No. T-SQL, with the T-SQL encryption functions like EncrypByKey and DecryptByKey, or whichever of the similar functions you identify as meeting your requirements for protection, key management and all the rest of the admin around encryption.
You certainly can do it in .Net if you want with whatever the .Net encryption functions are.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability