'Chaum is also building into PrivaTegrity another feature that's sure to be far more controversial: a carefully controlled backdoor > that allows anyone doing something "generally recognized as evil" to have their anonymity and privacy stripped altogether.' [...] Those of us who have been in the field for a while will (hazily) remember that back in the 80's, Chaum invented the first practical cryptocurrency. However, he patented his 'blind signature' algorithms, which were the heart of the system, and he and the DigiCash corporation (which was created to exploit the patents) were extremely restrictive in their licensing. Reportedly, this was because Chaum was concerned that Bad People might use it for money laundering.The system saw very little use. Much more detail can be found in the cypherpunks mailing list archives. ....which is a long way of saying that for Chaum to cripple his system with a back door seems consistent with his earlier reported behavior. Peter Trei https://marc.info/?l=cryptography&m=145223202406590&w=1