what is public key cryptography?

Question

ok so i know the basics but i have a few questions.
- is this like something people can use or is it like a FBI thing that no one can use
-when they say encrypting messages do they mean like text messages or emails or like federal documents
-how do you do it? cant you just sign your name at the bottom and they know its yours?
im in 7th grade and im 13 so please dont use big words that i cant comprehend. thx!!

Answer 1

It involves two keys, one to lock or encrypt the plaintext and one to unlock or decrypt the cyphertext. (dont ask me what those are i have NO idea). None can do both jobs. One of these keys is kept public and one is private.



these keys use asymmetric algorithms. the pair of keys are mathematically linked.



you can easily use it on microsoft when sending emails with just a few clicks, so yes it is easy to use. btw you know who i am so you will get this, lazy americans... and no you dont have to send two emails.

Answer 2

It's not just an FBI thing. In fact, Public Key Cryptography is built-in to products and software that you probably use everyday.



Public Key Cryptography is also known as "asymmetric encryption". Contrast that to "symmetric encryption", which you might have played with on paper a bit.



In symmetric encryption, the same "key" is used for encryption and decryption of a message. So, the first problem you have is getting the same, secret key to both the sender and receiver, and keeping the key secret.



In asymmetric, or Public Key, encryption, different keys are used for encryption and decryption. You have a Private Key, and a Public Key, which is shared, and can even be listed in a directory. If I want to send you a secret message, I encrypt it with your Public Key, and you are the only one who can decrypt it, because decryption needs your Private Key.



I hope that helps.

Answer 3

1. Anyone can use it. Everyone SHOULD use it, but people get lazy.



2. You can encrypt just about anything, text (emails, messages you send over IM protocols, etc.), you can also encrypt ANY file. So if you were sending something that you only wanted the other person to see, without your ISP snooping in, or your email provider reading/looking, then you could encrypt it for the other person.



The file backup service "Spideroak" encrypts all the data on YOUR end, before it gets sent to them, so even if they wanted to break privacy, they couldn't.



3. You get software like GPG (gnu privacy guard) or windows users call it PGP (pretty good privacy)



Just 'Signing' the name? like what? Actually scanning your written signature? I guess that's ok sometimes, but if you sent your signature through the internet, then there's no guarantee that someone couldn't just copy it and fake being you. With gpg you can digitally sign and encrypt data so that it's 100% only someone with your private key and password made the file/signature. This can even be legally binding, since it's so secure.

Answer 4

http://en.wikipedia.org/wiki/Public-key_cryptography