26. Encryption

cryptography

What is the use of mathematical algorithms to transform information into a form where it's not readable by unauthorized individuals, but authorized individuals have the ability to transform it back into its readable form?

encryption and decryption

Cryptography depends upon what two basic operations?

algorithm

What is a set of mathematical instructions that you follow to achieve a result?

the plaintext message and an encryption key

What two inputs are used for encryption algorithms?

the encrypted message, otherwise known as the ciphertext, and a decryption key

What two inputs are used for decryption algorithms?

symmetric and asymmetric

What are two of the major categories of encryption algorithms?

Asymmetric encryption algorithms

Which algorithm is also known as public key cryptography?

the recipient's public key, which is publicly known

In asymmetric cryptography, the sender of a message would encrypt it with what key belong to the recipient?

private key

In asymmetric cryptography, the recipient would then use what key to decrypt the message? 

False. Asymmetric cryptography is slower.

True or False?

Asymmetric cryptography is faster than symmetric cryptography.

confidentiality

What goal of cryptography ensures that unauthorized individuals are not able to gain access to sensitive information?

integrity

What goal of cryptography is to protect messages against unauthorized modification?

authentication

What goal of cryptography is to verify the identity of users?

obfuscation

What goal of cryptography is to make data unintelligible?

 non-repudiation

What goal of cryptography is so that the recipient of a message can prove to an independent third party that the message actually came from the alleged sender?

code

What is a system that substitutes one meaningful word or phrase for another? This might be done for secrecy purposes, or it might be done for efficiency of communications, allowing a short message to convey a detailed meaning. 

Ciphers

What are systems that use mathematical algorithms to encrypt and decrypt message?

Stream ciphers

What kind of cipher works on one character of the message at a time? They perform their action on a single character or a single bit, and then move on to the next character or bit. 

Block ciphers

What kind of cipher works on chunks of the message known as blocks at the same time? They might take 100 characters of a message, for example, and encrypt all of those characters at once. 

Substitution ciphers

What kind of cipher changes the characters in a message?

Transposition ciphers

What kind of cipher doesn’t change the characters in a message, but instead they rearrange them? They're basically scrambling up the message in a way that only someone who knows the decryption key can unscramble them. 

Rotation Cipher

What kind of substitution cipher simply rotates the alphabet several positions to the left or right?

 exclusive OR operation

What is a logical operation that is true when one and only one of the inputs is true?

Pseudorandom number generators

What uses a complex series of inputs and mathematical functions to produce numbers that are very close to random?

Confusion

What is the concept?

A cipher must hide the connection between the cipher text and the key to make it more difficult to crack. In technical terms, every bit of the cipher text must depend on more than one bit of the encryption key.

Diffusion

What is the concept?

Changing a single bit of the plain text should produce a change that is spread across a large portion of the cipher text. Ideally, changing one bit of the plain text would change at least half of the bits of the cipher text. 

True

True or False?

The longer your key, the more secure your information will be. 

The downside is as keys get longer, the performance of the algorithm goes down.

Because it is totally random.

Why is the one-time pad unbreakable?

It's very difficult to distribute one time pads.

The one time pad is the perfect algorithm, so why isn’t it widely used today?

1st phase - initiation

In what phase of the cryptographic lifecycle does the organization realizes that it needs a new cryptographic system and gathers the requirements for that system?

 2nd phase - acquisition and development

In what phase of the cryptographic lifecycle does the organization develop or, more likely, acquires the cryptographic system. The organization finds an appropriate combination of software, hardware, and algorithms that meet their objectives.

3rd phase - implementation and assessment

In what phase of the cryptographic lifecycle does the organization configure their system for use and assess whether it properly meets the organization's security objectives.

4th phase - operations and maintenance

In what phase of the cryptographic lifecycle does the organization ensure the continued secure operation of the crypto system.

5th phase - sunset

In what phase of the cryptographic lifecycle does the organization stops using the system and destroys or archives sensitive material, such as the keys that it used with the system.