Adding subkeys, generating keys: Verify subkeys comply to public key algorithm policy

pgpainless-core/src/main/java/org/pgpainless/key/generation/KeyRingBuilder.java

@@ -39,11 +39,13 @@ import org.bouncycastle.openpgp.operator.PGPDigestCalculator;
 import org.pgpainless.PGPainless;
 import org.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.algorithm.KeyFlag;
+import org.pgpainless.algorithm.PublicKeyAlgorithm;
 import org.pgpainless.algorithm.SignatureType;
 import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import org.pgpainless.implementation.ImplementationFactory;
 import org.pgpainless.key.generation.type.KeyType;
 import org.pgpainless.key.protection.UnlockSecretKey;
+import org.pgpainless.policy.Policy;
 import org.pgpainless.provider.ProviderFactory;
 import org.pgpainless.signature.subpackets.SelfSignatureSubpackets;
 import org.pgpainless.signature.subpackets.SignatureSubpackets;
@@ -62,6 +64,7 @@ public class KeyRingBuilder implements KeyRingBuilderInterface<KeyRingBuilder> {
 
     @Override
     public KeyRingBuilder setPrimaryKey(@Nonnull KeySpec keySpec) {
+        verifyKeySpecCompliesToPolicy(keySpec, PGPainless.getPolicy());
         verifyMasterKeyCanCertify(keySpec);
         this.primaryKeySpec = keySpec;
         return this;
@@ -69,6 +72,7 @@ public class KeyRingBuilder implements KeyRingBuilderInterface<KeyRingBuilder> {
 
     @Override
     public KeyRingBuilder addSubkey(@Nonnull KeySpec keySpec) {
+        verifyKeySpecCompliesToPolicy(keySpec, PGPainless.getPolicy());
         this.subkeySpecs.add(keySpec);
         return this;
     }
@@ -107,6 +111,16 @@ public class KeyRingBuilder implements KeyRingBuilderInterface<KeyRingBuilder> {
         return this;
     }
 
+    private void verifyKeySpecCompliesToPolicy(KeySpec keySpec, Policy policy) {
+        PublicKeyAlgorithm publicKeyAlgorithm = keySpec.getKeyType().getAlgorithm();
+        int bitStrength = keySpec.getKeyType().getBitStrength();
+
+        if (!policy.getPublicKeyAlgorithmPolicy().isAcceptable(publicKeyAlgorithm, bitStrength)) {
+            throw new IllegalArgumentException("Public key algorithm policy violation: " +
+                    publicKeyAlgorithm + " with bit strength " + bitStrength + " is not acceptable.");
+        }
+    }
+
     private void verifyMasterKeyCanCertify(KeySpec spec) {
         if (!hasCertifyOthersFlag(spec)) {
             throw new IllegalArgumentException("Certification Key MUST have KeyFlag CERTIFY_OTHER");

pgpainless-core/src/main/java/org/pgpainless/key/generation/KeySpec.java

@@ -27,7 +27,7 @@ public class KeySpec {
     }
 
     @Nonnull
-    KeyType getKeyType() {
+    public KeyType getKeyType() {
         return keyType;
     }
 

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/KeyType.java

@@ -33,6 +33,12 @@ public interface KeyType {
      */
     PublicKeyAlgorithm getAlgorithm();
 
+    /**
+     * Return the strength of the key in bits.
+     * @return
+     */
+    int getBitStrength();
+
     /**
      * Return an implementation of {@link AlgorithmParameterSpec} that can be used to generate the key.
      *

