共用题干 第二篇

Credit Card Only Works When Spoken To

A credit card that will not work unless it hears its owner"s voice could become an
important weapon in the fight against fraud（欺骗）.
The card requires users to give a spoken password that it recognizes using a built-in
voice-recognition chip.The idea is to prevent thieves using a stolen card or fraudsters using
someone else"s credit card details to buy goods online.
A model built by engineers at Beepcard in Santa Monica,California,represents the
first attempt to pack a microphone,a loudspeaker,a battery and a voice-recognition chip
into a standard-sized credit card.
They are not quite there yet:the card is the length and width of an ordinary credit card,
but it is still about three times as thick.The company now plans to make it thinner.
The voice card is based on an earlier Beepcard technology designed to prevent fraud in
online transactions.This earlier card has no microphone,but has a built-in loudspeaker
that it uses to " squawk"（发出叫声）a voice ID signal via a computer"s microphone to an
online server.
By verifying（证实）that the signal matches the card details,the server can establish
that the user is not simply keying in a credit card number but actually has the card to hand.
The ID code changes each time the card is used in a pre-ordered sequence that only the server knows.
This prevents fraudsters recording the beeps, noting the card details and then playing
back the audible ID when they key in the details later.But this earlier technology cannot
prevent fraudulent use of stolen cards.The new one can.
The new voice card also identifies itself by its ID squawk,but it will not do this until it
has verified the legitimate（合法的）user"s spoken password. Thieves will be unable to use
the card because even if they knew the password they would have to be able to copy the
owner"s voice with a high degree of accuracy.
The challenge for Beepcard has been to develop voice-recognition and audio circuitry
that can be powered by a mini battery embedded（嵌入的）in a credit card. To maximize
battery life,the electronics are only switched on when the card is being used.Pressing a
button on the card"s surface prompts it to utter "Say your password" in female voice.If the
voice-recognition software proves that the password is authentic（真实的）,it sends its ID
squawk which the server then identifies,allowing the transaction to proceed. What can we learn from the last paragraph about the voice card?