1 files changed, 294 insertions, 0 deletions
diff --git a/lib/src/main/java/com/trilead/ssh2/signature/ECDSASHA2Verify.java b/lib/src/main/java/com/trilead/ssh2/signature/ECDSASHA2Verify.java
new file mode 100644
index 0000000..c9c237f
--- /dev/null
+++ b/lib/src/main/java/com/trilead/ssh2/signature/ECDSASHA2Verify.java
@@ -0,0 +1,294 @@
+/**
+ *
+ */
+package com.trilead.ssh2.signature;
+
+import java.io.IOException;
+import java.math.BigInteger;
+import java.security.InvalidKeyException;
+import java.security.KeyFactory;
+import java.security.NoSuchAlgorithmException;
+import java.security.Signature;
+import java.security.SignatureException;
+import java.security.interfaces.ECPrivateKey;
+import java.security.interfaces.ECPublicKey;
+import java.security.spec.ECFieldFp;
+import java.security.spec.ECParameterSpec;
+import java.security.spec.ECPoint;
+import java.security.spec.ECPublicKeySpec;
+import java.security.spec.EllipticCurve;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.KeySpec;
+
+import com.trilead.ssh2.log.Logger;
+import com.trilead.ssh2.packets.TypesReader;
+import com.trilead.ssh2.packets.TypesWriter;
+
+/**
+ * @author Kenny Root
+ *
+ */
+public class ECDSASHA2Verify {
+	private static final Logger log = Logger.getLogger(ECDSASHA2Verify.class);
+
+	public static ECPublicKey decodeSSHECDSAPublicKey(byte[] key) throws IOException
+	{
+		TypesReader tr = new TypesReader(key);
+
+		String key_format = tr.readString();
+
+		if (key_format.equals("ecdsa-sha2-nistp256") == false)
+			throw new IllegalArgumentException("This is not an ecdsa-sha2-nistp256 public key");
+
+		String curveName = tr.readString();
+		byte[] groupBytes = tr.readByteString();
+
+		if (tr.remain() != 0)
+			throw new IOException("Padding in ECDSA public key!");
+
+		if (!"nistp256".equals(curveName)) {
+			throw new IOException("Curve is not nistp256");
+		}
+
+		ECParameterSpec nistp256 = ECDSASHA2Verify.EllipticCurves.nistp256;
+		ECPoint group = ECDSASHA2Verify.decodeECPoint(groupBytes, nistp256.getCurve());
+		if (group == null) {
+			throw new IOException("Invalid ECDSA group");
+		}
+
+		KeySpec keySpec = new ECPublicKeySpec(group, nistp256);
+
+		try {
+			KeyFactory kf = KeyFactory.getInstance("EC");
+			return (ECPublicKey) kf.generatePublic(keySpec);
+		} catch (NoSuchAlgorithmException nsae) {
+			IOException ioe = new IOException("No RSA KeyFactory available");
+			ioe.initCause(nsae);
+			throw ioe;
+		} catch (InvalidKeySpecException ikse) {
+			IOException ioe = new IOException("No RSA KeyFactory available");
+			ioe.initCause(ikse);
+			throw ioe;
+		}
+	}
+
+	public static byte[] encodeSSHECDSAPublicKey(ECPublicKey key) throws IOException {
+		TypesWriter tw = new TypesWriter();
+
+		tw.writeString("ecdsa-sha2-nistp256");
+
+		tw.writeString("nistp256");
+
+		tw.writeBytes(encodeECPoint(key.getW(), key.getParams().getCurve()));
+
+		return tw.getBytes();
+	}
+
+	public static byte[] decodeSSHECDSASignature(byte[] sig) throws IOException {
+		byte[] rsArray = null;
+
+		/* Hopefully a server obeying the standard... */
+		TypesReader tr = new TypesReader(sig);
+
+		String sig_format = tr.readString();
+		if (sig_format.equals("ecdsa-sha2-nistp256") == false)
+			throw new IOException("Peer sent wrong signature format");
+
+		rsArray = tr.readByteString();
+
+		if (tr.remain() != 0)
+			throw new IOException("Padding in ECDSA signature!");
+
+		byte[] rArray;
+		byte[] sArray;
+		{
+			TypesReader rsReader = new TypesReader(rsArray);
+			rArray = rsReader.readMPINT().toByteArray();
+			sArray = rsReader.readMPINT().toByteArray();
+		}
+
+		int first = rArray.length;
+		int second = sArray.length;
+
+		/* We can't have the high bit set, so add an extra zero at the beginning if so. */
+		if ((rArray[0] & 0x80) != 0) {
+			first++;
+		}
+		if ((sArray[0] & 0x80) != 0) {
+			second++;
+		}
+
+		/* Calculate total output length */
+		int length = 6 + first + second;
+		byte[] asn1 = new byte[length];
+
