Information Cryptography Security
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The document discusses various topics in cryptography and information security including: 1. Cryptography involves hiding the meaning of messages through techniques like transposition which rearranges letters or substitution which replaces letters. 2. Traditional encryption methods discussed are the Rail Fence cipher, Spartan scytale, and Caesar cipher. The Vigenere cipher uses multiple cipher alphabets. 3. Modern cryptography uses secret key cryptography with ciphers like DES and public key cryptography with algorithms like RSA using public/private key pairs.
Information Cryptography Security
- 1. Information Cryptography & Security Week 7
- 2. Information Security & Authentication Cryptography Derived from the Greek word kryptos (meaning ‘hidden’) The aim of Cryptography is to hide its meaning , rather than the existence of a message Cryptography can be divided into 2 branches, such as: 1. Transposition 2. Substitution
- 3. Cryptographic Methods 1. The Rail-Fence Transposition It is a transposition cryptography in which the message is written with alternate letters on separate upper and lower lines. For instance: “Rail-Fence” Transposition Cryptography (Singh, 2000)
- 4. Cryptographic Methods 2. The Spartan scytale Other transposition cryptography in the military device The Scytale is a wooden staff around which a strip of leather or parchment is wound. For instance: Spartan scytale (Singh, 2000)
- 5. Cryptographic Methods 3. The Caesar Shift Cipher By substitution, Julius Caesar replaced each letter in the message with the letter that is 3 places further down the alphabet. For instance: “The Caesar Cipher” (Singh, 2000)
- 6. Cryptographic Methods 4. The Vigenere Square cipher The Vigenere cipher lies in using 26 distinct cipher alphabets. For instance: (Singh, 2000)
- 7. Cryptographic Methods Form of transposition cipher (Singh, 2000)
- 8. Exercises Encrypt a message: “SBY IS OUR PRESIDENT” in the Rail-Fence transposition cipher, the Caesar cipher, and the Vigenere cipher. For Vigenere cipher, the key = “SUHENDRO”. Encrypt a message: “ALO” by using Key = “TOP” in binary numbers with a simple transposition cipher.
- 9. Older Cryptographic Machine Enigma Machine In the World War II, a German cryptographic machine was invented by Arthur Scherbius. (Singh, 2000)
- 10. Modern Cryptography Other Cryptographic methods: 1. Secret Key Cryptography 2. Public Key Cryptography
- 11. Modern Cryptography 1. “Secret Key” Cryptography It uses a secret key such as Data Encryption Standard (DES) DES is a National Institute of Standards & Technology (NIST) standard key cryptography method that uses a 56-bit key. ( http:// www.nist.gov ) DES lets both sender and receiver use the same key to encrypt or decrypt.
- 12. Modern Cryptography 1. Process of “Secret Key” Cryptography Ref: http://dret.net/lectures/web-fall08/img/secret-key.gif
- 13. Modern Cryptography 2. “Public Key” Cryptography It uses a private key (kept by owner) & public key is published The public key uses a standard RSA (Rivest-Shamir-Adleman) Data Security, Inc. Redwood City, CA. ( http:// www.rsa.com ) It is more secured than a secret key cryptography
- 14. Modern Cryptography 2. Process of “Public Key” Cryptography Ref: http://dret.net/lectures/web-spring09/img/public-key-secret-encrypt.gif
- 15. Digital Signature The ‘signature’ is an encrypted digest of the file (text message, executable, etc) Digital Signature uses hash functions to the message along with a private key. The message’s signature generates according to PGP (Pretty Good Privacy) or SMIME (Secure Multipurpose Internet Mail Extensions) standards. Note: PGP is a software widely used for signing and encrypting email messages.
- 16. Digital Signature Process of Digital Signature Authentication Ref: http://www.infosec.gov.hk/english/itpro/images/digital_signature.gif
- 17. Digital Certificate Digital Certificate (Certs) ensures if a public key belongs to the owner. Digital Certificate (Certs) consists of: 1. A public key 2. Certificate Information (i.e.: Identity of user, such as name, userID, etc) 3. One or more Digital Signature
- 18. Digital Certificate Example: Digital Certificate Ref: http://www.mysecurecyberspace.com/encyclopedia/index/digitalcertificate.pic1.jpeg Ref: http://media.photobucket.com/image/digital%20certificate%20image/msanto/One-Offs2009/GearsofWarDigitalCertificate.jpg
- 19. Digital Watermark A pattern of bits embedded into a file used to identify the source of illegal copies. If a digital watermark is placed into a master copy of an audio CD, DVD, file, etc then all copies of that disc are uniquely identified. Example: Ref: http://www.bytescout.com/images/examples/watermarking/watermarked_image_sample_text_fits_page.png
- 20. References Singh, S. (2000).The Code Book Freedman, A. (2001). Computer Desktop Encyclopedia