1.1 Overview of cryptography and its applications

Cryptography is the art of secure communication in a world full of potential threats. It's like having a secret language that only you and your friends understand, keeping your messages safe from prying eyes.

In this digital age, cryptography is everywhere - from your WhatsApp chats to online banking. It's the invisible shield that protects your data, verifies identities, and ensures the integrity of information as it travels across the internet.

Cryptography and its goals

Fundamentals of cryptography

Top images from around the web for Fundamentals of cryptography

• 

  How TLS/SSL and X.509 really works View original

  Is this image relevant?

• 

  Information Security Principles View original

  Is this image relevant?

• 

  Chapter 6: Information Systems Security – Information Systems for Business and Beyond View original

  Is this image relevant?

• 

  How TLS/SSL and X.509 really works View original

  Is this image relevant?

• 

  Information Security Principles View original

  Is this image relevant?

1 of 3

Top images from around the web for Fundamentals of cryptography

• 

  How TLS/SSL and X.509 really works View original

  Is this image relevant?

• 

  Information Security Principles View original

  Is this image relevant?

• 

  Chapter 6: Information Systems Security – Information Systems for Business and Beyond View original

  Is this image relevant?

• 

  How TLS/SSL and X.509 really works View original

  Is this image relevant?

• 

  Information Security Principles View original

  Is this image relevant?

1 of 3

• Cryptography encompasses techniques for secure communication in adversarial environments
• Employs mathematical algorithms and protocols to achieve security objectives
• Focuses on design of secure systems and analysis of potential vulnerabilities
• Forms the foundation of the CIA triad (confidentiality, integrity, authentication)
  • Confidentiality keeps information secret from unauthorized parties
  • Integrity guarantees information remains unaltered during transmission or storage
  • Authentication verifies identities of communicating parties or message origins

Applications of cryptographic goals

• Secure messaging apps use end-to-end encryption to ensure confidentiality
• Digital signatures provide integrity and authentication for electronic documents
• Password hashing protects stored credentials through one-way encryption
• Blockchain technologies leverage cryptography for secure, decentralized transactions
• Virtual Private Networks (VPNs) create confidential tunnels over public networks
• Full-disk encryption maintains data confidentiality on storage devices

Cryptography in digital systems

Secure communication and data protection

• HTTPS protocol secures web browsing through encryption and authentication
• End-to-end encrypted messaging apps (Signal, WhatsApp) protect user communications
• Virtual Private Networks (VPNs) establish secure connections over public networks
• Full-disk encryption safeguards data on laptops and mobile devices
• Secure key exchange protocols (Diffie-Hellman) establish shared secrets over insecure channels

Digital signatures and content protection

• Digital signatures verify authenticity and integrity of electronic documents and software
• Code signing certificates protect software distributions from tampering
• Digital Rights Management (DRM) systems use cryptography to control access to copyrighted content
• Time-stamping services provide cryptographic proof of document existence at a specific time
• Blockchain technologies use digital signatures for transaction validation

Symmetric vs Asymmetric Cryptography

Symmetric cryptography characteristics

• Uses a single shared key for both encryption and decryption
• Offers faster processing and simpler implementation compared to asymmetric cryptography
• Common algorithms include AES (Advanced Encryption Standard), DES (Data Encryption Standard), and ChaCha20
• Primarily used for bulk data encryption and securing communication sessions
• Requires secure key distribution methods to share secret keys between parties
• Vulnerable to key compromise if a single party's key is exposed

Asymmetric cryptography features

• Employs a pair of mathematically related public and private keys
• Enables additional features like digital signatures and secure key exchange
• Common algorithms include RSA (Rivest-Shamir-Adleman), ECC (Elliptic Curve Cryptography), and DSA (Digital Signature Algorithm)
• Used for secure key exchange, digital signatures, and initial authentication
• Provides better key management for large-scale systems compared to symmetric cryptography
• Computationally more intensive than symmetric cryptography for equivalent key strengths

Hybrid systems and key management

• Hybrid systems combine symmetric and asymmetric cryptography to leverage their strengths
  • Example: TLS protocol uses asymmetric cryptography for key exchange, then symmetric for data encryption
• Key management crucial for both symmetric and asymmetric systems
  • Symmetric systems require secure key distribution methods
  • Asymmetric systems need robust public key infrastructure (PKI) for key verification
• Choice between symmetric and asymmetric depends on security requirements and performance constraints
  • High-volume data encryption often uses symmetric algorithms for speed
  • User authentication and digital signatures typically employ asymmetric techniques

Cryptography for secure data

Protection against unauthorized access

• Strong encryption algorithms make decryption computationally infeasible without proper keys
  • Example: AES-256 provides 256-bit security, requiring $2^{256}$ operations to brute-force
• Cryptography safeguards sensitive information during transmission over insecure networks
  • Encrypted email protects message contents from eavesdropping
• Secure storage solutions use encryption to protect data at rest
  • Encrypted databases prevent unauthorized access to sensitive records

Ensuring data integrity and authenticity

• Cryptographic hash functions detect any tampering or modification of information
  • Example: SHA-256 produces a unique 256-bit digest for any input data
• Digital signatures combine encryption and hashing to verify message integrity and origin
  • Signed software updates ensure authenticity of distributed code
• Message Authentication Codes (MACs) provide integrity and authentication for symmetric key systems
  • HMAC algorithm commonly used in secure communication protocols

Compliance and non-repudiation

• Cryptography supports compliance with data protection regulations and industry standards
  • Example: GDPR requires encryption of personal data in many scenarios
• Non-repudiation prevents parties from denying involvement in transactions or communications
  • Digital signatures on contracts provide cryptographic proof of agreement
• Secure logging and auditing systems use cryptography to ensure tamper-evident records
  • Blockchain-based systems provide immutable audit trails for financial transactions