Fix signing and include strategies

src/main/java/de/vanitasvitae/crypto/pgpainless/Main.java

@@ -1,166 +0,0 @@
-package de.vanitasvitae.crypto.pgpainless;
-
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.nio.charset.Charset;
-import java.security.InvalidAlgorithmParameterException;
-import java.security.NoSuchAlgorithmException;
-import java.security.NoSuchProviderException;
-import java.security.Security;
-import java.util.Collections;
-
-import de.vanitasvitae.crypto.pgpainless.algorithm.CompressionAlgorithm;
-import de.vanitasvitae.crypto.pgpainless.algorithm.HashAlgorithm;
-import de.vanitasvitae.crypto.pgpainless.algorithm.SymmetricKeyAlgorithm;
-import de.vanitasvitae.crypto.pgpainless.key.SecretKeyRingProtector;
-import de.vanitasvitae.crypto.pgpainless.key.generation.type.length.RsaLength;
-import org.bouncycastle.jce.provider.BouncyCastleProvider;
-import org.bouncycastle.openpgp.PGPException;
-import org.bouncycastle.openpgp.PGPPublicKeyRing;
-import org.bouncycastle.openpgp.PGPSecretKeyRing;
-import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
-import org.bouncycastle.openpgp.operator.PBESecretKeyDecryptor;
-import org.bouncycastle.openpgp.operator.PBESecretKeyEncryptor;
-import org.bouncycastle.openpgp.operator.bc.BcKeyFingerprintCalculator;
-import org.bouncycastle.util.io.Streams;
-
-public class Main {
-
-    public static void main(String[] args)
-            throws PGPException, NoSuchAlgorithmException, NoSuchProviderException, InvalidAlgorithmParameterException,
-            IOException {
-
-        Security.addProvider(new BouncyCastleProvider());
-
-        PGPSecretKeyRing a = PGPainless.generateKeyRing().simpleRsaKeyRing("a@b.c", RsaLength._2048);
-        PGPSecretKeyRing b = PGPainless.generateKeyRing().simpleRsaKeyRing("b@c.d", RsaLength._2048);
-
-        SecretKeyRingProtector secretKeyRingDecryptor = new SecretKeyRingProtector() {
-            @Override
-            public PBESecretKeyDecryptor getDecryptor(Long keyId) {
-                return null;
-            }
-
-            @Override
-            public PBESecretKeyEncryptor getEncryptor(Long keyId) {
-                return null;
-            }
-        };
-
-        byte[] m = "Dies ist ein verschlüsselter Text.".getBytes();
-        ByteArrayInputStream fromPlain = new ByteArrayInputStream(m);
-        ByteArrayOutputStream toEncrypted = new ByteArrayOutputStream();
-
-        OutputStream encryptor = PGPainless.createEncryptor().onOutputStream(toEncrypted)
-                .toRecipient(b.getPublicKey())
-                .usingAlgorithms(SymmetricKeyAlgorithm.AES_256, HashAlgorithm.SHA512, CompressionAlgorithm.UNCOMPRESSED)
-                .signWith(a, secretKeyRingDecryptor)
-                .asciiArmor();
-
-        Streams.pipeAll(fromPlain, encryptor);
-        fromPlain.close();
-        encryptor.close();
-
-        System.out.println(new String(toEncrypted.toByteArray()));
-
-        ByteArrayInputStream fromEncrypted = new ByteArrayInputStream(toEncrypted.toByteArray());
-        ByteArrayOutputStream toPlain = new ByteArrayOutputStream();
-
-        PainlessResult.ResultAndInputStream resultAndInputStream  = PGPainless.createDecryptor()
-                .onInputStream(fromEncrypted)
-                .decryptWith(new PGPSecretKeyRingCollection(Collections.singleton(b)), secretKeyRingDecryptor)
-                .verifyWith(Collections.singleton(a.getPublicKey().getKeyID()),
-                        Collections.singleton(new PGPPublicKeyRing(a.getPublicKey().getEncoded(), new BcKeyFingerprintCalculator())))
-                .ignoreMissingPublicKeys()
-                .build();
-
-        InputStream decryptor = resultAndInputStream.getInputStream();
-
-        Streams.pipeAll(decryptor, toPlain);
-        decryptor.close();
-        toPlain.close();
-
-        PainlessResult result = resultAndInputStream.getResult();
-
-        System.out.println(b.getPublicKey().getKeyID() + " " + result.getDecryptionKeyId());
-        System.out.println(new String(toPlain.toByteArray()));
-    }
-
-    private static void gpg(PGPSecretKeyRing a, PGPSecretKeyRing b, SecretKeyRingProtector secretKeyRingDecryptor)
-            throws IOException, PGPException {
-        String gpg = "-----BEGIN PGP MESSAGE-----\n" +
