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58 Cards in this Set
- Front
- Back
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What is encryption? |
Change data into a form that is unreadable and not understandable by anyone who is not intended to |
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Why use encryption? |
To minimise the risk of being intercepted by hackers when the data is transmitted over a public network |
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What is eavesdropper |
A person who intercept the data being transmitted |
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What are the security concerns? |
Confidentiality - The data can only be read and decrypted by the person who the data is intended to Authenticity - The need to identify the data whether the source is legitimate Non repudiation - The sender and recipient both can't deny that they were part of the data transmission Integrity - The data will reach to the destination unchanged |
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What is plain text? |
The original data sent before putting through an encryption algorithm |
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What is cipher text? |
The product of the plain text when it is put through an encryption algorithm |
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What is block cipher? |
The encryption of the number of continuous bits in one go rather than one bit at a time |
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What is stream cipher |
The encryption of the number of bits in a sequence when they put through an encryption algorithm |
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What is block chaining? |
A form of encryption which the previous block of XOred with the block of cipher text which is encrypted to prevent identical blocks of plain text to produce identical cipher text |
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What is Symmetric encryption? |
Is an encryption that uses the same secret key to encrypt and decrypt messages |
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What are the disadvantages of using symmetrical encryption |
It suffers from key distribution problem which is cause when both the sender and the recipient uses the same secret key which the sender supplies the secret key to the recipient which can be intercepted The computer can crack the key within few seconds A single secret key is needed for both the sender and the recipient |
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How to solve the problem of symmetrical encryption? |
Use 256 bit encryption which produces 2^256 possible combinations |
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What is asymmetric encryption? |
The key that is used to encrypt is different from the key that is used to decrypt |
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How does asymmetric encryption works? |
1) Both the sender and the recipient generate their own matching pairs of private key and public key 2)The recipient sends the sender it's public key 3) The sender uses the recipient public key to encrypt the document and send to the recipient 4) The recipient receives the document and uses its private key to decrypt the document |
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What is a private key? |
An encryption or decryption key that is known to a single user |
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What is a public key? |
An encryption or decryption key that is known to all users |
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What is quantum cryptography? |
An encryption that is based on the laws of quantum mechanics It uses the physics of photons and physical quantum properties to produce a virtually unbreakable encryption system.This protects the data transmitted over fibre optic cables |
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What is quantum key encryption? |
A protocol that uses the quantum mechanics to securely send the encryption key over the fibre optic networks |
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What is qubit? |
The basic unit of quantum information |
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How do we use quantum cryptography to send the encryption key from a to b using quantum key distribution protocol? |
1) Sender uses a light source to generate light photons 2) The photons send through 4 random polarisers( vertical, horizontal,45 degree left ,and 45 degree right) 3)The polarised photons travels along the fibre optic cable to its destination 4) At the destination there wil be 2 beam splitters diagonal and vertical splitters 5)1 of the 2 beam splitters is chosen at random 6)Repeat the whole process until the whole encryption key has been transmitted from A TO B 7) The sender sends the sequence of beam splitter that were used 8) The recipient compares this sequence with the polarised sequence used at the sending station 9) The sender tells the recipient where in the sequence the correct beam splitters are used 10) This is to ensure that both sender and recipient are fully synchronised 11) The encryption key can be sent again safely and securely because although intercepted the hacker will find it impossible to read it. |
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What are the advantages of quantum cryptography |
It is simple to use It is virtually unhackable It requires lesser resources to maintain it It revolutionises secure communication as security is based on the laws of quantum mechanics rather than mathematical algorithms |
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What are the disadvantages of quantum cryptography |
It requires a dedicated line and a specialist hardware to setup which is expensive It has limited range It is possible for the polarization of light to be altered when transmitting down the fibre optic cable Other criminals can make use of the quantum cryptography which hides their illegal activities from the government law enforcers |
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What is a secure socket layer(SSL) |
A security protocol that is used when sending data over the internet |
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What is transport security layer |
An updated version of the secure socket layer It provides data integrity, encryption and authentication It ensures security and privacy between devices and user when communicating over a network When website and client communicate it prevents 3rd party eavesdropping |
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What is the purpose of Secure Socket Layer |
To encrypt data when users logs onto the website |
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What are the functions of Secure Socket Layer |
1) Data compression 2) Data integrity check |
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What are the examples of uses of Secure Socket Layer and Transport Layer Security |
- online shopping - use of social media - send and receive emails - online banking |
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How does Secure Socket Layer works? |
A user logs onto the website which the Secure Socket Layer will encrypt the data A user will know that Secure Socket Layer is used when they see there is a http protocol and a green padlock |
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How is transport layer security formed? |
Using record and handshake protocol |
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What is record protocol? |
It is used with or without encryption |
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What is handshake protocol? |
It allows webserver and client to authenticate each other and making use of encryption algorithms |
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What is handshake? |
The process of initiating the communication between 2 devices.1 of the device send message to another device requesting to exchange data |
