"Fingerprinting" chips to fight counterfeiting

As we all know that no two human fingerprints are exactly alike. For that reason, police often use them as evidence to link suspects to crime scenes.

The same goes for silicon chips: Manufacturing processes cause microscopic variations in chips that are unpredictable, permanent, and effectively impossible to clone.

MIT spinout Verayo is now using these unclonable variations to "fingerprint" silicon chips used in consumer-product tags—which can then be scanned via mobile device and authenticated—to aid in the fight against worldwide counterfeiting.

According to a 2013 United Nations report, about 2 to 5 percent of internationally traded goods—including electronics, food, and pharmaceuticals—are counterfeited, costing governments and private companies hundreds of billions of dollars annually.

"This is low-cost authentication using 'silicon biometrics,'" says Srini Devadas, the Edwin Sibley Webster Professor in MIT's Department of Electrical Engineering and Computer Science, and Verayo's co-founder and chief scientist.

Verayo's technology—now in use worldwide—is based on Devadas' seminal research into these variations within silicon chips, called "physical unclonable functions" (PUFs), which cause minute speed differences in a chip's response to electrical signals.

The Verayo technology assigns manufactured chips sets of 128-bit numbers—based on these speed differences—that are stored in a database in the cloud. Integrated into radio frequency identification (RFID) tags, the chips can be scanned by a mobile device or reader that will query the database to determine if the tag is authentic. A different 128-bit number is used for each authentication.

Verayo is currently targeting the consumer-product market, partnering last year with its largest client, Canon Inc., to incorporate Verayo's chips into RFID tags of cameras being sold across China. Other Verayo clients include gift- and loyalty-card providers. The technology can also be used to identify fake licenses and passports.

Now conducting pilot studies with wineries, the company is also seeking to penetrate the consumables market, which could significantly boost sales, Devadas says. "You can build this chip for a nickel, but you have to sell a lot of these chips to make money," he says.

But with more than 40 million chips sold worldwide since 2013, Devadas adds, "This is productization and academic success. As far as I'm concerned, this is great."

Racing signals

PUFs are created during silicon- integrated chip manufacturing, when wires vary in thickness, and the chemical vapor deposition process—used to produce semiconductor wafers—creates microscopic bumps. Depending on these variations, electrons flow with more or less resistance through different paths of the chip, varying processing speeds.

The PUF technology works by "racing" signals across the chips. Two identical electric signals—derived from an input "challenge"—are sent through the chip, at the same time, and assigned two different paths. The signals race toward a latch that measures what signal the chip processed slower or faster—called a "response." The output is a 1 if one path is faster, and 0 if the other is faster. Repeating the process with different input signals for each race will give a 128-bit number—and it can be repeated hundreds of times.

"Then, suddenly, you have a miniscule probability you're going to get the same 128-bit resolution for any given race," Devadas says.

When the tag is scanned, the reader will first identify the tag. Then, it will present the chip with a random challenge of the many that are stored in the database. If the response has 96 or more matching bits, it's considered authentic. Tags are attached to Canon camera packages, which consumers can scan using smartphones with near-field communication.

In 2002, Devadas and other MIT researchers delivered a seminal paper introducing silicon PUF technology at the Computer and Communications Security Conference, which coined the name and described the first integrated PUF circuit. This March, that paper earned an A. Richard Newton Technical Impact Award from the Institute of Electrical and Electronics Engineers and the Association for Computing Machinery—"which is a test of time for the concept and technology," Devadas says.

By 2004, Devadas and his students had developed a few dozen bulky, PUF-enabled circuits, labeling each with a human name, such as "Harold," "Cameron," and "Dennis." They stored the speed characteristics of each in a database on their computer; when a given circuit was scanned using a custom reader, its name would pop up on the screen.

This project earned Devadas a grant from the MIT Deshpande Center for Technological Innovation, and several government grants, which helped Verayo launch in its current Silicon Valley headquarters.

Keeping volatile secrets

Although Verayo is focused on the consumer space, the technology has other uses, such as generating "volatile secret keys," Devadas says, which would only be revealed when activated by voltage.

Because PUF chips do not store such secrets, Devadas says, they need voltage to reveal their unique numeric identification—which could be stored as cryptographic keys. "When the chip powers up, there will be this 128-bit number that gets generated, but it doesn't exist when the chip is powered down," Devadas says. "If I don't have a way of pulling [the key] out, I won't know what it is."

This technology has advantages, Devadas says, over traditional nonvolatile data-storage devices, such as flash or erasable programmable read-only memory chips, which retain hackable data even when switched off. These nonvolatile chips are still difficult to break into, he adds, but not as difficult as PUF-enabled chips, which need to be inspected internally when the chip is powered on and the right challenges are applied.