-                "\n" +
-                "hQGMAwAAAAAAAAAAAQv+JyovfiPxDiLe9XlgQAG6zD+YdRtZRuUJD+A+ZX4Sn0w0\n" +
-                "2Dl9Ehf7lKjIo0cIfVOUrgITnWIRWAyfrk5KiXdXcZ6dXxz/YJFnLSlgqUwq7GWi\n" +
-                "NYf3Uqg+/8f3Ucl0x6sr1oddwB9OI7zRJwDqEzTORjLBu1vtDlFPMPWwAeqDtZgz\n" +
-                "ikT6vSFfhVjVbgx4mztw7hatWNjXzNkl9+lojzo9IyiA+3SBsRe/2My3ZBjPx97f\n" +
-                "3YGMCvbggdX3C/MRV2iek2pFX7YTKasFeEy5Y1c09upqaEIpaJq8vi1Fu44dv0Rt\n" +
-                "gv4sdljaJXsFn9aoVFrp/xU4SyPiC1Z/KjqE3Zfyh+OMWKoWmtYH07/g8IGkkBCh\n" +
-                "xuDiyy813WS3xtCyX405Vd+rxYC3y1h1FtthdO/AIrYSWj6qI6hyK2tyYmwsg+oY\n" +
-                "1oaXhcTbWXsBO89v0YtmVK1bPVXq8ao/DQvrs84JsYsKzXA17gKyBLBUoTNn8h8A\n" +
-                "AXg455AN8iHi2u5pAKr7hQIMAwAAAAAAAAAAAQ/7Bg8SGEfMPmtDy/BazrYWaXvX\n" +
-                "1+WWRNM630ULPEq7LG4BKJJOOrhk0kNkjIsaXhgqn9bt3YxxuE1eOQksjn0sNOD7\n" +
-                "3NAOicHzQ7xOarvN9OUSGirc+EIn4ETRGKYF1TXHBSYnBeb+DLCbRZkBZhRrA5Lc\n" +
-                "z08kWrGRfq5Bz6eMatBTO1L8XTIxHPgc9/LNv7OqcIfT0udjOQMkA7oxCz5mLl2b\n" +
-                "dApsDEFNKNaGgRzSf2rDqw0SGkDxYsXI6IYrVSEm6uDt+ScybS0KkcEgg+I9l91n\n" +
-                "XgqQQaXpYnHgETqKYfcUOk5iEND5Lvik/XhHNViaL3CdOkxFLTa0wfy0y0IsV2Y3\n" +
-                "xGkMOWdDjXlY8UWRgoK61M91phgZ48zfSoVvXNDrjOJzm1jn8CFFFov4Gse7CtlM\n" +
-                "A+3ntVdjL94jkp+2mU3e9kzCOG+ChylLuqlGTvavbHt/rzuZooi/6g1VHy1r+v9I\n" +
-                "rWKX6q55H8JzZXZOrfED39QocK9b1BjtEca/Qnqw82+IVY/CufBmnmbOWUkHq1zP\n" +
-                "6nj840HxH1zV5vHf8vlXxV7/iBesAF94dLT/Hp0E7+Ilyp/pQaQjMS2RLycMUJQJ\n" +
-                "pQey81gpuOWD6YIbvgnrMBMrJLyJSk3r3sMdJ3DCPxHC+OyvHxddA5TdL2e4aP3L\n" +
-                "OzKql59v1w+9Doe3LEPSPgEVAdUUg0nEl5lg9LLqaepaYp8NfsEC1Rnk/MLxciJu\n" +
-                "9oNjqPqQxKTv4aQO/Qb8gHFb3O34OnNKz+CzrX5Q\n" +
-                "=sVVl\n" +
-                "-----END PGP MESSAGE-----";
-
-        ByteArrayInputStream inputStream = new ByteArrayInputStream(gpg.getBytes());
-
-        InputStream decryptor = PGPainless.createDecryptor().onInputStream(inputStream)
-                .decryptWith(new PGPSecretKeyRingCollection(Collections.singleton(b)), secretKeyRingDecryptor)
-                .doNotVerify()
-                .build()
-                .getInputStream();
-
-    }
-
-    public static void symm(PGPSecretKeyRing a, PGPSecretKeyRing b, SecretKeyRingProtector secretKeyRingDecryptor)
-            throws IOException, PGPException {
-        byte[] bytes = "Diese Nachricht ist streng geheim!!!".getBytes(Charset.forName("UTF-8"));
-        ByteArrayInputStream fromPlain = new ByteArrayInputStream(bytes);
-        ByteArrayOutputStream toEncrypted = new ByteArrayOutputStream();
-
-        OutputStream encryptor = PGPainless.createEncryptor()
-                .onOutputStream(toEncrypted)
-                .toRecipient(b.getPublicKey())
-                .usingAlgorithms(SymmetricKeyAlgorithm.AES_256, HashAlgorithm.SHA512, CompressionAlgorithm.UNCOMPRESSED)
-                .signWith(a, secretKeyRingDecryptor)
-                .noArmor();
-
-        Streams.pipeAll(fromPlain, encryptor);
-        encryptor.close();
-
-        System.out.println(new String(toEncrypted.toByteArray(), Charset.forName("UTF-8")));
-
-        ByteArrayInputStream fromEncrypted = new ByteArrayInputStream(toEncrypted.toByteArray());
-        ByteArrayOutputStream toPlain = new ByteArrayOutputStream();
-
-        PainlessResult.ResultAndInputStream resultAndInputStream = PGPainless.createDecryptor()
-                .onInputStream(fromEncrypted)
-                .decryptWith(new PGPSecretKeyRingCollection(Collections.singleton(b)), secretKeyRingDecryptor)
-                .verifyWith(Collections.singleton(a.getPublicKey().getKeyID()),
-                        Collections.singleton(new PGPPublicKeyRing(a.getPublicKey().getEncoded(), new BcKeyFingerprintCalculator())))
-                .ignoreMissingPublicKeys()
-                .build();
-
-        InputStream decryptor = resultAndInputStream.getInputStream();
-
-        Streams.pipeAll(decryptor, toPlain);
-        decryptor.close();
-
-        PainlessResult result = resultAndInputStream.getResult();
-    }
-}

src/main/java/de/vanitasvitae/crypto/pgpainless/decryption_verification/DecryptionBuilder.java

