#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <assert.h>
#include "ssh.h"
}
}
+/*
+ * Verify that the public data in an RSA key matches the private
+ * data.
+ */
+int rsa_verify(struct RSAKey *key) {
+ Bignum n, ed, pm1, qm1, pm1qm1;
+ 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)(q-1). */
+ pm1 = copybn(key->p);
+ decbn(pm1);
+ qm1 = copybn(key->q);
+ decbn(qm1);
+ pm1qm1 = bigmul(pm1, qm1);
+ freebn(pm1);
+ freebn(qm1);
+ ed = modmul(key->exponent, key->private_exponent, pm1qm1);
+ sfree(pm1qm1);
+ cmp = bignum_cmp(ed, One);
+ sfree(ed);
+ if (cmp != 0)
+ return 0;
+
+ return 1;
+}
+
void freersakey(struct RSAKey *key) {
if (key->modulus) freebn(key->modulus);
if (key->exponent) freebn(key->exponent);
if (!rsa) return NULL;
getstring(&data, &len, &p, &slen);
- if (!p || memcmp(p, "ssh-rsa", 7)) {
+ if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) {
sfree(rsa);
return NULL;
}
len = rsastr_len(rsa);
p = smalloc(len);
- rsastr_fmt(p, rsa);
+ rsastr_fmt(p, rsa);
return p;
}
+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 = (ssh1_bignum_bitcount(rsa->exponent)+8)/8;
+ mlen = (ssh1_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;
+}
+
+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 = (ssh1_bignum_bitcount(rsa->private_exponent)+8)/8;
+ plen = (ssh1_bignum_bitcount(rsa->p)+8)/8;
+ qlen = (ssh1_bignum_bitcount(rsa->q)+8)/8;
+ ulen = (ssh1_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;
+}
+
+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;
+ }
+
+ return rsa;
+}
+
+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;
+ }
+
+ return rsa;
+}
+
static char *rsa2_fingerprint(void *key) {
struct RSAKey *rsa = (struct RSAKey *)key;
struct MD5Context md5c;
/*
* 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. As closely as I can tell, the meaning of it is:
+ * 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 --
+ * 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;
if (bignum_byte(out, bytes-2) != 1)
ret = 0;
/* Most of the rest should be FF. */
- for (i = bytes-3; i >= 20 + sizeof(asn1_weird_stuff); i--) {
+ for (i = bytes-3; i >= 20 + ASN1_LEN; i--) {
if (bignum_byte(out, i) != 0xFF)
ret = 0;
}
/* Then we expect to see the asn1_weird_stuff. */
- for (i = 20 + sizeof(asn1_weird_stuff) - 1, j=0; i >= 20; i--,j++) {
+ for (i = 20 + ASN1_LEN - 1, j=0; i >= 20; i--,j++) {
if (bignum_byte(out, i) != asn1_weird_stuff[j])
ret = 0;
}
return ret;
}
-int rsa2_sign(void *key, char *sig, int siglen,
- char *data, int datalen) {
- return 0; /* FIXME */
+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 = (ssh1_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 = (ssh1_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;
}
-struct ssh_signkey ssh_rsa = {
+const struct ssh_signkey ssh_rsa = {
rsa2_newkey,
rsa2_freekey,
rsa2_fmtkey,
+ rsa2_public_blob,
+ rsa2_private_blob,
+ rsa2_createkey,
+ rsa2_openssh_createkey,
rsa2_fingerprint,
rsa2_verifysig,
rsa2_sign,
projects / u / mdw / putty / blobdiff