--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ch/ethz/ssh2/crypto/PEMDecoder.java	Fri Jul 18 11:21:46 2014 -0700
@@ -0,0 +1,391 @@
+/*
+ * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
+ * Please refer to the LICENSE.txt for licensing details.
+ */
+package ch.ethz.ssh2.crypto;
+
+import java.io.BufferedReader;
+import java.io.CharArrayReader;
+import java.io.IOException;
+import java.math.BigInteger;
+import java.security.DigestException;
+
+import ch.ethz.ssh2.crypto.cipher.AES;
+import ch.ethz.ssh2.crypto.cipher.BlockCipher;
+import ch.ethz.ssh2.crypto.cipher.CBCMode;
+import ch.ethz.ssh2.crypto.cipher.DES;
+import ch.ethz.ssh2.crypto.cipher.DESede;
+import ch.ethz.ssh2.crypto.digest.MD5;
+import ch.ethz.ssh2.signature.DSAPrivateKey;
+import ch.ethz.ssh2.signature.RSAPrivateKey;
+import ch.ethz.ssh2.util.StringEncoder;
+
+/**
+ * PEM Support.
+ *
+ * @author Christian Plattner
+ * @version $Id: PEMDecoder.java 154 2014-04-28 11:45:02Z dkocher@sudo.ch $
+ */
+public class PEMDecoder
+{
+	private static final int PEM_RSA_PRIVATE_KEY = 1;
+	private static final int PEM_DSA_PRIVATE_KEY = 2;
+
+	private static int hexToInt(char c)
+	{
+		if ((c >= 'a') && (c <= 'f'))
+		{
+			return (c - 'a') + 10;
+		}
+
+		if ((c >= 'A') && (c <= 'F'))
+		{
+			return (c - 'A') + 10;
+		}
+
+		if ((c >= '0') && (c <= '9'))
+		{
+			return (c - '0');
+		}
+
+		throw new IllegalArgumentException("Need hex char");
+	}
+
+	private static byte[] hexToByteArray(String hex)
+	{
+		if (hex == null)
+			throw new IllegalArgumentException("null argument");
+
+		if ((hex.length() % 2) != 0)
+			throw new IllegalArgumentException("Uneven string length in hex encoding.");
+
+		byte decoded[] = new byte[hex.length() / 2];
+
+		for (int i = 0; i < decoded.length; i++)
+		{
+			int hi = hexToInt(hex.charAt(i * 2));
+			int lo = hexToInt(hex.charAt((i * 2) + 1));
+
+			decoded[i] = (byte) (hi * 16 + lo);
+		}
+
+		return decoded;
+	}
+
+	private static byte[] generateKeyFromPasswordSaltWithMD5(byte[] password, byte[] salt, int keyLen)
+			throws IOException
+	{
+		if (salt.length < 8)
+			throw new IllegalArgumentException("Salt needs to be at least 8 bytes for key generation.");
+
+		MD5 md5 = new MD5();
+
+		byte[] key = new byte[keyLen];
+		byte[] tmp = new byte[md5.getDigestLength()];
+
+		while (true)
+		{
+			md5.update(password, 0, password.length);
+			md5.update(salt, 0, 8); // ARGH we only use the first 8 bytes of the salt in this step.
+			// This took me two hours until I got AES-xxx running.
