Public Key Infrastructure - CompTIA Security+ Sy0-701 - 1.4

Summary

This script delves into the fundamentals of cryptography, focusing on Public Key Infrastructure (PKI) and its role in managing digital certificates. It contrasts symmetric and asymmetric encryption, highlighting the efficiency of the former and the security advantages of the latter. The explanation of key generation, distribution, and the secure exchange of encrypted messages using public and private keys provides insight into the practical applications of cryptography in ensuring data security.

Takeaways

• 🔒 Public Key Infrastructure (PKI) encompasses policies, procedures, hardware, and software for managing digital certificates, which involves extensive planning and decision-making in encryption methods.
• 🔑 PKI is also used to associate certificates with people or devices to establish trust through Certificate Authorities (CAs).
• 🔒 Symmetric encryption uses the same key for both encryption and decryption, often depicted as a single secret key that must be securely shared between parties.
• 🔑 Asymmetric encryption utilizes two mathematically related keys: a public key for encryption that can be shared openly, and a private key for decryption that must be kept secret.
• 🔐 The security of asymmetric encryption lies in the fact that even with access to the public key, deriving the private key is computationally infeasible.
• ⚡ Symmetric encryption is favored for its speed and low overhead, often used in conjunction with asymmetric encryption for optimal security.
• 🔑 Key generation in asymmetric cryptography is a one-time process involving randomization and large prime numbers, creating a pair of public and private keys.
• 📬 When sending encrypted messages, the public key is used to encrypt the message, ensuring that only the holder of the corresponding private key can decrypt it.
• 🛡️ The private key must be safeguarded with additional measures such as passwords to prevent unauthorized access.
• 🤝 In a corporate environment, managing a large number of public and private keys may require third-party services or internal key escrow systems to maintain data accessibility.
• 🏢 Organizations may implement key management policies to ensure continued access to encrypted data, even when original encryptors leave the company or change roles.

Q & A

What is the term 'public key infrastructure' commonly referred to in cryptography?

Public key infrastructure (PKI) commonly refers to the policies, procedures, hardware, and software responsible for creating, distributing, managing, storing, revoking, and performing other processes associated with digital certificates.

What is the role of a Certificate Authority (CA) in PKI?

A Certificate Authority (CA) is an entity that associates a certificate to people or devices, ensuring trust in the identity of a particular user or device.

What is symmetric encryption and how is it represented in media?

Symmetric encryption is a process where the same key is used for both encryption and decryption of information. In media, it's often represented as a single secret key kept secure, for example, inside a suitcase fastened to a delivery person with handcuffs.

Why is managing symmetric keys challenging as the number of users or devices increases?

Managing symmetric keys becomes challenging due to the difficulty of securely sharing keys among a large number of users or devices and keeping track of which keys correspond to which entities.

Why is symmetric encryption still widely used despite its scalability issues?

Symmetric encryption is still widely used because it is very fast and has less overhead compared to asymmetric encryption, making it suitable for certain applications where speed is critical.

What are the two keys used in asymmetric encryption and how are they related?

In asymmetric encryption, there are two keys: a public key used for encryption and a private key used for decryption. These keys are mathematically related and are created simultaneously during the same process.

How does the public key differ from the private key in terms of accessibility?

The public key can be seen and used by anyone and is often made available to the public, while the private key is accessible only to the individual or device it is assigned to and must be kept secret.

Why is it impossible to derive the private key from the public key in asymmetric encryption?

It is impossible to derive the private key from the public key due to the complex mathematical processes involved in their creation, which ensures that the relationship between the keys is one-way.

What is the key-generation process in asymmetric cryptography and why is it important?

The key-generation process in asymmetric cryptography involves creating a pair of public and private keys, often involving randomization and large prime numbers. It is important because it sets up the foundation for secure encryption and decryption using the public and private keys.

How does Alice's friend Bob use her public key to send an encrypted message?

Bob uses Alice's public key in asymmetric encryption software to convert his plaintext message into ciphertext, which can then be securely sent to Alice. Only Alice's private key can decrypt this ciphertext back into the original plaintext.

What are some scenarios where key management becomes crucial in an organization?

