# Data Encryption

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Difficulty

Intermediate

Video Transcription

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>> Hi there and welcome to our next

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>> lesson, data encryption.

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>> What we'll be covering in this lesson

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will be some encryption basics,

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issues around encryption, key elements,

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no pun intended, types of encryption schemes,

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and applications of cryptographic systems.

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Let's begin. Some basics of encryption.

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It's designed to protect data

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that's in transit over the networks,

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and it also protects information stored on computers.

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This is referred to as data at rest and data in transit,

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and so both of those states

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have basically a different types

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of encryption to protect it.

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It's basically also designed to

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deter and detect accidental deletion,

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and verify the authenticity

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of a transaction of a document.

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Just a couple of things on encryption issues.

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Encryption can be subject to

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government laws and regulations.

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Some countries restrict the import or export

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of different encryption schemes and encryption devices.

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Protection of the keys is paramount.

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If you don't protect the keys

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or if the keys are compromised,

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all your encrypted data is potentially at risk.

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An encryption could show a confidentiality,

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but it can't necessarily ensure

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the loss or modification of data.

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Basically, the data can be modified,

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in which case it can make it inaccessible to all,

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or the data can be lost and exfiltrated.

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A lot of cases, particularly with state-based actors,

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even if the data is encrypted,

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the information can be exfiltrated from the system and

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then stored and brute-forced

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until such a time as the key is discovered.

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It's important mechanism to remember for encryption,

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protects information but it's not

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the only thing that can protect information.

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A couple of key elements of encryption.

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We have the encryption algorithm,

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which is simply just a mathematically based function

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used to encrypt and decrypt the data.

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Now, you can write entire PhDs on encryption algorithms,

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but from a size perspective,

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the concept of what an encryption algorithm

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is is all you really need to know.

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Now, encryption keys are

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essentially the information that is used

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by the algorithm to make

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the encryption and decryption process unique.

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Think of an encryption key

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very much like a key to your door,

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it's unique to your door and can

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open your door and only your door.

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Now the key length, this is a length of the key itself,

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and the long the keys basically

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make the key more difficult to compromise.

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There are attacks against encryption and

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older encryption schemes can

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be brute-forced and easily

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decrypted via a number of techniques.

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The way to protect against that is

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to make the length of the key longer,

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so more complex and more difficult to attack.

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Different types of encryption schemes,

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now we'll cover these in detail in the coming slides.

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But you have your symmetric key systems which use

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a single unique key for encryption and decryption.

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Asymmetric key systems, which will use

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a decryption key which will

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be different to the encryption key.

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Basically, it has hash functions

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which will transform the text

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into something of an arbitrary length

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of fixed-width called the digest or a hash.

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The hash systems are one way only,

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and it can be used to enhance other encryption schemes

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or add authenticity or integrity properties,

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which we'll go into more detail shortly.

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There is also public key infrastructure

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and quantum cryptography.

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Symmetric key cryptographic system,

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so it's based on a symmetric encryption algorithm

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of which there are a number of different types.

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It will use a secret key to

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encrypt the plaintext to ciphertext,

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and it will use the same key to

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decrypt the ciphertext to the plaintext.

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Common example would be

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the data encryption scheme or DES,

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or the advanced encryption scheme,

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AES, which is more commonly used today.

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Some advantages and disadvantages.

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The keys are much shorter,

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so they're not necessarily as strong as other keys.

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It is less complicated and

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does use less processing power,

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but also the key distribution is a main issue.

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If you are wanting to protect

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a message with the symmetric key,

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you also need to work out a way

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to securely transmit the key

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to the person that you want to read the message.

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Asymmetric key cryptographic system.

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Basically,

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the main implementation that you'll come across

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here is probably public key cryptography,

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which we'll talk about separately in a coming slide.

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Now here, two keys we'll work together as a pair,

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now one key is kept private and

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the other key is publicly disclosed.

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Here's how the encryption process will generally work.

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We'll use the very common example

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from cryptography lessons with Bob and Alice.

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Bob will distribute his public key to Alice.