@@ -6,7 +6,6 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
 
-import de.vanitasvitae.crypto.pgpainless.PainlessResult;
 import de.vanitasvitae.crypto.pgpainless.key.SecretKeyRingProtector;
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPublicKeyRing;
@@ -89,7 +88,7 @@ public class DecryptionBuilder implements DecryptionBuilderInterface {
     class BuildImpl implements Build {
 
         @Override
-        public PainlessResult.ResultAndInputStream build() throws IOException, PGPException {
+        public DecryptionStream build() throws IOException, PGPException {
             return DecryptionStreamFactory.create(inputStream,
                     decryptionKeys, decryptionKeyDecryptor, verificationKeys, trustedKeyIds, missingPublicKeyCallback);
         }

src/main/java/de/vanitasvitae/crypto/pgpainless/decryption_verification/DecryptionBuilderInterface.java

@@ -4,7 +4,6 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.util.Set;
 
-import de.vanitasvitae.crypto.pgpainless.PainlessResult;
 import de.vanitasvitae.crypto.pgpainless.key.SecretKeyRingProtector;
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPublicKeyRing;
@@ -42,7 +41,7 @@ public interface DecryptionBuilderInterface {
 
     interface Build {
 
-        PainlessResult.ResultAndInputStream build() throws IOException, PGPException;
+        DecryptionStream build() throws IOException, PGPException;
 
     }
 

src/main/java/de/vanitasvitae/crypto/pgpainless/decryption_verification/DecryptionStream.java

@@ -0,0 +1,39 @@
+package de.vanitasvitae.crypto.pgpainless.decryption_verification;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+public class DecryptionStream extends InputStream {
+
+    private final InputStream inputStream;
+    private final PainlessResult.Builder resultBuilder;
+    private boolean isClosed = false;
+
+    DecryptionStream(InputStream wrapped, PainlessResult.Builder resultBuilder) {
+
+        if (wrapped == null) {
+            throw new NullPointerException("Wrapped InputStream MUST NOT be null!");
+        }
+
+        this.inputStream = wrapped;
+        this.resultBuilder = resultBuilder;
+    }
+
+    @Override
+    public int read() throws IOException {
+        return inputStream.read();
+    }
+
+    @Override
+    public void close() throws IOException {
+        inputStream.close();
+        this.isClosed = true;
+    }
+
+    public PainlessResult getResult() {
+        if (!isClosed) {
+            throw new IllegalStateException("DecryptionStream MUST be closed before the result can be accessed.");
+        }
+        return resultBuilder.build();
+    }
+}

src/main/java/de/vanitasvitae/crypto/pgpainless/decryption_verification/DecryptionStreamFactory.java

@@ -9,7 +9,6 @@ import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
 
-import de.vanitasvitae.crypto.pgpainless.PainlessResult;
 import de.vanitasvitae.crypto.pgpainless.PainlessStream;
 import de.vanitasvitae.crypto.pgpainless.algorithm.CompressionAlgorithm;
 import de.vanitasvitae.crypto.pgpainless.algorithm.SymmetricKeyAlgorithm;
@@ -60,7 +59,7 @@ public class DecryptionStreamFactory {
         this.missingPublicKeyCallback = missingPublicKeyCallback;
     }
 
-    public static PainlessResult.ResultAndInputStream create(InputStream inputStream,
+    public static DecryptionStream create(InputStream inputStream,
                                           PGPSecretKeyRingCollection decryptionKeys,
                                           SecretKeyRingProtector decryptor,
                                           Set<PGPPublicKeyRing> verificationKeys,
@@ -77,9 +76,7 @@ public class DecryptionStreamFactory {
         PGPObjectFactory objectFactory = new PGPObjectFactory(
                 PGPUtil.getDecoderStream(inputStream), new BcKeyFingerprintCalculator());
 
-        return new PainlessResult.ResultAndInputStream(
+        return new DecryptionStream(factory.wrap(objectFactory), factory.resultBuilder);
-                factory.resultBuilder,
-                new PainlessStream.In(factory.wrap(objectFactory)));
     }
 
     private InputStream wrap(PGPObjectFactory objectFactory) throws IOException, PGPException {

src/main/java/de/vanitasvitae/crypto/pgpainless/decryption_verification/PainlessResult.java

@@ -1,4 +1,4 @@
-package de.vanitasvitae.crypto.pgpainless;
+package de.vanitasvitae.crypto.pgpainless.decryption_verification;
 
 import java.util.Collections;
 import java.util.HashSet;
@@ -86,11 +86,11 @@ public class PainlessResult {
         return false;
     }
 
-    public static Builder getBuilder() {
+    static Builder getBuilder() {
         return new Builder();
     }
 
