Topic 8

Data security and integrity processes

Before you start this topic, recap AS work

AS Recap Topic 16

What you need to know for A2:-

Protecting data integrity - Explain the special security and integrity problems which

can arise during online updating of files

These video aims to remind you of the different security risks there are to data. Data security refers to the process of protecting data from unauthorized access and data corruption throughout its lifecycle.

Data security includes data encryption, hashing, tokenization, and key management practices that protect data across all applications and platforms.

Integrity of data refers to the accuracy and consistency of data stored in a database, data warehouse, data mart or other construct.

This is important as it guarantees and secures the searchability and traceability of your data to its original source.

Maintaining data integrity requires an understanding of the two types of data integrity: physical integrity and logical integrity.

Cryptography - Describe the need for and the purpose of cryptography.

Cryptography - Describe techniques of cryptography and their role in protecting data.

Cryptography - Follow algorithms and programs used in cryptography.

Cryptography - Compare cryptographic methods and their relative strength.

This video aims to discuss the need, use and techniques of cryptography.

This video was produced by Crash Course Computing - look them up on youtube; they have lots of videos useful at Alevel.

What is meant by a good cipher?

amount of secrecy should determine the amount of work needed to encrypt and decrypt
the cipher must work on all types of data
the algorithm should be simple to minimise implementation errors
If an error is introduced it should not impact the rest of the message
the size of the cipher text should be no larger than the original plain text

The strength of an encryption algorithm relies on the the key rather than the process of the cipher. The goal of the attack therefore focuses on trying to work out the key usually via brute-force which tries every combination to find match. An alternative is statistical analysis: if certain groups of characters appear more often than others in the cipher text then the frequencies can be compared with the frequencies of certain groups pf characters in plain English.

When looking at the strength of an encryption algorithm, it is important that is adds diffusion. Diffusion will ensure that each letter of plain text will impact more than one letter in the cipher text. By combining different letters together in different ways you limit the predictability of the resultant cipher. This can be combined with random data to further gaurd against frequency or dictionary attacks. By using Exclusive OR (XOR) and a random seed, a stream of random data can be created. This operation can be undone by the destination if it knows the random seed, as the values produced by any random number generator will be the same if the seed is the same. This process is know as salting.

The strength of the key will depend on how vulnerable the cipher text is to a brute-force attack. Small keys, which are under 56 bits, can be broken by modern computers in a few day. However larger keys, 128-bit or above, would take millions of years to break brute-force.

Past Paper questions walk through

Symmetric Encryption (encrypted and decrypted using same key)

Asymmetric Encryption (encrypted using public key, decrypted using private key

What is the need for and purpose of cryptography?

Describe techniques of cryptography and their role in protecting data

Compare cryptographic methods and their relative strength

Caesar Shift (Substitution Cipher) | 101 ComputingA Caesar Shift cipher is a type of mono-alphabetic substitution cipher where each letter of the plain text is shifted a fixed number of places down the alphabet. For example, with a shift of 1, letter A would be replaced by letter B, letter B would be replaced by letter C, and so on. This type of substitution Cipher is named after Julius Caesar, who used it to communicate with his generals. Key+5Plain text alphabet:ABCDEFGHIJKLMNOPQRSTUVWXYZ Cipher text alphabet:FGHIJKLMNOPQRSTUVWXYZABCDE This type of cipher is a form of symmetric encryption as the same key can be used to both encrypt and decrypt a message. (e.g. If a message is encrypted with a key of +5, it can be decrypted with a key of -5). You can generate your own encryption keys and encrypt your own messages using our online Caesar Shift substitution engine: Frequency Analysis One approach used to help decrypt a Caesar shift substitution cipher is to use a frequency analysis based on counting the number of occurrence of

Symmetric vs. Asymmetric Encryption | 101 ComputingCryptography is the art of encoding and decoding secret messages. Cryptographic techniques have been used for thousands of years, well before the introduction of computers, and the techniques have evolved since. (e.g. See how the Caesar Cipher was used by the roman empire 2000 years ago). More recently, with the introduction of electronics and later on computer science, it has been possible to implement more advanced encryption techniques based on complex mathematical calculations. (e.g. See Alan Turing's work on breaking codes encrypted by the Germans using the Enigma Machine during World War 2). Symmetric Encryption At this stage, encryption techniques were based on symmetric encryption algorithms. With such algorithms a single secret key is needed to both encrypt and decrypt a message. The secret key is possessed by both parties involved in the communication, the sender and the receiver. Symmetric Encryption: The same cryptographic key is used both to encrypt and decrypt messages.

XOR Encryption Algorithm | 101 ComputingThe XOR Encryption algorithm is a very effective yet easy to implement method of symmetric encryption. Due to its effectiveness and simplicity, the XOR Encryption is an extremely common component used in more complex encryption algorithms used nowadays. The XOR encryption algorithm is an example of symmetric encryption where the same key is used to both encrypt and decrypt a message. Symmetric Encryption: The same cryptographic key is used both to encrypt and decrypt messages. The XOR Encryption algorithm is based on applying an XOR mask using the plaintext and a key: Reapplying the same XOR mask (using the same key) to the cipher text outputs the original plain text. The following truth table (based on the XOR truth table) demonstrates how the encryption process works. P (Plain text) K (Key) C (Cipher)=P XOR K K (Key) P (Plain Text)=C XOR K 00000 10101 01110 11011 The XOR encryption algorithm can be applied to any digital/binary information, included text based information

This video attempts to describe how an asymmetric encryption algorithm works. Focus on the bits which show how the public and private keys are developed and used (in the middle of the video).

XOR Encryption - Tech-FAQThe XOR encryption is a simple symmetric cipher that is used in many applications where security is not a defined requirement. The XOR Operator XOR (Exclusive OR) is a bitwise operator from binary mathematics. The six bitwise operators, as defined in the C programming language, are: Operation Symbol AND & Inclusive OR | Exclusive OR

Here is a past paper question which combines your theory knowledge of Cryptography with your ability to apply XOR encryption to a message (in binary).

WJEC 2017

Looking at 8(b) in a bit more detail:

Original Message = O K ! (ASCII characters)

0100 1111 0100 1011 0010 0001 (convert to binary equivalent)

XOR Key 1111 0011 1111 0011 1111 0011 (XOR key repeated for each character in message)

XOR the two lines above together:

Encrypted string 1011 1100 1011 1000 1101 0010 ** This answer gets you the 3 marks for Qu 8(b) **

------------------------------------------------------------------------------------------------------------------------

Note: this is an example of symmetric encryption, where the same key is used to encrypt and decrypt the message. If you take the encrypted string and reapply XOR using the same key (1111 0011), you will get the original message, as follows:

Encrypted string 1011 1100 1011 1000 1101 0010

XOR Key 1111 0011 1111 0011 1111 0011

0100 1111 0100 1011 0010 0001

O K ! = Original Message

Biometrics - Describe the purpose and use of contemporary biometric technologies..

Biometrics - Describe the benefits and drawbacks of biometric technologies.

Biometrics - Describe the complexities of capturing, storing and processing biometric data.

This video aims to take you through what are biometrics, how they work and what the benefits and drawback are.

Malicious software and mechanisms of attack and defence - Describe types and mechanisms of malicious software and their vectors.

Malicious software and mechanisms of attack and defence - Describe black hat hacking, white hat hacking and penetration testing.

This video gives you good background information

This video goes into detail about the three purposes to hacking.

Julian Assange, the man behind Wikileaks, says he’s the victim of a US conspiracy to punish him for exposing alleged US war crimes.