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/ecc/EllipticCurve.java

@@ -15,22 +15,28 @@ import org.pgpainless.key.generation.type.xdh.XDHSpec;
  * {@link XDHSpec} and {@link org.pgpainless.key.generation.type.eddsa.EdDSACurve}.
  */
 public enum EllipticCurve {
-    _P256("prime256v1"), // prime256v1 is equivalent to P-256, see https://tools.ietf.org/search/rfc4492#page-32
+    _P256("prime256v1", 256), // prime256v1 is equivalent to P-256, see https://tools.ietf.org/search/rfc4492#page-32
-    _P384("secp384r1"), // secp384r1 is equivalent to P-384, see https://tools.ietf.org/search/rfc4492#page-32
+    _P384("secp384r1", 384), // secp384r1 is equivalent to P-384, see https://tools.ietf.org/search/rfc4492#page-32
-    _P521("secp521r1"), // secp521r1 is equivalent to P-521, see https://tools.ietf.org/search/rfc4492#page-32
+    _P521("secp521r1", 521), // secp521r1 is equivalent to P-521, see https://tools.ietf.org/search/rfc4492#page-32
-    _SECP256K1("secp256k1"),
+    _SECP256K1("secp256k1", 256),
-    _BRAINPOOLP256R1("brainpoolP256r1"),
+    _BRAINPOOLP256R1("brainpoolP256r1", 256),
-    _BRAINPOOLP384R1("brainpoolP384r1"),
+    _BRAINPOOLP384R1("brainpoolP384r1", 384),
-    _BRAINPOOLP512R1("brainpoolP512r1")
+    _BRAINPOOLP512R1("brainpoolP512r1", 512)
     ;
 
     private final String name;
+    private final int bitStrength;
 
-    EllipticCurve(@Nonnull String name) {
+    EllipticCurve(@Nonnull String name, int bitStrength) {
         this.name = name;
+        this.bitStrength = bitStrength;
     }
 
     public String getName() {
         return name;
     }
+
+    public int getBitStrength() {
+        return bitStrength;
+    }
 }

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/ecc/ecdh/ECDH.java

@@ -34,6 +34,11 @@ public final class ECDH implements KeyType {
         return PublicKeyAlgorithm.ECDH;
     }
 
+    @Override
+    public int getBitStrength() {
+        return curve.getBitStrength();
+    }
+
     @Override
     public AlgorithmParameterSpec getAlgorithmSpec() {
         return new ECNamedCurveGenParameterSpec(curve.getName());

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/ecc/ecdsa/ECDSA.java

@@ -35,6 +35,11 @@ public final class ECDSA implements KeyType {
         return PublicKeyAlgorithm.ECDSA;
     }
 
+    @Override
+    public int getBitStrength() {
+        return curve.getBitStrength();
+    }
+
     @Override
     public AlgorithmParameterSpec getAlgorithmSpec() {
         return new ECNamedCurveGenParameterSpec(curve.getName());

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/eddsa/EdDSA.java

@@ -35,6 +35,11 @@ public final class EdDSA implements KeyType {
         return PublicKeyAlgorithm.EDDSA;
     }
 
+    @Override
+    public int getBitStrength() {
+        return curve.getBitStrength();
+    }
+
     @Override
     public AlgorithmParameterSpec getAlgorithmSpec() {
         return new ECNamedCurveGenParameterSpec(curve.getName());

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/eddsa/EdDSACurve.java

@@ -7,16 +7,22 @@ package org.pgpainless.key.generation.type.eddsa;
 import javax.annotation.Nonnull;
 
 public enum EdDSACurve {
-    _Ed25519("ed25519"),
+    _Ed25519("ed25519", 256),
     ;
 
     final String name;
+    final int bitStrength;
 
-    EdDSACurve(@Nonnull String curveName) {
+    EdDSACurve(@Nonnull String curveName, int bitStrength) {
         this.name = curveName;
+        this.bitStrength = bitStrength;
     }
 
     public String getName() {
         return name;
     }
+
+    public int getBitStrength() {
+        return bitStrength;
+    }
 }

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/elgamal/ElGamal.java

@@ -36,6 +36,11 @@ public final class ElGamal implements KeyType {
         return PublicKeyAlgorithm.ELGAMAL_ENCRYPT;
     }
 
+    @Override
+    public int getBitStrength() {
+        return length.getLength();
+    }
+
     @Override
     public AlgorithmParameterSpec getAlgorithmSpec() {
         return new ElGamalParameterSpec(length.getP(), length.getG());

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/rsa/RSA.java

@@ -36,6 +36,11 @@ public class RSA implements KeyType {
         return PublicKeyAlgorithm.RSA_GENERAL;
     }
 
+    @Override
+    public int getBitStrength() {
+        return length.getLength();
+    }
+
     @Override
     public AlgorithmParameterSpec getAlgorithmSpec() {
         return new RSAKeyGenParameterSpec(length.getLength(), RSAKeyGenParameterSpec.F4);

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/xdh/XDH.java

@@ -32,6 +32,11 @@ public final class XDH implements KeyType {
         return PublicKeyAlgorithm.ECDH;
     }
 
