src/main/java/com/trilead/ssh2/crypto/PEMDecoder.java
package com.trilead.ssh2.crypto;
import java.io.BufferedReader;
import java.io.CharArrayReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.DigestException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.DSAPrivateKeySpec;
import java.security.spec.DSAPublicKeySpec;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPrivateKeySpec;
import java.security.spec.ECPublicKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.security.spec.RSAPrivateCrtKeySpec;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.Arrays;
import java.util.Locale;
import com.trilead.ssh2.crypto.cipher.AES;
import com.trilead.ssh2.crypto.cipher.BlockCipher;
import com.trilead.ssh2.crypto.cipher.DES;
import com.trilead.ssh2.crypto.cipher.DESede;
import com.trilead.ssh2.crypto.keys.Ed25519PrivateKey;
import com.trilead.ssh2.crypto.keys.Ed25519PublicKey;
import com.trilead.ssh2.packets.TypesReader;
import com.trilead.ssh2.signature.DSASHA1Verify;
import com.trilead.ssh2.signature.ECDSASHA2Verify;
import com.trilead.ssh2.signature.Ed25519Verify;
import com.trilead.ssh2.signature.RSASHA1Verify;
import org.mindrot.jbcrypt.BCrypt;
/**
* PEM Support.
*
* @author Christian Plattner, plattner@trilead.com
* @version $Id: PEMDecoder.java,v 1.2 2008/04/01 12:38:09 cplattne Exp $
*/
public class PEMDecoder
{
public static final int PEM_RSA_PRIVATE_KEY = 1;
public static final int PEM_DSA_PRIVATE_KEY = 2;
public static final int PEM_EC_PRIVATE_KEY = 3;
public static final int PEM_OPENSSH_PRIVATE_KEY = 4;
private static final byte[] OPENSSH_V1_MAGIC = new byte[] {
'o', 'p', 'e', 'n', 's', 's', 'h', '-', 'k', 'e', 'y', '-', 'v', '1', '\0',
};
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.");
MessageDigest md5;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
throw new IllegalArgumentException("VM does not support MD5", e);
}
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, tmp.length);
} catch (DigestException e) {
throw new IOException("could not digest password", 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 IOException("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 IOException("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;
}
public static final 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;
}
if (line.startsWith("-----BEGIN EC PRIVATE KEY-----")) {
endLine = "-----END EC PRIVATE KEY-----";
ps.pemType = PEM_EC_PRIVATE_KEY;
break;
}
if (line.startsWith("-----BEGIN OPENSSH PRIVATE KEY-----")) {
endLine = "-----END OPENSSH PRIVATE KEY-----";
ps.pemType = PEM_OPENSSH_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 */
}
StringBuffer keyData = new StringBuffer();
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 byte[] decryptData(byte[] data, byte[] pw, byte[] salt, int rounds, String algo) throws IOException
{
BlockCipher bc;
int keySize;
String algoLower = algo.toLowerCase(Locale.US);
if (algoLower.equals("des-ede3-cbc"))
{
bc = new DESede.CBC();
keySize = 24;
}
else if (algoLower.equals("des-cbc"))
{
bc = new DES.CBC();
keySize = 8;
}
else if (algoLower.equals("aes-128-cbc") || algoLower.equals("aes128-cbc"))
{
bc = new AES.CBC();
keySize = 16;
}
