Cipher Cryptography Lecture Notes PDF

Cipher Cryptography College of Engineering and Information Technology  Scripting Language vs Programming Language College of Engineering and Information Technology  Cryptography - the process of communicating secretly through...

Cipher Cryptography College of Engineering and Information Technology  Scripting Language vs Programming Language College of Engineering and Information Technology  Cryptography - the process of communicating secretly through the use of ciphers, and cryptanalysis, the process of cracking or deciphering such secret communications. – a method of protecting communication and information through the use of codes so that only those who are meant to receive the information can read and process it. – a set of calculations called algorithms that transform hard to decipher messages: cryptographic key generating, digital signatures, and verifications. College of Engineering and Information Technology  ENCRYPTION AND DECRYPTION PROCESS Procedure Conversion Algorithm Techniques College of Engineering and Information Technology  TECHNIQUES Cryptology – defined as the study of cryptography or cryptanalysis. Cryptology and cryptanalysis - are the disciplines that relate to cryptography and techniques like microdots and image-word merging help hide information in transit or storage. Confidentiality Non-repudiation Integrity Authentication College of Engineering and Information Technology  TECHNIQUES: Cryptosystems– include the regulation of human behaviors like choosing complicated passwords and logging off unused systems. Cryptographic algorithm - set of procedures that encrypt or decrypt messages to secure computer system communications within devices such as smartphones as well as applications. Types: Symmetric Cryptography Asymmetric Hybrid Cryptography Cryptography College of Engineering and Information Technology  Symmetric Cryptography Algorithm College of Engineering and Information Technology  Symmetric Key Cryptography 1. Plaintext – is the original data / message that the algorithm uses as input. 2. Encryption algorithm – The encryption algorithm performs various mathematical operations on this plaintext data to encrypt it.. Ciphertext – This is the scrambled message that is the 3. result of the encryption algorithm. If intercepted by an untrusted user, it is merely seen as garbled data.. College of Engineering and Information Technology  Symmetric Key Cryptography 4. Secret Key – also input to the encryption algorithm. The encrypted data / message is then sent to the end user, who uses the same secret key to decipher the data. 5. Decryption Algorithm – It takes the ciphertext, the secret key, and produces the original data / message. In simple words, it runs the encryption algorithm in reverse sequence. College of Engineering and Information Technology  Symmetric Ciphers – cryptosystems that use the same key to encrypt and decrypt messages. Types: Block cipher operates on blocks of a fixed size, usually 64 or 128 bits. Blowfish DES AES (Rijndael) Stream ciphers generate a stream of pseudo-random bits, usually either one bit or byte at a time. Keystream XORed College of Engineering and Information Technology  Block Cipher Confusion – refers to methods used to hide relationships between the plaintext, the ciphertext, and the key. Diffusion - serves to spread the influence of the plaintext bits and the key bits over as much of the ciphertext as possible. DES uses a Feistel network – used in many block ciphers to ensure that the algorithm is invertible College of Engineering and Information Technology  Symmetric Ciphers Data Encryption System(DES) Encryption Algorithm – Algorithms create a fixed length of block ciphers with a secret key that the sender uses to encipher data and the receiver uses to decipher data. Advanced Encryption Standard (AES) Encryption Algorithm – the Rijndail algorithm that is capable of 256-bit (or more) key to prevent hacker intrusions: Wireless security, Processor security and file encryption, SSL/TLS protocol (website security), Wi-Fi security, Mobile app encryption, VPN (virtual College privateandnetwork), etc of Engineering Information Technology  Block Cipher PLAINTE A B C D E F XT CIPHERTE D E F A B C XT CIPHERTEXT: FDCB Key = 3 PLAINTEXT: C A F E College of Engineering and Information Technology  Stream Cipher (OTP) Plaintex M E E T M E O U T S I D E t Numeric 1 4 4 19 12 4 14 20 19 18 8 3 4 al 2 Plaintex t OTP B D U F G H W E I U F G W Numeric 1 3 20 5 6 7 22 4 8 20 5 6 22 al OTP Numeric 1 7 24 24 18 11 10 24 1 12 13 9 0 al 3 Ciphert Numerical ext ciphertext = Numerical plaintext + Numerical OTP Ciphert N H Y Y S L K Y B M N J A iphertext ext College of= N I Y Y and Engineering SL KYBMNJA Information Technology  Stream Cipher (OTP) Ciphert N I Y Y S L K Y B M N J A ext Numeric 1 7 24 24 18 11 10 24 1 12 13 9 0 al 3 Ciphert ext OTP B D U F G H W E I U F G W Numeric 1 3 20 5 6 7 22 4 8 20 5 6 22 al OTP Numeric 1 4 4 19 12 4 17 20 19 18 8 3 4 al 2 Plaintex umerical ciphertext = Numerical Ciphertext + Numerical OTP t PLainte M E E T M E O U T S I D E College xt of Engineering and Information Technology  TECHNIQUES: Cipher – method in which a message is transformed to conceal its real meaning. Cipher algorithm - protocol embedded process involves private and public key generation for data encryption/decryption, digital signing, and verification for message authentication. College of Engineering and Information Technology  Reverse Cipher College of Engineering and Information Technology  Reverse cipher - encrypts a message by printing it in reverse order. College of Engineering and Information Technology  Reverse Cipher OUTPUT:.daed era meht fo owt fi ,terces a peek nac eerhT 4. message = '.daed era meht fo owt fi ,terces a peek nac eerhT’ decrypt OUTPUT:and College of Engineering Three can keep a secret, if two of them are dead. Information Technology  THANK YOU! College of Engineering and Information Technology