From a0ba6828c982bfce4192162e45f6c853a976790a Mon Sep 17 00:00:00 2001
From: Paul Schaub <vanitasvitae@fsfe.org>
Date: Wed, 26 Oct 2022 18:22:50 +0200
Subject: [PATCH] Remove superfluous states

---
 .../syntax_check/PDA.java                     | 26 +++----------------
 .../syntax_check/StackAlphabet.java           |  4 ---
 2 files changed, 3 insertions(+), 27 deletions(-)

diff --git a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/PDA.java b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/PDA.java
index 0d6ba28c..c77b50cc 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/PDA.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/PDA.java
@@ -67,7 +67,7 @@ public class PDA {
 
                     case Signature:
                         if (stackItem == ops) {
-                            return CorrespondingSignature;
+                            return LiteralMessage;
                         } else {
                             throw new MalformedOpenPgpMessageException(this, input, stackItem);
                         }
@@ -96,7 +96,7 @@ public class PDA {
                 switch (input) {
                     case Signature:
                         if (stackItem == ops) {
-                            return CorrespondingSignature;
+                            return CompressedMessage;
                         } else {
                             throw new MalformedOpenPgpMessageException(this, input, stackItem);
                         }
@@ -125,7 +125,7 @@ public class PDA {
                 switch (input) {
                     case Signature:
                         if (stackItem == ops) {
-                            return CorrespondingSignature;
+                            return EncryptedMessage;
                         } else {
                             throw new MalformedOpenPgpMessageException(this, input, stackItem);
                         }
@@ -147,26 +147,6 @@ public class PDA {
             }
         },
 
-        CorrespondingSignature {
-            @Override
-            State transition(InputAlphabet input, PDA automaton) throws MalformedOpenPgpMessageException {
-                StackAlphabet stackItem = automaton.popStack();
-                if (input == InputAlphabet.EndOfSequence) {
-                    if (stackItem == terminus && automaton.stack.isEmpty()) {
-                        return Valid;
-                    } else {
-                        // premature end of stream
-                        throw new MalformedOpenPgpMessageException(this, input, stackItem);
-                    }
-                } else if (input == InputAlphabet.Signature) {
-                    if (stackItem == ops) {
-                        return CorrespondingSignature;
-                    }
-                }
-                throw new MalformedOpenPgpMessageException(this, input, stackItem);
-            }
-        },
-
         Valid {
             @Override
             State transition(InputAlphabet input, PDA automaton) throws MalformedOpenPgpMessageException {
diff --git a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/StackAlphabet.java b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/StackAlphabet.java
index 6030fbc8..a8a2a213 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/StackAlphabet.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/syntax_check/StackAlphabet.java
@@ -13,10 +13,6 @@ public enum StackAlphabet {
      * OnePassSignature (in case of BC this represents a OnePassSignatureList).
      */
     ops,
-    /**
-     * ESK. Not used, as BC combines encrypted data with their encrypted session keys.
-     */
-    esk,
     /**
      * Special symbol representing the end of the message.
      */