System.Security.Cryptography.DSACryptoServiceProvider.VerifyHash C# (CSharp) Method

        public bool VerifyHash(byte[] rgbHash, string str, byte[] rgbSignature)
        {
            if (rgbHash == null)
                throw new ArgumentNullException(nameof(rgbHash));
            if (rgbSignature == null)
                throw new ArgumentNullException(nameof(rgbSignature));

            int calgHash = CapiHelper.NameOrOidToHashAlgId(str);

            return CapiHelper.VerifySign(
                SafeProvHandle,
                SafeKeyHandle,
                CapiHelper.CALG_DSS_SIGN,
                calgHash,
                rgbHash,
                rgbSignature);
        }

        public static Boolean Test(Session session)
        {
            Boolean bRes = true;
            //String xml1, xml2, xml3;
            //String sign1, sign2, sign3;
            byte[] hashval = new byte[20];
            for (int i = 0; i < hashval.Length; i++) hashval[i] = (Byte)i;

            DSACryptoServiceProvider dsa1 = new DSACryptoServiceProvider(session);
            DSACryptoServiceProvider dsa2 = new DSACryptoServiceProvider(session);
            //DSACryptoServiceProvider dsa3 = new DSACryptoServiceProvider(session);

            DSAParameters dsaParams = dsa1.ExportParameters(true);

            byte[] sig1 = dsa1.SignHash(hashval, MechanismType.SHA_1);

            //sign1 = (Convert.ToBase64String(sig1));

            //xml1 = dsa1.ToXmlString(true);


            dsa2.ImportParameters(dsaParams);
            //dsa2.FromXmlString(xml1);

            //xml2 = (dsa2.ToXmlString(true));
            //xml3 = (dsa3.ToXmlString(true));

            byte[] sig2 = dsa2.SignHash(hashval, MechanismType.SHA_1);
            //sign2 = (Convert.ToBase64String(sig2));

            //dsa3.HashAlgorithm = MechanismType.SHA_1;
            //byte[] sig3 = dsa3.SignHash(hashval);
            //sign3 = (Convert.ToBase64String(sig3));

            //if ((xml1 != xml2) || (xml2 != xml3))
            //{
            //    Log.Comment("WRONG : ToXmlString results are different");
            //    Log.Comment("XML1:\n" + xml1);
            //    Log.Comment("XML2:\n" + xml2);
            //    Log.Comment("XML3:\n" + xml3);
            //    bRes = false;
            //}

            //Log.Comment(xml1);

            /*        if ( (sign1!=sign2) || (sign2!=sign3) ) {
                        Log.Comment("WRONG : signatures are different");
                        Log.Comment("First: " + sign1);
                        Log.Comment("Second: " + sign2);
                        Log.Comment("Third: " + sign3);
        	
                        bRes = false;
                    } */

            //Log.Comment("\n" + sign1);

            if (!dsa1.VerifyHash(hashval, MechanismType.SHA_1, sig2))
            {
                Log.Comment("WRONG : Signature check (1) failed");
                bRes = false;
            }
            if (!dsa2.VerifyHash(hashval, MechanismType.SHA_1, sig1))
            {
                Log.Comment("WRONG : Signature check (1) failed");
                bRes = false;
            }
            //if (!dsa3.VerifyHash(hashval, sig1))
            //{
            //    Log.Comment("WRONG : Signature check (1) failed");
            //    bRes = false;
            //}

            return bRes;
        }