Made it use BouncyCastle to do MD5 digests when in the browser

Author: michaelcheers

src/iTextSharp.LGPLv2.Core/MD5.cs

@@ -0,0 +1,34 @@
+using Org.BouncyCastle.Crypto.Digests;
+using System;
+using System.Runtime.CompilerServices;
+using System.Security.Cryptography;
+
+namespace iTextSharp
+{
+    /// <summary>
+    /// RFC1321: The MD5 Message-Digest Algorithm
+    /// https://datatracker.ietf.org/doc/html/rfc1321
+    /// </summary>
+    public sealed class MD5BouncyCastle : HashAlgorithm
+    {
+        public static new HashAlgorithm Create() =>
+            System.Runtime.InteropServices.RuntimeInformation.OSDescription == "Browser" ? new MD5BouncyCastle() : MD5.Create();
+        private MD5BouncyCastle() { }
+
+        private MD5Digest _digestInternal = new();
+
+        public override void Initialize() {}
+
+        protected override void HashCore(byte[] array, int ibStart, int cbSize)
+        {
+            _digestInternal.BlockUpdate(array, ibStart, cbSize);
+        }
+
+        protected override byte[] HashFinal()
+        {
+            byte[] output = new byte[_digestInternal.GetByteLength()];
+            _digestInternal.DoFinal(output, 0);
+            return output;
+        }
+    }
+}

src/iTextSharp.LGPLv2.Core/iTextSharp/text/ImgJBIG2.cs

@@ -52,7 +52,7 @@ public ImgJbig2(int width, int height, byte[] data, byte[] globals) : base((Uri)
                 _global = globals;
                 try
                 {
-                    using (var md5 = MD5.Create())
+                    using (var md5 = MD5BouncyCastle.Create())
                     {
                         _globalHash = md5.ComputeHash(_global);
                     }

src/iTextSharp.LGPLv2.Core/iTextSharp/text/pdf/PdfEncryption.cs

@@ -116,7 +116,7 @@ public static byte[] CreateDocumentId()
             long time = DateTime.Now.Ticks + Environment.TickCount;
             long mem = GC.GetTotalMemory(false);
             string s = time + "+" + mem + "+" + (Seq++);
-            return MD5.Create().ComputeHash(Encoding.ASCII.GetBytes(s));
+            return MD5BouncyCastle.Create().ComputeHash(Encoding.ASCII.GetBytes(s));
         }
 
         public static PdfObject CreateInfoId(byte[] id)
@@ -396,8 +396,7 @@ public void SetCryptoMode(int mode, int kl)
 
         public void SetHashKey(int number, int generation)
         {
-#if NET40
-            using (var md5 = new MD5CryptoServiceProvider())
+            using (var md5 = MD5BouncyCastle.Create())
             {
                 md5.Initialize();
                 Extra[0] = (byte)number;
@@ -415,22 +414,6 @@ public void SetHashKey(int number, int generation)
                 md5.TransformFinalBlock(Extra, 0, 0);
                 Key = md5.Hash;
             }
-#else
-            using (var md5 = IncrementalHash.CreateHash(HashAlgorithmName.MD5))
-            {
-                Extra[0] = (byte)number;
-                Extra[1] = (byte)(number >> 8);
-                Extra[2] = (byte)(number >> 16);
-                Extra[3] = (byte)generation;
-                Extra[4] = (byte)(generation >> 8);
-                md5.AppendData(Mkey, 0, Mkey.Length);
-                md5.AppendData(Extra, 0, Extra.Length);
-                if (_revision == AES_128)
-                    md5.AppendData(_salt, 0, _salt.Length);
-
-                Key = md5.GetHashAndReset();
-            }
-#endif
 
             KeySize = Mkey.Length + 5;
             if (KeySize > 16)
@@ -443,7 +426,7 @@ public void SetHashKey(int number, int generation)
         public void SetupAllKeys(byte[] userPassword, byte[] ownerPassword, int permissions)
         {
             if (ownerPassword == null || ownerPassword.Length == 0)
-                ownerPassword = MD5.Create().ComputeHash(CreateDocumentId());
+                ownerPassword = MD5BouncyCastle.Create().ComputeHash(CreateDocumentId());
 
