1 files changed, 5 insertions, 75 deletions

diff --git a/sshlib/src/main/java/com/trilead/ssh2/signature/ECDSASHA2Verify.java b/sshlib/src/main/java/com/trilead/ssh2/signature/ECDSASHA2Verify.java
index f628ae7..89cacfb 100644
--- a/sshlib/src/main/java/com/trilead/ssh2/signature/ECDSASHA2Verify.java
+++ b/sshlib/src/main/java/com/trilead/ssh2/signature/ECDSASHA2Verify.java
@@ -24,6 +24,7 @@ import java.security.spec.KeySpec;
 import java.util.Map;
 import java.util.TreeMap;
 
+import com.trilead.ssh2.crypto.SimpleDERReader;
 import com.trilead.ssh2.log.Logger;
 import com.trilead.ssh2.packets.TypesReader;
 import com.trilead.ssh2.packets.TypesWriter;
@@ -267,24 +268,6 @@ public class ECDSASHA2Verify {
 		}
 	}
 
-	private static final int readLength(byte[] sig, int offset, int numOctets) throws IOException {
-		if (numOctets > 4 || numOctets <= 0) {
-			throw new IOException("Cannot decode DER length");
-		}
-
-		long length = 0L;
-		for (int i = 0; i < numOctets; i++) {
-			length <<= 8;
-			length |= sig[offset++];
-		}
-
-		if (length > 0xFFFFFFL || length < 0L) {
-			throw new IOException("Invalid DER length");
-		}
-
-		return (int) length;
-	}
-
 	public static byte[] encodeSSHECDSASignature(byte[] sig, ECParameterSpec params) throws IOException
 	{
 		TypesWriter tw = new TypesWriter();
@@ -299,64 +282,11 @@ public class ECDSASHA2Verify {
 		 *      0x02 <len> <data[len]>
 		 */
 
-		if (sig[0] != 0x30) {
-			throw new IOException("Invalid signature format");
-		}
-
-		final int seqHeaderLength;
-		final int seqLength;
-		if ((sig[1] & 0x80) != 0) {
-			int seqHeaderOctets = sig[1] & 0x7F;
-			seqHeaderLength = seqHeaderOctets + 1;
-			seqLength = readLength(sig, 2, seqHeaderOctets);
-		} else {
-			seqHeaderLength = 1;
-			seqLength = sig[1];
-		}
-
-		if ((seqLength == 0) || (1 + seqHeaderLength + seqLength != sig.length) || (sig[1 + seqHeaderLength] != 0x02)) {
-			throw new IOException("Invalid signature format");
-		}
-
-		final int rHeaderLength;
-		final int rLength;
-		if ((sig[1 + seqHeaderLength + 1] & 0x80) != 0) {
-			int rHeaderOctets = sig[seqHeaderLength + 2] & 0x7F;
-			rHeaderLength = rHeaderOctets + 1;
-			rLength = readLength(sig, seqHeaderLength + 3, rHeaderOctets);
-		} else {
-			rHeaderLength = 1;
-			rLength = sig[seqHeaderLength + 2];
-		}
-
-		if ((rLength == 0) || (rLength > seqLength - (rHeaderLength + 1 + 1 + 1)) ||
-				sig[1 + seqHeaderLength + 1 + rHeaderLength + rLength] != 0x02)  {
-			throw new IOException("Invalid signature format");
-		}
-
-		final int sHeaderLength;
-		final int sLength;
-		if ((sig[1 + seqHeaderLength + 1 + rHeaderLength + rLength + 1] & 0x80) != 0) {
-			int sHeaderOctets = sig[1 + seqHeaderLength + 1 + rHeaderLength + rLength + 1] & 0x7F;
-			sHeaderLength = sHeaderOctets + 1;
-			sLength = readLength(sig, 4 + rHeaderLength + rLength, sHeaderOctets);
-		} else {
-			sHeaderLength = 1;
-			sLength = sig[1 + seqHeaderLength + 1 + rHeaderLength + rLength + 1];
-		}
-
-		if ((sLength == 0) || 2 + rHeaderLength + rLength + sHeaderLength + sLength > seqLength) {
-			throw new IOException("Invalid signature format");
-		}
-
-		byte[] rArray = new byte[rLength];
-		byte[] sArray = new byte[sLength];
-
-		System.arraycopy(sig, 1 + seqHeaderLength + 1, rArray, 0, rLength);
-		System.arraycopy(sig, 1 + seqHeaderLength + 1 + rLength + 1 + sHeaderLength, sArray, 0, sLength);
+		SimpleDERReader reader = new SimpleDERReader(sig);
+		SimpleDERReader seqReader = new SimpleDERReader(reader.readSequenceAsByteArray());
 
-		BigInteger r = new BigInteger(1, rArray);
-		BigInteger s = new BigInteger(1, sArray);
+		BigInteger r = seqReader.readInt();
+		BigInteger s = seqReader.readInt();
 
 		// Write the <r,s> to its own types writer.
 		TypesWriter rsWriter = new TypesWriter();