Biometrics 简明教程

Biometrics - Overview

生物特征识别一词由两个词组成——Bio（希腊语中的生命）和 Metrics（测量）。生物特征识别是信息技术的一个分支，旨在基于个人特征确定一个人的身份。

The term Biometrics is composed of two words − Bio (Greek word for Life) and Metrics (Measurements). Biometrics is a branch of information technology that aims towards establishing one’s identity based on personal traits.

生物特征识别目前是信息安全领域的一个热门术语，因为它能高度准确地识别个人。

Biometrics is presently a buzzword in the domain of information security as it provides high degree of accuracy in identifying an individual.

What is Biometrics?

生物特征识别是一种用于识别、分析和测量个人生理和行为特征的技术。

Biometrics is a technology used to identify, analyze, and measure an individual’s physical and behavioral characteristics.

每个人都是独一无二的，这使他和其他人截然不同。生理特征，如指纹、虹膜颜色、头发颜色、手部几何形状，以及行为特征，如言语的音调和口音、签名或打电脑键盘的方式等，使一个人与众不同。

Each human being is unique in terms of characteristics, which make him or her different from all others. The physical attributes such as finger prints, color of iris, color of hair, hand geometry, and behavioral characteristics such as tone and accent of speech, signature, or the way of typing keys of computer keyboard etc., make a person stand separate from the rest.

个人特征的这些独特性被生物特征识别系统用于：

This uniqueness of a person is then used by the biometric systems to −

  1. Identify and verify a person.

  2. Authenticate a person to give appropriate rights of system operations.

  3. Keep the system safe from unethical handling.

What is a Biometric System?

生物特征识别系统是一种技术，它将个人的生理特征、行为特征或这两者作为输入，进行分析，并将个人识别为真正的用户或恶意用户。

A biometric system is a technology which takes an individual’s physiological, behavioral, or both traits as input, analyzes it, and identifies the individual as a genuine or malicious user.

Evolution of Biometrics

生物特征识别这个概念已经存在好几年了。在 14 世纪，中国就开始对商人及其子女采取指纹识别，以将他们与其他人区分开来。指纹识别至今仍被使用。

The idea of biometrics was present since few years from now. In 14th century, China practiced taking finger prints of merchants and their children to separate them from all others. Fingerprinting is still used today.

  1. In the 19th century, an Anthropologist named Alphonse Bertillion developed a method (named Bertillionage) of taking body measurements of persons to identify them. He had realized that even if some features of human body are changed, such as length of hair, weight, etc., some physical traits of body remain unchanged, such as length of fingers. This method diminished quickly as it was found that the persons with same body measurements alone can be falsely taken as one. Subsequently, Richard Edward Henry from Scotland Yard developed a method for fingerprinting.

  2. The idea of retinal identification was conceived by Dr. Carleton Simon and Dr. Isadore Goldstein in 1935. In 1976, a research and development effort was put in at EyeDentify Inc. The first commercial retina scanning system was made available in 1981.

  3. Iris recognition was invented by John Daugman in 1993 at Cambridge University.

  4. In 2001, Biometrics Automated Toolset (BAT) was introduced in Kosovo, which provided a concrete identification means.

今天，生物特征识别已经成为一門独立的研究领域，拥有精确的个人身份识别技术。

Today, biometric has come up as an independent field of study with precise technologies of establishing personal identities.

Why Biometrics is Required?

随着信息技术在银行、科学、医药等领域的应用日益广泛，迫切需要保护系统和数据免遭未经授权的用户侵害。

With increasing use of Information Technology in the field of banking, science, medication, etc., there is an immense need to protect the systems and data from unauthorized users.

生物特征识别用于 authenticating 和 authorizing 个人。尽管这些术语经常配对使用；但它们的意思不同。

Biometrics is used for authenticating and authorizing a person. Though these terms are often coupled; they mean different.

Authentication (Identification)

此过程试图找出问题的答案， “您是否是您自己聲稱的那个人？” 或，“我认识您吗？” 这是将一个人的生物特征识别与整个数据库进行一对多的匹配和比较。

This process tries to find out answer of question, “Are you the same who you are claiming to be?”, or, “Do I know you?” This is one-to-many matching and comparison of a person’s biometrics with the whole database.

Verification

这是匹配的一对一过程，候选人输入的实时样本与数据库中先前存储的模板进行比较。如果两者匹配度超过 70%，则验证成功。

This is the one-to-one process of matching where live sample entered by the candidate is compared with a previously stored template in the database. If both are matching with more than 70% agreeable similarity, then the verification is successful.

Authorization

这是向经过验证的用户分配访问权限的过程。它试图找出问题的答案，“您是否有访问此资源的某些权限？”

It is the process of assigning access rights to the authenticated or verified users. It tries to find out the answer for the question, “Are you eligible to have certain rights to access this resource?”

Shortcomings of Conventional Security Aids

信息系统安全的传统方法使用身份证、密码、个人识别号码 (PIN) 等。它们有以下缺点−

The conventional methods of information system security used ID cards, passwords, Personal Identification Numbers (PINs), etc. They come with the following disadvantages −

  1. They all mean recognizing some code associated with the person rather than recognizing the person who actually produced it.

