Obscure crypto error log

.pubnub.yml

@@ -1,8 +1,13 @@
 name: c-sharp
-version: "8.3.2"
+version: "8.3.3"
 schema: 1
 scm: github.com/pubnub/c-sharp
 changelog:
+  - date: 2026-07-20
+    version: v8.3.3
+    changes:
+      - type: feature
+        text: "Obscure exceptions thrown by cryptors to be available in logs only."
   - date: 2026-07-15
     version: v8.3.2
     changes:
@@ -1004,14 +1009,14 @@ features:
     - QUERY-PARAM
 supported-platforms:
   -
-    version: Pubnub 'C#' 8.3.2
+    version: Pubnub 'C#' 8.3.3
     platforms:
       - Windows 10 and up
       - Windows Server 2008 and up
     frameworks:
       - .Net Framework 4.5+
   -
-    version: PubnubPCL 'C#' 8.3.2
+    version: PubnubPCL 'C#' 8.3.3
     platforms:
       - Xamarin.Android
       - Xamarin.iOS
@@ -1023,7 +1028,7 @@ supported-platforms:
     frameworks:
       - .Net 4.5+
   -
-    version: PubnubUWP 'C#' 8.3.2
+    version: PubnubUWP 'C#' 8.3.3
     platforms:
       - Windows Phone 10
       - Universal Windows Apps
@@ -1047,7 +1052,7 @@ sdks:
             distribution-type: source
             distribution-repository: GitHub
             package-name: Pubnub
-            location: https://github.com/pubnub/c-sharp/releases/tag/v8.3.2
+            location: https://github.com/pubnub/c-sharp/releases/tag/v8.3.3
             requires:
               -
                 name: ".Net"
@@ -1288,7 +1293,7 @@ sdks:
             distribution-type: source
             distribution-repository: GitHub
             package-name: PubNubPCL
-            location: https://github.com/pubnub/c-sharp/releases/tag/v8.3.2
+            location: https://github.com/pubnub/c-sharp/releases/tag/v8.3.3
             requires:
               -
                 name: ".Net"
@@ -1639,7 +1644,7 @@ sdks:
             distribution-type: source
             distribution-repository: GitHub
             package-name: PubnubUWP
-            location: https://github.com/pubnub/c-sharp/releases/tag/v8.3.2
+            location: https://github.com/pubnub/c-sharp/releases/tag/v8.3.3
             requires:
               -
                 name: "Universal Windows Platform Development"

CHANGELOG

@@ -1,3 +1,7 @@
+v8.3.3 - July 20 2026
+-----------------------------
+- Added: obscure exceptions thrown by cryptors to be available in logs only.
+
 v8.3.2 - July 15 2026
 -----------------------------
 - Fixed: added additional checks to ensure that post-reconnection handshaking doesn't start with null values of Channels and ChannelGroups.

src/Api/PubnubApi/Model/PNStatusCategoryHelper.cs

@@ -66,8 +66,10 @@ public static PNStatusCategory GetPNStatusCategory(Exception ex)
             {
                 ret = PNStatusCategory.PNNetworkIssuesCategory;
             }
-            else if (errorType == "System.Security.Cryptography.CryptographicException" && errorMessage == "Padding is invalid and cannot be removed.")
+            else if (errorType == "PubnubApi.PNException" && errorMessage == "Decrypt Error")
             {
+                // All crypto failure modes now surface as a single generic "Decrypt Error" so that
+                // bad padding and wrong block length map to the same category (no padding-oracle bit).
                 ret = PNStatusCategory.PNDecryptionErrorCategory;
             }
             else if (errorType == "System.Runtime.InteropServices.SEHException" && errorMessage == "External component has thrown an exception.")

src/Api/PubnubApi/Properties/AssemblyInfo.cs

@@ -11,8 +11,8 @@
 [assembly: AssemblyProduct("Pubnub C# SDK")]
 [assembly: AssemblyCopyright("Copyright ©  2021")]
 [assembly: AssemblyTrademark("")]
-[assembly: AssemblyVersion("8.3.2")]
-[assembly: AssemblyFileVersion("8.3.2")]
+[assembly: AssemblyVersion("8.3.3")]
+[assembly: AssemblyFileVersion("8.3.3")]
 // Setting ComVisible to false makes the types in this assembly not visible
 // to COM components.  If you need to access a type in this assembly from
 // COM, set the ComVisible attribute to true on that type.

