The sales aspect of Clipper was a new encryption algorithm based on 80- bit encryption keys. 24 times as large as the DES key space. The catch was that acceptance of the new algorithm would involve acceptance of the NSA backdoor. Sandia e-cash is a simple extension of the trustee notion. Anonymity or privacy in financial transactions generally means an inability to determine an individual's spending patterns.
Anonymity requires first and foremost protection from the prying eyes of the bank.
Your private behavior is potentially public information. Unlinkability is therefore an aspect of anonymity. Unlinkability means such probability is negligible. To have untraceability, the information a person reveals about himself by making payments must be statistically independent of the information a person reveals about himself by making withdrawals. Anonymity and privacy thus ultimately hinges on concealing this type of information from the bank itself.