else if (algoLower.equals("aes-192-cbc") || algoLower.equals("aes192-cbc"))
{
bc = new AES.CBC();
keySize = 24;
}
else if (algoLower.equals("aes-256-cbc") || algoLower.equals("aes256-cbc"))
{
bc = new AES.CBC();
keySize = 32;
}
else if (algoLower.equals("aes-128-ctr") || algoLower.equals("aes128-ctr"))
{
bc = new AES.CTR();
keySize = 16;
}
else if (algoLower.equals("aes-192-ctr") || algoLower.equals("aes192-ctr"))
{
bc = new AES.CTR();
keySize = 24;
}
else if (algoLower.equals("aes-256-ctr") || algoLower.equals("aes256-ctr"))
{
bc = new AES.CTR();
keySize = 32;
}
else
{
throw new IOException("Cannot decrypt PEM structure, unknown cipher " + algo);
}
if (rounds == -1)
{
bc.init(false, generateKeyFromPasswordSaltWithMD5(pw, salt, keySize), salt);
}
else
{
byte[] key = new byte[keySize];
byte[] iv = new byte[bc.getBlockSize()];
byte[] keyAndIV = new byte[key.length + iv.length];
new BCrypt().pbkdf(pw, salt, rounds, keyAndIV);
System.arraycopy(keyAndIV, 0, key, 0, key.length);
System.arraycopy(keyAndIV, key.length, iv, 0, iv.length);
bc.init(false, key, iv);
}
if ((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[data.length];
for (int i = 0; i < data.length / bc.getBlockSize(); i++)
{
bc.transformBlock(data, i * bc.getBlockSize(), dz, i * bc.getBlockSize());
}
if (rounds == -1) {
/* Now check and remove RFC 1423/PKCS #7 padding */
return removePadding(dz, bc.getBlockSize());
} else {
/* New style is to check the padding after reading the comment. */
return dz;
}
}
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]);
byte[] dz = decryptData(ps.data, pw, salt, -1, algo);
ps.data = dz;
ps.dekInfo = null;
ps.procType = null;
}
public static final boolean isPEMEncrypted(PEMStructure ps) throws IOException
{
if (ps.pemType == PEM_OPENSSH_PRIVATE_KEY) {
TypesReader tr = new TypesReader(ps.data);
byte[] magic = tr.readBytes(OPENSSH_V1_MAGIC.length);
if (!Arrays.equals(OPENSSH_V1_MAGIC, magic)) {
throw new IOException("Could not find OPENSSH key magic: " + new String(magic));
}
tr.readString();
String kdfname = tr.readString();
return !"none".equals(kdfname);
}
if (ps.procType == null)
return false;
if (ps.procType.length != 2)
throw new IOException("Unknown Proc-Type field.");
if (!"4".equals(ps.procType[0]))
throw new IOException("Unknown Proc-Type field (" + ps.procType[0] + ")");
return "ENCRYPTED".equals(ps.procType[1]);
}
public static KeyPair decode(char[] pem, String password) throws IOException
{
PEMStructure ps = parsePEM(pem);
return decode(ps, password);
}
public static KeyPair decode(PEMStructure ps, String password) throws IOException
{
if (isPEMEncrypted(ps) && ps.pemType != PEM_OPENSSH_PRIVATE_KEY)
{
if (password == null)
throw new IOException("PEM is encrypted, but no password was specified");
try {
decryptPEM(ps, password.getBytes("ISO-8859-1"));
} catch (UnsupportedEncodingException e) {
decryptPEM(ps, password.getBytes("ISO-8859-1"));
}
}
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.");
DSAPrivateKeySpec privSpec = new DSAPrivateKeySpec(x, p, q, g);
DSAPublicKeySpec pubSpec = new DSAPublicKeySpec(y, p, q, g);
return generateKeyPair("DSA", privSpec, pubSpec);
}
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();
// TODO: is this right?
