diff --git a/bulletin-board-server/src/test/java/meerkat/bulletinboard/BulletinBoardServerTest.java b/bulletin-board-server/src/test/java/meerkat/bulletinboard/BulletinBoardServerTest.java
index e0801af..eb43f15 100644
--- a/bulletin-board-server/src/test/java/meerkat/bulletinboard/BulletinBoardServerTest.java
+++ b/bulletin-board-server/src/test/java/meerkat/bulletinboard/BulletinBoardServerTest.java
@@ -1,11 +1,5 @@
 package meerkat.bulletinboard;
 
-import java.io.File;
-import java.nio.file.Files;
-import java.nio.file.NoSuchFileException;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-
 import org.junit.Test;
 
 import meerkat.bulletinboard.sqlserver.SQLiteBulletinBoardServer;
diff --git a/bulletin-board-server/src/test/java/meerkat/bulletinboard/GenericBulletinBoardServerTest.java b/bulletin-board-server/src/test/java/meerkat/bulletinboard/GenericBulletinBoardServerTest.java
index 36a998b..279ee7c 100644
--- a/bulletin-board-server/src/test/java/meerkat/bulletinboard/GenericBulletinBoardServerTest.java
+++ b/bulletin-board-server/src/test/java/meerkat/bulletinboard/GenericBulletinBoardServerTest.java
@@ -8,7 +8,6 @@ import java.security.InvalidKeyException;
 import java.security.KeyStore;
 import java.security.KeyStoreException;
 import java.security.NoSuchAlgorithmException;
-import java.security.SecureRandom;
 import java.security.SignatureException;
 import java.security.UnrecoverableKeyException;
 import java.security.cert.CertificateException;
diff --git a/meerkat-common/src/main/java/meerkat/crypto/DigitalSignature.java b/meerkat-common/src/main/java/meerkat/crypto/DigitalSignature.java
index 587522f..5386c5f 100644
--- a/meerkat-common/src/main/java/meerkat/crypto/DigitalSignature.java
+++ b/meerkat-common/src/main/java/meerkat/crypto/DigitalSignature.java
@@ -2,8 +2,6 @@ package meerkat.crypto;
 
 import com.google.protobuf.Message;
 
-import javax.security.auth.callback.CallbackHandler;
-import javax.security.auth.callback.PasswordCallback;
 import java.io.IOException;
 import java.io.InputStream;
 import java.security.InvalidKeyException;
@@ -11,7 +9,6 @@ import java.security.KeyStore;
 import java.security.SignatureException;
 import java.security.UnrecoverableKeyException;
 import java.security.cert.CertificateException;
-import java.util.List;
 import static meerkat.protobuf.Crypto.*;
 
 /**
diff --git a/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSADeterministicSignature.java b/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSADeterministicSignature.java
index 992dbbb..0afbdd7 100644
--- a/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSADeterministicSignature.java
+++ b/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSADeterministicSignature.java
@@ -2,43 +2,25 @@ package meerkat.crypto.concrete;
 
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Message;
-import meerkat.crypto.DigitalSignature;
 import meerkat.protobuf.Crypto;
 import meerkat.protobuf.Crypto.Signature;
-import meerkat.util.Hex;
 import org.bouncycastle.asn1.ASN1Integer;
 import org.bouncycastle.asn1.DERSequence;
-import org.bouncycastle.crypto.Digest;
 import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
-import org.bouncycastle.crypto.params.ECDomainParameters;
 import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
 import org.bouncycastle.crypto.signers.DSAKCalculator;
 import org.bouncycastle.crypto.signers.ECDSASigner;
 import org.bouncycastle.crypto.signers.HMacDSAKCalculator;
-import org.bouncycastle.jcajce.provider.asymmetric.util.DSAEncoder;
 import org.bouncycastle.jcajce.provider.asymmetric.util.ECUtil;
-import org.bouncycastle.jce.ECKeyUtil;
-import org.bouncycastle.jce.ECPointUtil;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import javax.security.auth.callback.Callback;
-import javax.security.auth.callback.CallbackHandler;
-import javax.security.auth.callback.PasswordCallback;
-import javax.security.auth.callback.UnsupportedCallbackException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.math.BigInteger;
-import java.nio.ByteBuffer;
 import java.security.*;
-import java.security.cert.Certificate;
 import java.security.cert.*;
 import java.security.interfaces.ECPrivateKey;
-import java.security.spec.ECParameterSpec;
-import java.util.Collection;
-import java.util.Enumeration;
-import java.util.HashMap;
-import java.util.Map;
 
 
 /**
diff --git a/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSASignature.java b/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSASignature.java
index 6cbcf8d..615b06e 100644
--- a/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSASignature.java
+++ b/meerkat-common/src/main/java/meerkat/crypto/concrete/ECDSASignature.java
@@ -108,7 +108,6 @@ public class ECDSASignature extends GlobalCryptoSetup implements DigitalSignatur
                 logger.error("Certificate must be in X509 format; got {} instead!", cert.getClass().getCanonicalName());
                 continue;
             }
-            PublicKey pubKey = cert.getPublicKey();
             ByteString keyId = computeCertificateFingerprint(cert);
             loadedCertificates.put(keyId, cert);
         }
diff --git a/meerkat-common/src/main/java/meerkat/crypto/concrete/ECElGamalEncryption.java b/meerkat-common/src/main/java/meerkat/crypto/concrete/ECElGamalEncryption.java
index 8718dd7..1e075bf 100644
--- a/meerkat-common/src/main/java/meerkat/crypto/concrete/ECElGamalEncryption.java
+++ b/meerkat-common/src/main/java/meerkat/crypto/concrete/ECElGamalEncryption.java
@@ -1,7 +1,6 @@
 package meerkat.crypto.concrete;
 
