Encryption Part I: Introduction to Encryption 2

The second video in our Introduction to Encryption, covering Asymmetric (or Private Key) encryption and hashing.

[CyberSinke]

First video was fantastic, with just the right amount of detail. This one jumps over the question of how can a public key convert a message into something, and then another, private, key can turn this something back into original message.

[rmahmoud]

Working with Asymmetric Algorithms
Asymmetric algorithms use two keys to encrypt and decrypt data. These asymmetric keys
are referred to as the public key and the private key. The sender uses the public key to
encrypt a message, and the receiver uses the private key to decrypt the message; what one
key does, the other one undoes. As you may recall, symmetrical systems require the key to
be private between the two parties. With asymmetric systems, each circuit has one key.
The public ket may be truly public key or it may be a secret between the 2 parties
if someone wants to send you an encrypted message they can use your public key to encrypt the message and then send to you the message,
you can use your private key to decrypt the message .The private key is always protect the privacy of the message

[daixtr]

Thank you. Your explanations are presented very well. It helps a lot. But i have some clarification on the below timestamps:

1:08 ... the public key cannot be used to decrypt?
1:49 ... it's uni-directional??

I think the public key can be used to decrypt which will then verify the sender. And secondly, i think it can be used bi-directionally. Thanks for any clarification.

[hugesinker]

Questions-- How can a public key encrypt a message, but not be reversed to decrypt the message?  How might that work in a simple paper/pencil message?  What options are available for digital encryption of this sort?  Is entropy relevant to asymmetric encryption?

[mulllhausen]

i like your use of the padlock to represent a public key. i've always thought it should be called a padlock and not a public key.

[moazeldefrawy]

in the private key method if Eve has the encrypting key can why can't she decrypt the masseges from bob to alice ? it's like if i want to send 5 i will send 10 which is 5 * 2 so if i know that every number is *2 then when bob sends 20 to alice i can understand that's it's 10 ??

[boring-username]

Hashing made no sense to me until I saw this video. The same text string will always convert to the same hash, so there is no need to store the password itself. Genius! Now, I'm assuming different algorithms will produce different hashes, right?

[BlackVinylMusic]

I see you've answered the same question below, however i think your explanation lacks clarity

[ExplosiveBrohoof]

I don't understand how private key encryption works. If Alice sends an encrypted message to Bob, then how is Bob supposed to be able to read it? He's just as incapable of decrypting that message as Eve is, right?

[BlackVinylMusic]

I'm confused, you say the public key cannot be used to decrypt anything only for encryption, yet other videos say the public key can be used for decryption, and later you say the public key can be used to verify the message is encrypted by Alice's private key, how is this so if Bob cannot decrypt the message?

[kilroy]

Private-key encryption sure sounds like public-key encryption, I'm assuming the terms are synonymous.