             permissions |= (int)((_revision == STANDARD_ENCRYPTION_128 || _revision == AES_128) ? 0xfffff0c0 : 0xffffffc0);
             permissions &= unchecked((int)0xfffffffc);
@@ -480,7 +463,7 @@ public void SetupByUserPassword(byte[] documentId, byte[] userPassword, byte[] o
         private byte[] computeOwnerKey(byte[] userPad, byte[] ownerPad)
         {
             byte[] ownerKey = new byte[32];
-            var md5 = MD5.Create();
+            var md5 = MD5BouncyCastle.Create();
             byte[] digest = md5.ComputeHash(ownerPad);
             if (_revision == STANDARD_ENCRYPTION_128 || _revision == AES_128)
             {
@@ -549,9 +532,8 @@ private void setupGlobalEncryptionKey(byte[] documentId, byte[] userPad, byte[]
             Mkey = new byte[_keyLength / 8];
             byte[] digest = new byte[Mkey.Length];
 
-#if NET40
             //fixed by ujihara in order to follow PDF refrence
-            using (var md5 = new MD5CryptoServiceProvider())
+            using (var md5 = MD5BouncyCastle.Create())
             {
                 md5.Initialize();
                 md5.TransformBlock(userPad, 0, userPad.Length, userPad, 0);
@@ -571,33 +553,14 @@ private void setupGlobalEncryptionKey(byte[] documentId, byte[] userPad, byte[]
 
                 Array.Copy(md5.Hash, 0, digest, 0, Mkey.Length);
             }
-#else
-            //fixed by ujihara in order to follow PDF refrence
-            var md5 = IncrementalHash.CreateHash(HashAlgorithmName.MD5);
-            md5.AppendData(userPad, 0, userPad.Length);
-            md5.AppendData(ownerKey, 0, ownerKey.Length);
-
-            byte[] ext = new byte[4];
-            ext[0] = (byte)permissions;
-            ext[1] = (byte)(permissions >> 8);
-            ext[2] = (byte)(permissions >> 16);
-            ext[3] = (byte)(permissions >> 24);
-            md5.AppendData(ext, 0, 4);
-            if (documentId != null)
-                md5.AppendData(documentId, 0, documentId.Length);
-            if (!_encryptMetadata)
-                md5.AppendData(MetadataPad, 0, MetadataPad.Length);
-
-            Array.Copy(md5.GetHashAndReset(), 0, digest, 0, Mkey.Length);
-#endif
 
 
             // only use the really needed bits as input for the hash
             if (_revision == STANDARD_ENCRYPTION_128 || _revision == AES_128)
             {
                 for (int k = 0; k < 50; ++k)
                 {
-                    using (var md5Hash = MD5.Create())
+                    using (var md5Hash = MD5BouncyCastle.Create())
                     {
                         Array.Copy(md5Hash.ComputeHash(digest), 0, digest, 0, Mkey.Length);
                     }
@@ -617,22 +580,13 @@ private void setupUserKey()
             if (_revision == STANDARD_ENCRYPTION_128 || _revision == AES_128)
             {
                 byte[] digest;
-#if NET40
-                using (var md5 = new MD5CryptoServiceProvider())
+                using (var md5 = MD5BouncyCastle.Create())
                 {
                     md5.Initialize();
                     md5.TransformBlock(_pad, 0, _pad.Length, _pad, 0);
                     md5.TransformFinalBlock(DocumentId, 0, DocumentId.Length);
                     digest = md5.Hash;
                 }
-#else
-                using (var md5 = IncrementalHash.CreateHash(HashAlgorithmName.MD5))
-                {
-                    md5.AppendData(_pad, 0, _pad.Length);
-                    md5.AppendData(DocumentId, 0, DocumentId.Length);
-                    digest = md5.GetHashAndReset();
-                }
-#endif
                 Array.Copy(digest, 0, UserKey, 0, 16);
                 for (int k = 16; k < 32; ++k)
                     UserKey[k] = 0;

src/iTextSharp.LGPLv2.Core/iTextSharp/text/pdf/PdfSmartCopy.cs

@@ -176,7 +176,7 @@ private void serObject(PdfObject obj, int level, ByteBuffer bb)
                     serDic((PdfDictionary)obj, level - 1, bb);
                     if (level > 0)
                     {
-                        using (var md5 = MD5.Create())
+                        using (var md5 = MD5BouncyCastle.Create())
                         {
                             bb.Append(md5.ComputeHash(PdfReader.GetStreamBytesRaw((PrStream)obj)));
                         }