+
+			int copy = (keyLen < tmp.length) ? keyLen : tmp.length;
+
+            try {
+                md5.digest(tmp, 0);
+            }
+            catch(DigestException e) {
+                throw new IOException(e);
+            }
+
+            System.arraycopy(tmp, 0, key, key.length - keyLen, copy);
+
+			keyLen -= copy;
+
+			if (keyLen == 0)
+				return key;
+
+			md5.update(tmp, 0, tmp.length);
+		}
+	}
+
+	private static byte[] removePadding(byte[] buff, int blockSize) throws IOException
+	{
+		/* Removes RFC 1423/PKCS #7 padding */
+
+		int rfc_1423_padding = buff[buff.length - 1] & 0xff;
+
+		if ((rfc_1423_padding < 1) || (rfc_1423_padding > blockSize))
+			throw new PEMDecryptException("Decrypted PEM has wrong padding, did you specify the correct password?");
+
+		for (int i = 2; i <= rfc_1423_padding; i++)
+		{
+			if (buff[buff.length - i] != rfc_1423_padding)
+				throw new PEMDecryptException("Decrypted PEM has wrong padding, did you specify the correct password?");
+		}
+
+		byte[] tmp = new byte[buff.length - rfc_1423_padding];
+		System.arraycopy(buff, 0, tmp, 0, buff.length - rfc_1423_padding);
+		return tmp;
+	}
+
+	private static PEMStructure parsePEM(char[] pem) throws IOException
+	{
+		PEMStructure ps = new PEMStructure();
+
+		String line = null;
+
+		BufferedReader br = new BufferedReader(new CharArrayReader(pem));
+
+		String endLine = null;
+
+		while (true)
+		{
+			line = br.readLine();
+
+			if (line == null)
+				throw new IOException("Invalid PEM structure, '-----BEGIN...' missing");
+
+			line = line.trim();
+
+			if (line.startsWith("-----BEGIN DSA PRIVATE KEY-----"))
+			{
+				endLine = "-----END DSA PRIVATE KEY-----";
+				ps.pemType = PEM_DSA_PRIVATE_KEY;
+				break;
+			}
+
+			if (line.startsWith("-----BEGIN RSA PRIVATE KEY-----"))
+			{
+				endLine = "-----END RSA PRIVATE KEY-----";
+				ps.pemType = PEM_RSA_PRIVATE_KEY;
+				break;
+			}
+		}
+
+		while (true)
+		{
+			line = br.readLine();
+
+			if (line == null)
+				throw new IOException("Invalid PEM structure, " + endLine + " missing");
+
+			line = line.trim();
+
+			int sem_idx = line.indexOf(':');
+
+			if (sem_idx == -1)
+				break;
+
+			String name = line.substring(0, sem_idx + 1);
+			String value = line.substring(sem_idx + 1);
+
+			String values[] = value.split(",");
+
+			for (int i = 0; i < values.length; i++)
+				values[i] = values[i].trim();
+
+			// Proc-Type: 4,ENCRYPTED
+			// DEK-Info: DES-EDE3-CBC,579B6BE3E5C60483
+
+			if ("Proc-Type:".equals(name))
+			{
+				ps.procType = values;
+				continue;
+			}
+
+			if ("DEK-Info:".equals(name))
+			{
+				ps.dekInfo = values;
+				continue;
+			}
+			/* Ignore line */
+		}
+
+		StringBuilder keyData = new StringBuilder();
+
+		while (true)
+		{
+			if (line == null)
+				throw new IOException("Invalid PEM structure, " + endLine + " missing");
+
+			line = line.trim();
+
+			if (line.startsWith(endLine))
+				break;
+
+			keyData.append(line);
+
+			line = br.readLine();
+		}
+
+		char[] pem_chars = new char[keyData.length()];
+		keyData.getChars(0, pem_chars.length, pem_chars, 0);
+
+		ps.data = Base64.decode(pem_chars);
+
+		if (ps.data.length == 0)
+			throw new IOException("Invalid PEM structure, no data available");
+
+		return ps;
+	}
+
+	private static void decryptPEM(PEMStructure ps, byte[] pw) throws IOException
+	{
+		if (ps.dekInfo == null)
+			throw new IOException("Broken PEM, no mode and salt given, but encryption enabled");
+
+		if (ps.dekInfo.length != 2)
+			throw new IOException("Broken PEM, DEK-Info is incomplete!");
+
+		String algo = ps.dekInfo[0];
+		byte[] salt = hexToByteArray(ps.dekInfo[1]);
+
+		BlockCipher bc = null;
+
+		if (algo.equals("DES-EDE3-CBC"))
+		{
+			DESede des3 = new DESede();
+			des3.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 24));