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Alice will encrypt the message for Bob

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with the public key and send it back to Bob.

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Bob will receive the message from Alice and

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use the private key to decrypt the message.

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The private key, by the nature of it being a private key,

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is only held by Bob.

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Therefore, Alice can send a message to Bob encrypted

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with his public key knowing

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that only Bob can actually decrypt it,

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because only Bob has the private key.

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Now public key cryptography systems,

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so these were developed to

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solve the key distribution problem.

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First practical implementation is the Ron Rivest,

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Adi Shamir, and Leonard Adleman,

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so the RSA algorithm.

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A couple of advantages and disadvantages.

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Key distribution, the problem is now solved.

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Basically, if you want to send a message to

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somebody that you haven't seen before,

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haven't met, or don't have regular communication with,

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you can get their public key which

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is readily accessible and know that

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that message will stay secret until

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it reaches the intended recipient,

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who is the only one who has access to the private key.

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One disadvantage is the key length

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does need to be a lot larger.

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It is an advantage and disadvantage to a degree.

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Obviously, the larger the key,

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the stronger the protection.

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But also it makes it more difficult for processing on

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smaller systems which may not necessarily have

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the processing capability for the size of the key.

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That brings us onto a disadvantage there,

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the complex algorithm will need high processing power.

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In small devices, Internet of Things type

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devices which may have

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very limited hard drive space, RAM,

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etc, or processing power,

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these types of algorithms might not be very efficient.

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Now a hash function will be used for digital signatures.

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What the hash will do,

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will provide the properties of

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data integrity, authentication, and non-repudiation.

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It basically ensures the genuineness of

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a particular item that

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has been run through a hash function.

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Public key infrastructure,

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so this is designed to

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manage the process of key distribution,

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revocation, or replacement.

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It's an infrastructure that is simply

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designed to manage the transmission,

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and storage, maintenance of power breaking private keys.

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Basically, it is the power behind

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the security of modern Internet services.

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You've got a couple of components.

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You've got your certificate authority,

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you've got your certificate revocation list,

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and your registration authorities,

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and each of these work together to

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provide a process that you can securely and

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safely guarantee that a public or

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a private key are kept

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in the manner that they need to be kept in.

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Now, quantum cryptography,

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it refers to the possibility of using

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properties of quantum computing

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for cryptographic purposes.

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At this stage, it is predominantly theoretical.

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However, some organizations have

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made some research progress in the last few years.

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Some large tech organizations such as Google and

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Microsoft are leading the way with

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developing actual practical uses

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for quantum cryptography.

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Now, one of the key benefits here would be to

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determine if a message has been intercepted or read.

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Quantum cryptography would have

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a state change if

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the message was in any way tampered with,

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so that we give a level of assurance

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to that particular message transmission.

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Now let's talk about applications

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of cryptographic systems.

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Commonly you'll see cryptographic systems

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in the implementation of Transport Layer Security,

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so that is very much the encryption that

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powers a lot of Internet sites.

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If you see a website with HTTPS,

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it's using a form of Transport Layer Security or TLS,

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and that can either be up to

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version 1.3 is the most current,

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and certainly some of the older versions issues

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that you'll need to be aware of.

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TLS 2 version 1 and

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1.1 are generally not considered secure today.

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TLS also replaced the old Secure Sockets Layer, or SSL,

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which is highly vulnerable to attack these days,

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and realistically you shouldn't be seeing

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that in use in any systems.

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We also have IPSEC,

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IP Security and Secure Shell,

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which are two additional secure communications protocols.

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We also have Secure Multipurpose

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Internet Mail Extensions or S/MIME,

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which is a way of putting encryption over the top of

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the standard email protocol,

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and to give it some level of protection.

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That's our lesson. We've covered

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some of the encryption basics,

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some of the issues that you're likely

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to encounter with encryption,

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a few of the key elements

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of what makes up an encryption scheme,

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different types of encryption schemes,

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and the applications of cryptographic systems.

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I hope you enjoyed the lesson,

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and I will see you at the next one.

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