"All of cryptography is based on something remaining secret," Devadas says. "PUFs are a way of generating those secrets in a more physically secure manner."

Attracting funding from the Department of Defense, this concept could help, for instance, ensure that drones don't connect with hacked servers, or that wearables don't share data with unauthorized servers.

Devadas says the PUF-technology market has seen significant growth in recent years, with other companies now developing in the space. But the competition doesn't discourage the PUF pioneer—in fact, Devadas is excited about the increased interest.

"It does feel like the world is coming around," he says. "And we're still here—that's the beauty of it."

Engineers develop the first on-chip RF circulator that doubles WiFi speeds with a single antenna

Last year, Columbia Engineering researchers were the first to invent a technology—full-duplex radio integrated circuits (ICs)—that can be implemented in nanoscale CMOS to enable simultaneous transmission and reception at the same frequency in a wireless radio. That system required two antennas, one for the transmitter and one for the receiver. And now the team, led by Electrical Engineering Associate Professor Harish Krishnaswamy, has developed a breakthrough technology that needs only one antenna, thus enabling an even smaller overall system. This is the first time researchers have integrated a non-reciprocal circulator and a full-duplex radio on a nanoscale silicon chip. The circulator research is published online April 15 in Nature Communications and the paper detailing the single-chip full-duplex radio with the circulator and additional echo cancellation was presented at the 2016 IEEE International Solid-State Circuits Conference on February 2.

"This technology could revolutionize the field of telecommunications," says Krishnaswamy, director of the Columbia High-Speed and Mm-wave IC (CoSMIC) Lab. "Our circulator is the first to be put on a silicon chip, and we get literally orders of magnitude better performance than prior work. Full-duplex communications, where the transmitter and the receiver operate at the same time and at the same frequency, has become a critical research area and now we've shown that WiFi capacity can be doubled on a nano scale silicon chip with a single antenna. This has enormous implications for devices like smartphones and tablets."

Krishnaswamy's group has been working on silicon radio chips for full duplex communications for several years and became particularly interested in the role of the circulator, a component that enables full-duplex communications where the transmitter and the receiver share the same antenna. In order to do this, the circulator has to "break" Lorentz Reciprocity, a fundamental physical characteristic of most electronic structures that requires electromagnetic waves travel in the same manner in forward and reverse directions.

"Reciprocal circuits and systems are quite restrictive because you can't control the signal freely," says PhD student Negar Reiskarimian, who developed the circulator and is lead author of the Nature Communications paper. "We wanted to create a simple and efficient way, using conventional materials, to break Lorentz Reciprocity and build a low-cost nanoscale circulator that would fit on a chip. This could open up the door to all kinds of exciting new applications."

The traditional way of breaking Lorentz Reciprocity and building radio-frequency circulators has been to use magnetic materials such as ferrites, which lose reciprocity when an external magnetic field is applied. But these materials are not compatible with silicon chip technology, and ferrite circulators are bulky and expensive. Krishnaswamy and his team were able to design a highly miniaturized circulator that uses switches to rotate the signal across a set of capacitors to emulate the non-reciprocal "twist" of the signal that is seen in ferrite materials. Aside from the circulator, they also built a prototype of their full-duplex system—a silicon IC that included both their circulator and an echo-cancelling receiver—and demonstrated its capability at the 2016 IEEE International Solid- State Circuits Conference this past February.

"Being able to put the circulator on the same chip as the rest of the radio has the potential to significantly reduce the size of the system, enhance its performance, and introduce new functionalities critical to full duplex," says PhD student Jin Zhou, who integrated the circulator with the full-duplex receiver that featured additional echo cancellation.

Non-reciprocal circuits and components have applications in many different scenarios, from radio-frequency full-duplex communications and radar to building isolators that prevent high-power transmitters from being damaged by back-reflections from the antenna. The ability to break reciprocity also opens up new possibilities in radio-frequency signal processing that are yet to be discovered. Full-duplex communications is of particular interest to researchers because of its potential to double network capacity, compared to half-duplex communications that current cell phones and WiFi radios use. The Krishnaswamy group is already working on further improving the performance of their circulator, and exploring "beyond-circulator" applications of non-reciprocity.

"What really excites me about this research is that we were able to make a contribution at a theoretically fundamental level, which led to the publication in Nature Communications, and also able to demonstrate a practical RF circulator integrated with a full-duplex receiver that exhibited a factor of nearly a billion in echo cancellation, making it the first practical full-duplex receiver chip and which led to the publication in the 2016 IEEE ISSCC," Krishnaswamy adds. "It is rare for a single piece of research, or even a research group, to bridge fundamental theoretical contributions with implementations of practical relevance. It is extremely rewarding to supervise graduate students who were able to do that!"