Key management becomes crucial in scenarios such as when a user leaves the organization and access to their encrypted data is still needed, or when multiple organizations need to decrypt data encrypted as part of a joint project.

Why might an organization consider key escrow for managing private keys?

An organization might consider key escrow to ensure the availability and uptime of their data, allowing decryption of information even if the original encryptor is no longer accessible, such as in cases where a user departs or a department restructures.

Outlines

00:00

🔒 Introduction to Public Key Infrastructure and Encryption

This paragraph introduces the concept of Public Key Infrastructure (PKI), a broad term in cryptography that encompasses the policies, procedures, hardware, and software involved in managing digital certificates. It explains the processes of creation, distribution, management, storage, revocation, and other certificate-related tasks. The paragraph also touches on symmetric encryption, where the same key is used for both encryption and decryption, and highlights the challenges of key distribution and management at scale. It sets the stage for a deeper dive into public key encryption, contrasting it with symmetric encryption and emphasizing the importance of key secrecy.

05:01

🔑 Asymmetric Encryption and Key Generation

The second paragraph delves into asymmetric encryption, detailing the creation of a public-private key pair, which involves a complex process of randomization and the use of large prime numbers. It explains that the public key can be shared widely, while the private key must be kept secure and often password-protected. The paragraph illustrates the encryption process using Alice and Bob as examples, where Bob uses Alice's public key to encrypt a message that only Alice can decrypt with her private key. It also discusses the management of keys in larger organizations, including the potential use of third-party key escrow services to maintain access to encrypted data, even when the original encryptor is no longer available.

Keywords

💡Public Key Infrastructure (PKI)

Public Key Infrastructure is a set of policies, procedures, hardware, and software that manage digital certificates. It is central to the video's theme as it sets the stage for understanding the complexities of digital security. In the script, PKI is described as involving the creation, distribution, management, storage, revocation, and other processes associated with digital certificates, which is fundamental to the trust and security in digital communications.

💡Certificate Authority (CA)

A Certificate Authority is an entity that issues digital certificates, which are used to establish the identity of individuals or devices in a network. The CA is integral to the concept of trust in the video, as it is responsible for verifying the identity of certificate holders. The script mentions CA in the context of associating a certificate with people or devices, ensuring that they are who they claim to be.

💡Symmetric Encryption

Symmetric Encryption is a cryptographic method where the same key is used for both encryption and decryption of data. This concept is fundamental to the video as it contrasts with asymmetric encryption and introduces the idea of a shared secret. The script uses the analogy of a suitcase handcuffed to a delivery person to illustrate the importance of keeping the symmetric key secure.

💡Asymmetric Encryption

Asymmetric Encryption is a cryptographic system that uses two different but mathematically related keys: a public key for encryption and a private key for decryption. This concept is central to the video's narrative on encryption methods. The script explains that while the public key can be shared widely, the private key must be kept secret, highlighting the security advantage of this system.

💡Private Key

A Private Key is a unique cryptographic key that is kept secret and is used for decryption in asymmetric encryption. In the video, the private key is emphasized as a critical component of security, as it is the only means to decrypt data encrypted with the corresponding public key. The script illustrates this by describing how the private key is protected and used to decrypt messages sent by others.

💡Public Key

A Public Key is the counterpart to a private key in asymmetric encryption and can be shared openly without compromising security. The script explains that anyone can use the public key to encrypt data, which can then only be decrypted by the holder of the corresponding private key, demonstrating the public key's role in secure communication.

💡Key Generation

Key Generation is the process of creating a pair of cryptographic keys, typically a public-private key pair, used in asymmetric encryption. The video script describes this process as involving a lot of randomization and the combination of large prime numbers, emphasizing its complexity and the importance of a secure key generation process.

💡Key Escrow

Key Escrow refers to the practice of storing private keys with a trusted third party for recovery purposes. In the video, key escrow is presented as a solution for managing private keys in large organizations, ensuring that encrypted data remains accessible even if the original encryptor is no longer available.

💡Ciphertext

Ciphertext is the result of encrypting plaintext using a cryptographic key. The script uses the term to describe the output of the asymmetric encryption process, which can only be decrypted by the intended recipient using their private key, illustrating the secure transmission of information.