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What are the advantages of using Transport Layer Security |
Transport Layer Security separates the record protocol from the handshaking It can make use of session caching which improves the overall performance of the communication It can extend transport layer security by adding new authentication methods |
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What is session caching? |
A function that remembers the computer previous session to prevent the need to establish a new link when a new session is attempted |
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What is the advantage of using session caching? |
It avoids the need to use as much computer time for each connection |
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What is functions of Secure Socket Layer and Transport Layer Security |
Encryption of data Identifying the client and the server to make sure they know who they are communicating with |
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What is certificate authority? |
A commercial organisation that generates a digital certificate that is requested by the website owner or individual |
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What is public key infrastructure? |
A set of protocols , standards and services that uses digital certificates issued by the certificate authority to authenticate each other |
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What is digital signature |
An electronic way of validating the authenticity of the digital document and identifying the sender It is used to identify by showing proof that it is sent by a known user |
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What is the purpose of digital signatures? |
Data integrity Authentication Non repudiation Confidentiality |
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What is the digest? |
Is a fixed size numerical representation of the contents of the message that is produced by the hashing algorithm.It can be encrypted to form a digital signature |
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What is hashing ? |
A function that converts data string into numerical string which is use in cryptography |
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How does the hashing algorithm works? |
1)The sender's private key and the digest are put into an encryption algorithm to produce a digital signature 2) the plain text and digital signature are sent to the recipient in 2 separate files 3) the recipient receives the digital signature and put through the decryption algorithm to produce a digest 4) the recipient receives the plain text and put through the hashing algorithm to produce a digest 5) if both digest are the same,the documents are correctly send |
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What is the disadvantage of hashing algorithm |
The public key can be forged by hackers which cause the receipient to be uncertain of whether the message is from a legitimate source |
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What is a digital certificate |
An electronic document that is use to proof the identity of the website owner or the individual.It contains a public key and information that is use to identify the website owner or individual which is issued by certificate authority |
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What are in the digital certificate |
Serial number Version number Public key Validity( start date and expiry date of the certificate) |
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How the digital certificate is acquired? |
1) The person A will be the receiver and has a matching public private key . person A will contact the CA 2) CA confirms the identity of person A 3)Person A's send the public key to the CA 4) The CA creates a digital certificate and put Person A's public key into the document 5)The CA uses CA private key to for encryption and to add digital signatures 6) The CA sends back the digital certificate to Person A 7) Person A will post the digital certificate on the website 8) Once posted on the website anyone who wants to use Person A's public key must download the digital certificate from the website and use CA's public key to extract Person A's public key |
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What does the sender needs to do so that only the recipient can read the message? |
Sender needs to encrypt the message using the recipient's public key and the recipient needs to decrypt the message using its own private key |
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What should be part of the software to proof that the software is authentic? |
Digital signature |
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What is the process for ensuring that the software is authentic and has not been changed |
The software has being put through a hashing algorithm Hash total is encrypted with the public key The digital signature is decrypted using public key The receiver has the sender's public key |
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What are the security parameters in the handshake process? |
Encryption method Public or private key used Session ID Uniquely identifies a series of messages between server and client Authentication method Digital certificate or digital signature Session type Reusable or not |
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How can you be sure that the sender sends the key to the specific person? |
By the sender showing the digital certificate which contains the sender public key. The sender is able to decrypt the certificate using the CA's public key |
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How does the handshake protocol works? |
1) The client sends some communication data to the server 2) Client ask the server to identify itself 3) The server sending it's digital certificate including the public key 4) The client validates the TLS certificate 5) The client sends it's digital certificates 6) The client sends an encrypted message to the server using the server 's public key 7) The server can use its private key for decrypting the message and getting the data needed for generating symmetric key 8) Both server and client compute symmetrical key 9) The client sends back a digital signed acknowledgement to start an encrypted session 10) The server sents back a digital signed acknowledgement to start an encrypted session |
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How digital signature is produced by the CA? |
By using hashing algorithm to generate a message digest from the particular certificate.Message digest is encrypted with CA's private key |
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How a digital signature is produced for transmission with the message? |
The message is hashed with agreed hashing algorithm to produce a message digest The message digest is encrypted with the sender's private key so the digital signature can be decrypted with sender's public key |
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What are the advantages of asymmetric encryption |
It allows non - repudiation It allows message authentication It has increase message security as one key is private |
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What is the reason for asymmetric cryptography? |
Only the receiver has the key to decrypt the message. Private key don't need to be transmitted |
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How a digital signature is used to verify a message when it is received? |
The message together with the digital signature is decrypted using the receiver’s private key • The digital signature received is decrypted with the sender’s public key to recover the message digest sent • The decrypted message received is hashed with the agreed hashing algorithm to reproduce the message digest of themessage received • The two message digests are compared • if both digests are the same the message has not been altered // if they are different the message has beenaltered. |
