Network Security v1.0 - Module 16 (Basic Integrity and Authenticity)

Module 16: Basic Integrity and Authenticity

Integrity and Authenticity:

• Secure Communications Elements:

  • Data Integrity: Ensures data is unaltered in transit.

  • Origin Authentication: Ensures the message is from the claimed sender (e.g., HMAC).

  • Confidentiality: Ensures only the authorized recipient can read the message.

  • Data Non-Repudiation: Guarantees the sender cannot deny sending the message.

Cryptographic Hash Functions:

• How It Works: A hash function takes an input (message) and produces a fixed-size hash value that uniquely represents the input.

• Properties: Hashing is one-way (cannot be reversed) and collision-free (two inputs cannot produce the same hash).

MD5, SHA, and HMAC:

• MD5: A 128-bit digest algorithm, outdated and insecure for modern use.

• SHA-1, SHA-2, and SHA-3: Provide stronger integrity checks.

• HMAC: Combines a hash function with a secret key, providing origin authentication and data integrity protection against man-in-the-middle attacks.

Origin Authentication:

• HMAC Process:

  • Sender computes an HMAC digest using a shared secret key and sends the message with the digest.

  • Receiver computes the HMAC and compares it with the sent digest to verify integrity and authentication.

Key Management:

• Key Length and Keyspace:

  • Key Length: Determines the security level of the encryption.

  • Keyspace: The set of all possible keys, increasing exponentially with key length.

• Key Management Challenges: Involves key generation, distribution, storage, and revocation.

Confidentiality:

• Symmetric Encryption: Both the sender and receiver use the same pre-shared key (e.g., AES).

• Asymmetric Encryption: Uses different keys for encryption and decryption (e.g., RSA, PKI).

• Diffie-Hellman: A protocol for generating a shared secret key over an unsecured channel.