internal static EncryptionInstructions BuildInstructionsUsingInstructionFileV2()

in src/EncryptionUtilsV2.cs [496:547]
39 lines of code
4 McCabe index (conditional complexity)

        internal static EncryptionInstructions BuildInstructionsUsingInstructionFileV2(GetObjectResponse response, EncryptionMaterialsBase materials)
        {
            using (TextReader textReader = new StreamReader(response.ResponseStream))
            {
                var jsonData = JsonMapper.ToObject(textReader);

                if (jsonData[XAmzKeyV2] != null)
                {
                    // The envelope contains data in V2 format
                    var encryptedEnvelopeKey = Base64DecodedDataValue(jsonData, XAmzKeyV2);
                    var decryptedEnvelopeKey = DecryptNonKmsEnvelopeKeyV2(encryptedEnvelopeKey, materials);

                    var initializationVector = Base64DecodedDataValue(jsonData, XAmzIV);
                    var materialDescription = JsonMapper.ToObject<Dictionary<string, string>>((string)jsonData[XAmzMatDesc]);

                    var cekAlgorithm = StringValue(jsonData, XAmzCekAlg);
                    var wrapAlgorithm = StringValue(jsonData, XAmzWrapAlg);

                    var instructions = new EncryptionInstructions(materialDescription, decryptedEnvelopeKey, null,
                        initializationVector, wrapAlgorithm, cekAlgorithm);

                    return instructions;
                }
                else if (jsonData[XAmzKey] != null)
                {
                    // The envelope contains data in V1 format
                    var encryptedEnvelopeKey = Base64DecodedDataValue(jsonData, XAmzKey);
                    var decryptedEnvelopeKey = DecryptNonKMSEnvelopeKey(encryptedEnvelopeKey, materials);

                    var initializationVector = Base64DecodedDataValue(jsonData, XAmzIV);
                    var materialDescription = JsonMapper.ToObject<Dictionary<string, string>>((string)jsonData[XAmzMatDesc]);

                    var instructions = new EncryptionInstructions(materialDescription, decryptedEnvelopeKey, null, initializationVector);

                    return instructions;
                }
                else if (jsonData[EncryptedEnvelopeKey] != null)
                {
                    // The envelope contains data in older format
                    var encryptedEnvelopeKey = Base64DecodedDataValue(jsonData, EncryptedEnvelopeKey);
                    var decryptedEnvelopeKey = DecryptNonKMSEnvelopeKey(encryptedEnvelopeKey, materials);

                    var initializationVector = Base64DecodedDataValue(jsonData, IV);

                    return new EncryptionInstructions(materials.MaterialsDescription, decryptedEnvelopeKey, initializationVector);
                }
                else
                {
                    throw new ArgumentException("Missing parameters required for decryption");
                }
            }
        }