pace-it, security+ 6.1: introduction to cryptography (part 1)

Introduction to cryptography I.

Instructor, PACE-IT Program – Edmonds Community College

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Education M.B.A., IT Management, Western Governor’s University B.S., IT Security, Western Governor’s University

Entrepreneur, executive leader, and proven manger with 10+ years of experience turning complex issues into efficient and effective solutions. Strengths include developing and mentoring diverse workforces, improving processes, analyzing business needs and creating the solutions required— with a focus on technology.

Brian K. Ferrill, M.B.A.

Introduction to cryptography I.PACE-IT.

– Cryptographic services.

– Encryption basics.

Cryptographic services.Introduction to cryptography I.


– Cryptography.» The process of deriving a code value from a set of data

—taking a clear text message and creating a ciphertext message.

• Also, the process of decoding the ciphertext message to obtain the clear text message.

» Offers three basic services: encryption, hashing, and authentication.

– Encryption services.» The process of taking a clear text message (or set of

data) and scrambling it through the use of a cipher—an algorithmic process.

• Used to secure messages and data sets against theft or loss, including its interception while in transit.

» There are different types and methods of encryption that can used.


– Hashing services.» The process of taking a set of data and using an

algorithmic process to generate a value (known as the hashed value or message digest) that only the original data value can generate.

• The hashed value is generated and is appended to the data and is used to help ensure the integrity of the data.

» If the data, with the hashed value, is sent to another party, that party can use the same hashing algorithm on the data and compare the two hashed values.

• If the two hashed values match, the integrity is ensured.

– Authentication services.» A cryptographic method used to prove that the creators

of messages are in fact who they say they are.» Used for non-repudiation purposes—the person

sending the message, once authenticated, cannot claim that the message did not come from him or her.

• Usually achieved through the use of digital signatures.

Encryption basics.Introduction to cryptography I.

Encryption algorithms work by using a key to scramble the data (or message), so that if the data is intercepted, it can’t be read.

To unscramble the data, the process is reversed. Encryption algorithms are either symmetrical or asymmetrical in nature.With symmetrical encryption algorithms, both sides of the communication use the same key to encrypt and decrypt the data. With asymmetrical encryption algorithms, one key is used to encrypt the data and a different key is used to decrypt the data (the key that encrypts the data cannot be used to decrypt it). Asymmetrical encryption is more secure, but it also requires more management and computing resources.



– Encryption key exchange.» In order for encryption to function between different

entities, the proper keys must be used (e.g., exchanged between the communicating parties).

• The key exchange may occur in-band—as part of the communication session.

• The key exchange may occur out-of-band—outside of the data communication channel (e.g., sharing the encryption key over the phone, then sending encrypted data over the Internet).

– Key types.» Symmetrical encryption key types.

• Preshared key (PSK): the encryption key is shared before the communication session starts—out-of-band key exchange (a PSK can also be called a secret key or private key).

• Session key: a random key that is generated during the communication session—in-band key exchange.

» Asymmetrical encryption key type.• Uses a public key and a private key system referred to

as public key infrastructure (PKI) to manage the keys—in-band key exchange.


– Basic encryption methods.» Stream cipher: the encryption occurs one bit at a

time.• The encryption process is fast and, if an error occurs,

it will usually only affect a single bit.» Block cipher: the encryption takes place on

predetermined blocks of data (e.g., 64-bits at a time).• The encryption process is slower and more error

prone, but is considered to be more secure than the stream type method.

– Steganography.» The process of encoding (or concealing) data within a

graphic file.• The person receiving the graphic file must use

steganography software to read the secured data.» Can be used to place an encoded message on a

graphic image on a website that the recipient can retrieve and decode.


– Transportation encryption.» It may be vital that certain information flowing across

public networks (e.g., the Internet) be kept secure during the transportation process.

• It may also be wise to provide security when using communication channels on private networks.

» Specific protocols have been developed to help secure communication channels.

• HTTPS (HTTP Secure): used to encrypt communication between a Web server and a client (utilizes SSL or TLS to provide the encryption).

• SSL/TLS (Secure Socket Layer/Transport Layer Security): used to encrypt communication channels, usually at the transport layer (Layer 4) of the Open Systems Interconnection (OSI) model.

• S/MIME: (Secure/Multipurpose Internet Mail Extension): used to encrypt email messages.

• IPsec (Internet Protocol Security): a suite of protocols that are used to authenticate users and encrypt the communication channel.

What was covered.Introduction to cryptography I.

Cryptography is the process of taking clear text data and converting it to ciphertext through the use of algorithms. Cryptography provides three basic services: encryption—used to secure data against theft or loss, hashing—used to ensure the integrity of data, and authentication—used to authenticate users and to enforce non-repudiation.

Topic

Cryptographic services.

Summary

Encryption works by using an algorithmic key to scramble data. If the same key is used on both ends of the encryption process, it is symmetrical; if different keys are used, it is asymmetrical. Encryption keys may be exchanged either in-band or out-of-band. And they may be a PSK, a session key, or part of a PKI process. The encryption process may involve a stream or block cipher. Steganography is the process of encoding data in a graphic file. Transport encryption is used to secure data during the transmission process.

Encryption basics.

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