BigInteger primeP = dr.readInt();
BigInteger primeQ = dr.readInt();
BigInteger expP = dr.readInt();
BigInteger expQ = dr.readInt();
BigInteger coeff = dr.readInt();
RSAPrivateKeySpec privSpec = new RSAPrivateCrtKeySpec(n, e, d, primeP, primeQ, expP, expQ, coeff);
RSAPublicKeySpec pubSpec = new RSAPublicKeySpec(n, e);
return generateKeyPair("RSA", privSpec, pubSpec);
}
if (ps.pemType == PEM_EC_PRIVATE_KEY) {
SimpleDERReader dr = new SimpleDERReader(ps.data);
byte[] seq = dr.readSequenceAsByteArray();
if (dr.available() != 0)
throw new IOException("Padding in EC PRIVATE KEY DER stream.");
dr.resetInput(seq);
BigInteger version = dr.readInt();
if ((version.compareTo(BigInteger.ONE) != 0))
throw new IOException("Wrong version (" + version + ") in EC PRIVATE KEY DER stream.");
byte[] privateBytes = dr.readOctetString();
String curveOid = null;
byte[] publicBytes = null;
while (dr.available() > 0) {
int type = dr.readConstructedType();
SimpleDERReader cr = dr.readConstructed();
switch (type) {
case 0:
curveOid = cr.readOid();
break;
case 1:
publicBytes = cr.readOctetString();
break;
}
}
ECDSASHA2Verify verifier = ECDSASHA2Verify.getVerifierForOID(curveOid);
if (verifier == null)
throw new IOException("invalid OID");
BigInteger s = new BigInteger(1, privateBytes);
byte[] publicBytesSlice = new byte[publicBytes.length - 1];
System.arraycopy(publicBytes, 1, publicBytesSlice, 0, publicBytesSlice.length);
ECParameterSpec params = verifier.getParameterSpec();
ECPoint w = verifier.decodeECPoint(publicBytesSlice);
ECPrivateKeySpec privSpec = new ECPrivateKeySpec(s, params);
ECPublicKeySpec pubSpec = new ECPublicKeySpec(w, params);
return generateKeyPair("EC", privSpec, pubSpec);
}
if (ps.pemType == PEM_OPENSSH_PRIVATE_KEY) {
TypesReader tr = new TypesReader(ps.data);
byte[] magic = tr.readBytes(OPENSSH_V1_MAGIC.length);
if (!Arrays.equals(OPENSSH_V1_MAGIC, magic)) {
throw new IOException("Could not find OPENSSH key magic: " + new String(magic));
}
String ciphername = tr.readString();
String kdfname = tr.readString();
byte[] kdfoptions = tr.readByteString();
int numberOfKeys = tr.readUINT32();
// TODO support multiple keys
if (numberOfKeys != 1) {
throw new IOException("Only one key supported, but encountered bundle of " + numberOfKeys);
}
// OpenSSH discards this, so we will as well.
tr.readByteString();
byte[] dataBytes = tr.readByteString();
if ("bcrypt".equals(kdfname)) {
if (password == null) {
throw new IOException("PEM is encrypted, but no password was specified");
}
TypesReader optionsReader = new TypesReader(kdfoptions);
byte[] salt = optionsReader.readByteString();
int rounds = optionsReader.readUINT32();
byte[] passwordBytes;
try {
passwordBytes = password.getBytes("UTF-8");
} catch (UnsupportedEncodingException e) {
passwordBytes = password.getBytes();
}
dataBytes = decryptData(dataBytes, passwordBytes, salt, rounds, ciphername);
} else if (!"none".equals(ciphername) || !"none".equals(kdfname)) {
throw new IOException("encryption not supported");
}
TypesReader trEnc = new TypesReader(dataBytes);
int checkInt1 = trEnc.readUINT32();
int checkInt2 = trEnc.readUINT32();
if (checkInt1 != checkInt2) {
throw new IOException("Decryption failed when trying to read private keys");
}
String keyType = trEnc.readString();
KeyPair keyPair;
if (Ed25519Verify.ED25519_ID.equals(keyType)) {
byte[] publicBytes = trEnc.readByteString();