-    public static class Builder {
+    static class Builder {
 
         private final Set<Long> recipientKeyIds = new HashSet<>();
         private Long decryptionKeyId;
@@ -139,25 +139,4 @@ public class PainlessResult {
             return new PainlessResult(recipientKeyIds, decryptionKeyId, symmetricKeyAlgorithm, compressionAlgorithm, integrityProtected, signatureKeyIds, verifiedSignatureKeyIds);
         }
     }
-
-    public static class ResultAndInputStream {
-        private final PainlessResult.Builder resultBuilder;
-        private final PainlessStream.In inputStream;
-
-        public ResultAndInputStream(PainlessResult.Builder resultBuilder, PainlessStream.In inputStream) {
-            this.resultBuilder = resultBuilder;
-            this.inputStream = inputStream;
-        }
-
-        public PainlessResult getResult() {
-            if (!inputStream.isClosed()) {
-                throw new IllegalStateException("InputStream must be closed before the PainlessResult can be accessed.");
-            }
-            return resultBuilder.build();
-        }
-
-        public PainlessStream.In getInputStream() {
-            return inputStream;
-        }
-    }
 }

src/main/java/de/vanitasvitae/crypto/pgpainless/decryption_verification/SignatureVerifyingInputStream.java

@@ -4,12 +4,10 @@ import java.io.FilterInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.security.SignatureException;
-import java.util.Iterator;
 import java.util.Map;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-import de.vanitasvitae.crypto.pgpainless.PainlessResult;
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPObjectFactory;
 import org.bouncycastle.openpgp.PGPOnePassSignature;

src/main/java/de/vanitasvitae/crypto/pgpainless/decryption_verification/VerificationFeedbackCallback.java

@@ -1,6 +0,0 @@
-package de.vanitasvitae.crypto.pgpainless.decryption_verification;
-
-public class VerificationFeedbackCallback {
-
-
-}

src/main/java/de/vanitasvitae/crypto/pgpainless/encryption_signing/EncryptionBuilder.java

@@ -3,16 +3,25 @@ package de.vanitasvitae.crypto.pgpainless.encryption_signing;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
 
-import de.vanitasvitae.crypto.pgpainless.PublicKeyNotFoundException;
 import de.vanitasvitae.crypto.pgpainless.SecretKeyNotFoundException;
 import de.vanitasvitae.crypto.pgpainless.algorithm.CompressionAlgorithm;
 import de.vanitasvitae.crypto.pgpainless.algorithm.HashAlgorithm;
 import de.vanitasvitae.crypto.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import de.vanitasvitae.crypto.pgpainless.key.SecretKeyRingProtector;
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.PublicKeySelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.SecretKeySelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.impl.And;
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.impl.EncryptionKeySelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.impl.NoRevocation;
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.impl.SignatureKeySelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.key.selection.keyring.PublicKeyRingSelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.key.selection.keyring.SecretKeyRingSelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.util.MultiMap;
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPrivateKey;
 import org.bouncycastle.openpgp.PGPPublicKey;
@@ -42,19 +51,22 @@ public class EncryptionBuilder implements EncryptionBuilderInterface {
     class ToRecipientsImpl implements ToRecipients {
 
         @Override
-        public WithAlgorithms toRecipient(PGPPublicKey key) {
+        public WithAlgorithms toRecipients(PGPPublicKey... keys) {
-            if (!key.isEncryptionKey()) {
+            for (PGPPublicKey k : keys) {
-                throw new IllegalStateException("Public Key " + Long.toHexString(key.getKeyID()) + " is not capable of encryption.");
+                if (encryptionKeySelector().accept(null, k)) {
+                    EncryptionBuilder.this.encryptionKeys.add(k);
+                } else {
+                    throw new IllegalArgumentException("Key " + k.getKeyID() + " is not a valid encryption key.");
+                }
             }
-            EncryptionBuilder.this.encryptionKeys.add(key);
             return new WithAlgorithmsImpl();
         }
 
         @Override
-        public WithAlgorithms toRecipients(Set<PGPPublicKeyRing> keys) {
+        public WithAlgorithms toRecipients(PGPPublicKeyRing... keys) {
             for (PGPPublicKeyRing ring : keys) {
                 for (PGPPublicKey k : ring) {
-                    if (k.isEncryptionKey()) {
+                    if (encryptionKeySelector().accept(null, k)) {
                         EncryptionBuilder.this.encryptionKeys.add(k);
                     }
                 }
@@ -63,25 +75,20 @@ public class EncryptionBuilder implements EncryptionBuilderInterface {
         }
 
