made adaptions for my programming class next semester.

Author: thsc42

src/net/sharksystem/crypto/BasicCryptoKeyStorage.java

@@ -5,7 +5,10 @@
 
 import javax.crypto.KeyGenerator;
 import javax.crypto.SecretKey;
+import java.io.*;
 import java.security.*;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.X509EncodedKeySpec;
 import java.util.HashMap;
 
 public class BasicCryptoKeyStorage implements BasicCryptoParameters {
@@ -20,8 +23,11 @@ public class BasicCryptoKeyStorage implements BasicCryptoParameters {
     public static int DEFAULT_AES_KEY_SIZE = 128; // TODO we can do better
     public static final String DEFAULT_SIGNATURE_ALGORITHM = "SHA256withRSA";
 
+    // for debugging only - we don't have private key in real apps
     private HashMap<String, KeyPair> peerKeyPairs = new HashMap<>();
 
+    private HashMap<CharSequence, PublicKey> peerPublicKeys = new HashMap<CharSequence, PublicKey>();
+
     public BasicCryptoKeyStorage(String ownerID) throws ASAPSecurityException {
         // generate owners key pair;
         this.ownerID = ownerID;
@@ -95,11 +101,24 @@ public PublicKey getPublicKey() throws ASAPSecurityException {
     @Override
     public PublicKey getPublicKey(CharSequence subjectID) throws ASAPSecurityException {
         KeyPair keyPair = this.peerKeyPairs.get(subjectID);
-        if(keyPair == null) throw new ASAPSecurityException("no key pair for " + subjectID);
+        if(keyPair == null) {
+            // try there - which is more likely
+            PublicKey publicKey = this.peerPublicKeys.get(subjectID);
+            if(publicKey != null) {
+                // got it
+                return publicKey;
+            }
+            // else
+            throw new ASAPSecurityException("no key pair for " + subjectID);
+        }
 
         return keyPair.getPublic();
     }
 
+    void putPublicKey(CharSequence peer, PublicKey key) {
+        this.peerPublicKeys.put(peer, key);
+    }
+
     /**
      * In reality there cannot be such a method - but we are in a test.
      * @param subjectID
@@ -142,4 +161,59 @@ public void addKeyPair(String peerID, KeyPair keyPair) {
 
         this.peerKeyPairs.put(peerID, keyPair);
     }
+
+    /**
+     * Write storage owners' public key to stream
+     * @param os
+     */
+    public void writePublicKey(OutputStream os) throws ASAPSecurityException, IOException {
+        PublicKey publicKey = this.getPublicKey();
+
+        String format = publicKey.getFormat();
+        String algorithm = publicKey.getAlgorithm();
+        byte[] byteEncodedPublicKey = publicKey.getEncoded();
+        int length = byteEncodedPublicKey.length;
+
+        // makes it much easier to serialize simple data
+        DataOutputStream dos = new DataOutputStream(os);
+
+        // write to stream
+        dos.writeUTF(format);
+        dos.writeUTF(algorithm);
+        dos.writeInt(byteEncodedPublicKey.length);
+
+        // write encoded key directly on stream
+        os.write(byteEncodedPublicKey);
+    }
+
+    /**
+     * Read public key from another peer from an extern source (input stream)
+     * @param peer
+     * @param is
+     */
+    public void readPublicKey(CharSequence peer, InputStream is) throws ASAPSecurityException, IOException, NoSuchAlgorithmException, InvalidKeySpecException {
+        DataInputStream dis = new DataInputStream(is);
+
+        // read in same order as written
+        String format = dis.readUTF();
+        String algorithm = dis.readUTF();
+        int len = dis.readInt();
+
+        // allocate memory
+        byte[] byteEncodedPublicKey = new byte[len];
+
+        // read encoded key directly from stream
+        is.read(byteEncodedPublicKey);
+
+        // create key object
+
+        // should be revised - why?
+        X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(byteEncodedPublicKey);
+
+        KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
+        PublicKey publicKey = keyFactory.generatePublic(pubKeySpec);
+
+        // store it
+        this.putPublicKey(peer, publicKey);
+    }
 }

test/net/sharksystem/asap/BasisCryptoTests.java

@@ -0,0 +1,42 @@
+package net.sharksystem.asap;
+
+import net.sharksystem.crypto.ASAPCryptoAlgorithms;
+import net.sharksystem.crypto.BasicCryptoKeyStorage;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
+import java.security.spec.InvalidKeySpecException;
+
+public class BasisCryptoTests {
+    public static final String ALICE_ID = "Alice";
+    public static final String BOB_ID = "Bob";
+
+    @Test
+    public void publicKeyExportImport() throws ASAPSecurityException, IOException, InvalidKeySpecException, NoSuchAlgorithmException {
+        BasicCryptoKeyStorage aliceStorage = new BasicCryptoKeyStorage(ALICE_ID);
+        // a message
+        String msg = "Hi Bob";
+
+        // convert to bytes
+        byte[] msgBytes = msg.getBytes();
+
+        // sign a message - with Alice' private key
+        byte[] signatureBytes = ASAPCryptoAlgorithms.sign(msgBytes, aliceStorage);
+
+        // Alice could now send message with signature to bob - we are in a test, nothing to do here.
+
+        // Bob need to know Alice' public key to verify - simulate transfer
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        aliceStorage.writePublicKey(baos);
+
+        BasicCryptoKeyStorage bobStorage = new BasicCryptoKeyStorage(BOB_ID);
+        // store Alice' public key with Bob
+        bobStorage.readPublicKey(ALICE_ID, new ByteArrayInputStream(baos.toByteArray()));
+
+        Assert.assertTrue(ASAPCryptoAlgorithms.verify(msgBytes, signatureBytes, ALICE_ID, bobStorage));
+    }
+}