commit 2472be710f8518caab1f62999c50970b475f162f
Author: Angel Yankov <angel.yankov@suse.com>
Date:   Wed May 28 16:17:10 2025 +0300

    Fix ElGamal side channel issue

diff --git a/pubkey.h b/pubkey.h
index 31e00a33..b12ef458 100644
--- a/pubkey.h
+++ b/pubkey.h
@@ -1854,8 +1854,13 @@ public:
 
 			SecByteBlock derivedKey(encAlg.GetSymmetricKeyLength(encAlg.GetMaxSymmetricPlaintextLength(ciphertextLength)));
 			derivAlg.Derive(params, derivedKey, derivedKey.size(), z, q, parameters);
-
-			return encAlg.SymmetricDecrypt(derivedKey, ciphertext, ciphertextLength, plaintext, parameters);
+			DecodingResult res =  encAlg.SymmetricDecrypt(derivedKey, ciphertext, ciphertextLength, plaintext, parameters);
+			Element z2 = agreeAlg.AgreeWithStaticPrivateKey(params, q, true, key.GetPrivateExponent());
+			if (z == z2) {
+			} else {
+				return DecodingResult();
+			}
+			return res;
 		}
 		catch (DL_BadElement &)
 		{