Chapter 353: Pinkman's Decryption!

Casting a glance around at everyone, Pinkman continued:

"So, those flashlights aren't flashlights at all, or rather, they aren't just flashlights. Each one of them is a modified RFID transceiver. The casing looks like a flashlight, but the internal circuitry has been completely replaced."

"When those guests pointed the flashlight's beam at the bank card balance on the back of the invitation, they were, in effect, allowing their own mobile phones to get close to the reading area of that 'flashlight.' That 'flashlight' read all the information on your phone, which includes the bank card's—card number, cardholder name, expiration date, and the most critical thing—the CVV."

As he spoke, Pinkman put down the bank card, picked up the black box, and patted it with his palm.

"At the same time, Chu Chen on the stage—or more accurately, a certain device on or near Chu Chen—was reading Brian Thompson's bank card information in the same way. He didn't need to hack into the bank's network, and he didn't need to crack any encryption algorithms. He simply inserted a 'man-in-the-middle' between the card and the POS machine. What this middleman does is very simple: intercept the read signal sent by the POS machine, forward the signal to the card's chip, then intercept the information returned by the chip and forward it to the POS machine. In this process, the middleman can do one other thing simultaneously—modify the information."

He took a second item out of his canvas bag.

It was a POS machine, the kind most common in supermarkets, with a white casing, gray buttons, and a small screen displaying the interface for entering an amount.

Pinkman placed the POS machine on the table, pointed the antenna of the black box toward the POS machine, and then placed the bank card on the sensing area of the POS machine.

"Beep."

A line of text popped up on the POS machine's screen: Amount 20.00. Then a line of small text: Please confirm.

Pinkman did not press confirm. He took the bank card away from the POS machine, held it up to his eyes, and looked at it.

"You all know the normal transaction process. You buy things at a supermarket, the cashier enters the amount, you bring your bank card close to the POS machine, the POS machine reads your card information, initiates a transaction request to the bank, the bank verifies if your account balance is sufficient, deducts the money, returns a success command, and the POS machine prints a receipt. The whole process takes a few seconds at the fastest, or tens of seconds at the slowest. But in this process, there is one step that is the most vulnerable—the step where the POS machine reads your card information."

He placed the bank card on the table and picked up the black box again.

"Because the communication between the POS machine and the card is radio frequency communication. It does not require physical contact. As long as it is within an effective distance, anyone can emit an RF signal requesting your card to return information. Your card cannot distinguish whether this signal comes from a merchant's POS machine or a handheld device from a stranger on the roadside. It only knows—a legitimate card reader is requesting a read, and it should respond."

He held the box up into the air, pointing the antenna toward the ceiling.

"Those 'flashlights' of Chu Chen's are each an independent card reader. They read the bank card information of all the audience members present and, through some method—perhaps Bluetooth, perhaps Wi-Fi, perhaps encrypted radio waves—transmitted this information in real-time to a central processing device on the stage. That central processing device contained Brian Thompson's bank card information. Then, he did something extremely simple, extremely crude, but extremely effective."

Pinkman picked up the POS machine and placed it on his left side. Then he placed the black box on his right side.

"He 'wrote' Brian's bank card information into every bank card present. It wasn't really written into the physical chip, but rather, when the transaction request was sent, he replaced the cardholder's own information with Brian's information. When Monica pointed her 'flashlight' at her bank card, that 'flashlight' didn't send a read request, but a transaction request—transferring two hundred thousand dollars from Brian's account to Monica's account. The POS machine received this transaction request, saw Brian's card information, and thus initiated a transfer from Brian's account to Monica's account to the bank. The bank system verified Brian's account balance—it was sufficient, so it approved the transaction. In the whole process, whether Monica's own bank card had money or not was completely irrelevant. What mattered was that Brian's bank card information was 'worn' on her card at that instant."

Hearing this, Lin Xu suddenly interrupted and asked:

"But the problem is, such technology is very difficult to realize. First of all, ordinary RFID transceivers don't work at all when it comes to large-sum transfers. Secondly, even the most powerful central processing equipment cannot complete such large-scale calculations in a short time because the computing Force is insufficient, unless you bring in a quantum computer."

"Secondly, the effective distance of RFID cannot be controlled. You said that after modification it can reach fifteen to twenty meters, but at the Metropolitan Opera House, the distance from the stage to the audience seats is far more than twenty meters. The audience from the second row back is at least thirty meters away from the stage. How did those 'flashlights' transmit the card information back to the stage?"

Pinkman did not answer.

He took a third item out of his canvas bag.

It was a white box the size of a mobile phone, with no buttons on the surface, only a very small LED indicator light, emitting a faint, blue light under the illumination of the room lights.

"A repeater." Pinkman placed the white box on the table. "It receives the card information transmitted by the flashlights and then forwards it to the central processor on the stage via an encrypted channel. Repeaters can be connected in series—one person passes it to the person in front of them, and that person passes it to the person in front of them, like a relay baton. The audience seating at the Metropolitan Opera House is tiered; every row is higher than the row in front, and the line of sight is unobstructed. If a repeater were placed in the middle of every row—hidden under the seat, inside the armrest, or in some audience member's bag—the signal could be passed up level by level. Finally, it would reach the stage."

Pinkman raised his head and looked at everyone in the conference room.

"Of course, I am only providing a line of thought. As for technical matters, I cannot give you any advice, because this is not my profession. I am only interested in the magic itself; as for the rest, that is up to you."

In the evidence bag on the conference table, that Tarot Card of Death was glowing with a grayish-white light under the illumination of the lights.

The knight riding on the gray horse held that black flag, and the white rose on the flag face was blooming quietly above the Gothic-style "DEATH."

"Thank you for providing us with a line of thought." Henry's voice returned to that unhurried rhythm from before. "But there is one question I still hope you can clarify."

He put the evidence bag back on the table and pointed his finger at that Death card.

"How did he disappear? On the stage, under everyone's gaze, between two frames of the surveillance footage, this is too inconceivable..."

Pinkman was silent.

His cane was tucked under his arm, both hands were in his trouser pockets, and his body leaned forward slightly, looking at that card.

He looked for a long time.

Finally, he said softly: "Sorry, I cannot answer this question for you, because I am also looking for the answer to this question."

The clock on the wall of the Command Center ticked away.

Every time the second hand jumped, it was telling everyone: Chu Chen was still in this world, in some place they didn't know, doing something they didn't know.

And the cards in his hand—there was only one left to be played!