Use the BouncyCastle provider so we can be sure we won't get

NoSuchAlgorithmExceptions. Key generation is *slow* - I guess that's a
good sign. ;-)

components/net/sf/briar/crypto/CryptoComponentImpl.java

@@ -0,0 +1,66 @@
+package net.sf.briar.crypto;
+
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.security.Security;
+import java.security.Signature;
+
+import net.sf.briar.api.crypto.CryptoComponent;
+import net.sf.briar.api.crypto.KeyParser;
+
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+
+public class CryptoComponentImpl implements CryptoComponent {
+
+	private static final String PROVIDER = "BC";
+	private static final String DIGEST_ALGO = "SHA-256";
+	private static final String KEY_PAIR_ALGO = "RSA";
+	private static final String SIGNATURE_ALGO = "SHA256withRSA";
+
+	private final KeyParser keyParser;
+	private final KeyPairGenerator keyPairGenerator;
+
+	CryptoComponentImpl() {
+		Security.addProvider(new BouncyCastleProvider());
+		try {
+			keyParser = new KeyParserImpl(KEY_PAIR_ALGO, PROVIDER);
+			keyPairGenerator = KeyPairGenerator.getInstance(KEY_PAIR_ALGO,
+					PROVIDER);
+		} catch(NoSuchAlgorithmException impossible) {
+			throw new RuntimeException(impossible);
+		} catch(NoSuchProviderException impossible) {
+			throw new RuntimeException(impossible);
+		}
+	}
+
+	public KeyPair generateKeyPair() {
+		return keyPairGenerator.generateKeyPair();
+	}
+
+	public KeyParser getKeyParser() {
+		return keyParser;
+	}
+
+	public MessageDigest getMessageDigest() {
+		try {
+			return MessageDigest.getInstance(DIGEST_ALGO, PROVIDER);
+		} catch(NoSuchAlgorithmException impossible) {
+			throw new RuntimeException(impossible);
+		} catch(NoSuchProviderException impossible) {
+			throw new RuntimeException(impossible);
+		}
+	}
+
+	public Signature getSignature() {
+		try {
+			return Signature.getInstance(SIGNATURE_ALGO, PROVIDER);
+		} catch(NoSuchAlgorithmException impossible) {
+			throw new RuntimeException(impossible);
+		} catch(NoSuchProviderException impossible) {
+			throw new RuntimeException(impossible);
+		}
+	}
+}