💡Plaintext

Plaintext is the original, unencrypted form of a message or data. The video script contrasts plaintext with ciphertext, demonstrating the process of encryption and decryption. The term is used to explain the transformation of readable data into a secure format and back to its original form.

💡Digital Certificate

A Digital Certificate is an electronic document used to prove the ownership of a public key and is issued by a Certificate Authority. The script mentions digital certificates in the context of PKI, emphasizing their role in establishing trust and verifying identities in digital communications.

Highlights

Public Key Infrastructure (PKI) encompasses policies, procedures, hardware, and software for managing digital certificates.

PKI involves significant planning and decision-making regarding encryption methods within a company.

PKI is used to associate certificates with people or devices for identity verification.

Symmetric encryption uses the same key for both encryption and decryption.

The secrecy of the symmetric key is crucial as it can decrypt any data encrypted with it.

Scalability issues arise with symmetric encryption when distributing keys to multiple individuals or devices.

Symmetric encryption is favored for its speed and low overhead compared to asymmetric encryption.

Asymmetric encryption uses a public key for encryption and a private key for decryption, with both keys being mathematically related.

The private key in asymmetric encryption must remain secure and private.

The public key can be used by anyone to encrypt data for the private key holder.

Asymmetric encryption ensures that even if the ciphertext is intercepted, it cannot be decrypted without the private key.

The creation of public and private keys involves randomization and large prime numbers.

Key generation for asymmetric encryption is typically a one-time process at the beginning.

Distributing the public key widely while keeping the private key secure is essential in asymmetric encryption.

Private keys can be password-protected to add an extra layer of security.

In a corporate environment, key management for a large number of users may require third-party services or key escrow.

Key escrow allows organizations to maintain access to encrypted data even if the original encryptor is no longer available.

Transcripts

The term public key infrastructure

is a very broad term in cryptography,

but it commonly refers to policies and procedures,

this might also include hardware and software,

that is responsible for creating, distributing,

managing, storing, revoking, and performing

other processes associated with digital certificates.

Although that seems relatively straightforward, even

in the smallest of companies, this

can involve a great deal of planning

and a lot of decisions that have to be made

about the encryption and methods that you

use within your company.

You might also hear the term PKI used as a way

to associate a certificate to people or devices.

This is usually in conjunction with a Certificate Authority,

or CA.

And it's generally based around how

you may be able to trust that a particular user

or a particular device is really who they say they are.

Before we get into the details of public key encryption, let's

first start with symmetric encryption.

As this name implies, symmetric encryption

means that any time you're performing

a decryption of some information,

you're using the same key that was used to originally encrypt

that information.

In the movies, we often refer to this single secret key being

shown as something inside of a suitcase,

and that suitcase is fastened to the delivery person

with a pair of handcuffs.

This ensures that no one else can gain access

to that symmetric key, which is very important because if you

have the symmetric key, you're able to decrypt anything

that was originally encrypted with that same key.

Sometimes, you'll hear about this process

of symmetric encryption being described

as a secret key algorithm, where that symmetric key is

that one secret key.

You might also hear this referred to as a shared secret

because the same key is used for both the encryption

and the decryption process.

So you have to share the key if you expect someone else to be

able to decrypt that data.

As you might already be thinking,

if you have to provide this secret key

to every single person who needs to decrypt the data,

then you're probably going to have a scalability problem.

Once you get above 10 individuals or devices,

it now becomes very difficult to not only share

the keys between all of these different people

but also manage which keys happen to go with which person

or which device.

As you dive deeper into the world of cryptography,

you'll notice though that we still use symmetric encryption

quite a bit.

And the reason is that it's very fast.

It has very little overhead as compared to something

like asymmetric encryption.

So we usually are using both.

We're using asymmetric encryption

to perform some functions and symmetric encryption

for others.

So if symmetric encryption is encrypting and decrypting

with the same key, asymmetric encryption

is encrypting and decrypting with two different keys.

These two keys that we use, the one for encryption

and the other key for decryption,

are two keys that are mathematically related.

In fact, we create both of these keys at the same time

during the same process.

And that provides that mathematical relationship

between those two keys.

This means once you've created these two mathematically

created keys, you then assign one of them

as being the private key and the other one

as being the public key.

