+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;
+}
+
+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;
+}
+
+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;
+}
+
+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 = 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;
+ }
+
+ return rsa;
+}
+
+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;
+}
+
+static int rsa2_pubkey_bits(void *blob, int len)
+{
+ struct RSAKey *rsa;
+ int ret;
+
+ rsa = rsa2_newkey((char *) blob, len);
+ ret = bignum_bitcount(rsa->modulus);
+ rsa2_freekey(rsa);
+
+ return ret;
+}
+
+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;
+}
+
+/*
+ * 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,
+};
+
+#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;
+ }
+ 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;
+ }
+ /* 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;
+}