Fmdszqujpo! Encryption!

Encryption  Group Activity 1:  Take the message you were given, and create your own encryption.  You can encrypt it anyway you want  Try to make an interesting version that you think no other group will be able to guess!

Encryption  What do you all think Encryption is?  Where do you think a good place is to use encryption?

Encryption  To change information from one form to another especially to hide its meaning. (from the merriam-webster dictionary)  In cryptography, encryption is the process of encoding messages or information in such a way that only authorized parties can read it. (from our favorite site Wikipedia)cryptography

Encoding  Encoding is the act of transforming data so that it may be properly consumed by another party  Encoding is not used for security purposes  Common Encoding Schemes  HTML  URL  Unicode  Hex

Encryption  Encryption is similar to encoding, except it implements the use of a key  A key is typically a random string of bits used to scramble and unscramble data  Different types of Encryption  Symmetric Key Encryption  Public Key Encryption  Common Encryption Schemes  WEP  TKIP  AES-CCMP

Encryption Exhaustive Key Search

Cracking Activity 1  For this activity, we will list each of the messages up here, and then each group should choose a message and try to crack the encryption and get the message.

Cracking Activity 1  The messages are:

More Definitions, yay  There are 2 types of encryption, weak encryption and strong encryption.  Weak encryption means that although it is encrypted, it is a simple algorithm, or simple way to encrypt it, and can be cracked in minutes to anything less than a day or so. An example of this is from a security flaw found in March. This flaw is from the days when the government enforced that products be exported with weak encryption, but then was forgotten, and wasn’t discovered till this year, leaving a lot of time for any number of people to exploit it. The encryption was 512 bits, which can be cracked in about 7 hours if you have a good enough set of computers (or using a cloud of computers).

Definitions cont.  Strong encryption means that the data/message is encrypted with either a very complex algorithm, or it is encrypted enough times that it takes a long time to decrypt. An example is that you use 2048 bit encryption, or if you want to keep the weak encryption algorithm, you can encrypt the data multiple times to make it stronger (like encrypting a message with one method, then encrypting the result with another, and so on for 5 different encrypted algorithms).

Definitions cont.  One last definition that is good to know is what we mean when we say we will crack encryption. When we say crack we mean break it or decrypt it in some shape or form.

Example 1 – Caesar cipher

 A Caesar cipher is an algorithm that uses the English alphabet to change a message into something else. You choose a number from 1 to 25, and for each letter in the message you want to encrypt, you add the number to it and change to the new letter. Example 1 – Caesar cipher

 Let’s say we want to take this phrase ‘thisisencryptionclass’ and use the Caesar cipher to encrypt it. Let’s say we choose 5 as our ‘key’, which means the value we want to change it with. First thing we can do is right out the alphabet from 0 to 25, and place the letters with the numbers.   a b c d e f g h i j k l m n o p q r s t u v w x y z Example 1 – Caesar cipher

 t h i s i s e n c r y p t i o n c l a s s    a b c d e f g h i j k l m n o p q r s t u v w x y z  So the message in number form is:  Example 1 – Caesar cipher

 Ok, now that we have the message as a number, let’s convert it using the key.  Our key = 5 in this case, so add 5 to every number (and when it hits 25, start back at 0 ie = = 2 Example 1 – Caesar cipher   …..… 

 Finally, let’s convert that back to letters:  (remember:   a b c d e f g h i j k l m n o p q r s t u v w x y z Example 1 – Caesar cipher   y m n x n x j s h w d u y n t s h q f x x

 That means our original message: thisisencryptionclass  Is now encrypted and looks like this:  ymnxnxjshwduyntshqfxx  Pretty simple right? Example 1 – Caesar cipher

Example 2 – Substitution Cipher

 The Substitution cipher goes one step further, and instead of using a single key, we just arbitrarily change the way we have the letters. Example 2 – Substitution Cipher  For this example, let’s use the following for our substitution key:  a b c d e f g h i j k l m n o p q r s t u v w x y z  j d k e b o a p r i l u m n w q s f z x c v b s t y

 Now, using the same message we had in example one, we substitute each letter for the one in the key we made.  thisisencryptionclass is the message and gets encrypted to: Example 2 – Substitution Cipher  t h i s i s e n c r y p t i o n c l a s s  x p r z r z b n k f t q x r w n k u j z z  a b c d e f g h i j k l m n o p q r s t u v w x y z  j d k e b o a p r i l u m n w q s f z x c v b s t y