As the name implies, the private key

is the one that only one person or one device

would have access to.

No one else has access to this private key.

The public key, however, can be seen and used by anyone.

The public key, just as that name implies,

can be available to the public.

If you've never used asymmetric cryptography before,

this next part may not seem intuitive,

but this is what adds the power and the magic to performing

asymmetric cryptography.

Everyone who has the public key can

encrypt data and send it to you by using that public key.

The private key that you have is the only key

that can decrypt any of that data encrypted

with the public key.

For example, there may be a number of different individuals

that are encrypting data using your public key

and sending you that information.

If any of those individuals happens to gain access

to this information that's encrypted,

they would not be able to decrypt it with the public key,

because the only key that can decrypt it is the private key,

and you're the only one that owns the private key.

Another important consideration is

although both the public and private key are mathematically

related, you can't derive one key

by simply looking at or owning another key.

Because of the math associated with the creation

of these public and private keys,

there's no way to reverse engineer the private key,

even if you happen to have the public key.

And that is one of the big benefits

of public key cryptography.

If you've ever used an application that

takes advantage of asymmetric encryption, such as PGP or GPG,

you've gone through the process of creating

your public private key pair.

This process of creating a public and private key

is something that occurs simultaneously,

and it usually involves a lot of randomization,

a combination of very large prime numbers,

and a lot of cryptography behind the scenes.

If you're creating these keys as an individual,

this is usually a process you only have to go through once

at the very beginning.

And from that point going forward,

you have your private key and your public key.

So in the case of Alice, she's creating or generating

a new pair of keys.

The key-generation process usually

only takes a few moments.

And it outputs two separate keys.

One of those keys it identifies as the public key.

And it labels the other key the private key.

At this point, we can distribute our public key to our friends.

We can post it on our website or attach it

to our social media pages.

We would then take the private key,

save it locally, and make sure that it is protected.

Very often, we would assign a password to a private key

so that you had to know the password to gain access.

This adds another level of protection,

just in case a third party happens

to come across or gain access to our private key.

So now that Alice has created a public and a private key,

she's made the public key available to everyone.

There is a friend of hers named Bob

who would like to send Alice an encrypted message.

Bob starts on his laptop by writing the message

that we'll refer to as this plaintext that says,

"Hello, Alice."

And he has Alice's public key because, as the public key,

it's available for anyone to use.

This goes into your asymmetric encryption software, which

then creates the ciphertext.

This is the combination of the plaintext

and Alice's public key.

At this point, this ciphertext can be sent to Alice

and can be viewed, effectively, by anyone.

There's no way to decrypt this information

without the private key.

Even if somebody gains access to the ciphertext

and they gain access to the public key,

they still would not be able to somehow

reverse engineer the plaintext.

Now that Bob's created the ciphertext,

Bob can send that over to Alice.

Alice sees that this is encrypted data

and uses her private key to decrypt the ciphertext.

At that point, we're back to the plaintext.

And as you can see, it is identical to the plain text

that Bob originally sent.

When you're dealing with a single person who

happens to have their own public and private key pair,

it's up to the individual to manage those.

And at some time in the future, if you

need to decrypt the information, that individual simply

goes to their private key and decrypts

anything that may still be encrypted on their system.

But when you're working in an environment with hundreds

or thousands of users, and each of these users

has their own public and private key pair,

you may need some way to manage that very large amount of data.

This may be a third party, where you hand over private keys,

and they maintain those private keys

until you happen to need them.

Or perhaps you're performing your own key escrow.

Once everybody creates their keys,

you can store the keys locally.

And if that user happens to leave the company or move

to a different department, you'll

still have the private keys SO that you can decrypt everything

they've been working on.

This is something commonly seen when

you need to provide some way to decrypt data

even if you're not the person that originally encrypted

that information.

For example, as we mentioned earlier,

a user may leave the organization,

but we still need access to all of their encrypted data.

Or it may be a government agency that is working with a partner,

and both of those organizations need

to decrypt data that may have been encrypted

as part of this project.

Handing your private key off to someone else

to be able to manage the process may

seem a little controversial.

But in some cases, it's required in order

to maintain uptime and availability of all

of your organization's data.