From a167d4c1dd96c1bbc0616965971195db9f565df8 Mon Sep 17 00:00:00 2001
From: Eliot Jones <elioty@hotmail.co.uk>
Date: Wed, 18 Dec 2019 14:54:56 +0000
Subject: [PATCH] fix bug where hex tokens for document identifier lost bytes
 due to encoding

---
 .../CrossReference/CrossReferenceTable.cs     |  1 -
 .../CrossReference/TrailerDictionary.cs       | 12 +++++-----
 .../Encryption/EncryptionHandler.cs           | 24 ++++++++++++++++---
 3 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/src/UglyToad.PdfPig/CrossReference/CrossReferenceTable.cs b/src/UglyToad.PdfPig/CrossReference/CrossReferenceTable.cs
index b12edd45..7dcc9b94 100644
--- a/src/UglyToad.PdfPig/CrossReference/CrossReferenceTable.cs
+++ b/src/UglyToad.PdfPig/CrossReference/CrossReferenceTable.cs
@@ -2,7 +2,6 @@
 {
     using System;
     using System.Collections.Generic;
-    using CrossReference;
     using Util.JetBrains.Annotations;
 
     /// <summary>
diff --git a/src/UglyToad.PdfPig/CrossReference/TrailerDictionary.cs b/src/UglyToad.PdfPig/CrossReference/TrailerDictionary.cs
index 13c1b233..adc207fe 100644
--- a/src/UglyToad.PdfPig/CrossReference/TrailerDictionary.cs
+++ b/src/UglyToad.PdfPig/CrossReference/TrailerDictionary.cs
@@ -39,9 +39,9 @@
         public IndirectReference? Info { get; }
 
         /// <summary>
-        /// A list containing two-byte strings which act as file identifiers.
+        /// A list containing two-byte string tokens which act as file identifiers.
         /// </summary>
-        public IReadOnlyList<string> Identifier { get; }
+        public IReadOnlyList<IDataToken<string>> Identifier { get; }
 
         /// <summary>
         /// The document's encryption dictionary.
@@ -77,17 +77,17 @@
 
             if (dictionary.TryGet(NameToken.Id, out ArrayToken arr))
             {
-                var ids = new List<string>(arr.Data.Count);
+                var ids = new List<IDataToken<string>>(arr.Data.Count);
 
                 foreach (var token in arr.Data)
                 {
                     if (token is StringToken str)
                     {
-                        ids.Add(str.Data);
+                        ids.Add(str);
                     }
                     else if (token is HexToken hex)
                     {
-                        ids.Add(hex.Data);
+                        ids.Add(hex);
                     }
                 }
 
@@ -95,7 +95,7 @@
             }
             else
             {
-                Identifier = EmptyArray<string>.Instance;
+                Identifier = EmptyArray<IDataToken<string>>.Instance;
             }
 
             if (dictionary.TryGet(NameToken.Encrypt, out var encryptionToken))
diff --git a/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs b/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs
index 9c5fddd0..20db5c25 100644
--- a/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs
+++ b/src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs
@@ -42,9 +42,27 @@
         {
             this.encryptionDictionary = encryptionDictionary;
 
-            var documentIdBytes = trailerDictionary.Identifier != null && trailerDictionary.Identifier.Count == 2 ?
-                OtherEncodings.StringAsLatin1Bytes(trailerDictionary.Identifier[0])
-                : EmptyArray<byte>.Instance;
+            byte[] documentIdBytes;
+
+            if (trailerDictionary.Identifier != null && trailerDictionary.Identifier.Count == 2)
+            {
+                var token = trailerDictionary.Identifier[0];
+
+                switch (token)
+                {
+                    case HexToken hex:
+                        documentIdBytes = hex.Bytes.ToArray();
+                        break;
+                    default:
+                        documentIdBytes = OtherEncodings.StringAsLatin1Bytes(token.Data);
+                        break;
+                }
+              
+            }
+            else
+            {
+                documentIdBytes = EmptyArray<byte>.Instance;
+            }
 
             password = password ?? string.Empty;