Why Are We Here?
• 84% of you have learned safe practices for online activities in school or at home.
• We’re going to build upon your basic Internet “street smarts.”
• We’ll focus on some technologies that are used to protect private information:– Encryption: Digital code that stores information
securely– Passwords: How to hacker-proof your accounts
Cryptography
cipher: a method of encryption, including the algorithm, key(s), and other variables used to encode and decode a message
keyword: word or phrase used in conjunction with an algorithm to encrypt and decrypt messages – like a password!
encryption: conversion of plaintext to ciphertextdecryption: conversion of ciphertext to plaintext
cryptanalysis: the process of deciphering an encrypted message without knowing the algorithmsand keys used to perform the encryption.
plaintext: an original unencrypted message or a message that has been successfully decryptedciphertext or cryptogram: an encoded message resulting from encryption
code: the system or set of rules for converting words or phrases into a cryptogram
Background of Cryptography
The Old Testament Book of Jeremiah employs a reversed-alphabet cipher to encode sensitive words.
The ATBASH Cipher
Background of Cryptography
Julius Caesar made code by shifting the alphabet over by three letters and then substituting Greek letters for Roman.
Background of Cryptography
Thomas Jefferson used a 26-letter cipher wheel to encrypt/decrypt official correspondence while serving as ambassador to France.
Recipient would need own deviceto decode the message.
plaintext
ciphertext
Background of Cryptanalysis
The Enigma, a mechanical encryption machine with four rotary ciphers, was used by the Germans in WWII. Its code . was thought to be unbreakable.
The Allies built the giant“Bombe” machine to crack the Enigma cipher.
Cryptograms and Passwords
Lessons learned from cryptanalysis of the Enigma code drive home two practices we now observe in setting passwords:
– Change them regularly The Germans rotated their Enigma keys daily.
– Don’t write them down The Allies might never have broken the code if not for documentation they got from captured U-boats.
The Vigenère Cipher
The simple way to use the cipher is by choosing one row to use for encryption – like Julius Caesar did!
However, this method is not the most secure.
What is a weakness of the cryptogram produced by this method?
Repeating letters may tip off a cryptanalyst as to the method behind the code!
plaintext: A M A ND A
The Vigenère Cipher
The better way to use the cipher is to switch rows before encoding each letter.
This can be done in sequence orin the order determined by a keyword.
KEYWORD
plaintext:
Using multiple alphabets rotated in keyword order strengthens the code!
A M A ND A
Digital Encryption Activity
We’ve seen the advantage of using a polyalphabetic cipher for encryption.
Let’s see what happens when we use multiple keywords with the cipher…
Everyday Uses of Encryption
• Securing email transmissions• Securing web transactions
– Wherever you see a URL beginning “https:\\”
• Securing wireless networks• Securing individual files
What is the key to encryption and decryption of each of these? …a PASSWORD!
Passwords
• Passwords need to have two qualities:
1.
2.
Secure and difficult to crack.
Easy to remember
Passwords
• Cracking a Password– Brute Force
• Using Common Passwords
– Guessing• Using Known Passwords
“12345”“qwerty”“password”
Your Name: “amanda”Your Birthday: “1286”Your favorite TV Show: “spongebob
Passwords
• Creating a good password:– Dlkj509$13409oi$dslSDF90tq39u45^0qujnkja
98q^u09509340%nd8sq3450934oikljfna0q#095
• How are you going to remember that?
Passwords
• Some Tricks for making a good Password:– Make up an anagram:
• Mrs. Funnell’s class is my favorite part of the day. I can’t wait.
• M.F’cimfpotd.Icw.• M.F’c1m4p0td.Icw.
Passwords
• Don’t– Write down your password– Share your password– Create bad password hints
• Obvious hints: “My teacher’s name”• Starts with “M.F”
Facebook and Social NetworksThe first popular social networking websites took off in the early 2000s
Provide an online presence w/o need for a personal website
Encourage connecting with other users, establishing a online network that resembles real-life social circle
Allow users to share news, etc. with many friends at once vs. sharing one-on-one via email
Is Facebook For Me?
• At age 13, young people can register for Facebook accounts.
• 29% of your classmates are already active on Facebook.
• While Facebook is a fun way to stay connected with friends and family, it is also a source of leaks for private information.
• How will you protect your privacy if you join Facebook?
• By default, your profile, photos, and posts can be viewed by everyone
• Contact information visible to “friends”
• Accept “friend” requests carefully
• “Friends of friends” are not under your control
• Use the “Preview My Profile” option
• “Checking in” places not a great idea
Facebook and Social Networking
Sharing Personal Information
Facebook and Social Networking
Click here to jump to Amanda’s profile for tour of what NOT
to show.
Recommend one thing on this profile that Mark should hide from public view.
Facebook and Social Networking
…and photos other people have taken of him.
Visitors to Mark’s Facebook page see both photos he has uploaded…
When and why might that be a problem?
Click here to jump to Amanda’s profile
for DOs and DON’Ts of photos to
share.
• 4/5 have been taught internet security
• 1/4 do things on the internet that their parents don’t know about
• 1/5 opened an email attachment from someone they don’t know