Amazon.S3.Encryption.EncryptionUtils.IsEncryptionInfoInInstructionFile C# (CSharp) Method

        internal static bool IsEncryptionInfoInInstructionFile(GetObjectResponse response)
        {
            MetadataCollection metadata = response.Metadata;

            if (metadata[instructionFileInfo] != null)
                return true;
            else
                return false;
        }
#endregion

        /// <summary>
        /// Performs decryption of data by getting encryption information
        /// from object metadata or instruction file.
        /// </summary>
        /// <param name="response">AmazonWebServiceResponse on which decryption is performed</param>
        /// <param name="request">IRequest</param>
        /// <param name="webResponseData">IWebResponseData</param>
        protected override void ProcessResponseHandlers(AmazonWebServiceResponse response, IRequest request, IWebResponseData webResponseData)
        {
            base.ProcessResponseHandlers(response, request, webResponseData);

            var initiateMultiPartUploadRequest = request.OriginalRequest as InitiateMultipartUploadRequest;
            var initiateMultiPartResponse      = response as InitiateMultipartUploadResponse;

            if (initiateMultiPartResponse != null)
            {
                byte[] envelopeKey = initiateMultiPartUploadRequest.EnvelopeKey;
                byte[] iv          = initiateMultiPartUploadRequest.IV;

                UploadPartEncryptionContext contextForEncryption = new UploadPartEncryptionContext();
                contextForEncryption.EnvelopeKey = envelopeKey;
                contextForEncryption.NextIV      = iv;
                contextForEncryption.FirstIV     = iv;
                contextForEncryption.PartNumber  = 0;

                //Add context for encryption of next part
                currentMultiPartUploadKeys.Add(initiateMultiPartResponse.UploadId, contextForEncryption);
            }

            var uploadPartRequest  = request.OriginalRequest as UploadPartRequest;
            var uploadPartResponse = response as UploadPartResponse;

            if (uploadPartResponse != null)
            {
                string uploadID = uploadPartRequest.UploadId;
                UploadPartEncryptionContext encryptedUploadedContext = null;

                if (!currentMultiPartUploadKeys.TryGetValue(uploadID, out encryptedUploadedContext))
                {
                    throw new AmazonS3Exception("encryption context for multi part upload not found");
                }

                if (uploadPartRequest.IsLastPart == false)
                {
                    object stream = null;

                    if (!uploadPartRequest.RequestState.TryGetValue(S3CryptoStream, out stream))
                    {
                        throw new AmazonS3Exception("cannot retrieve S3 crypto stream from request state, hence cannot get Initialization vector for next uploadPart ");
                    }

                    var encryptionStream = stream as AESEncryptionUploadPartStream;
                    encryptedUploadedContext.NextIV = encryptionStream.InitializationVector;
                }
            }

            var getObjectResponse = response as GetObjectResponse;

            if (getObjectResponse != null)
            {
                if (EncryptionUtils.IsEncryptionInfoInMetadata(getObjectResponse) == true)
                {
                    DecryptObjectUsingMetadata(getObjectResponse);
                }
                else
                {
                    GetObjectResponse instructionFileResponse = null;
                    try
                    {
                        GetObjectRequest instructionFileRequest = EncryptionUtils.GetInstructionFileRequest(getObjectResponse);
                        instructionFileResponse = S3ClientForInstructionFile.GetObject(instructionFileRequest);
                    }
                    catch (AmazonServiceException ace)
                    {
                        throw new AmazonServiceException(string.Format(CultureInfo.InvariantCulture, "Unable to decrypt data for object {0} in bucket {1}",
                                                                       getObjectResponse.Key, getObjectResponse.BucketName), ace);
                    }

                    if (EncryptionUtils.IsEncryptionInfoInInstructionFile(instructionFileResponse) == true)
                    {
                        DecryptObjectUsingInstructionFile(getObjectResponse, instructionFileResponse);
                    }
                }
            }

            var completeMultiPartUploadRequest  = request.OriginalRequest as CompleteMultipartUploadRequest;
            var completeMultipartUploadResponse = response as CompleteMultipartUploadResponse;

            if (completeMultipartUploadResponse != null)
            {
                if (amazonS3CryptoConfig.StorageMode == CryptoStorageMode.InstructionFile)
                {
                    UploadPartEncryptionContext context = currentMultiPartUploadKeys[completeMultiPartUploadRequest.UploadId];
                    byte[] envelopeKey                  = context.EnvelopeKey;
                    byte[] iv                           = context.FirstIV;
                    byte[] encryptedEnvelopeKey         = EncryptionUtils.EncryptEnvelopeKey(envelopeKey, this.encryptionMaterials);
                    EncryptionInstructions instructions = new EncryptionInstructions(EncryptionMaterials.EmptyMaterialsDescription, envelopeKey, encryptedEnvelopeKey, iv);

                    PutObjectRequest instructionFileRequest = EncryptionUtils.CreateInstructionFileRequest(completeMultiPartUploadRequest, instructions);

                    S3ClientForInstructionFile.PutObject(instructionFileRequest);
                }

                //Clear Context data since encryption is completed
                currentMultiPartUploadKeys.Clear();
            }
        }