Como encriptar cadenas y campos en SQL server

http://www.devjoker.com/contenidos/catss/82/Como-encriptar-o-cifrar-cadenas-y-campos-en-SQL-server-2005-ENCRYPTBYPASSPHRASE-y-DECRYPTBYPASSPHRASE.aspx

https://www.codeproject.com/Questions/376609/How-to-encrypt-decrypt-string-in-sql-server

declare @encrypt varbinary(200) 
select @encrypt = EncryptByPassPhrase('key', 'abc' )
select @encrypt 
 
select convert(varchar(100),DecryptByPassPhrase('key', @encrypt ))