transaction or other operation is repudiated by the party recorded as
initiating it. Examples include repudiating a stock trade, claiming your
account was broken into and that you didn't do it, and asserting that an
electronic funds transfer was not done.
Complexity: Repudiation has been
addressed with cryptographic techniques, but for the most part, these
techniques are easily broken - in the sense that a person wishing to
repudiate a future transaction can always act to make repudiation
supportable. In stock trades, this problem has been around for a long time
and is primarily addressed by recording all telephone calls (which form the
basis for each transaction) and using the recorded message to resolve the
issue when a disagreement is identified.