Challenge: “876261”
Server sends
User “unlocks”
authentication token
by keying in Personal
Identification Number
User enters challenge
into authentication
token
Token returns an
encrypted response
to the challenge
“722512”
“1105”
“876261”
User responds to
server with unique
response
Server compares
response
“722512”
(Server and token
share a secret
encryption key
that user never
has access to)
(Secret key: “0x8A5F42”)
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