Example 3

 For this example, we will explore public/private key encryption  First off, go to  We will use this site for the public/private key encryption

Example 3  unencrypted message:  thisisencryptionclass

Example 3  public key:  -----BEGIN PGP PUBLIC KEY BLOCK-----  Version: BCPG C# v  mQENBFWUN4IBCACLRN0U0mcGe69UWvc0k7ZYZ5NH1eyIqpRzuISgjvC3AUBWqROk  yveE/zKUDBcYTge3G2yEOuAfTA6lCGPhXfSug6un9r1ddWcmfQK4BSVqFurlZpcC  x10f5ZLsIsJyDXML8GgKk3q0HhPxiE9qVnrhq1lV1KHaAaf60ifbr2dpTZkxLP9Q  hd/1it+wpByNO6xq+lx47CVbOoiCDIQxqPI1CixqnZGmFQ8MNf5dqtDN2i6aVoIb  TtYQSQppKO/bUG6//8mosmWfCQ9T7dHDRgX6KRVTv6PxsmXXFuj4iurcjFPK+9GP  mBf/ml8LwxhHM0b2wc2RTouc7KMrZ2yEQ2VHABEBAAG0HHdiZjAwMDdAdGlnZXJt

Example 3  YWlsLmF1YnVybi5lZHWJARwEEAECAAYFAlWUN4IACgkQnqgOCvo1SJWYiAf/S8bH  P/nUwfVTwyPQ4SHmhA7Dk4ywYuAsrMp6zuaHlPu1s21CMc88GLupcaT8CNdb9I7J  qZeTKVUwRlZAR/CkkF8IcAq/02QrNrZA9Uj0ZaGvxvy9x6MjTazDPkqPJ7IoYmIG  BlvSwGY2LQW5piuHuBgi2VSv8g3d1/4unVph0iiqCosAKldHrLJBkKe0evr0eF1H  BG1htjf9M5t2GyUk2OQ/rw+wYE2bYPZQjtYdgjE3U+hyZpBotrTQFl4ZvuDQdffU  ok2Hrw/vAy92KlM1UcjBO7m2VV52e5TdUVru/tnhvKADzpAn3LgQUVbj5W0GXPds  T+qMeOSA6Iw2fO8gsg==  =LzLX  -----END PGP PUBLIC KEY BLOCK-----

Example 3  encrypted message:  -----BEGIN PGP MESSAGE-----  Version: BCPG C# v  hQEMA56oDgr6NUiVAQf+OZxioO1wGz3nnEImnyjrKViYBCN4boM+gKGiVo2RRPWw  +Pw8FDyjL2jO8CiX1+UTTZma0x9IXxHhoiQbA5Yncy9Hkn98SuPjvAm4CBvVqwTt  p4l6vm8eGdN8PqHfyGOVgbmvyoAfF8ciG5v5WLk3hJOUYy5t8MHSEltK/DA2RWQw  muUt5ExVxV7usHjUknRXT8FMbRfBZ+maGR5AxLbYnxFwQG5gkldjT4FbXI/cSxEC  p1dgUBL9+TLB/S2SCUCTiblpAn6AlaSfA3lpSU767aoRFhFqdiX+ObYDM6duOXNG  /VB80WwC3T9hMeHy1+KMPKeX3rfWRFmYmC8OfhCroskzr7AEPSOX19hwGijRPpUi  8IcaQyMcZ+mvuyIXP2XAtZgwDjWU9/twrQII1oUI/py6Tsq5  =5kkc  -----END PGP MESSAGE-----

Cracking Activity 2  Let’s go to this website to do some encryption and decryption:  As a group, create a few messages  Then take those messages and encrypt them  Next, bring them up to me and put a note that tells me which encryption you used for it  Finally, each group should choose a few (not your own) and try to decrypt them. Once you’ve decrypted them, tell us which you chose, what encryption it was, and what the message is

Public/Private Key Activity  Go to the website:  Split each group in half, and each half will play a role  One will be the owner of the public/private keys, and the other will be the one to send the message  The owner should give the sender their public key, and the sender should use the public key to encrypt the message. The sender then gives the message to the owner, who decrypts it using the private key and password for their keys  Next, each half should reverse roles  Finally, both halves will be owners and senders.