         @Override
-        public WithAlgorithms toRecipients(Set<Long> keyIds, Set<PGPPublicKeyRingCollection> keys)
+        public <O>WithAlgorithms toRecipients(PublicKeyRingSelectionStrategy<O> ringSelectionStrategy,
-                throws PublicKeyNotFoundException {
+                                              MultiMap<O, PGPPublicKeyRingCollection> keys) {
-            Set<PGPPublicKeyRing> rings = new HashSet<>();
+            MultiMap<O, PGPPublicKeyRing> acceptedKeyRings = ringSelectionStrategy.selectKeyRingsFromCollections(keys);
-
+            for (O identifier : acceptedKeyRings.keySet()) {
-            for (PGPPublicKeyRingCollection collection : keys) {
+                Set<PGPPublicKeyRing> acceptedSet = acceptedKeyRings.get(identifier);
-                for (long keyId : keyIds) {
+                for (PGPPublicKeyRing ring : acceptedSet) {
-                    try {
+                    for (PGPPublicKey k : ring) {
-                        PGPPublicKeyRing ring = collection.getPublicKeyRing(keyId);
+                        if (encryptionKeySelector().accept(null, k)) {
-                        if (ring != null) {
+                            EncryptionBuilder.this.encryptionKeys.add(k);
-                            rings.add(ring);
-                            keyIds.remove(keyId);
-                        }
-                    } catch (PGPException e) {
-                        throw new PublicKeyNotFoundException(e);
                         }
                     }
                 }
-
+            }
-            return toRecipients(rings);
+            return new WithAlgorithmsImpl();
         }
 
         @Override
@@ -93,17 +100,23 @@ public class EncryptionBuilder implements EncryptionBuilderInterface {
     class WithAlgorithmsImpl implements WithAlgorithms {
 
         @Override
-        public WithAlgorithms andToSelf(PGPPublicKey key) {
+        public WithAlgorithms andToSelf(PGPPublicKey... keys) {
-            EncryptionBuilder.this.encryptionKeys.add(key);
+            for (PGPPublicKey k : keys) {
+                if (encryptionKeySelector().accept(null, k)) {
+                    EncryptionBuilder.this.encryptionKeys.add(k);
+                } else {
+                    throw new IllegalArgumentException("Key " + k.getKeyID() + " is not a valid encryption key.");
+                }
+            }
             return this;
         }
 
         @Override
-        public WithAlgorithms andToSelf(Set<PGPPublicKeyRing> keyRings) {
+        public WithAlgorithms andToSelf(PGPPublicKeyRing... keyRings) {
             for (PGPPublicKeyRing ring : keyRings) {
                 for (Iterator<PGPPublicKey> i = ring.getPublicKeys(); i.hasNext(); ) {
                     PGPPublicKey key = i.next();
-                    if (key.isEncryptionKey()) {
+                    if (encryptionKeySelector().accept(null, key)) {
                         EncryptionBuilder.this.encryptionKeys.add(key);
                     }
                 }
@@ -111,6 +124,24 @@ public class EncryptionBuilder implements EncryptionBuilderInterface {
             return this;
         }
 
+        public <O>WithAlgorithms andToSelf(PublicKeyRingSelectionStrategy<O> ringSelectionStrategy,
+                                           MultiMap<O, PGPPublicKeyRingCollection> keyRingCollections) {
+            MultiMap<O, PGPPublicKeyRing> acceptedKeyRings =
+                    ringSelectionStrategy.selectKeyRingsFromCollections(keyRingCollections);
+            for (O identifier : acceptedKeyRings.keySet()) {
+                Set<PGPPublicKeyRing> acceptedSet = acceptedKeyRings.get(identifier);
+                for (PGPPublicKeyRing k : acceptedSet) {
+                    for (Iterator<PGPPublicKey> i = k.getPublicKeys(); i.hasNext(); ) {
+                        PGPPublicKey key = i.next();
+                        if (encryptionKeySelector().accept(null, key)) {
+                            EncryptionBuilder.this.encryptionKeys.add(key);
+                        }
+                    }
+                }
+            }
+            return this;
+        }
+
         @Override
         public SignWith usingAlgorithms(SymmetricKeyAlgorithm symmetricKeyAlgorithm,
                                         HashAlgorithm hashAlgorithm,
@@ -136,16 +167,24 @@ public class EncryptionBuilder implements EncryptionBuilderInterface {
     class SignWithImpl implements SignWith {
 
         @Override
-        public Armor signWith(PGPSecretKeyRing key, SecretKeyRingProtector decryptor) {
+        public <O> Armor signWith(SecretKeyRingProtector decryptor, PGPSecretKey... keys) {
-            return signWith(Collections.singleton(key), decryptor);
+            for (PGPSecretKey s : keys) {
+                if (EncryptionBuilder.this.<O>signingKeySelector().accept(null, s)) {
+                    signingKeys.add(s);
+                } else {
+                    throw new IllegalArgumentException("Key " + s.getKeyID() + " is not a valid signing key.");
+                }
+            }
+            EncryptionBuilder.this.signingKeysDecryptor = decryptor;
+            return new ArmorImpl();
         }
 
         @Override
-        public Armor signWith(Set<PGPSecretKeyRing> keys, SecretKeyRingProtector decryptor) {
+        public <O> Armor signWith(SecretKeyRingProtector decryptor, PGPSecretKeyRing... keys) {
             for (PGPSecretKeyRing key : keys) {
                 for (Iterator<PGPSecretKey> i = key.getSecretKeys(); i.hasNext(); ) {
                     PGPSecretKey s = i.next();
-                    if (s.isSigningKey()) {
+                    if (EncryptionBuilder.this.<O>signingKeySelector().accept(null, s)) {
                         EncryptionBuilder.this.signingKeys.add(s);
                     }
                 }
@@ -155,23 +194,23 @@ public class EncryptionBuilder implements EncryptionBuilderInterface {
         }
 