src/Api/PubnubApi/PubnubApi.csproj

@@ -14,15 +14,15 @@
 
   <PropertyGroup>
     <PackageId>Pubnub</PackageId>
-    <PackageVersion>8.3.2</PackageVersion>
+    <PackageVersion>8.3.3</PackageVersion>
     <Title>PubNub C# .NET - Web Data Push API</Title>
     <Authors>Pandu Masabathula</Authors>
     <Owners>PubNub</Owners>
     <PackageLicenseFile>LICENSE.txt</PackageLicenseFile>
     <PackageIconUrl>http://pubnub.s3.amazonaws.com/2011/powered-by-pubnub/pubnub-icon-600x600.png</PackageIconUrl>
     <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
     <RepositoryUrl>https://github.com/pubnub/c-sharp/</RepositoryUrl>
-    <PackageReleaseNotes>Added additional checks to ensure that post-reconnection handshaking doesn't start with null values of Channels and ChannelGroups.</PackageReleaseNotes>
+    <PackageReleaseNotes>Obscure exceptions thrown by cryptors to be available in logs only.</PackageReleaseNotes>
     <PackageTags>Web Data Push Real-time Notifications ESB Message Broadcasting Distributed Computing</PackageTags>
     <!--<Summary>PubNub is a Massively Scalable Web Push Service for Web and Mobile Games.  This is a cloud-based service for broadcasting messages to thousands of web and mobile clients simultaneously</Summary>-->
     <Description>PubNub is a Massively Scalable Web Push Service for Web and Mobile Games.  This is a cloud-based service for broadcasting messages to thousands of web and mobile clients simultaneously</Description>

src/Api/PubnubApi/Security/Crypto/Cryptors/AesCbcCryptor.cs

@@ -100,7 +100,7 @@ public override string Decrypt(string encryptedData)
             catch(Exception ex)
             {
                 logger?.Error($"AesCbcCryptor Error while decrypting string data. ErrorMessage {ex.Message}, StackTrace {ex.StackTrace}");
-                throw new PNException("Decrypt Error", ex);
+                throw new PNException("Decrypt Error");
             }
         }
         public override byte[] Decrypt(byte[] encryptedData)
@@ -139,7 +139,7 @@ public override byte[] Decrypt(byte[] encryptedData)
             catch (Exception ex)
             {
                 logger?.Error($"AesCbcCryptor Error while decrypting bytes. ErrorMessage {ex.Message}, StackTrace {ex.StackTrace}");
-                throw new PNException("Decrypt Error", ex);
+                throw new PNException("Decrypt Error");
             }
         }
 

src/Api/PubnubApi/Security/Crypto/Cryptors/CryptorBase.cs

@@ -74,8 +74,20 @@ protected byte[] InternalDecrypt(byte[] dataBytes, byte[] ivBytes, byte[] keyByt
 
                 using(ICryptoTransform decrypto = aesAlg.CreateDecryptor())
                 {
-                    byte[] buffer = decrypto.TransformFinalBlock(dataBytes, 0, dataBytes.Length);
-                    return buffer;
+                    try
+                    {
+                        byte[] buffer = decrypto.TransformFinalBlock(dataBytes, 0, dataBytes.Length);
+                        return buffer;
+                    }
+                    catch (CryptographicException ex)
+                    {
+                        // Collapse every crypto failure mode (bad padding, wrong block length, etc.)
+                        // into one generic error. The native message distinguishes these cases and
+                        // would otherwise expose a padding-oracle bit to a caller submitting ciphertexts.
+                        // The specific cause is kept in the internal log only, never on the thrown exception.
+                        logger?.Error($"Decryption failed: {ex.Message}");
+                        throw new PNException("Decrypt Error");
+                    }
                 }
             }
         }

src/Api/PubnubApi/Security/Crypto/Cryptors/LegacyCryptor.cs

@@ -111,7 +111,7 @@ public override string Decrypt(string encryptedData)
             catch(Exception ex)
             {
                 logger?.Error($"LegacyCryptor Error while decrypting string data. ErrorMessage {ex.Message}, StackTrace {ex.StackTrace}");
-                throw new PNException("Decrypt Error", ex);
+                throw new PNException("Decrypt Error");
             }
         }
         public override byte[] Decrypt(byte[] encryptedData)
@@ -144,7 +144,7 @@ public override byte[] Decrypt(byte[] encryptedData)
             catch(Exception ex)
             {
                 logger?.Error($"LegacyCryptor Error while decrypting bytes. ErrorMessage {ex.Message}, StackTrace {ex.StackTrace}");
-                throw new PNException("Decrypt Error", ex);
+                throw new PNException("Decrypt Error");
             }
         }
 

