* Java ASN.1 encoding: *
* SEQUENCE ::= {
* r INTEGER,
* s INTEGER
* }
*
*/
public static byte[] encodeSSHDSASignature(byte[] ds)
{
TypesWriter tw = new TypesWriter();
tw.writeString("ssh-dss");
int len, index;
index = 3;
len = ds[index++] & 0xff;
byte[] r = new byte[len];
System.arraycopy(ds, index, r, 0, r.length);
index = index + len + 1;
len = ds[index++] & 0xff;
byte[] s = new byte[len];
System.arraycopy(ds, index, s, 0, s.length);
byte[] a40 = new byte[40];
/* Patch (unsigned) r and s into the target array. */
int r_copylen = (r.length < 20) ? r.length : 20;
int s_copylen = (s.length < 20) ? s.length : 20;
System.arraycopy(r, r.length - r_copylen, a40, 20 - r_copylen, r_copylen);
System.arraycopy(s, s.length - s_copylen, a40, 40 - s_copylen, s_copylen);
tw.writeString(a40, 0, 40);
return tw.getBytes();
}
public static byte[] decodeSSHDSASignature(byte[] sig) throws IOException
{
byte[] rsArray = null;
if (sig.length == 40)
{
/* OK, another broken SSH server. */
rsArray = sig;
}
else
{
/* Hopefully a server obeying the standard... */
TypesReader tr = new TypesReader(sig);
String sig_format = tr.readString();
if (sig_format.equals("ssh-dss") == false)
throw new IOException("Peer sent wrong signature format");
rsArray = tr.readByteString();
if (rsArray.length != 40)
throw new IOException("Peer sent corrupt signature");
if (tr.remain() != 0)
throw new IOException("Padding in DSA signature!");
}
int i = 0;
int j = 0;
byte[] tmp;
if (rsArray[0] == 0 && rsArray[1] == 0 && rsArray[2] == 0) {
j = ((rsArray[i++] << 24) & 0xff000000) | ((rsArray[i++] << 16) & 0x00ff0000)
| ((rsArray[i++] << 8) & 0x0000ff00) | ((rsArray[i++]) & 0x000000ff);
i += j;
j = ((rsArray[i++] << 24) & 0xff000000) | ((rsArray[i++] << 16) & 0x00ff0000)
| ((rsArray[i++] << 8) & 0x0000ff00) | ((rsArray[i++]) & 0x000000ff);
tmp = new byte[j];
System.arraycopy(rsArray, i, tmp, 0, j);
rsArray = tmp;
}
/* ASN.1 */
int frst = ((rsArray[0] & 0x80) != 0 ? 1 : 0);
int scnd = ((rsArray[20] & 0x80) != 0 ? 1 : 0);
/* Calculate output length */
int length = rsArray.length + 6 + frst + scnd;
tmp = new byte[length];
/* DER-encoding to match Java */
tmp[0] = (byte) 0x30;
if (rsArray.length != 40)
throw new IOException("Peer sent corrupt signature");
/* Calculate length */
tmp[1] = (byte) 0x2c;
tmp[1] += frst;
tmp[1] += scnd;
/* First item */
tmp[2] = (byte) 0x02;
/* First item length */
tmp[3] = (byte) 0x14;
tmp[3] += frst;
/* Copy in the data for first item */
System.arraycopy(rsArray, 0, tmp, 4 + frst, 20);
/* Second item */
tmp[4 + tmp[3]] = (byte) 0x02;
/* Second item length */
tmp[5 + tmp[3]] = (byte) 0x14;
tmp[5 + tmp[3]] += scnd;
/* Copy in the data for the second item */
System.arraycopy(rsArray, 20, tmp, 6 + tmp[3] + scnd, 20);
/* Swap buffers */
rsArray = tmp;
return rsArray;
}
public static boolean verifySignature(byte[] message, byte[] ds, DSAPublicKey dpk) throws IOException
{
try {
Signature s = Signature.getInstance("SHA1withDSA");
s.initVerify(dpk);
s.update(message);
return s.verify(ds);
} catch (NoSuchAlgorithmException e) {
IOException ex = new IOException("No such algorithm");
ex.initCause(e);
throw ex;
} catch (InvalidKeyException e) {
IOException ex = new IOException("No such algorithm");
ex.initCause(e);
throw ex;
} catch (SignatureException e) {
IOException ex = new IOException();
ex.initCause(e);
throw ex;
}
}
public static byte[] generateSignature(byte[] message, DSAPrivateKey pk, SecureRandom rnd) throws IOException
{
try {
Signature s = Signature.getInstance("SHA1withDSA");
s.initSign(pk);
s.update(message);
return s.sign();
} catch (NoSuchAlgorithmException e) {
IOException ex = new IOException();
ex.initCause(e);
throw ex;
} catch (InvalidKeyException e) {
IOException ex = new IOException();
ex.initCause(e);
throw ex;
} catch (SignatureException e) {
IOException ex = new IOException();
ex.initCause(e);
throw ex;
}
}
}