What is Public and Private Key Encryption?

How does public and private key encryption work? How is asynchronous encryption different than symmetric encryption?

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Contents
0:00 Types of cryptography - Caesar DES AES asymmetric and hashing
0:45 Symmetric vs asymmetric encryption
1:15 public vs private keys
1:30 Whitfield Diffie New Directions in Cryptography
1:55 PGP Phil Zimmerman 1991 US Customs
2:50 Symmetric Encryption Standard Password Problems
4:10 Asymmetric encryption advantages
4:50 GPG gen-key
5:10 Share public key in GPG
5:35 import public key into gpg encrypt for user

[ricardo_alonzo]

I have to say, I watched some of your videos on WCF during my last quarter and they were super helpful. I'm glad you've made videos on this topic as well, because now I have a cripto class to prepare for! Thank you!

[myajayb]

Very simple and elegant explanation. Love it.

[ggo]

Very smooth explaination. I was confused before I watched the video, but then all became clear. Just a question came to my mind while reading the comment.

Do my friend and I have to have the same tool of encryption or everyone can have his own tool.

Thank you,

[mustarikulislam]

Thank you so much, sir. It helped me out.

[shmoo]

I randomly found this video while working on my essay for Communications in Grand Canyon University!

[BenEverett]

How about adding a link to the next video in the comments? Otherwise, I can't find it. It should also be explained that public and private keys are generated together and they are mathematically related to one another. A public can't be used to derive the private key and vice versa. Without telling the view that, the viewer will never quite understand how the keys can work and be secure.

[lukakavteli]

i don't get it like u can encrypt with the public key but how he decrypts with his private key if i did encryption? when i havn't sent any password? how i allow my friends privet keys to decrypt it?

[exodus]

I would like to know is there a way to know if a public keys private key is odd or random

[muhammadali]

Hi. If you say, the answer to the question, whether governments should be able to check communication is always "no", then this would be the end of criminal investigation, which I think is not what you really want, right? With respect to terror, Putin, China, white-collar-crime, interner-fraud, child pornography etc. public authorities MUST not be excluded from any communication media.

[kaushikdr]

Wonderful video! I am still a bit confused about how using a public/private key solves the problem of having your key stolen in transfer?

Even if I share my public key to the entire world, when I send an email to someone, they have to have the right private key to open it. Don't I have to give them the private key ahead of time?

Also, what is the point of even knowing the sender's public key and putting it globally for decrypting a message? The only thing that should matter is the private key, right?

[matiastrane]

Very good description! I understand it like this: My friend, that wants to send me an encrypted message, creates the message which is the reason it doesn't need to be encrypted, yet. Then he wants to send it to me over the internet, which would require encryption for it to be private. I create public and private keys and provide him with the public key, so he can encrypt it and i can decrypt it with the private key. Is this correct? If so, i have a follow-up question: For me an my friend to be able to send encrypted messages to each other, we would both need a set of public and private keys, right?

[yapayzeka]

0:45 image is misleading. open and lock goes both ways.

[sssapss]

Ok what about the privat key how they havit i need explanation for private key

[TINTUHD]

Great video.

Question: How does the public key know which private key will work? Since it never knows the private key.

[amitchauhan]

Thanks Respected Prof. I could not find its next video. Can you point me to it and its playlist? At the end you were decrypting the message, i want to see what happened next.

[mermaidinclouds]

Well, where I really don't agree with the government keeping a third-eye on our data, I do see a point where it is required to surveillance terrorism activities, given, government don't turn to use data for their own purpose without an agreement.

[thunderstruckx]

What the hell is wrong with the comment section???
Thx for the video btw)

[DeputyDawgAtl]

Ok what i'm still tripping on (Using Alice and Bob in my example) - I get that Bob's public and private key are mathematically linked.  However if Alice is across the globe how is her public and private linked to Bob.  So as I understand it, Bob will use his public key to encrypt a message and send to Alice which she uses  her private key to decrypt.   OK i'm fine with that. But how is Alices private key linked to Bobs key?     If Bob wants to send another msg, say to Tom - again he uses his public key to encrypt.  Tom uses his private to decrypt - how is Tom's key linked?  I'm missing something super basic here.  Any help appreciated

[silverjohnson]

doesn't really explain how it works, more of how to use it.

[charlotteharris]

Tabbyhacks on !nsta got my private key ready