From 6d4f37b1546b0f525ba97496e6130c5f0cc4b11f Mon Sep 17 00:00:00 2001
From: David Hedberg <david.hedberg@gmail.com>
Date: Sat, 20 Feb 2021 14:27:55 +0100
Subject: [PATCH] Don't hash the data to sign when using EDDSA

---
 .../NfcSyncPGPContentSignerBuilder.java       | 58 +++++++++++++++++++
 .../keychain/pgp/CanonicalizedSecretKey.java  |  4 +-
 2 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/OpenKeychain/src/main/java/org/bouncycastle/openpgp/operator/jcajce/NfcSyncPGPContentSignerBuilder.java b/OpenKeychain/src/main/java/org/bouncycastle/openpgp/operator/jcajce/NfcSyncPGPContentSignerBuilder.java
index e38e70c21..95580d07a 100644
--- a/OpenKeychain/src/main/java/org/bouncycastle/openpgp/operator/jcajce/NfcSyncPGPContentSignerBuilder.java
+++ b/OpenKeychain/src/main/java/org/bouncycastle/openpgp/operator/jcajce/NfcSyncPGPContentSignerBuilder.java
@@ -7,12 +7,14 @@
 
 package org.bouncycastle.openpgp.operator.jcajce;
 
+import org.bouncycastle.bcpg.PublicKeyAlgorithmTags;
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPrivateKey;
 import org.bouncycastle.openpgp.operator.PGPContentSigner;
 import org.bouncycastle.openpgp.operator.PGPContentSignerBuilder;
 import org.bouncycastle.openpgp.operator.PGPDigestCalculator;
 
+import java.io.ByteArrayOutputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.security.Provider;
@@ -93,6 +95,10 @@ public class NfcSyncPGPContentSignerBuilder
     public PGPContentSigner build(final int signatureType, final long keyID)
         throws PGPException
     {
+        if (keyAlgorithm == PublicKeyAlgorithmTags.EDDSA) {
+            return buildEdDSASigner(signatureType, keyID);
+        }
+
         final PGPDigestCalculator digestCalculator = digestCalculatorProviderBuilder.build().get(hashAlgorithm);
 
         return new PGPContentSigner()
@@ -139,4 +145,56 @@ public class NfcSyncPGPContentSignerBuilder
             }
         };
     }
+
+    public PGPContentSigner buildEdDSASigner(final int signatureType, final long keyID)
+        throws PGPException
+    {
+        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+
+        return new PGPContentSigner()
+        {
+            public int getType()
+            {
+                return signatureType;
+            }
+
+            public int getHashAlgorithm()
+            {
+                return hashAlgorithm;
+            }
+
+            public int getKeyAlgorithm()
+            {
+                return keyAlgorithm;
+            }
+
+            public long getKeyID()
+            {
+                return keyID;
+            }
+
+            public OutputStream getOutputStream()
+            {
+                return outputStream;
+            }
+
+            public byte[] getSignature() {
+                byte[] rawData = outputStream.toByteArray();
+
+                ByteBuffer buf = ByteBuffer.wrap(rawData);
+                if (signedHashes.containsKey(buf)) {
+                    return (byte[]) signedHashes.get(buf);
+                }
+                // catch this when signatureGenerator.generate() is executed and divert to card,
+                // when doing the operation again reuse creationTimestamp (this will be hashed)
+                throw new NfcInteractionNeeded(rawData, getHashAlgorithm());
+            }
+
+            public byte[] getDigest()
+            {
+                return outputStream.toByteArray();
+            }
+        };
+
+    }
 }
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java
index 697e5da7d..6ee583e8c 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java
@@ -255,7 +255,9 @@ public class CanonicalizedSecretKey extends CanonicalizedPublicKey {
 
     private PGPContentSignerBuilder getAuthenticationContentSignerBuilder(int hashAlgorithm, Map<ByteBuffer,
             byte[]> signedHashes) {
-        if (getAlgorithm() == PublicKeyAlgorithmTags.EDDSA) {
+        if (
+            getAlgorithm() == PublicKeyAlgorithmTags.EDDSA
+                && mPrivateKeyState != PRIVATE_KEY_STATE_DIVERT_TO_CARD) {
             // content signer feeding the input directly into the signature engine,
             // since EdDSA hashes the input anyway
             return new EdDsaAuthenticationContentSignerBuilder(