src/Api/PubnubApi/Security/PubnubCrypto.cs

@@ -166,7 +166,10 @@ protected override byte[] EncryptOrDecrypt(bool type, byte[] dataBytes, bool dyn
                     {
                         LoggingMethod.WriteToLog(pubnubLog, $"[{DateTime.Now.ToString(CultureInfo.InvariantCulture)}] Error: Decryption Error. {ex}", config.LogVerbosity);
                     }
-                    throw;
+                    // Do not re-throw the raw CryptographicException: its native message (and the
+                    // resulting PNStatusCategory) distinguishes bad padding from wrong block length,
+                    // which is a padding-oracle signal. Surface a single generic error instead.
+                    throw new PNException("Decrypt Error");
                 }
             }
         }

src/Api/PubnubApiPCL/PubnubApiPCL.csproj

@@ -14,15 +14,15 @@
 
   <PropertyGroup>
     <PackageId>PubnubPCL</PackageId>
-    <PackageVersion>8.3.2</PackageVersion>
+    <PackageVersion>8.3.3</PackageVersion>
     <Title>PubNub C# .NET - Web Data Push API</Title>
     <Authors>Pandu Masabathula</Authors>
     <Owners>PubNub</Owners>
     <PackageLicenseFile>LICENSE.txt</PackageLicenseFile>
     <PackageIconUrl>http://pubnub.s3.amazonaws.com/2011/powered-by-pubnub/pubnub-icon-600x600.png</PackageIconUrl>
     <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
     <RepositoryUrl>https://github.com/pubnub/c-sharp/</RepositoryUrl>
-    <PackageReleaseNotes>Added additional checks to ensure that post-reconnection handshaking doesn't start with null values of Channels and ChannelGroups.</PackageReleaseNotes>
+    <PackageReleaseNotes>Obscure exceptions thrown by cryptors to be available in logs only.</PackageReleaseNotes>
     <PackageTags>Web Data Push Real-time Notifications ESB Message Broadcasting Distributed Computing</PackageTags>
     <!--<Summary>PubNub is a Massively Scalable Web Push Service for Web and Mobile Games.  This is a cloud-based service for broadcasting messages to thousands of web and mobile clients simultaneously</Summary>-->
     <Description>PubNub is a Massively Scalable Web Push Service for Web and Mobile Games.  This is a cloud-based service for broadcasting messages to thousands of web and mobile clients simultaneously</Description>

src/Api/PubnubApiUWP/PubnubApiUWP.csproj

@@ -16,15 +16,15 @@
 
   <PropertyGroup>
     <PackageId>PubnubUWP</PackageId>
-    <PackageVersion>8.3.2</PackageVersion>
+    <PackageVersion>8.3.3</PackageVersion>
     <Title>PubNub C# .NET - Web Data Push API</Title>
     <Authors>Pandu Masabathula</Authors>
     <Owners>PubNub</Owners>
     <PackageLicenseFile>LICENSE.txt</PackageLicenseFile>
     <PackageIconUrl>http://pubnub.s3.amazonaws.com/2011/powered-by-pubnub/pubnub-icon-600x600.png</PackageIconUrl>
     <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
     <RepositoryUrl>https://github.com/pubnub/c-sharp/</RepositoryUrl>
-    <PackageReleaseNotes>Added additional checks to ensure that post-reconnection handshaking doesn't start with null values of Channels and ChannelGroups.</PackageReleaseNotes>
+    <PackageReleaseNotes>Obscure exceptions thrown by cryptors to be available in logs only.</PackageReleaseNotes>
     <PackageTags>Web Data Push Real-time Notifications ESB Message Broadcasting Distributed Computing</PackageTags>
     <!--<Summary>PubNub is a Massively Scalable Web Push Service for Web and Mobile Games.  This is a cloud-based service for broadcasting messages to thousands of web and mobile clients simultaneously</Summary>-->
     <Description>PubNub is a Massively Scalable Web Push Service for Web and Mobile Games.  This is a cloud-based service for broadcasting messages to thousands of web and mobile clients simultaneously</Description>

src/Api/PubnubApiUnity/PubnubApiUnity.csproj

@@ -15,7 +15,7 @@
 
   <PropertyGroup>
     <PackageId>PubnubApiUnity</PackageId>
-    <PackageVersion>8.3.2</PackageVersion>
+    <PackageVersion>8.3.3</PackageVersion>
     <Title>PubNub C# .NET - Web Data Push API</Title>
     <Authors>Pandu Masabathula</Authors>
     <Owners>PubNub</Owners>

src/UnitTests/PubnubApi.Tests/EncryptionTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Text;
 using System.Collections.Generic;
 using NUnit.Framework;
@@ -1305,6 +1306,87 @@ public void TestHistoryDecryptionOnNonEncryptedMessage()
             Assert.True(passed);
         }
 
