Docstoc

encryption

Document Sample
encryption Powered By Docstoc
					Encryption
                    History
 First used by Spartan generals
        Strip of paper wrapped around a stick was unreadable,
        unless wrapped around another stick of the same size.


 Greeks invented cipher

                    1          2          3           4           5
                    1          A          B           C            D            E
                    2          F          G           H           I/J           K
                    3          L          M           N            O            P
SEND REINFORCEMENTS TO ITHACA
34 51 33 41 24 51 42 33 12 43 24 31 51 23 51 33 44 34 44 43 42 44 32 11 31 11
Other ciphers involved direct substitution of one letter
for another. a->z b->y etc.

Codes encrypt whole words at a time, by substituting
them for other words.

Translating between languages is a code.
  WWII Cipher Machines

     Cipher machines can use a new set of ciphers for each
     letter. A matching machine is needed to decode it.




Enigma:                        Lorenz:
 Modern Encryption:

    All based in the digital world

Algorithms:

    DES, CRYPT, RC2 and RC4, IDEA, RSA, SNEFRU,
    MD2, MD4, MD5, SHA, RIPE-MD, HAVAL,
    SKIPJACK, Dffie-Hellman, XOR, BLOWFISH
 One-Way Encryption (One-Way Hashing):


 SNEFRU, MD2, MD4, MD5, SHA, RIPE-MD

 Takes a sequence of bytes and sums them in a way very
 difficult to reverse.



 A change of one bit in a 500 MB file will drastically
         This is quite a function.
 change the value of a hashingneat sentence.
         8d733d555264b082fc50f6c19629f9fd
MD5:
         This is quite a neat sentence
         5c9c0885b958575ea6c347f2241dac69
Uses:

   Securely Storing Passwords
(“salt” is used to store passwords more securely)


   Verifying File Integrity
Reversible Encryption:

  DES – Data Encryption Standard        (Block Cipher)


  Most widely used encryption (currently in “triple-DES”
  form.



  Modified version of IBM's LUCIFER algorithm became
  DES July 15, 1977




  Uses 56 bit to cipher 64 bit blocks
DES Weakness:

   56 bit key is small.

   Deffie and Hellman outlined a plan for a $20,000,000
   computer capable of brute forcing DES (1975)



   EFF spent $220,000 on a computer capable of brute forcing
Solution:in 4.5 days (1998)
   DES
   Triple-DES

   Two keys are used to encrypt and decrypt and then re-
   encrypt the message
Blowfish:

  Like DES but with key length varying from 32 to 448 bits.


  Completely free

  Copyright and patent free


  Much simpler algorithm than DES, but just as, if not more,
  secure.
Public Key Encryption:

      Two Keys:

      One private and one public

      A message is encrypted with one or more public keys.
      Only the corresponding private keys can decrypt the
      massage.
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: MailVault 2.2 from MailVault Corporation http://www.mailvault.com
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=aWUE
-----END PGP PUBLIC KEY BLOCK-----
RSA Encryption:

      RSA – Ronald L. Rivest, Adi Shamir, and Leonard
      M. Adleman (1977)

     Relies on the fact that the product of two large primes
     is very hard to factor and a discrete log is hard to
     calculate (With conventional algorithms, it would take more time than
     is left in the universe to break a 2048 bit key)
Algorithm Rundown:
  Small primes will be used so it is more visible.

  Primes 7 and 5 are picked

  N = 7x5 = 35

  E is a number relativity prime to (7-1)(5-1) = 24
  E=5

  The public key is comprised of 35 and 5

  The private key D is the inverse of E mod (7-1)(5-1). This is done very quickly with the extended
  Euclidean algorithm.
  D=5

  To encrypt the number M = 2, we take C = M^E mod N = 2^5 mod 35 = 32

  C = 32

  The decrypted message will be C^D mod N = 32^5 mod 35 = 2
Breaking RSA:

       Must calculate a discrete log to crack C = M^E mod N


       2^31 mod 37 =         22
       3^31 mod 37 =         30
       4^31 mod 37 =          3
       6^31 mod 37 =         31
       7^31 mod 37 =         33
       8^31 mod 37 =         29
       9^31 mod 37 =         12
       10^31 mod 37=         10
       11^31 mod 37=         11
       12^31 mod 37=         16
Elliptic Curve Cryptology (ECC):
   Victor Miller and Neal Koblitz (1980)



  Uses a convoluted multiplication table from an elliptic
  Relies on the extreme difficulty of a discrete log in elliptic
  curve.
  groups.
   Elliptic Group Addition:
            y2 = x3 + Ax2 + B (mod p)




When there are large numbers of points, discrete logs
become VERY difficult. Therefore, key-sizes may be
smaller, providing the same level of encryption.
Encryption Laws:

  Until 1997, it was considered exporting arms to give a
  method of strong (larger than 64 bit) encryption to one
  overseas.

  Currently it is only illegal to give strong encryption to a
  blacklisted country. (Iraq, China, Pakistan, etc.)

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:3/5/2013
language:English
pages:18