Cryptography & Steganography

Cryptography & SteganographyLec. Sanchai YeewiyomSchool of Information and Communication TechnologyUniversity of Phayao235034 Security in Computer Systems and Networks

Cryptography Sniffer (Encrypt) (Decryption)

Cryptography

Cryptography Caesar Cipher

Ciphertext: WKH TXLFN EURZQ IRA MXPSV RYHU WKH ODCB GRJ Plaintext: the quick brown fox jumps over the lazy dog

Cryptography Monoalphabetic Cipher

Polyalphabetic Cipher

Cryptography One-Time Pad Key Plain Text Key Key Pad

Cryptography Encrypt

Decrypt

Cryptography

Cryptography 3 Symmetric Key Cryptography (Secret Key Cryptography)Asymmetric Key Cryptography (Public Key Cryptography)Hash Function

Symmetric Key Cryptography

Symmetric Key Cryptography

Symmetric Key Cryptography 2 Stream CipherBlock Cipher

Stream Cipher bit, byte word Feedback Key

Stream Cipher

Block Cipher Exp.Electronic Codebook (ECB)Cipher Block Chaining (CBC)

Electronic Codebook (ECB)Secret Key Block Plain Text Block Cipher Text Block Plain Text Key Block Cipher Text Brute Force

Electronic Codebook (ECB)

Cipher Block Chaining (CBC) Feedback Input Plain Text Exclusive-OR (XOR) Cipher Text Block

A B X0 0 00 1 11 0 11 1 0

Cipher Block Chaining (CBC)

A pixel-map version of the image on the left was encrypted with ECB mode to create the center image: OriginalEncrypted using ECB modeEncrypted using a more securemode, e.g. CBC

Symmetric Key Cryptography ExampleData Encryption Standard (DES)Triple-DESAdvanced Encryption Standard (AES)Rivest Ciphers (RC)Blowfish

Data Encryption Standard (DES) IBM Block Cipher Block 64 bit Key 56 bit Key

Triple-DES (3DES) DES 3 Key 112 168 bit

Advanced Encryption Standard (AES) National Institute of Standards and Technology (NIST) Block Cipher Block 128, 192 256 bit Key 128, 192 256 bit

AES

Rivest Ciphers (RC) Ron Rivest Version RC4 Stream Cipher Secure Socket Layer (SSL), Wired Equivalent Privacy (WEP) Key WEPRC6 Block Cipher RC5 AES Block 128 bit Key 128, 192 256 bit

Blowfish Bruce Schneier Block Cipher Block 64 bit Key 32 - 448 bit 16 CPU 32 bit Cache DES

Asymmetric Key CryptographyPublic Key Cryptography 2 (Public Key) (Private Key)

Asymmetric Key Cryptography

Asymmetric Key Cryptography PGP (Pretty Good Privacy) E-mail Session Key ( Symmetric Key) SessionKey

Asymmetric Key Cryptography

Asymmetric Key Cryptography Session Key Session Key Public Key Infrastructure (PKI) Key

Asymmetric Key Cryptography

Asymmetric Key Cryptography ExampleRSADigital SignatureDigital Certificate

RSA.. 2520 (Ron Rivest) (Adi Shamir) (Len Adleman) Encryption Digital Signature Protocol (e-commerce) Key Key 1,024 bit

Digital Signature (Authentication)- (Data Integrity)

Digital Signature (Authentication)

Digital Signature (Data Integrity)

Digital Certificate Public Key Certificate Authority (CA) Public Key Digital Certificate Website E-commerce Cybertrust, VeriSign etc.

(CA) 1. 2. 3. 4. 5. Khonthai CA6. 1. ()2. ()3. 4. Max Saving (Thailand) Co.,Ltd

Digital Certificate

Hash FunctionHash Function Oneway-encryption Algorithm Key Plaintext Hash Function Digital Fingerprint Message Digest Virus

Hash Function Operating System Password Login (Integrity) MD5, SHA-1

Hash Function ExampleMessage Digest (MD)Secure Hash Algorithm (SHA)

Message Digest (MD) Message Digest Digest (Digest) 128

Message Digest (MD)MD2MD4MD5

MD2 Ron Rivest Rivest Digest MD2 MD2 Digest 128

MD4 Rivest MD2 MD2 3 [ (Availability)] Digest MD4 Digest 128

MD5Rivest MD4 MD4 MD5 ( MD4) MD5 Digest 128

MD5

Secure Hash Algorithm (SHA) SHA MD4 National Security Agency (NSA) Digital Signature Secure Hash Standard (SHS) NIST SHA Digest 160

Secure Hash Algorithm (SHA)SHA-1SHA-256, SHA-384 SHA-512

SHA-1SHA-1 Algorithm Protocol SSL SHA-1 Digest 160

SHA-1

SHA-256, SHA-384 SHA-512NIST Algorithm 2001 Algorithm AES Algorithm Digest 256, 384 512

SHA-256

Steganography Watermark

Steganography

Steganography LSB (Least Significant Bit) (Picture, Sound, etc.)

Steganography

Steganographyhttp://www.mobilefish.com/services/steganography/steganography.php

Steganography

SteganographyExp. OpenPuff 4.00 (http://embeddedsw.net/OpenPuff_Steganography_Home.html)QuickStego (http://quickcrypto.com/free-steganography-software.html)MP3Stego (http://www.petitcolas.net/fabien/steganography/mp3stego/index.html)OurSecret (http://www.securekit.net/oursecret.htm)

Steganography StegAlyzer (http://www.sarc-wv.com/)Stegdetect (http://www.outguess.org/detection.php)XStegSecret (http://stegsecret.sourceforge.net/)

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