/src/main/java/ch/ethz/ssh2/crypto/PEMDecoder.java
Java | 385 lines | 270 code | 98 blank | 17 comment | 81 complexity | 8877ef733618d004d200eb87d4f5d113 MD5 | raw file
- /*
- * 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 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 $Id$
- */
- 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;
- md5.digest(tmp, 0);
- 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");
- }
- }