"Tivoisation is a technique that manufacturers use to produce a
computer, to sell to you, whose software they can update but you
can't.
"There are three elements involved in tivoisation:
"The manufacturer puts a chip in the computer which checks any
software before it is run and which will only allow authorised
software to be run.
"The chip can recognise authorised software by, for example,
comparing a checksum (like a fingerprint) to a list of authorised
checksums, or by checking for an encrypted signature.
"The manfucturer withholds the information which you would need
in order to make software authorised..."