 import com.google.protobuf.ByteString;
-import com.google.protobuf.CodedOutputStream;
 import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.Message;
 import meerkat.crypto.Encryption;
@@ -14,22 +13,18 @@ import org.bouncycastle.crypto.params.ECPublicKeyParameters;
 import org.bouncycastle.crypto.util.PublicKeyFactory;
 import org.bouncycastle.jce.spec.ECParameterSpec;
 import org.bouncycastle.math.ec.ECCurve;
-import org.bouncycastle.math.ec.ECFieldElement;
 import org.bouncycastle.math.ec.ECPoint;
 import org.bouncycastle.util.BigIntegers;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import qilin.primitives.concrete.ECElGamal;
 import qilin.primitives.concrete.ECGroup;
-import qilin.primitives.PseudorandomGenerator;
-import qilin.primitives.generic.ElGamal;
 import qilin.util.PRGRandom;
 import qilin.util.Pair;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.math.BigInteger;
-import java.security.SecureRandom;
 import java.security.spec.*;
 import java.util.Random;
 
diff --git a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSADeterministicSignatureTest.java b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSADeterministicSignatureTest.java
index 95b9d3e..cc41497 100644
--- a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSADeterministicSignatureTest.java
+++ b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSADeterministicSignatureTest.java
@@ -2,14 +2,12 @@ package meerkat.crypto.concrete;
 
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Message;
-import meerkat.protobuf.BulletinBoardAPI.UnsignedBulletinBoardMessage;
+
+import meerkat.crypto.concrete.ECDSASignature;
 import meerkat.protobuf.Crypto;
 import org.junit.Test;
 
-import java.io.InputStream;
 import java.math.BigInteger;
-import java.security.KeyStore;
-
 import static org.junit.Assert.*;
 
 /**
diff --git a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSASignatureTest.java b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSASignatureTest.java
index e0337a9..37c2d1b 100644
--- a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSASignatureTest.java
+++ b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECDSASignatureTest.java
@@ -3,7 +3,7 @@ package meerkat.crypto.concrete;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Message;
 import meerkat.protobuf.Crypto;
-import meerkat.protobuf.BulletinBoardAPI.*;
+import meerkat.crypto.concrete.ECDSASignature;
 import org.junit.Before;
 import org.junit.Test;
 
diff --git a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalEncryptionTest.java b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalEncryptionTest.java
index 0d628e8..bb52df9 100644
--- a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalEncryptionTest.java
+++ b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalEncryptionTest.java
@@ -1,18 +1,15 @@
 package meerkat.crypto.concrete;
 
-import meerkat.protobuf.BulletinBoardAPI;
 import meerkat.protobuf.ConcreteCrypto;
 import meerkat.protobuf.Crypto;
 import meerkat.protobuf.Voting;
 import org.bouncycastle.math.ec.ECPoint;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import qilin.primitives.concrete.ECElGamal;
 import qilin.primitives.concrete.ECGroup;
-import qilin.primitives.generic.ElGamal;
 import qilin.util.Pair;
 
 import java.math.BigInteger;
diff --git a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalUtils.java b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalUtils.java
index fec4803..44efe69 100644
--- a/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalUtils.java
+++ b/meerkat-common/src/test/java/meerkat/crypto/concrete/ECElGamalUtils.java
@@ -77,7 +77,7 @@ public class ECElGamalUtils {
 
         try {
             java.lang.reflect.Method newBuilder = plaintextMessageType.getMethod("newBuilder");
-            GeneratedMessage.Builder builder = (GeneratedMessage.Builder) newBuilder.invoke(plaintextMessageType);
+            GeneratedMessage.Builder<?> builder = (GeneratedMessage.Builder<?>) newBuilder.invoke(plaintextMessageType);
             builder.mergeDelimitedFrom(in);
             return plaintextMessageType.cast(builder.build());
         } catch (Exception e) {
diff --git a/restful-api-common/src/main/java/meerkat/rest/ProtobufMessageBodyReader.java b/restful-api-common/src/main/java/meerkat/rest/ProtobufMessageBodyReader.java
index 853d962..d09e213 100644
--- a/restful-api-common/src/main/java/meerkat/rest/ProtobufMessageBodyReader.java
+++ b/restful-api-common/src/main/java/meerkat/rest/ProtobufMessageBodyReader.java
@@ -32,7 +32,7 @@ public class ProtobufMessageBodyReader implements MessageBodyReader<Message> {
                             InputStream entityStream) throws IOException, WebApplicationException {
         try {
             Method newBuilder = type.getMethod("newBuilder");
-            GeneratedMessage.Builder builder = (GeneratedMessage.Builder) newBuilder.invoke(type);
+            GeneratedMessage.Builder<?> builder = (GeneratedMessage.Builder<?>) newBuilder.invoke(type);
             return builder.mergeFrom(entityStream).build();
         } catch (Exception e) {
             throw new WebApplicationException(e);