         @Override
-        public Armor signWith(Set<Long> keyIds, Set<PGPSecretKeyRingCollection> keyRings, SecretKeyRingProtector decryptor)
+        public <O>Armor signWith(SecretKeyRingSelectionStrategy<O> ringSelectionStrategy,
-                throws SecretKeyNotFoundException {
+                                 SecretKeyRingProtector decryptor,
-            Set<PGPSecretKeyRing> rings = new HashSet<>();
+                                 MultiMap<O, PGPSecretKeyRingCollection> keyRingCollections) {
-            for (PGPSecretKeyRingCollection collection : keyRings) {
+            MultiMap<O, PGPSecretKeyRing> acceptedKeyRings =
-                for (long keyId : keyIds) {
+                    ringSelectionStrategy.selectKeyRingsFromCollections(keyRingCollections);
-                    try {
+            for (O identifier : acceptedKeyRings.keySet()) {
-                        PGPSecretKeyRing ring = collection.getSecretKeyRing(keyId);
+                Set<PGPSecretKeyRing> acceptedSet = acceptedKeyRings.get(identifier);
-                        if (ring != null) {
+                for (PGPSecretKeyRing k : acceptedSet) {
-                            rings.add(ring);
+                    for (Iterator<PGPSecretKey> i = k.getSecretKeys(); i.hasNext(); ) {
-                            keyIds.remove(keyId);
+                        PGPSecretKey s = i.next();
-                        }
+                        if (EncryptionBuilder.this.<O>signingKeySelector().accept(null, s)) {
-                    } catch (PGPException e) {
+                            EncryptionBuilder.this.signingKeys.add(s);
-                        throw new SecretKeyNotFoundException(keyId);
                         }
                     }
                 }
-            return signWith(rings, decryptor);
+            }
+            return new ArmorImpl();
         }
 
         @Override
@@ -211,4 +250,16 @@ public class EncryptionBuilder implements EncryptionBuilderInterface {
                     EncryptionBuilder.this.asciiArmor);
         }
     }
+
+    <O> PublicKeySelectionStrategy<O> encryptionKeySelector() {
+        return new And.PubKeySelectionStrategy<>(
+                new NoRevocation.PubKeySelectionStrategy<>(),
+                new EncryptionKeySelectionStrategy<>());
+    }
+
+    <O> SecretKeySelectionStrategy<O> signingKeySelector() {
+        return new And.SecKeySelectionStrategy<>(
+                new NoRevocation.SecKeySelectionStrategy<>(),
+                new SignatureKeySelectionStrategy<>());
+    }
 }

src/main/java/de/vanitasvitae/crypto/pgpainless/encryption_signing/EncryptionBuilderInterface.java

@@ -10,10 +10,14 @@ import de.vanitasvitae.crypto.pgpainless.algorithm.CompressionAlgorithm;
 import de.vanitasvitae.crypto.pgpainless.algorithm.HashAlgorithm;
 import de.vanitasvitae.crypto.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import de.vanitasvitae.crypto.pgpainless.key.SecretKeyRingProtector;
+import de.vanitasvitae.crypto.pgpainless.key.selection.keyring.PublicKeyRingSelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.key.selection.keyring.SecretKeyRingSelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.util.MultiMap;
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPublicKey;
 import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
+import org.bouncycastle.openpgp.PGPSecretKey;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
 
@@ -23,12 +27,12 @@ public interface EncryptionBuilderInterface {
 
     interface ToRecipients {
 
-        WithAlgorithms toRecipient(PGPPublicKey key);
+        WithAlgorithms toRecipients(PGPPublicKey... keys);
 
-        WithAlgorithms toRecipients(Set<PGPPublicKeyRing> keys);
+        WithAlgorithms toRecipients(PGPPublicKeyRing... keys);
 
-        WithAlgorithms toRecipients(Set<Long> keyIds, Set<PGPPublicKeyRingCollection> keys)
+        <O> WithAlgorithms toRecipients(PublicKeyRingSelectionStrategy<O> selectionStrategy,
-                throws PublicKeyNotFoundException;
+                                       MultiMap<O, PGPPublicKeyRingCollection> keys);
 
         SignWith doNotEncrypt();
 
@@ -36,9 +40,12 @@ public interface EncryptionBuilderInterface {
 
     interface WithAlgorithms {
 
-        WithAlgorithms andToSelf(PGPPublicKey key);
+        WithAlgorithms andToSelf(PGPPublicKey... keys);
 
-        WithAlgorithms andToSelf(Set<PGPPublicKeyRing> keys);
+        WithAlgorithms andToSelf(PGPPublicKeyRing... keys);
+
+        <O> WithAlgorithms andToSelf(PublicKeyRingSelectionStrategy<O> selectionStrategy,
+                                    MultiMap<O, PGPPublicKeyRingCollection> keys);
 
         SignWith usingAlgorithms(SymmetricKeyAlgorithm symmetricKeyAlgorithm,
                                  HashAlgorithm hashAlgorithm,
@@ -50,12 +57,13 @@ public interface EncryptionBuilderInterface {
 
     interface SignWith {
 
-        Armor signWith(PGPSecretKeyRing key, SecretKeyRingProtector decryptor);
+        <O> Armor signWith(SecretKeyRingProtector decryptor, PGPSecretKey... keys);
 
