From 54b33eeed23616a375b1ba83a4cf2a596377bfd9 Mon Sep 17 00:00:00 2001
From: Peter Dettman <peter.dettman@bouncycastle.org>
Date: Fri, 5 Apr 2024 14:11:01 +0700
Subject: DTLS: more robust exclusion of stream ciphers

---
 crypto/src/tls/DtlsProtocol.cs | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/crypto/src/tls/DtlsProtocol.cs b/crypto/src/tls/DtlsProtocol.cs
index 566d07cb4..73e9a4070 100644
--- a/crypto/src/tls/DtlsProtocol.cs
+++ b/crypto/src/tls/DtlsProtocol.cs
@@ -76,15 +76,14 @@ namespace Org.BouncyCastle.Tls
         /// <exception cref="IOException"/>
         internal static int ValidateSelectedCipherSuite(int selectedCipherSuite, short alertDescription)
         {
-            switch (TlsUtilities.GetEncryptionAlgorithm(selectedCipherSuite))
+            int encryptionAlgorithm = TlsUtilities.GetEncryptionAlgorithm(selectedCipherSuite);
+            if (EncryptionAlgorithm.NULL != encryptionAlgorithm)
             {
-            case EncryptionAlgorithm.RC4_40:
-            case EncryptionAlgorithm.RC4_128:
-            case -1:
-                throw new TlsFatalAlert(alertDescription);
-            default:
-                return selectedCipherSuite;
+                int cipherType = TlsUtilities.GetEncryptionAlgorithmType(encryptionAlgorithm);
+                if (cipherType < 0 || CipherType.stream == cipherType)
+                    throw new TlsFatalAlert(alertDescription);
             }
+            return selectedCipherSuite;
         }
     }
 }
-- 
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