For example, when you introduce yourself to someone, you present your identity to her. When you travel on a plane, you have to wait in a line to have your bags checked. Before placing your bags on the conveyor belt to be scanned, you present your driver's license or government ID card to a law enforcement, security officer. The process of presenting your ID card to the officer is called identification.
After you present your ID card to the officer, she reads your ID card and compares your physical face to the printed photo of your face. The process of comparing your physical face to the printed face on the ID card is called authentication. If your physical face matches the face on the printed ID card, then you are successfully authenticated. The officer may also compare your name on the ID card against the name that is printed on the airline ticket.
The process of validating your identity is called authentication. Formally, authentication is the process whereby a human or computer validates that you are who you say you are.
Human-Generated Facial Signatures
When the officer views your photo on the ID card, she looks for distinguishable physical characteristics on your face. She identifies features on your face. It is this combination of unique characteristics that forms a visual signature of you. She then looks at your physical face and creates a second physical signature, after which she compares the signature of your printed face with the signature of your physical face. If they match, then you are successfully authenticated and can proceed to the conveyor belt. She may also perform additional checks as already mentioned.
The process that her brain performs when creating human facial signatures and storing them in her brain's memory is called an algorithm. Formally, an algorithm is a finite sequence of steps or rules that produce a solution to a problem.
Computer-Generated Facial Signatures
Computers can execute algorithms more efficiently than humans. While the human brain can form a visual signature of someone by identifying unique combinations of visual, facial characteristics, a computer can also create a visual signature of a person's identity. In contrast to a human, a computer can identify millions of tiny pixels in a photograph and compare them against the pixels in another photograph. Computer algorithms perform shading and blending to identify facial features with extreme precision. A unique signature is generated that is both computationally complex and reproducible. If you are standing at a 90 degree angle to a camera instead of an 85 degree angle, then the same unique signature of your face can be generated. If you are standing at an 80 degree angle to the camera and you are wearing make up, then the same signature can be created. If there are 300 million other people also getting their photos taken at these angles, both with and without makeup, the computer can still generate unique signatures for every single human. The computer representation of this information is typically a long string of numbers. Your name and birth date are typically appended to this long string of numbers. The entire string or a partial length of the string are then stored in computer memory so that the computation of the signature can be easily recalled when needed. Replacing your name with someone else's name in this string or modifying your unique physical characteristics could mean the creation of an identity that is not you.
It is for this reason that your signature must be stored in a secure computer system. Microprocessor-based storage chips often provide an encrypted, non-volatile medium for the storage of identification information. This cryptographic storage medium is usually accompanied by a small, embedded, and highly optimized microprocessor for performing computationally expensive cryptographic operations or algorithms such as encryption, decryption, and signature generation.
As we grow older and our physical features change, computer algorithms should compensate for these changes and generate the same or similar unique signatures. DNA can also be used to uniquely identify humans. Computer algorithms should properly compensate for changes in human DNA so that individuals can be uniquely identified.
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