L.O: STUDENTS WILL BE ABLE TO EXPLAIN PUBLIC

KEY ENCRYPTION.40-45 minutes

DO NOW:

READ Unit 2 Lab 6: Encryption, Page 3

Public Key Encryption:• the methods discussed

so far all have a basic weakness: the encryption method or key needs to be kept secret. But keeping the key private is almost as hard as keeping the message private.

In 1976 Ron Rivest, AdiShamir, and Len Adleman

devised an ingenious method (now known as RSA) that

allows a person to announce publicly how anyone can

encode a message to him so that only he is able to

decipher it.

The information, which is given away to

everybody, is called the public key. The

information which is needed for deciphering

(the private key) is known only by the

person for whom the message is intended.

If Bob wants to send Alice a secret message, he

enciphers it with Alice's public key. Then no one

else can decipher it, even knowing her public key. Only her private key can

undo the encryption, and you can't figure out the

private key from the public key.

For You To Do

1. It may seem incredible that Alice can make her encryption key public and still no one except her can decrypt her message. The RSA method relies on some mathematics and on some limitations on the speed of current computers. Read "Secrecy Changes Forever" (Blown to Bits pages 178-181) to understand some of how this works

Here is a model of public key encryption (from wikimedia.org)

2. With a partner, discuss how these pictures are different. Would you trust this method to work to send your own

credit card number?

Take it further: (extension activity)Read "The Key Agreement Protocol" and "Public Keys for Private

Messages" (Blown to Bits pages 181-183) for more details on Public Key Encryption.

HOMEWORK:read Chapter 5 of “Blown to Bits”.

Reading through the entire chapter will be helpful, especially to get a better understanding of the

evolution of encryption methods and some details of public key encryption.

Learning Objectives:1. LO 6.3.1 Identify existing cybersecurity

concerns and potential options to address these issues with the Internet and the systems built on it. [P1]

2. LO 7.5.2 Evaluate online and print sources for appropriateness and credibility [P5]

GIVE EXAMPLES OF THESE LEARNING OBJECTIVES IN THE LESSON

Enduring Understandings:

1. EU 6.3 Cybersecurity is an important concern for the Internet and the systems built on it.

2. EU 7.5 An investigative process is aided by effective organization and selection of resources. Appropriate technologies and tools facilitate the accessing of information and enable the ability to evaluate the credibility of sources

EXPLAIN THESE “ENDURING UNDERSTANDINGS”

Essential Knowledge:1. EK 1.2.5A The context in which an artifact is used

determines the correctness, usability, functionality, and suitability of the artifact.

2. EK 1.2.5B A computational artifact may have weaknesses, mistakes, or errors depending on the type of artifact.

3. EK 1.2.5C The functionality of a computational artifact may be related to how it is used or perceived.

4. EK 1.2.5D The suitability (or appropriateness) of a computational artifact may be related to how it is used or perceived.

5. EK 3.2.2D Maintaining privacy of large data sets containing personal information can be challenging.

EXPLAIN THESE “ENDURING UNDERSTANDINGS”

Essential Knowledge:

• 6.EK 3.3.1A Digital data representations involve trade-offs related to storage, security, and privacy concerns.

• 7.EK 3.3.1B Security concerns engender trade-offs in storing and transmitting information.

• 8.EK 3.3.1F Security and privacy concerns arise with data containing personal information.

• 9. EK 5.4.1L An explanation of a program helps people understand the functionality and purpose of it.

• 10. EK 5.4.1M The functionality of a program is often described by how a user interacts with it

EXPLAIN THESE “ENDURING UNDERSTANDINGS”

Essential Knowledge:

• 11.EK 6.1.1A The Internet connects devices and networks all over the world.

• 12.EK 6.1.1D The Internet and the systems built on it facilitate collaboration.

• 13.EK 6.3.1A The trust model of the Internet involves trade-offs.

• 14. EK 6.3.1B The DNS was not designed to be completely secure.

• 15. EK 6.3.1C Implementing cybersecurity has software, hardware, and human components.

• 16. EK 6.3.1D Cyber warfare and cyber crime have widespread and potentially devastating effects

EXPLAIN THESE “ENDURING UNDERSTANDINGS”

Essential Knowledge:

• 17. EK 6.3.1H Cryptography is essential to many models of cybersecurity.

• 18. EK 6.3.1I Cryptography has a mathematical foundation.

• 19. EK 6.3.1J Open standards help ensure cryptography is secure.

• 20. EK 6.3.1K Symmetric encryption is a method of encryption involving one key for encryption and decryption.

• 21. EK 6.3.1L Public key encryption, which is not symmetric, is an encryption method that is widely used because of the functionality it provides.

EXPLAIN THESE “ENDURING UNDERSTANDINGS”

Essential Knowledge:

• 22.EK 6.3.1M Certificate authorities (CAs) issue digital certificates that validate the ownership of encrypted keys used in secured communications and are based on a trust model.

• 23.EK 7.3.1A Innovations enabled by computing raise legal and ethical concerns.

• 24.EK 7.3.1G Privacy and security concerns arise in the development and use of computational systems and artifacts.

• 25.EK 7.3.1L Commercial and governmental curationof information may be exploited if privacy and other protections are ignored.

EXPLAIN THESE “ENDURING UNDERSTANDINGS”