-        Armor signWith(Set<PGPSecretKeyRing> keyRings, SecretKeyRingProtector decryptor)
+        <O> Armor signWith(SecretKeyRingProtector decryptor, PGPSecretKeyRing... keyRings);
-                throws SecretKeyNotFoundException;
 
-        Armor signWith(Set<Long> keyIds, Set<PGPSecretKeyRingCollection> keys, SecretKeyRingProtector decryptor)
+        <O> Armor signWith(SecretKeyRingSelectionStrategy<O> selectionStrategy,
+                          SecretKeyRingProtector decryptor,
+                          MultiMap<O, PGPSecretKeyRingCollection> keys)
                 throws SecretKeyNotFoundException;
 
         Armor doNotSign();

src/main/java/de/vanitasvitae/crypto/pgpainless/key/selection/key/impl/And.java

@@ -0,0 +1,44 @@
+package de.vanitasvitae.crypto.pgpainless.key.selection.key.impl;
+
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.PublicKeySelectionStrategy;
+import de.vanitasvitae.crypto.pgpainless.key.selection.key.SecretKeySelectionStrategy;
+import org.bouncycastle.openpgp.PGPPublicKey;
+import org.bouncycastle.openpgp.PGPSecretKey;
+
+public class And {
+
+    public static class PubKeySelectionStrategy<O> extends PublicKeySelectionStrategy<O> {
+
+        private final PublicKeySelectionStrategy<O> left;
+        private final PublicKeySelectionStrategy<O> right;
+
+        public PubKeySelectionStrategy(PublicKeySelectionStrategy<O> left,
+                                       PublicKeySelectionStrategy<O> right) {
+            this.left = left;
+            this.right = right;
+        }
+
+        @Override
+        public boolean accept(O identifier, PGPPublicKey key) {
+            return left.accept(identifier, key) && right.accept(identifier, key);
+        }
+    }
+
+    public static class SecKeySelectionStrategy<O> extends SecretKeySelectionStrategy<O> {
+
+        private final SecretKeySelectionStrategy<O> left;
+        private final SecretKeySelectionStrategy<O> right;
+
+        public SecKeySelectionStrategy(SecretKeySelectionStrategy<O> left,
+                                       SecretKeySelectionStrategy<O> right) {
+            this.left = left;
+            this.right = right;
+        }
+
+        @Override
+        public boolean accept(O identifier, PGPSecretKey key) {
+            return left.accept(identifier, key) && right.accept(identifier, key);
+        }
+    }
+
+}

src/main/java/de/vanitasvitae/crypto/pgpainless/util/BCUtil.java

@@ -1,10 +1,12 @@
 package de.vanitasvitae.crypto.pgpainless.util;
 
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
+import java.util.List;
 
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPublicKey;
@@ -12,7 +14,6 @@ import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
-import org.bouncycastle.openpgp.operator.bc.BcKeyFingerprintCalculator;
 
 public class BCUtil {
 
@@ -26,14 +27,23 @@ public class BCUtil {
         return new PGPSecretKeyRingCollection(Arrays.asList(rings));
     }
 
-    public static PGPPublicKeyRing publicKeyRingFromSecretKeyRing(PGPSecretKeyRing ring) throws IOException {
+    public static PGPPublicKeyRing publicKeyRingFromSecretKeyRing(PGPSecretKeyRing secring) {
-        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+        List<PGPPublicKey> list = new ArrayList<>();
-        for (Iterator<PGPPublicKey> i = ring.getPublicKeys(); i.hasNext(); ) {
+        for (Iterator<PGPPublicKey> i = secring.getPublicKeys(); i.hasNext(); ) {
             PGPPublicKey k = i.next();
-            k.encode(buffer);
+            list.add(k);
+        }
+
+        // TODO: Change to simply using the List constructor once BC 1.60 gets released.
+        try {
+            Constructor<PGPPublicKeyRing> constructor;
+            constructor = PGPPublicKeyRing.class.getDeclaredConstructor(List.class);
+            constructor.setAccessible(true);
+            PGPPublicKeyRing pubring = constructor.newInstance(list);
+            return pubring;
+        } catch (NoSuchMethodException | IllegalAccessException | InstantiationException | InvocationTargetException e) {
+            e.printStackTrace();
+            return null;
         }
-        buffer.close();
-        ByteArrayInputStream in = new ByteArrayInputStream(buffer.toByteArray());
-        return new PGPPublicKeyRing(in, new BcKeyFingerprintCalculator());
     }
 }

src/test/java/de/vanitasvitae/crypto/pgpainless/BCUtilTest.java

@@ -0,0 +1,43 @@
+package de.vanitasvitae.crypto.pgpainless;
+
+import static junit.framework.TestCase.assertEquals;
+
+import java.io.IOException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.util.Iterator;
+
+import de.vanitasvitae.crypto.pgpainless.util.BCUtil;
+import org.bouncycastle.openpgp.PGPException;
+import org.bouncycastle.openpgp.PGPPublicKey;
+import org.bouncycastle.openpgp.PGPPublicKeyRing;
+import org.bouncycastle.openpgp.PGPSecretKeyRing;
+import org.junit.Test;
+
+public class BCUtilTest extends AbstractPGPainlessTest {
+
+    @Test
+    public void test()
+            throws PGPException, NoSuchAlgorithmException, NoSuchProviderException, InvalidAlgorithmParameterException,
+            IOException {
+        PGPSecretKeyRing sec = PGPainless.generateKeyRing().simpleEcKeyRing("Hallo Welt");
+        PGPPublicKeyRing pub = BCUtil.publicKeyRingFromSecretKeyRing(sec);
+
+        int secSize = 0;
+        Iterator<PGPPublicKey> secPubIt = sec.getPublicKeys();
+        while (secPubIt.hasNext()) {
+            secPubIt.next();
+            secSize++;
+        }
+
+        int pubSize = 0;
+        Iterator<PGPPublicKey> pubPubIt = pub.getPublicKeys();
+        while (pubPubIt.hasNext()) {
+            pubPubIt.next();
+            pubSize++;
+        }
+
+        assertEquals(secSize, pubSize);
+    }
+}

