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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