Public Key Infrastructure - CompTIA Security+ Sy0-701 - 1.4
Summary
TLDRThis 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
🔒 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.
🔑 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.
Mindmap
Keywords
💡Public Key Infrastructure (PKI)
💡Certificate Authority (CA)
💡Symmetric Encryption
💡Asymmetric Encryption
💡Private Key
💡Public Key
💡Key Generation
💡Key Escrow
💡Ciphertext
💡Plaintext
💡Digital Certificate
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.
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