+		/* ASN.1 SEQUENCE tag */
+		asn1[0] = (byte) 0x30;
+
+		/* Size of SEQUENCE */
+		asn1[1] = (byte) (4 + first + second);
+
+		/* ASN.1 INTEGER tag */
+		asn1[2] = (byte) 0x02;
+
+		/* "r" INTEGER length */
+		asn1[3] = (byte) first;
+
+		/* Copy in the "r" INTEGER */
+		System.arraycopy(rArray, 0, asn1, (4 + first) - rArray.length, rArray.length);
+
+		/* ASN.1 INTEGER tag */
+		asn1[rArray.length + 4] = (byte) 0x02;
+
+		/* "s" INTEGER length */
+		asn1[rArray.length + 5] = (byte) second;
+
+		/* Copy in the "s" INTEGER */
+		System.arraycopy(sArray, 0, asn1, (6 + first + second) - sArray.length, sArray.length);
+
+		return asn1;
+	}
+
+	public static byte[] encodeSSHECDSASignature(byte[] sig) throws IOException
+	{
+		TypesWriter tw = new TypesWriter();
+
+		tw.writeString("ecdsa-sha2-nistp256");
+
+		int rLength = sig[3];
+		int sLength = sig[5 + rLength];
+
+		byte[] rArray = new byte[rLength];
+		byte[] sArray = new byte[sLength];
+
+		System.arraycopy(sig, 4, rArray, 0, rLength);
+		System.arraycopy(sig, 6 + rLength, sArray, 0, sLength);
+
+		BigInteger r = new BigInteger(rArray);
+		BigInteger s = new BigInteger(sArray);
+
+		// Write the <r,s> to its own types writer.
+		TypesWriter rsWriter = new TypesWriter();
+		rsWriter.writeMPInt(r);
+		rsWriter.writeMPInt(s);
+		tw.writeBytes(rsWriter.getBytes());
+
+		return tw.getBytes();
+	}
+
+	public static byte[] generateSignature(byte[] message, ECPrivateKey pk) throws IOException
+	{
+		try {
+			Signature s = Signature.getInstance("SHA256withECDSA");
+			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;
+		}
+	}
+
+	public static boolean verifySignature(byte[] message, byte[] ds, ECPublicKey dpk) throws IOException
+	{
+		try {
+			Signature s = Signature.getInstance("SHA256withECDSA");
+			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;
+		}
+	}
+
+	/**
+	 * Decode an OctetString to EllipticCurvePoint according to SECG 2.3.4
+	 */
+	public static ECPoint decodeECPoint(byte[] M, EllipticCurve curve) {
+		if (M.length == 0) {
+			return null;
+		}
+
+		// M has len 2 ceil(log_2(q)/8) + 1 ?
+		int elementSize = (curve.getField().getFieldSize() + 7) / 8;
+		if (M.length != 2 * elementSize + 1) {
+			return null;
+		}
+
+		// step 3.2
+		if (M[0] != 0x04) {
+			return null;
+		}
+
+		// Step 3.3
+		byte[] xp = new byte[elementSize];
+		System.arraycopy(M, 1, xp, 0, elementSize);
+
+		// Step 3.4
+		byte[] yp = new byte[elementSize];
+		System.arraycopy(M, 1 + elementSize, yp, 0, elementSize);
+
+		ECPoint P = new ECPoint(new BigInteger(1, xp), new BigInteger(1, yp));
+
+		// TODO check point 3.5
+
+		// Step 3.6
+		return P;
+	}
+
+	/**
+	 * Encode EllipticCurvePoint to an OctetString
+	 */
+	public static byte[] encodeECPoint(ECPoint group, EllipticCurve curve)
+	{
+		// M has len 2 ceil(log_2(q)/8) + 1 ?
+		int elementSize = (curve.getField().getFieldSize() + 7) / 8;
+		byte[] M = new byte[2 * elementSize + 1];
+
+		// Uncompressed format
+		M[0] = 0x04;
+
+		{
+			byte[] affineX = group.getAffineX().toByteArray();
+			System.arraycopy(affineX, 0, M, 1, elementSize - affineX.length);
+		}
+
+		{
+			byte[] affineY = group.getAffineY().toByteArray();
+			System.arraycopy(affineY, 0, M, 1 + elementSize, elementSize - affineY.length);
+		}
+
+		return M;
+	}
+
+	public static class EllipticCurves {
+		public static ECParameterSpec nistp256 = new ECParameterSpec(
+				new EllipticCurve(
+						new ECFieldFp(new BigInteger("FFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFF", 16)),
+						new BigInteger("FFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFC", 16),
+						new BigInteger("5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b", 16)),
+				new ECPoint(new BigInteger("6B17D1F2E12C4247F8BCE6E563A440F277037D812DEB33A0F4A13945D898C296", 16),
+							new BigInteger("4FE342E2FE1A7F9B8EE7EB4A7C0F9E162BCE33576B315ECECBB6406837BF51F5", 16)),
+				new BigInteger("FFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551", 16),
+				1);
+	}
+}