Warning: PasswordDeriveBytes for deriving key material from a password and is preferred in new applications

Hi,
I got an warning as given below while i am using password cryptography methods
'Public Overrides Function GetBytes(cb As Integer) As Byte()' is obsolete: 'Rfc2898DeriveBytes replaces PasswordDeriveBytes for deriving key material from a password and is preferred in new applications.'.
Can any one give me a solution for clear this warning.
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