+    @Override
+    public int getBitStrength() {
+        return spec.getBitStrength();
+    }
+
     @Override
     public AlgorithmParameterSpec getAlgorithmSpec() {
         return new ECNamedCurveGenParameterSpec(spec.getName());

pgpainless-core/src/main/java/org/pgpainless/key/generation/type/xdh/XDHSpec.java

@@ -7,15 +7,17 @@ package org.pgpainless.key.generation.type.xdh;
 import javax.annotation.Nonnull;
 
 public enum XDHSpec {
-    _X25519("X25519", "curve25519"),
+    _X25519("X25519", "curve25519", 256),
     ;
 
     final String name;
     final String curveName;
+    final int bitStrength;
 
-    XDHSpec(@Nonnull String name, @Nonnull String curveName) {
+    XDHSpec(@Nonnull String name, @Nonnull String curveName, int bitStrength) {
         this.name = name;
         this.curveName = curveName;
+        this.bitStrength = bitStrength;
     }
 
     public String getName() {
@@ -25,4 +27,8 @@ public enum XDHSpec {
     public String getCurveName() {
         return curveName;
     }
+
+    public int getBitStrength() {
+        return bitStrength;
+    }
 }

pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java

@@ -70,6 +70,7 @@ import org.pgpainless.signature.subpackets.SignatureSubpacketGeneratorUtil;
 import org.pgpainless.signature.subpackets.SignatureSubpackets;
 import org.pgpainless.signature.subpackets.SignatureSubpacketsHelper;
 import org.pgpainless.signature.subpackets.SignatureSubpacketsUtil;
+import org.pgpainless.util.BCUtil;
 import org.pgpainless.util.CollectionUtils;
 import org.pgpainless.util.Passphrase;
 import org.pgpainless.util.selection.userid.SelectUserId;
@@ -169,7 +170,6 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
             @Nonnull Passphrase subKeyPassphrase,
             @Nonnull SecretKeyRingProtector secretKeyRingProtector)
             throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, PGPException, IOException {
-
         PGPKeyPair keyPair = KeyRingBuilder.generateKeyPair(keySpec);
 
         SecretKeyRingProtector subKeyProtector = PasswordBasedSecretKeyRingProtector
@@ -216,11 +216,19 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
             @Nonnull SecretKeyRingProtector primaryKeyProtector,
             @Nonnull KeyFlag keyFlag,
             KeyFlag... additionalKeyFlags)
-            throws PGPException, IOException {
+            throws PGPException, IOException, NoSuchAlgorithmException {
         KeyFlag[] flags = concat(keyFlag, additionalKeyFlags);
         PublicKeyAlgorithm subkeyAlgorithm = PublicKeyAlgorithm.fromId(subkey.getPublicKey().getAlgorithm());
         SignatureSubpacketsUtil.assureKeyCanCarryFlags(subkeyAlgorithm);
 
+        // check key against public key algorithm policy
+        PublicKeyAlgorithm publicKeyAlgorithm = PublicKeyAlgorithm.fromId(subkey.getPublicKey().getAlgorithm());
+        int bitStrength = BCUtil.getBitStrength(subkey.getPublicKey());
+        if (!PGPainless.getPolicy().getPublicKeyAlgorithmPolicy().isAcceptable(publicKeyAlgorithm, bitStrength)) {
+            throw new IllegalArgumentException("Public key algorithm policy violation: " +
+                    publicKeyAlgorithm + " with bit strength " + bitStrength + " is not acceptable.");
+        }
+
         PGPSecretKey primaryKey = secretKeyRing.getSecretKey();
         KeyRingInfo info = PGPainless.inspectKeyRing(secretKeyRing);
         PublicKeyAlgorithm signingKeyAlgorithm = PublicKeyAlgorithm.fromId(primaryKey.getPublicKey().getAlgorithm());

pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditorInterface.java

@@ -119,7 +119,7 @@ public interface SecretKeyRingEditorInterface {
             @Nonnull SecretKeyRingProtector primaryKeyProtector,
             @Nonnull KeyFlag keyFlag,
             KeyFlag... additionalKeyFlags)
-            throws PGPException, IOException;
+            throws PGPException, IOException, NoSuchAlgorithmException;
 
     /**
      * Revoke the key ring.