How To Desolder a PCB?

What is Soldering and Desoldering?

Soldering is a process in which two or more items (usually metal) are joined together by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Desoldering is the removal of solder and components from a circuit board for troubleshooting, repair, replacement, and salvage.

While soldering is an important skill, being able to desolder is also important. In some cases, it can be even more important than soldering itself.  This document attempts to teach soldering through a few simple steps. Tips and tricks are also provided at the end.

How To Desolder

Step 1: Equipment 

Desoldering requires two main things: a soldering iron and a device to remove solder.

Soldering irons are the heat source used to melt solder. Irons of the 15W to 30W range are good for most electronics/printed circuit board work. Anything higher in wattage and you risk damaging either the component or the board. Note that you should not use so-called soldering guns. These are very high wattage and generate most of their heat by passing an electrical current through a wire. Because of this, the wire carries a stray voltage that could damage circuits and components.

The choice of your solder removing device is also important. There are two main ones; vacuum pumps (solder suckers) and solder wick. They both do the same thing, so what you use will depend on your personal opinion or experiences. I suggest keeping both on hand though, as you may find that each works well in different situations. Solder suckers usually look like large syringes. There is a spring loaded plunger, and a button to release it. The plunger is pushed down. When you want to suck up the solder, you position the nozzle over the molten solder and hit the button. The plunger moves up, creating a vacuum and sucking up the solder. Solder wick, on the other hand, has no moving parts. It looks like wick used in oil lamps, except that it is made of copper. To use it, you put the wick over the joint and heat it. One thing to note about solder wick is that it is expensive, and because it is expendable, a solder sucker may be a better choice if you plan to do a lot of desoldering. I personally prefer to use a sucker to remove most of the solder, then finish up with the wick.

Remember that when desoldering, the resin in the solder and the coating on the board may releases fumes. These fumes are harmful to your eyes and lungs. Therefore, always work in a well ventilated area. Hot solder is also dangerous. Be sure not to let it splash around because it will burn you almost instantly. Eye protection is also advised.

Step 2: Surface Preparation

There isn't really too much to worry about when removing solder. Just make sure to get any grease, varnish or glue off the joint before you start heating. If you don't, you will probably foul the tip of your soldering iron pretty quickly.

Step 3: Apply Heat

Lay the iron tip so that it rests against both the component lead and the board. Normally, it takes one or two seconds to heat the component up enough to solder, but larger components and larger soldering pads on the board can increase the time.

Step 4: Remove Solder

Solder Sucker: Push down the plunger so it locks into place. Usually, you will feel or hear a click. If the tool has been used before, a small "plug" of solder may be pushed out of the nozzle. Once the solder sucker is cocked, put the nozzle into the molten solder and press the button. The plunger will pop up quickly take the solder with it. This should remove most, if not all, the solder from the joint. Don't worry if the tip softens a little, but don't melt it. You may need to repeat this step a few times in order to get all the solder.

Solder Wick: You will probably want to heat the wick first. Before applying any heat to the joint, lay the wick over it and put the tip of the iron on the wick. It will take a second or two to heat up, but once it is hot you will feel the wick slide. You should also see the solder flow into it. You probably won't have to repeat this step. Once a section of wick is filled with solder, it is used up and must be replaced. Since the wick comes on a spool, all you need to do is cut off the used sections and take some more off the spool.

Step 5: Clean Up

You may wish to clean the solder pad and surrounding pad to remove any resin and left over solder. There are commercial products available to take off the resin, but 000 steel wool works well of you are careful.

Damaged Solder Pads

Occasionally, you may damage a solder pad in your efforts. Usually, this just involves lifting the pad from the board, but not actually separating the traces. If this is the case, then it should be fine if you just leave it. If this is not the case and you actually break the trace, you will need to use a small piece of wire to connect the pad to where it is supposed to go. Just follow the trace until you find a suitable location for soldering. Usually, this is the next closest solder joint. Then, jumper the wire between the two points.

Tips and Tricks

Desoldering is just like soldering in that it is something that needs to be practiced. These tips should help you become successful quickly.

1. Use heatsinks. Heatsinks are a must for the leads of sensitive components such as ICs and transistors. If you don't have a clip on heatsink, then a pair of pliers is a good substitute.

2. Keep the iron tip clean. A clean iron tip means better heat conduction. Use a wet sponge to clean the tip between joints.

3. Check the pads. Use a continuity tester to check to make sure you did not damage the pad or trace when you removed the solder. If you did, then follow the steps above to fix it.

