Problem while downloading encrypted file from amazon S3

cloudEncryptS3 = new cAmazonS3();
                        cloudEncryptS3.cAmazonEncryptS3(cloudAccountObj.AccountId, cloudAccountObj.SecretKey, cloudAccountObj.IsSSL == Constants.CONSTANT_ONE ? true : false, item.EncryptAlgoName, item.EncryptAlgoValue);

			request = new GetObjectRequest
                        {
                            BucketName = bucketName,
                            Key = keyName
                        };
                        

                        try
                        {
                            response = encryptClient.GetObject(request);
                        }
                        catch (Exception ex)
                        {
                            cGlobalSettings.oLogger.WriteLogException("| S3Progress.cs::DownLoadS3File() |", ex);



    public void cAmazonEncryptS3(string accessKey, string secretKey, bool IsSSL, string algoName, int algoValue)
        {
            encryptClient = null;
            AmazonS3CryptoConfiguration config = null;
            EncryptionMaterials encryp = null;
            Aes aesObj = null;
            DES desObj = null;
            TripleDES desTripleObj = null;
            RC2 rcObj = null;
            try
            {
                config = new AmazonS3CryptoConfiguration
                {
                    ServiceURL = "https://s3.amazonaws.com",
                    UseHttp = IsSSL,
                    StorageMode = CryptoStorageMode.ObjectMetadata
                };
                if (algoName.ToLower().Contains("aes"))
                {

                    aesObj = Aes.Create();
                    aesObj.BlockSize = algoValue;
                    encryp = new EncryptionMaterials(aesObj);
                }
                else if (algoName.ToLower().Contains("des"))
                {
                    if (algoValue == 64)
                    {
                        desObj = DES.Create();
                        desObj.BlockSize = algoValue;
                        encryp = new EncryptionMaterials(desObj);
                    }
                    else
                    {
                        desTripleObj = TripleDES.Create();
                        desTripleObj.BlockSize = algoValue;
                        encryp = new EncryptionMaterials(desTripleObj);
                    }
                }
                else if (algoName.ToLower().Contains("rc"))
                {
                    rcObj = RC2.Create();
                    rcObj.BlockSize = algoValue;
                    encryp = new EncryptionMaterials(rcObj);
                }
                else
                {
                    aesObj = Aes.Create();
                    aesObj.BlockSize = 128;
                    encryp = new EncryptionMaterials(aesObj);
                }

                encryptClient = new AmazonS3EncryptionClient(accessKey, secretKey, config, encryp);
            }
            catch (Exception ex)
            {
                cGlobalSettings.oLogger.WriteLogException("cAmazonS3.cs::cAmazonEncryptS3()", ex);
            }
            finally
            {
                config = null;
                encryp = null;
                aesObj = null;
                desObj = null;
                desTripleObj = null;
                rcObj = null;
            }
        }                    }