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Support v3 PuTTY keys (#716)
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* Support v3 PuTTY keys

* add test for putty v3 key

* Format PuTTYKeyFile to fix Codacy warnings

Signed-off-by: Jeroen van Erp <[email protected]>

Co-authored-by: Jeroen van Erp <[email protected]>
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@BerndSchuller @hierynomus
BerndSchuller and hierynomus authored Sep 20, 2021
1 parent 6f98737 commit 2e1ef9d
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Showing 2 changed files with 43 additions and 24 deletions.
48 changes: 24 additions & 24 deletions src/main/java/net/schmizz/sshj/userauth/keyprovider/PuTTYKeyFile.java
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,7 @@

/**
* <h2>Sample PuTTY file format</h2>
*
* <pre>
* PuTTY-User-Key-File-2: ssh-rsa
* Encryption: none
Expand All @@ -70,8 +71,7 @@
*/
public class PuTTYKeyFile extends BaseFileKeyProvider {

public static class Factory
implements net.schmizz.sshj.common.Factory.Named<FileKeyProvider> {
public static class Factory implements net.schmizz.sshj.common.Factory.Named<FileKeyProvider> {

@Override
public FileKeyProvider create() {
Expand All @@ -88,33 +88,35 @@ public String getName() {
private byte[] publicKey;

/**
* Key type. Either "ssh-rsa" for RSA key, or "ssh-dss" for DSA key.
* Key type
*/
@Override
public KeyType getType() throws IOException {
return KeyType.fromString(headers.get("PuTTY-User-Key-File-2"));
for (String h : headers.keySet()) {
if (h.startsWith("PuTTY-User-Key-File-")) {
return KeyType.fromString(headers.get(h));
}
}
return KeyType.UNKNOWN;
}

public boolean isEncrypted() {
// Currently the only supported encryption types are "aes256-cbc" and "none".
return "aes256-cbc".equals(headers.get("Encryption"));
}

private Map<String, String> payload
= new HashMap<String, String>();
private Map<String, String> payload = new HashMap<String, String>();

/**
* For each line that looks like "Xyz: vvv", it will be stored in this map.
*/
private final Map<String, String> headers
= new HashMap<String, String>();

private final Map<String, String> headers = new HashMap<String, String>();

protected KeyPair readKeyPair() throws IOException {
this.parseKeyPair();
final Buffer.PlainBuffer publicKeyReader = new Buffer.PlainBuffer(publicKey);
final Buffer.PlainBuffer privateKeyReader = new Buffer.PlainBuffer(privateKey);
publicKeyReader.readBytes(); // The first part of the payload is a human-readable key format name.
publicKeyReader.readBytes(); // The first part of the payload is a human-readable key format name.
if (KeyType.RSA.equals(this.getType())) {
// public key exponent
BigInteger e = publicKeyReader.readMPInt();
Expand All @@ -131,10 +133,8 @@ protected KeyPair readKeyPair() throws IOException {
throw new IOException(s.getMessage(), s);
}
try {
return new KeyPair(
factory.generatePublic(new RSAPublicKeySpec(n, e)),
factory.generatePrivate(new RSAPrivateKeySpec(n, d))
);
return new KeyPair(factory.generatePublic(new RSAPublicKeySpec(n, e)),
factory.generatePrivate(new RSAPrivateKeySpec(n, d)));
} catch (InvalidKeySpecException i) {
throw new IOException(i.getMessage(), i);
}
Expand All @@ -155,10 +155,8 @@ protected KeyPair readKeyPair() throws IOException {
throw new IOException(s.getMessage(), s);
}
try {
return new KeyPair(
factory.generatePublic(new DSAPublicKeySpec(y, p, q, g)),
factory.generatePrivate(new DSAPrivateKeySpec(x, p, q, g))
);
return new KeyPair(factory.generatePublic(new DSAPublicKeySpec(y, p, q, g)),
factory.generatePrivate(new DSAPrivateKeySpec(x, p, q, g)));
} catch (InvalidKeySpecException e) {
throw new IOException(e.getMessage(), e);
}
Expand Down Expand Up @@ -187,8 +185,8 @@ protected KeyPair readKeyPair() throws IOException {
if (ecdsaCurve != null) {
BigInteger s = new BigInteger(1, privateKeyReader.readBytes());
X9ECParameters ecParams = NISTNamedCurves.getByName(ecdsaCurve);
ECNamedCurveSpec ecCurveSpec =
new ECNamedCurveSpec(ecdsaCurve, ecParams.getCurve(), ecParams.getG(), ecParams.getN());
ECNamedCurveSpec ecCurveSpec = new ECNamedCurveSpec(ecdsaCurve, ecParams.getCurve(), ecParams.getG(),
ecParams.getN());
ECPrivateKeySpec pks = new ECPrivateKeySpec(s, ecCurveSpec);
try {
PrivateKey privateKey = SecurityUtils.getKeyFactory(KeyAlgorithm.ECDSA).generatePrivate(pks);
Expand Down Expand Up @@ -247,7 +245,8 @@ protected void parseKeyPair() throws IOException {
}