  2. They can be forgotten, lost, or stolen.

  3. They can be bypassed or easily compromised.

  4. They are not precise.

在这种情况下，系统的安全性会受到威胁。当系统需要高水平的可靠保护时，生物识别技术会通过将身份与个人联系得更紧密来提供帮助。

In such cases, the security of the system is threatened. When the systems need high level of reliable protection, biometrics comes to help by binding the identity more oriented to individual.

Basic Components of a Biometric System

通常，生物识别系统可以分为四个基本组成部分。让我们简要查看它们−

In general, a biometric system can be divided into four basic components. Let us see them briefly −

biometric basic components

Input Interface (Sensors)

它是将人体生物数据转换成数字形式的生物识别系统的传感组件。

It is the sensing component of a biometrics system that converts human biological data into digital form.

例如，

For example,

  1. A Metal Oxide Semiconductor (CMOS) imager or a Charge Coupled Device (CCD) in the case of face recognition, handprint recognition, or iris/retinal recognition systems.

  2. An optical sensor in case of fingerprint systems.

  3. A microphone in case of voice recognition systems.

Processing Unit

处理组件是微处理器、数字信号处理器 (DSP) 或处理从传感器捕获的数据的计算机。

The processing component is a microprocessor, Digital Signal Processor (DSP), or computer that processes the data captured from the sensors.

生物样本的处理包括−

The processing of the biometric sample involves −

  1. Sample image enhancement

  2. Sample image normalization

  3. Feature extraction

  4. Comparison of the biometric sample with all stored samples in database.

Database Store

数据库存储注册的样本，在认证时对其进行召回以进行匹配。对于识别，可以是来自随机存取存储器 (RAM)、闪存 EPROM 或数据服务器的任何内存。对于验证，会使用可移动存储元件，如接触式或非接触式智能卡。

The database stores the enrolled sample, which is recalled to perform a match at the time of authentication. For identification, there can be any memory from Random Access Memory (RAM), flash EPROM, or a data server. For verification, a removable storage element like a contact or contactless smart card is used.

Output Interface

输出接口将生物识别系统的决策传达给用户，以启用对该用户的访问。这可以是简单的串行通信协议 RS232，或更高带宽的 USB 协议。它也可以是 TCP/IP 协议、射频识别 (RFID)、蓝牙或许多蜂窝协议之一。

The output interface communicates the decision of the biometric system to enable the access to the user. This can be a simple serial communication protocol RS232, or the higher bandwidth USB protocol. It could also be TCP/IP protocol, Radio Frequency Identification (RFID), Bluetooth, or one of the many cellular protocols.

General Working of a Biometric System

生物识别系统执行识别和验证一般需要四个步骤−

There are four general steps a biometric system takes to perform identification and verification −

  1. 1. Acquire live sample from candidate. (using sensors)

  2. 2. Extract prominent features from sample. (using processing unit)

  3. 3. Compare live sample with samples stored in database. (using algorithms)

  4. 4. Present the decision. (Accept or reject the candidate.)

生物识别样本从候选用户获取。从样本中提取突出特征，然后将其与存储在数据库中的所有样本进行比较。当输入样本与数据库中某个样本匹配时，生物识别系统将允许该人访问资源；否则拒绝。

The biometric sample is acquired from candidate user. The prominent features are extracted from the sample and it is then compared with all the samples stored in the database. When the input sample matches with one of the samples in the database, the biometric system allows the person to access the resources; otherwise prohibits.

identification and verification

Biometrics Terminology

Biometric Template - 从生物样本中提取的独特特征的数字参考。

Biometric Template − It is a digital reference of the distinct characteristics that are extracted from a biometric sample.

Candidate/Subject - 输入其生物样本的人。

Candidate/Subject − A person who enters his biometric sample.

Closed-Set Identification - 已知数据库中存在那个人。

Closed-Set Identification − The person is known to be existing in the database.

Enrollment - 候选人第一次使用生物识别系统时，将记录基本信息，如姓名、地址等，然后记录候选人的生物特征。

Enrollment − It is when a candidate uses a biometric system for the first time, it records the basic information such as name, address, etc. and then records the candidate’s biometric trait.

False Acceptance Rate (FAR) - 生物识别系统会错误地将未经授权的用户识别为有效用户的可能性度量。

False Acceptance Rate (FAR) − It is the measure of possibility that a biometric system will incorrectly identify an unauthorized user as a valid user.

low FAR ensures high security 提供的生物识别系统。

A biometric system providing low FAR ensures high security.

False Reject Rate (FRR) - 生物识别系统错误地将授权用户拒绝为无效用户的可能性度量。

False Reject Rate (FRR) − It is the measure of possibility that the biometric system will incorrectly reject an authorized user as an invalid user.

Open-Set Identification - 不能保证数据库中存在那个人。

Open-Set Identification − The person is not guaranteed to be existing in the database.

Task - 当生物识别系统搜索数据库以查找匹配样本时。

Task − It is when the biometric system searches the database for matching sample.

Application Areas of Biometrics

生物识别系统有用的应用程序有很多。以下给出其中几个：

There are a number of applications where biometric systems are useful. Few of them are given below −

  1. Controlling workplace access.

  2. Identity establishment of people for authentic citizenship and immigration systems.

  3. Applying access control to sensitive information and systems.

  4. Identifying criminals by forensics.

  5. Executing online e-commerce transactions.

  6. Fraud and theft reduction.

  7. Law enforcement.