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Ethical Hacking Simplified. Cryptography continuation.

Asymmetric Encryption: This type of encryption was fully unveiled in in mid 1970s by Whitfield Diffie and Martin Hellman. This new technology solved the problem of using one key to encrypt and decrypt.


Asymmetric cryptography introduces the public key system into encryption, where the key that encrypt is known as the public key and the key that decrypt is known as private key. Who ever is part of the system is having two separate keys i.e. the public and his unique confidential private key. The public key can be access by the team mates but the private key is sorely to the assigned. Take for example, in an ATM (debit)  card, there is a some number on the card which anyone can have access to, but there is always a PIN(personal identification number) which is secret. If one possesses your debit card, he cannot make withdrawals through ATM machine why? Because he doesn't have your private key which is your PIN. Making this more secured than the symmetric metric. Take for example the serial number on your ATM card can be used as the PIN number, when a third person has access to your card, he definitely have sull access to your account! But mind you, you still have to keep your debit card secured, because it can be used fro online transactions even without your PIN! 

Both the public and the private keys can be used for encryption, but if one is used for encryption only the other can be used for decryption. If public key is used to encrypt data only the private key can be used to decrypt it and vice-versa.
Public keys has to be associated to the user in a trusted manner. Using PKI(public key infrastructure) anyone can send encrypt data, one thing is only the one with the private key can access the data. Example you can give you P.O box number to anyone send message, but only you can retrieve that message or document. Another advantage of PKI is, it meets the requirement for privacy and authentication since only the right guy can decrypt the data.

Who does it works?

Let me use the name Salim and Zainab. If Salim needs to send message to Zainab, he has to access her public key and encrypt the message. When the message reaches her. She will use her private key to decrypt the message. Here only Zainab can have access to that message since she is the only one who suppose to the keys to unlock or decrypt the data. If he uses his private key to encrupt the message, using digital signal became possible. So here his public key will act as private key thus making the message to be accessed only using his public key.
Signing an electronic message

When Salim want to send message to Zainab, after he created the message he have to do some mathematical computation against it and uses his and uses his private key to complete the operation. Upon arriving at his sweetheart she will verify if the message is from him by using his public key. If the key can reverse the message then its from salim if it cant? Its not from him.
Reference: Sybex CEH
to be continued

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