes - 3; i >= 20 + ASN1_LEN; i--) {
+ if (bignum_byte(out, i) != 0xFF)
+ ret = 0;
}
- str[len] = '\0';
+ /* Then we expect to see the asn1_weird_stuff. */
+ for (i = 20 + ASN1_LEN - 1, j = 0; i >= 20; i--, j++) {
+ if (bignum_byte(out, i) != asn1_weird_stuff[j])
+ ret = 0;
+ }
+ /* Finally, we expect to see the SHA-1 hash of the signed data. */
+ SHA_Simple(data, datalen, hash);
+ for (i = 19, j = 0; i >= 0; i--, j++) {
+ if (bignum_byte(out, i) != hash[j])
+ ret = 0;
+ }
+
+ return ret;
}
-#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;
+unsigned char *rsa2_sign(void *key, char *data, int datalen, int *siglen)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ unsigned char *bytes;
+ int nbytes;
+ unsigned char hash[20];
+ Bignum in, out;
+ int i, j;
+
+ SHA_Simple(data, datalen, hash);
+
+ nbytes = (bignum_bitcount(rsa->modulus) - 1) / 8;
+ bytes = smalloc(nbytes);
+
+ bytes[0] = 1;
+ for (i = 1; i < nbytes - 20 - ASN1_LEN; i++)
+ bytes[i] = 0xFF;
+ for (i = nbytes - 20 - ASN1_LEN, j = 0; i < nbytes - 20; i++, j++)
+ bytes[i] = asn1_weird_stuff[j];
+ for (i = nbytes - 20, j = 0; i < nbytes; i++, j++)
+ bytes[i] = hash[j];
+
+ in = bignum_from_bytes(bytes, nbytes);
+ sfree(bytes);
+
+ out = modpow(in, rsa->private_exponent, rsa->modulus);
+ freebn(in);
+
+ nbytes = (bignum_bitcount(out) + 7) / 8;
+ bytes = smalloc(4 + 7 + 4 + nbytes);
+ PUT_32BIT(bytes, 7);
+ memcpy(bytes + 4, "ssh-rsa", 7);
+ PUT_32BIT(bytes + 4 + 7, nbytes);
+ for (i = 0; i < nbytes; i++)
+ bytes[4 + 7 + 4 + i] = bignum_byte(out, nbytes - 1 - i);
+ freebn(out);
+
+ *siglen = 4 + 7 + 4 + nbytes;
+ return bytes;
}
-#endif
+const struct ssh_signkey ssh_rsa = {
+ rsa2_newkey,
+ rsa2_freekey,
+ rsa2_fmtkey,
+ rsa2_public_blob,
+ rsa2_private_blob,
+ rsa2_createkey,
+ rsa2_openssh_createkey,
+ rsa2_openssh_fmtkey,
+ rsa2_fingerprint,
+ rsa2_verifysig,
+ rsa2_sign,
+ "ssh-rsa",
+ "rsa2"
+};