What was the purpose of adding the private-key to cryptology?

Question

public-key encryption went public and then the private-key was added, why?

Answer 1

Public key cryptography (ie. the cryptography that uses a private-key and public key) is important because it allows two parties who have never exchanged information before, to establish a secure channel of communication.  Traditional cryptography (ie. symmetric) always required that a pre-arranged key or secret be established via some trusted courier.  Public key crypto is what makes it possible to have secure transactions online.

Answer 2

It allows the key not to be accessed, for example:

If the method is public, for example with base64 (open, so decodable and encodable), the encode/decode functions are public, but the key is private

(key is ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmn...

Anyway, in short:

It allows the functions to be used, without people knowing how to reverse code and basically make a decoding function.

Answer 3

Basically, a public key is used to encrypt data that only the private key can decrypt. So if you're on a website and need to send encrypted information, your browser will receive a public key from the hosts web server and it will encrypt your data using this key.(the same public key can be sent to everyone on the website, knowing the public key cannot help you decrypt the data). Once the data has been received by the host (website), they can use their private key, which is known only to them to decrypt the data.

This works because encryption algorithms are designed to use very powerful "one-way" functions that cannot be reversed, so once you perform these one-way operations on your data, the key used to encrypt it cannot be used to do the opposite operation and decrypt it, only the secret key is capable of performing the correct operations to decrypt the data properly.

I would recommend reading about encryption algorithms (RSA, DES, AES etc.) if you are interested in learning how encryption actually works as this is a fairly basic explanation geared towards a beginner.

Answer 4

http://www.sepcot.com/files/college/COM4...

http://www.mail-archive.com/openssl-user...

http://www.cin.ufpe.br/~mjlt/rsa/Ed2.ppt

Regards,

Milind Kansagara

http://milindkansagara1984.blogspot.com