byte[] privateBytes = trEnc.readByteString();
PrivateKey privKey = new Ed25519PrivateKey(
Arrays.copyOfRange(privateBytes, 0, 32));
PublicKey pubKey = new Ed25519PublicKey(publicBytes);
keyPair = new KeyPair(pubKey, privKey);
} else if (keyType.startsWith("ecdsa-sha2-")) {
String curveName = trEnc.readString();
byte[] groupBytes = trEnc.readByteString();
BigInteger privateKey = trEnc.readMPINT();
final ECDSASHA2Verify verifier;
if (curveName.equals(ECDSASHA2Verify.ECDSASHA2NISTP256Verify.get().getCurveName())) {
verifier = ECDSASHA2Verify.ECDSASHA2NISTP256Verify.get();
} else if (curveName.equals(ECDSASHA2Verify.ECDSASHA2NISTP384Verify.get().getCurveName())) {
verifier = ECDSASHA2Verify.ECDSASHA2NISTP384Verify.get();
} else if (curveName.equals(ECDSASHA2Verify.ECDSASHA2NISTP521Verify.get().getCurveName())) {
verifier = ECDSASHA2Verify.ECDSASHA2NISTP521Verify.get();
} else {
throw new IOException("Invalid ECDSA group");
}
ECParameterSpec spec = verifier.getParameterSpec();
ECPoint group = verifier.decodeECPoint(groupBytes);
ECPublicKeySpec publicKeySpec = new ECPublicKeySpec(group, spec);
ECPrivateKeySpec privateKeySpec = new ECPrivateKeySpec(privateKey, spec);
keyPair = generateKeyPair("EC", privateKeySpec, publicKeySpec);
} else if (RSASHA1Verify.get().getKeyFormat().equals(keyType)) {
BigInteger n = trEnc.readMPINT();
BigInteger e = trEnc.readMPINT();
BigInteger d = trEnc.readMPINT();
BigInteger crtCoefficient = trEnc.readMPINT();
BigInteger p = trEnc.readMPINT();
RSAPrivateKeySpec privateKeySpec;
if (null == p || null == crtCoefficient) {
privateKeySpec = new RSAPrivateKeySpec(n, d);
} else {
BigInteger q = crtCoefficient.modInverse(p);
BigInteger pE = d.mod(p.subtract(BigInteger.ONE));
BigInteger qE = d.mod(q.subtract(BigInteger.ONE));
privateKeySpec = new RSAPrivateCrtKeySpec(n, e, d, p, q, pE, qE, crtCoefficient);
}
RSAPublicKeySpec publicKeySpec = new RSAPublicKeySpec(n, e);
keyPair = generateKeyPair("RSA", privateKeySpec, publicKeySpec);
} else if (DSASHA1Verify.get().getKeyFormat().equals(keyType)) {
BigInteger p = trEnc.readMPINT();
BigInteger q = trEnc.readMPINT();
BigInteger g = trEnc.readMPINT();
BigInteger y = trEnc.readMPINT();
BigInteger x = trEnc.readMPINT();
DSAPrivateKeySpec privateKeySpec = new DSAPrivateKeySpec(x, p, q, g);
DSAPublicKeySpec publicKeySpec = new DSAPublicKeySpec(y, p, q, g);
keyPair = generateKeyPair("DSA", privateKeySpec, publicKeySpec);
} else {
throw new IOException("Unknown key type " + keyType);
}
byte[] comment = trEnc.readByteString();
// Make sure the padding is correct first.
int remaining = tr.remain();
for (int i = 1; i <= remaining; i++) {
if (i != tr.readByte()) {
throw new IOException("Bad padding value on decrypted private keys");
}
}
return keyPair;
}
throw new IOException("PEM problem: it is of unknown type");
}
/**
* Generate a {@code KeyPair} given an {@code algorithm} and {@code KeySpec}.
*/
private static KeyPair generateKeyPair(String algorithm, KeySpec privSpec, KeySpec pubSpec)
throws IOException {
try {
final KeyFactory kf = KeyFactory.getInstance(algorithm);
final PublicKey pubKey = kf.generatePublic(pubSpec);
final PrivateKey privKey = kf.generatePrivate(privSpec);
return new KeyPair(pubKey, privKey);
} catch (NoSuchAlgorithmException ex) {
throw new IOException(ex);
} catch (InvalidKeySpecException ex) {
throw new IOException("invalid keyspec", ex);
}
}
}