/*
- * RSA implementation just sufficient for ssh client-side
- * initialisation step
- *
- * Rewritten for more speed by Joris van Rantwijk, Jun 1999.
+ * RSA implementation for PuTTY.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <assert.h>
#include "ssh.h"
+#include "misc.h"
+
+#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]))
+
+#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); }
+
+int makekey(unsigned char *data, int len, struct RSAKey *result,
+ unsigned char **keystr, int order)
+{
+ unsigned char *p = data;
+ int i, n;
+
+ if (len < 4)
+ return -1;
+
+ if (result) {
+ result->bits = 0;
+ for (i = 0; i < 4; i++)
+ result->bits = (result->bits << 8) + *p++;
+ } else
+ p += 4;
+
+ len -= 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) {
+ n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL);
+ if (n < 0) return -1;
+ p += n;
+ len -= n;
+ }
-typedef unsigned short *Bignum;
+ n = ssh1_read_bignum(p, len, result ? &result->modulus : NULL);
+ if (n < 0 || (result && bignum_bitcount(result->modulus) == 0)) return -1;
+ if (result)
+ result->bytes = n - 2;
+ if (keystr)
+ *keystr = p + 2;
+ p += n;
+ len -= n;
+
+ if (order == 1) {
+ n = ssh1_read_bignum(p, len, result ? &result->exponent : NULL);
+ if (n < 0) return -1;
+ p += n;
+ len -= n;
+ }
+ return p - data;
+}
-static unsigned short Zero[1] = { 0 };
+int makeprivate(unsigned char *data, int len, struct RSAKey *result)
+{
+ return ssh1_read_bignum(data, len, &result->private_exponent);
+}
-#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 rsaencrypt(unsigned char *data, int length, struct RSAKey *key)
+{
+ Bignum b1, b2;
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;
+ unsigned char *p;
+
+ if (key->bytes < length + 4)
+ return 0; /* RSA key too short! */
+
+ 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);
+ }
+ data[key->bytes - length - 1] = 0;
+
+ b1 = bignum_from_bytes(data, key->bytes);
+
+ b2 = modpow(b1, key->exponent, key->modulus);
+
+ p = data;
+ for (i = key->bytes; i--;) {
+ *p++ = bignum_byte(b2, i);
+ }
+
+ freebn(b1);
+ freebn(b2);
+
+ return 1;
}
-static void freebn(Bignum b) {
- free(b);
+static void sha512_mpint(SHA512_State * s, Bignum b)
+{
+ unsigned char lenbuf[4];
+ int len;
+ len = (bignum_bitcount(b) + 8) / 8;
+ PUT_32BIT(lenbuf, len);
+ SHA512_Bytes(s, lenbuf, 4);
+ while (len-- > 0) {
+ lenbuf[0] = bignum_byte(b, len);
+ SHA512_Bytes(s, lenbuf, 1);
+ }
+ memset(lenbuf, 0, sizeof(lenbuf));
}
/*
- * 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.
+ * This function is a wrapper on modpow(). It has the same effect
+ * as modpow(), but employs RSA blinding to protect against timing
+ * attacks.
*/
-static void bigmul(unsigned short *a, unsigned short *b, unsigned short *c,
- int len)
+static Bignum rsa_privkey_op(Bignum input, struct RSAKey *key)
{
- 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] = (unsigned short)t;
- t = t >> 16;
+ Bignum random, random_encrypted, random_inverse;
+ Bignum input_blinded, ret_blinded;
+ Bignum ret;
+
+ SHA512_State ss;
+ unsigned char digest512[64];
+ int digestused = lenof(digest512);
+ int hashseq = 0;
+
+ /*
+ * Start by inventing a random number chosen uniformly from the
+ * range 2..modulus-1. (We do this by preparing a random number
+ * of the right length and retrying if it's greater than the
+ * modulus, to prevent any potential Bleichenbacher-like
+ * attacks making use of the uneven distribution within the
+ * range that would arise from just reducing our number mod n.