src/test/java/de/vanitasvitae/crypto/pgpainless/EncryptDecryptTest.java

@@ -5,7 +5,6 @@ import static junit.framework.TestCase.assertTrue;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.charset.Charset;
 import java.security.InvalidAlgorithmParameterException;
@@ -16,6 +15,8 @@ import java.util.Collections;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import de.vanitasvitae.crypto.pgpainless.decryption_verification.DecryptionStream;
+import de.vanitasvitae.crypto.pgpainless.decryption_verification.PainlessResult;
 import de.vanitasvitae.crypto.pgpainless.key.SecretKeyRingProtector;
 import de.vanitasvitae.crypto.pgpainless.key.UnprotectedKeysProtector;
 import de.vanitasvitae.crypto.pgpainless.key.generation.type.length.RsaLength;
@@ -90,9 +91,9 @@ public class EncryptDecryptTest extends AbstractPGPainlessTest {
 
         OutputStream encryptor = PGPainless.createEncryptor()
                 .onOutputStream(envelope)
-                .toRecipients(Collections.singleton(recipientPub))
+                .toRecipients(recipientPub)
                 .usingSecureAlgorithms()
-                .signWith(sender, keyDecryptor)
+                .signWith(keyDecryptor, sender)
                 .noArmor();
 
         Streams.pipeAll(new ByteArrayInputStream(secretMessage), encryptor);
@@ -102,21 +103,20 @@ public class EncryptDecryptTest extends AbstractPGPainlessTest {
         // Juliet trieth to comprehend Romeos words
 
         ByteArrayInputStream envelopeIn = new ByteArrayInputStream(encryptedSecretMessage);
-        PainlessResult.ResultAndInputStream resultAndInputStream = PGPainless.createDecryptor()
+        DecryptionStream decryptor = PGPainless.createDecryptor()
                 .onInputStream(envelopeIn)
                 .decryptWith(BCUtil.keyRingsToKeyRingCollection(recipient), keyDecryptor)
                 .verifyWith(Collections.singleton(TestKeys.ROMEO_KEY_ID), BCUtil.keyRingsToKeyRingCollection(senderPub))
                 .ignoreMissingPublicKeys()
                 .build();
 
-        InputStream decryptor = resultAndInputStream.getInputStream();
         OutputStream decryptedSecretMessage = new ByteArrayOutputStream();
 
         Streams.pipeAll(decryptor, decryptedSecretMessage);
         decryptor.close();
 
         assertTrue(Arrays.equals(secretMessage, ((ByteArrayOutputStream) decryptedSecretMessage).toByteArray()));
-        PainlessResult result = resultAndInputStream.getResult();
+        PainlessResult result = decryptor.getResult();
         assertTrue(result.containsVerifiedSignatureFrom(senderPub));
         assertTrue(result.isIntegrityProtected());
         assertTrue(result.isSigned());

src/test/java/de/vanitasvitae/crypto/pgpainless/TestKeysTest.java

@@ -6,11 +6,11 @@ import static junit.framework.TestCase.assertTrue;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.InputStream;
 import java.nio.charset.Charset;
 import java.util.Arrays;
 import java.util.Collections;
 
+import de.vanitasvitae.crypto.pgpainless.decryption_verification.DecryptionStream;
 import de.vanitasvitae.crypto.pgpainless.key.UnprotectedKeysProtector;
 import de.vanitasvitae.crypto.pgpainless.util.BCUtil;
 import org.bouncycastle.openpgp.PGPException;
@@ -39,7 +39,7 @@ public class TestKeysTest extends AbstractPGPainlessTest {
     public void decryptVerifyTest() throws Exception {
         String encryptedMessage = TestKeys.TEST_MESSAGE_01;
 
-        PainlessResult.ResultAndInputStream resultAndInputStream = PGPainless.createDecryptor()
+        DecryptionStream decryptor = PGPainless.createDecryptor()
                 .onInputStream(new ByteArrayInputStream(encryptedMessage.getBytes()))
                 .decryptWith(new PGPSecretKeyRingCollection(Collections.singleton(juliet)), new UnprotectedKeysProtector())
                 .verifyWith(
@@ -48,7 +48,6 @@ public class TestKeysTest extends AbstractPGPainlessTest {
                 .ignoreMissingPublicKeys()
                 .build();
 
-        InputStream decryptor = resultAndInputStream.getInputStream();
         ByteArrayOutputStream toPlain = new ByteArrayOutputStream();
         Streams.pipeAll(decryptor, toPlain);
         decryptor.close();