Android Compability, again ;-) (#392)

* Rework SecurityUtils and PKCS8KeyFile for usage with SpongyCastle.

* Specifying providerName for registration is unneccessary.

* Update AndroidConfig, fix imports.

* Workaround for Android 5.0 bug when SpongyCastle is the default JCE provider.

On Android 5.0 reading the version from the jar does throw a SecurityException due to a bug in Android (see https://issuetracker.google.com/issues/36993752). Including that Exception in the catch provides a workaround for that issue.

src/main/java/net/schmizz/sshj/AndroidConfig.java

@@ -23,6 +23,9 @@ import net.schmizz.sshj.signature.SignatureRSA;
 import net.schmizz.sshj.transport.random.JCERandom;
 import net.schmizz.sshj.transport.random.SingletonRandomFactory;
 
+/**
+ * Registers SpongyCastle as JCE provider.
+ */
 public class AndroidConfig
         extends DefaultConfig {
 
@@ -30,13 +33,6 @@ public class AndroidConfig
         SecurityUtils.registerSecurityProvider("org.spongycastle.jce.provider.BouncyCastleProvider");
     }
 
-    public AndroidConfig(){
-        super();
-        initKeyExchangeFactories(true);
-        initRandomFactory(true);
-        initFileKeyProviderFactories(true);
-    }
-
     // don't add ECDSA
     protected void initSignatureFactories() {
         setSignatureFactories(new SignatureRSA.Factory(), new SignatureDSA.Factory(),

src/main/java/net/schmizz/sshj/DefaultConfig.java

@@ -92,7 +92,7 @@ public class DefaultConfig
             properties.load(DefaultConfig.class.getClassLoader().getResourceAsStream("sshj.properties"));
             String property = properties.getProperty("sshj.version");
             return "SSHJ_" + property.replace('-', '_'); // '-' is a disallowed character, see RFC-4253#section-4.2
-        } catch (IOException e) {
+        } catch (Exception e) {
             log.error("Could not read the sshj.properties file, returning an 'unknown' version as fallback.");
             return "SSHJ_VERSION_UNKNOWN";
         }

src/main/java/net/schmizz/sshj/common/SecurityUtils.java

@@ -18,11 +18,21 @@ package net.schmizz.sshj.common;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.security.GeneralSecurityException;
+import java.security.KeyFactory;
+import java.security.KeyPairGenerator;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.security.Provider;
+import java.security.PublicKey;
+import java.security.Security;
+import java.security.Signature;
+
 import javax.crypto.Cipher;
 import javax.crypto.KeyAgreement;
 import javax.crypto.Mac;
 import javax.crypto.NoSuchPaddingException;
-import java.security.*;
 
 import static java.lang.String.format;
 
@@ -37,12 +47,17 @@ public class SecurityUtils {
      */
     public static final String BOUNCY_CASTLE = "BC";
 
+    /**
+     * Identifier for the BouncyCastle JCE provider
+     */
+    public static final String SPONGY_CASTLE = "SC";
+
     /*
     * Security provider identifier. null = default JCE
     */
     private static String securityProvider = null;
 
-    // relate to BC registration
+    // relate to BC registration (or SpongyCastle on Android)
     private static Boolean registerBouncyCastle;
     private static boolean registrationDone;
 
@@ -82,6 +97,8 @@ public class SecurityUtils {
         return false;
     }
 
+
+
     public static synchronized Cipher getCipher(String transformation)
             throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException {
         register();
@@ -222,11 +239,11 @@ public class SecurityUtils {
      * Attempts registering BouncyCastle as security provider if it has not been previously attempted and returns
      * whether the registration succeeded.
      *
-     * @return whether BC registered
+     * @return whether BC (or SC on Android) registered
      */
     public static synchronized boolean isBouncyCastleRegistered() {
         register();
-        return BOUNCY_CASTLE.equals(securityProvider);
+        return BOUNCY_CASTLE.equals(securityProvider) || SPONGY_CASTLE.equals(securityProvider);
     }
 
     public static synchronized void setRegisterBouncyCastle(boolean registerBouncyCastle) {

src/main/java/net/schmizz/sshj/userauth/keyprovider/PKCS8KeyFile.java

@@ -16,6 +16,7 @@
 package net.schmizz.sshj.userauth.keyprovider;
 
 import net.schmizz.sshj.common.IOUtils;
+import net.schmizz.sshj.common.SecurityUtils;
 import net.schmizz.sshj.userauth.password.PasswordUtils;
 import org.bouncycastle.openssl.EncryptionException;
 import org.bouncycastle.openssl.PEMEncryptedKeyPair;
@@ -62,12 +63,12 @@ public class PKCS8KeyFile extends BaseFileKeyProvider {
                 final Object o = r.readObject();
 
                 final JcaPEMKeyConverter pemConverter = new JcaPEMKeyConverter();
-                pemConverter.setProvider("BC");
+                pemConverter.setProvider(SecurityUtils.getSecurityProvider());
 
                 if (o instanceof PEMEncryptedKeyPair) {
                     final PEMEncryptedKeyPair encryptedKeyPair = (PEMEncryptedKeyPair) o;
                     JcePEMDecryptorProviderBuilder decryptorBuilder = new JcePEMDecryptorProviderBuilder();
-                    decryptorBuilder.setProvider("BC");
+                    decryptorBuilder.setProvider(SecurityUtils.getSecurityProvider());
                     try {
                         passphrase = pwdf == null ? null : pwdf.reqPassword(resource);
                         kp = pemConverter.getKeyPair(encryptedKeyPair.decryptKeyPair(decryptorBuilder.build(passphrase)));