+			bc = new CBCMode(des3, salt, false);
+		}
+		else if (algo.equals("DES-CBC"))
+		{
+			DES des = new DES();
+			des.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 8));
+			bc = new CBCMode(des, salt, false);
+		}
+		else if (algo.equals("AES-128-CBC"))
+		{
+			AES aes = new AES();
+			aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 16));
+			bc = new CBCMode(aes, salt, false);
+		}
+		else if (algo.equals("AES-192-CBC"))
+		{
+			AES aes = new AES();
+			aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 24));
+			bc = new CBCMode(aes, salt, false);
+		}
+		else if (algo.equals("AES-256-CBC"))
+		{
+			AES aes = new AES();
+			aes.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, 32));
+			bc = new CBCMode(aes, salt, false);
+		}
+		else
+		{
+			throw new IOException("Cannot decrypt PEM structure, unknown cipher " + algo);
+		}
+
+		if ((ps.data.length % bc.getBlockSize()) != 0)
+			throw new IOException("Invalid PEM structure, size of encrypted block is not a multiple of "
+					+ bc.getBlockSize());
+
+		/* Now decrypt the content */
+
+		byte[] dz = new byte[ps.data.length];
+
+		for (int i = 0; i < ps.data.length / bc.getBlockSize(); i++)
+		{
+			bc.transformBlock(ps.data, i * bc.getBlockSize(), dz, i * bc.getBlockSize());
+		}
+
+		/* Now check and remove RFC 1423/PKCS #7 padding */
+
+		dz = removePadding(dz, bc.getBlockSize());
+
+		ps.data = dz;
+		ps.dekInfo = null;
+		ps.procType = null;
+	}
+
+	public static final boolean isPEMEncrypted(PEMStructure ps) throws IOException
+	{
+		if (ps.procType == null)
+			return false;
+
+		if (ps.procType.length != 2)
+			throw new IOException("Unknown Proc-Type field.");
+
+		if ("4".equals(ps.procType[0]) == false)
+			throw new IOException("Unknown Proc-Type field (" + ps.procType[0] + ")");
+
+		if ("ENCRYPTED".equals(ps.procType[1]))
+			return true;
+
+		return false;
+	}
+
+	public static final boolean isPEMEncrypted(char[] pem) throws IOException
+	{
+		return isPEMEncrypted(parsePEM(pem));
+	}
+
+	public static Object decode(char[] pem, String password) throws IOException
+	{
+		PEMStructure ps = parsePEM(pem);
+
+		if (isPEMEncrypted(ps))
+		{
+			if (password == null)
+				throw new IOException("PEM is encrypted, but no password was specified");
+
+			decryptPEM(ps, StringEncoder.GetBytes(password));
+		}
+
+		if (ps.pemType == PEM_DSA_PRIVATE_KEY)
+		{
+			SimpleDERReader dr = new SimpleDERReader(ps.data);
+
+			byte[] seq = dr.readSequenceAsByteArray();
+
+			if (dr.available() != 0)
+				throw new IOException("Padding in DSA PRIVATE KEY DER stream.");
+
+			dr.resetInput(seq);
+
+			BigInteger version = dr.readInt();
+
+			if (version.compareTo(BigInteger.ZERO) != 0)
+				throw new IOException("Wrong version (" + version + ") in DSA PRIVATE KEY DER stream.");
+
+			BigInteger p = dr.readInt();
+			BigInteger q = dr.readInt();
+			BigInteger g = dr.readInt();
+			BigInteger y = dr.readInt();
+			BigInteger x = dr.readInt();
+
+			if (dr.available() != 0)
+				throw new IOException("Padding in DSA PRIVATE KEY DER stream.");
+
+			return new DSAPrivateKey(p, q, g, y, x);
+		}
+
+		if (ps.pemType == PEM_RSA_PRIVATE_KEY)
+		{
+			SimpleDERReader dr = new SimpleDERReader(ps.data);
+
+			byte[] seq = dr.readSequenceAsByteArray();
+
+			if (dr.available() != 0)
+				throw new IOException("Padding in RSA PRIVATE KEY DER stream.");
+
+			dr.resetInput(seq);
+
+			BigInteger version = dr.readInt();
+
+			if ((version.compareTo(BigInteger.ZERO) != 0) && (version.compareTo(BigInteger.ONE) != 0))
+				throw new IOException("Wrong version (" + version + ") in RSA PRIVATE KEY DER stream.");
+
+			BigInteger n = dr.readInt();
+			BigInteger e = dr.readInt();
+			BigInteger d = dr.readInt();
+
+			return new RSAPrivateKey(d, e, n);
+		}
+
+		throw new IOException("PEM problem: it is of unknown type");
+	}
+
+}