+        /// <summary>
+        /// Padding-oracle hardening regression test.
+        /// Bad-padding and wrong-length ciphertexts must produce the exact same generic error,
+        /// with no distinguishing message, exception type, or inner (native) exception.
+        /// </summary>
+        [Test]
+        public void TestDecryptFailureModesAreIndistinguishable()
+        {
+            LegacyCryptor legacy = new LegacyCryptor("enigma", false);
+            AesCbcCryptor aes = new AesCbcCryptor("enigma");
+
+            // Legacy (static IV): 24 raw bytes are never block-aligned -> "wrong final block length".
+            PNException legacyWrongLength = CaptureDecryptFailure(() =>
+                legacy.Decrypt(Convert.ToBase64String(RandomBytes(24))));
+            // Legacy (static IV): a block-aligned input that fails PKCS7 unpadding -> "bad decrypt".
+            PNException legacyBadPadding = CaptureDecryptFailure(() =>
+                legacy.Decrypt(FindLegacyBadPaddingInput(legacy)));
+
+            // AES-CBC: tamper a valid ciphertext produced via round-trip encryption.
+            string validAes = aes.Encrypt("hello world - a message spanning more than one block");
+            byte[] validAesBytes = Convert.FromBase64String(validAes);
+            // Drop 5 trailing bytes so the ciphertext body is no longer block-aligned.
+            string aesWrongLengthInput = Convert.ToBase64String(validAesBytes.Take(validAesBytes.Length - 5).ToArray());
+            PNException aesWrongLength = CaptureDecryptFailure(() => aes.Decrypt(aesWrongLengthInput));
+            PNException aesBadPadding = CaptureDecryptFailure(() => aes.Decrypt(FindAesBadPaddingInput(aes, validAesBytes)));
+
+            foreach (var ex in new[] { legacyWrongLength, legacyBadPadding, aesWrongLength, aesBadPadding })
+            {
+                Assert.AreEqual("Decrypt Error", ex.Message, "Decrypt error message must be generic");
+                Assert.IsNull(ex.InnerException, "Native crypto exception must not be surfaced as inner exception");
+                StringAssert.DoesNotContain("Padding", ex.ToString());
+                StringAssert.DoesNotContain("block", ex.ToString());
+            }
+
+            // The whole point: bad padding and wrong length are not distinguishable at the call site.
+            Assert.AreEqual(legacyBadPadding.Message, legacyWrongLength.Message);
+            Assert.AreEqual(aesBadPadding.Message, aesWrongLength.Message);
+            Assert.AreEqual(legacyBadPadding.GetType(), legacyWrongLength.GetType());
+            Assert.AreEqual(aesBadPadding.GetType(), aesWrongLength.GetType());
+        }
+
+        private static PNException CaptureDecryptFailure(TestDelegate act)
+        {
+            return Assert.Throws<PNException>(act);
+        }
+
+        private static byte[] RandomBytes(int count)
+        {
+            byte[] buffer = new byte[count];
+            new Random().NextBytes(buffer);
+            return buffer;
+        }
+
+        private static string FindLegacyBadPaddingInput(LegacyCryptor legacy)
+        {
+            for (int attempt = 0; attempt < 2000; attempt++)
+            {
+                string candidate = Convert.ToBase64String(RandomBytes(16));
+                try { legacy.Decrypt(candidate); }
+                catch (PNException) { return candidate; }
+            }
+            Assert.Fail("Could not construct a block-aligned legacy input that fails unpadding");
+            return null;
+        }
+
+        private static string FindAesBadPaddingInput(AesCbcCryptor aes, byte[] validAesBytes)
+        {
+            Random rng = new Random();
+            for (int attempt = 0; attempt < 2000; attempt++)
+            {
+                byte[] tampered = (byte[])validAesBytes.Clone();
+                // Corrupt the final ciphertext byte so the last plaintext block's padding is (almost always) invalid.
+                tampered[tampered.Length - 1] ^= (byte)(rng.Next(1, 256));
+                string candidate = Convert.ToBase64String(tampered);
+                try { aes.Decrypt(candidate); }
+                catch (PNException) { return candidate; }
+            }
+            Assert.Fail("Could not construct an AES-CBC input that fails unpadding");
+            return null;
+        }
+
         private PNConfiguration CreateTestConfig()
         {
             PNConfiguration config = new PNConfiguration(new UserId("test"));