/**
* Converts a passphrase into a key, by following the convention that PuTTY uses.
* Converts a passphrase into a key, by following the convention that PuTTY
* uses.
* <p/>
* <p/>
* This is used to decrypt the private key when it's encrypted.
Expand All @@ -256,15 +255,16 @@ private byte[] toKey(final String passphrase) throws IOException {
try {
MessageDigest digest = MessageDigest.getInstance("SHA-1");

// The encryption key is derived from the passphrase by means of a succession of SHA-1 hashes.
// The encryption key is derived from the passphrase by means of a succession of
// SHA-1 hashes.

// Sequence number 0
digest.update(new byte[]{0, 0, 0, 0});
digest.update(new byte[] { 0, 0, 0, 0 });
digest.update(passphrase.getBytes());
byte[] key1 = digest.digest();

// Sequence number 1
digest.update(new byte[]{0, 0, 0, 1});
digest.update(new byte[] { 0, 0, 0, 1 });
digest.update(passphrase.getBytes());
byte[] key2 = digest.digest();

Expand Down
19 changes: 19 additions & 0 deletions src/test/java/net/schmizz/sshj/keyprovider/PuTTYKeyFileTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -226,6 +226,17 @@ public class PuTTYKeyFileTest {
"nLEIBzB8WEaMMgDz5qwlqq7eBxLPIIi9uHyjMf7NOsQ=\n" +
"Private-MAC: b200c6d801fc8dd8f84a14afc3b94d9f9bb2df90\n";

final static String v3_ecdsa = "PuTTY-User-Key-File-3: ecdsa-sha2-nistp256\n" +
"Encryption: none\n" +
"Comment: ecdsa-key-20210819\n" +
"Public-Lines: 3\n" +
"AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBP5mbdlgVmkw\n" +
"LzDkznoY8TXKnok/mlMkpk8FELFNSECnXNdtZ4B8+Bpqnvchhk/jY/0tUU98lFxt\n" +
"JR0o0l8B5y0=\n" +
"Private-Lines: 1\n" +
"AAAAIEblmwyKaGuvc6dLgNeHsc1BuZeQORTSxBF5SBLNyjYc\n" +
"Private-MAC: e1aed15a209f48fdaa5228640f1109a7740340764a96f97ec6023da7f92d07ea";

@Test
public void test2048() throws Exception {
PuTTYKeyFile key = new PuTTYKeyFile();
Expand Down Expand Up @@ -341,6 +352,14 @@ public void testEcDsa521() throws Exception {
assertEquals(key.getPublic(), referenceKey.getPublic());
}

@Test
public void testV3Key() throws Exception {
PuTTYKeyFile key = new PuTTYKeyFile();
key.init(new StringReader(v3_ecdsa));
assertNotNull(key.getPrivate());
assertNotNull(key.getPublic());
}

@Test
public void testCorrectPassphraseRsa() throws Exception {
PuTTYKeyFile key = new PuTTYKeyFile();
Expand Down

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