4. Use the proper iron. Remember that bigger joints will take longer to heat up with a 30W iron than with a 150W iron. While 30W is good for printed circuit boards and the like, higher wattages are great when desoldering heavy connections, such as those to a chassis.

5. Use both a solder sucker and solder wick. Use a solder sucker to remove the majority of the solder, then follow up with the wick to finish things up.

DIY 55-Watt Solar Light Bulb From An Ordinary Bottle Of Water

Solar products are pretty abundant right now. You can find countless gizmos, gadgets and inventions using the sun for the purpose of generating sustainable energy sufficient enough to power any number of devices. A lot of them, ironically, are designed to provide a light source. But what if you could make a DIY solar light with three simple ingredients that almost everyone already has lying about their house? Well, you can, but you probably don’t need to or you’re not going to want to. You see, you can make your own 55-watt light bulb in less than a minute and install it in under 30 (depending on the structure), but it’s doubtful you’ll want to make a hole in your roof to use it.

DIY Light Bulb

If you’ve got a thatched roof or shingled roof badly in need of repair, then this might be right up your alley. But, actually, that doesn’t have to be the case. While this DIY light bulb was created predominantly for inhabitants of third world countries or folks living without electricity, anyone can put the know-how to work. The concept is akin to a skylight, and hypothetically you could use it for a variety of applications like sheds, dugouts, lean-tos or cabins — anyplace a light source is needed and electricity may be lacking. Homesteaders and those shunning the technical life or looking for various ways to go green might even be interested in using these solar light bulbs.

Wireless Lamps

So, how do you make one? Simple, get yourself an ordinary clear-plastic bottle, fill it with water (if it isn't already), add some chlorine (keeps the water clean) and then make a small hole in the roof of the structure you intend to use it in and place the bottle so that it’s half inside and half outside of the structure, exposing the upper portion to light. The principle this works on is that the sunlight from above gets diffracted by the water and spreads light throughout the room below. Surprisingly, during daylight hours, this DIY light fixture is capable of producing enough light to make it comparable to a 55-watt light bulb inside a darkened room.

Solar Powered Lights

Even on cloudy days there is still enough light getting inside the bottle for it to work, just not as brightly. In congested rural villages, where homes are literally side by side and almost on top of one another, the small windows they have are often times rendered useless due to the close proximity to one another. These areas are also usually lacking in electricity, period, much less reliable electricity. The idea and implementation of these solar lights originates with a group known as the Empowering People Network (EPN), and the project is known as Liter of Light, which “aims to provide an ecologically and economically sustainable source of light to underprivileged communities around the world.”

Prepping Ideas

According to EPN’s website, the origin of the Liter of Light project is said to be the Philippines, and that, “In Bangladesh a micro entrepreneurship model has successfully been tested and implemented and we are currently working on initiating the same concept in our latest projects in Kenya and in South Africa.” Another benefit is the estimation by the group that 1000 solar bulbs will save 20 tons of CO2. The use of these solar lights will undoubtedly appeal to preppers, survivalists, off-gridders and those interested in inexpensive, eco-friendly alternative energy options. If you’re going to try this, just remember to run a bead of sealant around the bottle on the roof to prevent leaks during rainstorms. 

See more at http://www.kynix.com/Blog/ 

How to DIY simple wind charger so that we can ride and charge mobile phone

As we know,smartphones cost more in electricity.And nowadays people become more and more reliant on the mobile phone. Besides, they will have the feeling of nothing left to live for. So it is normal that people need to charge for their mobile phone from time to time. However, it is not easy to charge everywhere especially when you don’t take portable mobile power.Now a 16-year-old boy Thomas makes a simple wind charger assembling in the bike. It only costs him 5 dollars. Now he can charge for his smartphone when riding. Let’s see, how does he do that.

What the necessary tools are: soldering iron, glue gun and wire tape.

What the necessary materials are: an old CPU fan, a ring inductance coil, 2N2222 or 2N3904 or BC547 transistor, 5V boost module, five germanium diodes (Bought form Kynix semiconductor), small circuit board, old mobile phone battery and the bicycle fixator.

Then, it is the work by electrician and hand. First, disassemble the fan and find the leading wire to connect together and use the electronic gauge to check which wire lead is the highest and remove another leading wire. After that, connect the germanium diode and the circuit board to build the electricity bridge. At last, fix the lithium battery and circuit under the fan and then install in the bicycle. Of course, the premise is to connect the cellphone to check whether it can charge or not and then fix in the bicycle.

The speed of the simple charger cannot be comparable with the standard recharges. It only can be used in the urgent emergency and hope it can do help to you guys.