report on mintchip

Here is my report on reading
http://developer.mintchipchallenge.com/devguide/developing/common/mintchip-messages.html
and neighbor pages.

MintChip uses centrally assigned secure keys and 64-bit identities.

There are two types of messages in the protocol, "request" and "value".

Contrary to reports that Mintchip is either a new currency or a general
purpose wallet framework,
the version 1 protocol allows 8 bits for specifying currency but currently
only 0x01 is defined as CAD.

MintChip is therefore not conformant with the OpenTransact / TipJar
lightweight alternative currency visions, which require arbitrary URLs for
specifying currency.

A "request" message can contain up to 256 bytes of "annotation" and up to
256 bytes of URL which specifies where to send a value message, as well as
a 32-bit nonce.

A value message can represent 24 bits of Canadian cents, up to CAD
167,772.15, and is issued in response to a speciific request, and signed,

Apparently the MintChip approach to mitigating double-spending risk is to
rely on an impossibility of duplicating the MintChip device, which appears
to be a simple SD storage card, must have something more happening inside
it. In the event that an attacker develops a method for duplicating a
MintChip device including its balance, or perhaps simply prising the secret
key out of it somehow, that attacker would be able to double-spend or
otherwise forge improperly backed value messages:
http://developer.mintchipchallenge.com/devguide/developing/common/message-validation.htmlmakes
no mention of audit trails, central or otherwise.