+ * There are timing implications to the potential retries, of
+ * course, but all they tell you is the modulus, which you
+ * already knew.)
+ *
+ * To preserve determinism and avoid Pageant needing to share
+ * the random number pool, we actually generate this `random'
+ * number by hashing stuff with the private key.
+ */
+ while (1) {
+ int bits, byte, bitsleft, v;
+ random = copybn(key->modulus);
+ /*
+ * Find the topmost set bit. (This function will return its
+ * index plus one.) Then we'll set all bits from that one
+ * downwards randomly.
+ */
+ bits = bignum_bitcount(random);
+ byte = 0;
+ bitsleft = 0;
+ while (bits--) {
+ if (bitsleft <= 0) {
+ bitsleft = 8;
+ /*
+ * Conceptually the following few lines are equivalent to
+ * byte = random_byte();
+ */
+ if (digestused >= lenof(digest512)) {
+ unsigned char seqbuf[4];
+ PUT_32BIT(seqbuf, hashseq);
+ SHA512_Init(&ss);
+ SHA512_Bytes(&ss, "RSA deterministic blinding", 26);
+ SHA512_Bytes(&ss, seqbuf, sizeof(seqbuf));
+ sha512_mpint(&ss, key->private_exponent);
+ SHA512_Final(&ss, digest512);
+ hashseq++;
+
+ /*
+ * Now hash that digest plus the signature
+ * input.
+ */
+ SHA512_Init(&ss);
+ SHA512_Bytes(&ss, digest512, sizeof(digest512));
+ sha512_mpint(&ss, input);
+ SHA512_Final(&ss, digest512);
+
+ digestused = 0;
+ }
+ byte = digest512[digestused++];
+ }
+ v = byte & 1;
+ byte >>= 1;
+ bitsleft--;
+ bignum_set_bit(random, bits, v);
+ }
+
+ /*
+ * Now check that this number is strictly greater than
+ * zero, and strictly less than modulus.
+ */
+ if (bignum_cmp(random, Zero) <= 0 ||
+ bignum_cmp(random, key->modulus) >= 0) {
+ freebn(random);
+ continue;
+ } else {
+ break;
}
- c[i] = (unsigned short)t;
}
+
+ /*
+ * RSA blinding relies on the fact that (xy)^d mod n is equal
+ * to (x^d mod n) * (y^d mod n) mod n. We invent a random pair
+ * y and y^d; then we multiply x by y, raise to the power d mod
+ * n as usual, and divide by y^d to recover x^d. Thus an
+ * attacker can't correlate the timing of the modpow with the
+ * input, because they don't know anything about the number
+ * that was input to the actual modpow.
+ *
+ * The clever bit is that we don't have to do a huge modpow to
+ * get y and y^d; we will use the number we just invented as
+ * _y^d_, and use the _public_ exponent to compute (y^d)^e = y
+ * from it, which is much faster to do.
+ */
+ random_encrypted = modpow(random, key->exponent, key->modulus);
+ random_inverse = modinv(random, key->modulus);
+ input_blinded = modmul(input, random_encrypted, key->modulus);
+ ret_blinded = modpow(input_blinded, key->private_exponent, key->modulus);
+ ret = modmul(ret_blinded, random_inverse, key->modulus);
+
+ freebn(ret_blinded);
+ freebn(input_blinded);
+ freebn(random_inverse);
+ freebn(random_encrypted);
+ freebn(random);
+
+ return ret;
}
-/*
- * 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)
+Bignum rsadecrypt(Bignum input, struct RSAKey *key)
{
- 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;
- }
+ return rsa_privkey_op(input, key);
+}
- m0 = m[0];
- m1 = m[1];
+int rsastr_len(struct RSAKey *key)
+{
+ Bignum md, ex;
+ int mdlen, exlen;
- for (i = 0; i <= len; i++) {
- unsigned long t;
- unsigned int q, r, c;
+ md = key->modulus;
+ ex = key->exponent;
+ mdlen = (bignum_bitcount(md) + 15) / 16;
+ exlen = (bignum_bitcount(ex) + 15) / 16;
+ return 4 * (mdlen + exlen) + 20;
+}
- if (i == 0) {
- h = 0;
- } else {
- h = a[i-1];
- a[i-1] = 0;
- }
+void rsastr_fmt(char *str, struct RSAKey *key)
+{
+ Bignum md, ex;
+ int len = 0, i, nibbles;
+ static const char hex[] = "0123456789abcdef";
- /* 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 >= (unsigned long)m0 &&
- t > ((unsigned long) r << 16) + a[i+1])
- q--;
- }
+ md = key->modulus;
+ ex = key->exponent;
- /* 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;
- }
+ len += sprintf(str + len, "0x");
- /* 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] = (unsigned short)t;
- t = t >> 16;
- }
- }
- }
+ 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");
+
+ 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];
+
+ str[len] = '\0';
}
/*
- * 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.
