Data at REST ( Encrypting Data at the column level)

I'm working on a small assignment Requirements are as follows I have a SQL server 2016 table in which i have (ID, APP_ID, App_Name , P_Name, Date_Processed, and Encrypted_Data_Row) columns Table structure: USE [MasterInvDB] GO /****** Object: Table [dbo].[MasterInv] Script Date: 7/31/2020 4:31:15 PM ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[MasterInv]( [ID] [int] NOT NULL, [APP_ID] [int] NOT NULL, [App_Name] [varchar](30) NOT NULL, [P_Name] [varchar](30) NOT NULL, [Date_Processed] [datetime] NULL, [Encrypted_Data_Row] [varbinary](max) NULL, PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON,ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] GO I get XML file from 15 unique applications and each application has its own PGP or public/private keys. Sample XML. <ns0:MasterRec xmlns:ns0="[login to view URL]"> <AppID>101</AppID> <App_Name>CTMS</App_Name> <P_Name>XORISXC</P_Name> <Date_Processed>07312020</Date_Processed> </ns0:MasterRec>\ Requirement is we have to encrypt the xml using the application specific key and insert to Encrypted_Data_Row column. ID column is auto generated , AppID, App_Name, P_Name, Date_Processed should be taken from the XML and insert to the table unencrypted before encrypting the XML and insert to Encrypted_Data_Row column. If required you can create lookup tables to store the keys. we have SQL Server 2016 and .net framework 4.6 with VS 2015 environment. I'm looking for a SQL Stored procedure or a function for both encryption and decryption. I want the best solution which can scale up or down in future I can provide 2 PGP keys for 2 applications respectively. I need clear explanation Please let me know so that i can share the keys with passphrase for testing or you can create your own keys.