1. Summary of Encryption

2. What is encryption
In encryption, we use a key or key to control an algorithim with changes a plain text file to a cypertext file that, hopefully can only be decrypted by the intended recipient.
We do this to gain
Privacy – our message is only read by the intended recepient
Authenticity – the recepient knows who sent the message

3. Types of keys Symetrical Keys
The same key decrypts and encrypts the message
Gives us
Privacy
Authenticity
The problem is how to get the key to the recipient. This problem is as large as sending the encrypted message

4. Types of Keys Public Key
In public key cryptography there are two keys.
A public key, used to encrypt the message. This is publicly available
A private key, used to decrypt the message. This is know only to the intended recipient.
There is no key exchange problem. The public key is publicly available. (how we will discuss)

5. Public Key Cryptography
With public key cryptography we get
Privacy
We do not get authenticity.
The recipient can not prove who the message is from
To regain this, we use digital signatures as described in the last lecture.
Public Key Cryptography is the only form used in most internet and communication.

6. Practical Cryptography
In practice, we need to obtain public keys in a manner we can trust to avoid a, Man in the Middle, attack.
In a man in the middle attack, a malicious individual places him/herself in between two parties trying to communicate, and impersonates both.

7. Practical Cryptography
To avoid this, we incorporate public keys into digital certificates issued by Certificate Authorities
To use Cryptography, we generally need to obtain a digital certificate, from an authority.
To do this, we first need a certificate, for the Certificate Authority.
Lets look at those.

8. Certificate Authorities
Versign – Major player
Web site for certificates
digital_id.index.html
Thawte – a “Trust” Network
Originally independent
Absorbed by Verisign in 2000

9. Using the certificate Note:
Certificate allows you to receive encrypted
To send encrypted to someone, they must have a digital certificate.
To begin you must send your certificate to them, and they must send their certificate to you.

10. Outlook tutorial Tutorial Website
support.gateway.com/s/tutorials/Tu_ shtml
Gives the basics for setting up encrypted

11. Mac OS X tutorial Long tutorial, including obtaining the key on
/mail.html
In short, once the key is obtained, it needs to be installed in keychain.
From that point on, encryption is transparent. You click on an icon to encrypt outgoing mail. The Certificates are attached to entries in your address book.
Certificates are automatically captured when attached to incoming mail.

12. Onion Routing A way to mask your surfing from your ip Website

13. TorPark Secure browsing from public locations www.xerobank.com
Originally called Torpark
Released by our old friends, the Cult of the Dead Cow
Hacktivismo branch
Now commercial. (sigh) ;-(
Featured, I am told on the series, “Smallville”