Homework? Test?
The 'encryption' that protects the SQL passwords is a one-way hash.
If you want to enforce strong password policy, enable password policy on those logins. SQL will take the rules from the DC of the domain it's in.
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