+ * Generate a fingerprint string for the key. Compatible with the
+ * OpenSSH fingerprint code.
*/
-static void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result)
+void rsa_fingerprint(char *str, int len, struct RSAKey *key)
{
- 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;
+ 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);
}
-
- /* 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; }
+ numlen = ssh1_bignum_length(key->exponent) - 2;
+ for (i = numlen; i--;) {
+ unsigned char c = bignum_byte(key->exponent, i);
+ MD5Update(&md5c, &c, 1);
}
-
- /* 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;
+ 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';
}
+}
- /* 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));
- }
+/*
+ * 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;
+}
- /* Copy result to buffer */
- for (i = 0; i < mlen; i++)
- result[result[0] - i] = a[i+mlen];
+/* 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;
- /* 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);
-}
+ length = (ssh1_bignum_length(key->modulus) +
+ ssh1_bignum_length(key->exponent) + 4);
+ ret = snewn(length, unsigned char);
-int makekey(unsigned char *data, struct RSAKey *result,
- unsigned char **keystr) {
- unsigned char *p = data;
- Bignum bn[2];
- int i, j;
- int w, b;
+ 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);
- result->bits = 0;
- for (i=0; i<4; i++)
- result->bits = (result->bits << 8) + *p++;
+ *len = length;
+ return ret;
+}
- for (j=0; j<2; j++) {
+/* Given a public blob, determine its length. */
+int rsa_public_blob_len(void *data, int maxlen)
+{
+ unsigned char *p = (unsigned char *)data;
+ int n;
- w = 0;
- for (i=0; i<2; i++)
- w = (w << 8) + *p++;
+ if (maxlen < 4)
+ return -1;
+ p += 4; /* length word */
+ maxlen -= 4;
- result->bytes = b = (w+7)/8; /* bits -> bytes */
- w = (w+15)/16; /* bits -> words */
+ n = ssh1_read_bignum(p, maxlen, NULL); /* exponent */
+ if (n < 0)
+ return -1;
+ p += n;
- bn[j] = newbn(w);
+ n = ssh1_read_bignum(p, maxlen, NULL); /* modulus */
+ if (n < 0)
+ return -1;
+ p += n;
- if (keystr) *keystr = p; /* point at key string, second time */
+ return p - (unsigned char *)data;
+}
- for (i=1; i<=w; i++)
- bn[j][i] = 0;
- for (i=b; i-- ;) {
- unsigned char byte = *p++;
- if (i & 1)
- bn[j][1+i/2] |= byte<<8;
- else
- bn[j][1+i/2] |= byte;
- }
+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);
+}
- debug(bn[j]);
+/* ----------------------------------------------------------------------
+ * Implementation of the ssh-rsa signing key type.
+ */
+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((unsigned char *)p, length);
+ return b;
+}
+
+static void *rsa2_newkey(char *data, int len)
+{
+ char *p;
+ int slen;
+ struct RSAKey *rsa;
+
+ rsa = snew(struct RSAKey);
+ if (!rsa)
+ return NULL;
+ getstring(&data, &len, &p, &slen);
+
+ if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) {
+ sfree(rsa);
+ return NULL;
}
+ rsa->exponent = getmp(&data, &len);
+ rsa->modulus = getmp(&data, &len);
+ rsa->private_exponent = NULL;
+ rsa->comment = NULL;
- result->exponent = bn[0];
- result->modulus = bn[1];
+ return rsa;
+}
- return p - data;
+static void rsa2_freekey(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ freersakey(rsa);
+ sfree(rsa);
}
-void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) {
- Bignum b1, b2;
- int w, i;
- unsigned char *p;
+static char *rsa2_fmtkey(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ char *p;
+ int len;
+
+ len = rsastr_len(rsa);
+ p = snewn(len, char);
+ rsastr_fmt(p, rsa);
+ return p;
+}
- debug(key->exponent);
+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 = snewn(bloblen, unsigned char);
+ 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;
+}
- memmove(data+key->bytes-length, data, length);
- data[0] = 0;
- data[1] = 2;
+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 = snewn(bloblen, unsigned char);
+ 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;
+}
- for (i = 2; i < key->bytes-length-1; i++) {
- do {
- data[i] = random_byte();
- } while (data[i] == 0);
+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;
}
- data[key->bytes-length-1] = 0;
- w = (key->bytes+1)/2;
-
- b1 = newbn(w);
- b2 = newbn(w);
+ return rsa;
+}
- p = data;
- for (i=1; i<=w; i++)
- b1[i] = 0;
- for (i=key->bytes; i-- ;) {
- unsigned char byte = *p++;
- if (i & 1)
- b1[1+i/2] |= byte<<8;
- else
- b1[1+i/2] |= byte;
+static void *rsa2_openssh_createkey(unsigned char **blob, int *len)
+{
+ char **b = (char **) blob;
+ struct RSAKey *rsa;
+
+ rsa = snew(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;
}
- debug(b1);
+ return rsa;
+}
- modpow(b1, key->exponent, key->modulus, b2);
+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;
+}
- debug(b2);
+static int rsa2_pubkey_bits(void *blob, int len)
+{
+ struct RSAKey *rsa;
+ int ret;
- p = data;
- for (i=key->bytes; i-- ;) {
- unsigned char b;
- if (i & 1)
- b = b2[1+i/2] >> 8;
- else
- b = b2[1+i/2] & 0xFF;
- *p++ = b;
- }
+ rsa = rsa2_newkey((char *) blob, len);
+ ret = bignum_bitcount(rsa->modulus);
+ rsa2_freekey(rsa);
- freebn(b1);
- freebn(b2);
+ return ret;
}
-int rsastr_len(struct RSAKey *key) {
- Bignum md, ex;
-
- md = key->modulus;
- ex = key->exponent;
- return 4 * (ex[0]+md[0]) + 10;
+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, (unsigned char *)"\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 = snewn(strlen(buffer) + 1, char);
+ if (ret)
+ strcpy(ret, buffer);
+ return ret;
}
-void rsastr_fmt(char *str, struct RSAKey *key) {
- Bignum md, ex;
- int len = 0, i;
+/*
+ * 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 const unsigned char asn1_weird_stuff[] = {
+ 0x00, 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B,
+ 0x0E, 0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14,
+};
- md = key->modulus;
- ex = key->exponent;
+#define ASN1_LEN ( (int) sizeof(asn1_weird_stuff) )
- for (i=1; i<=ex[0]; i++) {
- sprintf(str+len, "%04x", ex[i]);
- len += strlen(str+len);
+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)+7) / 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;
+ }
+ freebn(out);
+
+ 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;
+static 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 = snewn(nbytes, unsigned char);
+
+ 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 = rsa_privkey_op(in, rsa);
+ freebn(in);
+
+ nbytes = (bignum_bitcount(out) + 7) / 8;
+ bytes = snewn(4 + 7 + 4 + nbytes, unsigned char);
+ 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_pubkey_bits,
+ rsa2_fingerprint,
+ rsa2_verifysig,
+ rsa2_sign,
+ "ssh-rsa",
+ "rsa2"
+};