Let us start with the last section of cryptography, that is the Public Infrastructure and Certificate
Authority.
In this lecture, we will learn to introduce and describe what is mean by public cryptography or public
infrastructure.
That is key.
Then we will see about certificate authority and relation between PCI and see, let's get started.
What is begi?
Public infrastructure is a technology for authenticating users and devices in the digital world.
The basic idea is to have one or more trusted parties digitally sign the documents certifying that a
particular cryptographic key belongs to a particular user or device.
The key can be used as an identify the user in digital networks.
The users and devices that have keys are often called as entities in general.
Anything can be associated with a key that it can use as its identity besides a user or device.
It could be a program process, manufacturer component or something else.
The purpose of PGI is to securely associate Akwe with an entity.
The trustor party signing the document, associating with the key is known as certificate authority.
The certificate authority also has a cryptographic key that it uses for signing these documents.
These documents are called certificates.
In the real world, there are many certificate authorities and most computers and Web browsers trust
100 or so certificate authorities by default.
Let us have a look at the key management in BGI.
The first step is the key generation, key establishment, the storage, key usage, Kilkivan and key
destruction.
But what is this in cryptography?
It is very tedious task to distribute the public and private keys between sender, a receiver.
If the key is known to the third party, then the whole security mechanism becomes worthless.
So there comes the need to secure the exchange of keys.
Not that there are two aspects for management distribution of public keys and use of public key encryption
to distribute secrets.
Distribution of public.
Public key can be distributed in full with public announcement publicly available directly public authority
and public certificates.
So what is a public announcement in public announcement?
The public is broadcasted to everyone, but the major weakness of this method is forgery.
Anyone can create a key claiming to be someone else and then broadcast it.
Then publicly available directly in this tape.
The public key is stored in a public database.
Directories are trusted here with properties like participant registration access and allowed to modify
our values at any time.
Public certification, this time, the authority provides a certificate to allow key exchange without
real time access to the public authority.
The certificate is accompanied with some other information and roads which are only restricted to the
authority.
All of this content is signed by the trusted publicly also difficult authority.
That is it.
And then it can be verified by anyone possessing the authority's public.
You have heard the word of certificate authority.
So what is the certificate authority?
A certificate authority also sometimes referred to as a certification authority, is a company or organization
that acts to validate the identities of entities such as websites, emails, companies or even individual
persons and bind them to cryptographic keys through the issuance of electronic documents known as digital
certificates.
A digital certificate provides authentication by serving as a credential to validate the identity of
the entity that it is issued encryption encryption for secure communication or insecure networks such
as the Internet.
And lastly, integrity, integrity of documents signed with the certificate so that they cannot be altered
by a third party in-transit.
Now, let us have a look at how digital certificates and certificate authority work together to produce
the public key infrastructure.
Consider Bob, is an applicant, typically an applicant for a digital certificate, will generate a
key pair consisting of a private and public key along with CSR.
You can see identifying information and public together give a CSR, a CSR stance for certificate signing
request.
A CSR is an encoded text file that includes the public key and other information that will be included
in the certificate.
Keeper and CSR generation are usually done on the server or the workstation where the certificate will
be installed and the type of information included in the CSR varies depending upon the validation level.
Unlike the public, the applicant's private key is kept secure and should never be shown to the CIA
or anyone else.
So if you are the applicant, you must remember your private key and you're not supposed to share this
private key, even with the certificate authority.
So once you are done generating the CSR, you send the application to the CIA.
That is certificate authority, who independently verifies that the information it contains is correct
and if so, digitally sign the certificate within issuing private key and sends it the applicant.
So when the signed certificate is presented to the third party, such as when that person accesses the
holders website, the recipient can cryptographically confirm the C is digital signal via C is publicly
so.
Insha C is signed the document with its public key and the third party can verify.
See it publicly because public key is a public knowledge.
It is readily available through the techniques that we have seen a couple of minutes ago.
Additionally, the recipient can use the certificate to confirm that sign content was sent by someone
in possession of the corresponding private key, and that information has not been altered since it
was signed.
But here is an important thing.
Although any organization such as company, department or a government agency can operate as the Certificate
Authority commercial C is like SSL dot com can provide publicly trusted certificates for purposes such
as as web websites, emails, documents, signing, etc..
A dot com provides PGI with public or private trust for both businesses and government customers.
You can go to the website to check more.
The main weakness of public PGI is that any certificate authority can sign a certificate for any person
or computer.
Among other things, intelligence agencies can use fraudulent certificates for espionage, malware,
forging and injections.
For this reason, only limited trust should be placed on certificates from public certificate authorities.
Make sure that you are aware that some organizations run their own private public infrastructures.
This means they run their own internal sort of authority and therefore then they also trust public keys
for the same entities.
There is no added security in the next chapter.
We will go into dive deeper of cyber security.
That is the applications of cryptography.