CompTia Security+: 1.4.6 Hashing and Digital Signatures

byNour Waazize • • 2 min read
0


Hashing and Digital Signatures in Cybersecurity

Hashing and digital signatures are fundamental concepts in cybersecurity, particularly in ensuring data integrity, authentication, and non-repudiation. Let’s break them down in detail.

Hashing

Hashing is a cryptographic function that converts input data (of any length) into a fixed-length string of characters, known as a hash value or digest. Hashing is widely used for data integrity verification, password storage, and digital signatures.

Characteristics of Hashing:

  1. Deterministic: The same input always produces the same hash.
  2. Fixed Output Length: No matter the size of the input, the output hash has a fixed length.
  3. Fast Computation: Hash functions should be efficient to compute.
  4. Pre-Image Resistance: It should be computationally infeasible to reverse-engineer the original input from the hash.
  5. Collision Resistance: Two different inputs should not produce the same hash value.
  6. Avalanche Effect: A small change in input produces a vastly different hash.

Common Hashing Algorithms:

  • MD5 (Message Digest Algorithm 5) – 128-bit output; outdated due to collision vulnerabilities.
  • SHA-1 (Secure Hash Algorithm 1) – 160-bit output; deprecated due to security flaws.
  • SHA-2 (SHA-256, SHA-384, SHA-512, etc.) – Secure and widely used.
  • SHA-3 – Newer cryptographic hash standard with enhanced security.
  • Bcrypt, Scrypt, Argon2 – Used for password hashing with added protection against brute force attacks.

Use Cases of Hashing:

  1. Data Integrity Verification: Hashing ensures that transmitted or stored data has not been altered.
  2. Password Storage: Instead of storing actual passwords, systems store hash values with salt (random data added to input before hashing).
  3. Digital Signatures: Hashing is used in digital signatures to verify message integrity.
  4. File Integrity Checks: Used in file verification tools like SHA256SUM or MD5SUM.
  5. Blockchain: Cryptographic hashing ensures security and immutability in blockchain transactions.

Digital Signatures

A digital signature is a cryptographic technique used to authenticate the origin of a message or document while ensuring its integrity and providing non-repudiation (the sender cannot deny sending the message). Digital signatures rely on asymmetric encryption (public-key cryptography).

How Digital Signatures Work:

  1. Hashing the Message: The sender first hashes the message using a secure hash function (e.g., SHA-256).
  2. Encrypting the Hash: The sender encrypts the hash with their private key, creating a digital signature.
  3. Sending the Message: The sender transmits the original message along with the digital signature.
  4. Verification by the Receiver:
    • The receiver decrypts the digital signature using the sender’s public key, revealing the original hash.
    • The receiver hashes the received message and compares it with the decrypted hash.
    • If both match, the message is verified as authentic and unaltered.

Properties of Digital Signatures:

  • Authentication: Confirms the sender’s identity.
  • Integrity: Ensures the message has not been tampered with.
  • Non-Repudiation: The sender cannot deny signing the message.

Common Digital Signature Algorithms:

  • RSA (Rivest-Shamir-Adleman) – A widely used asymmetric encryption algorithm.
  • DSA (Digital Signature Algorithm) – An alternative to RSA, developed by NIST.
  • ECDSA (Elliptic Curve Digital Signature Algorithm) – More efficient and secure than traditional RSA-based signatures.
  • EdDSA (Edwards-Curve Digital Signature Algorithm) – A modern, fast alternative to ECDSA.

Use Cases of Digital Signatures:

  1. Email Security (S/MIME, PGP): Verifies sender authenticity and message integrity.
  2. Software Code Signing: Ensures software updates and downloads are from trusted sources (e.g., Microsoft Authenticode, Apple's Gatekeeper).
  3. Document Signing: Used in electronic contracts and legal documents (e.g., DocuSign, Adobe Sign).
  4. SSL/TLS Certificates: Websites use digital signatures in SSL/TLS certificates for secure HTTPS connections.
  5. Blockchain Transactions: Used in cryptocurrency transactions to ensure authenticity.

Comparison of Hashing and Digital Signatures

Feature Hashing Digital Signatures
Purpose Ensures data integrity Ensures integrity, authentication, and non-repudiation
Cryptographic Type One-way function (cannot be reversed) Uses asymmetric encryption
Output Fixed-length hash value Encrypted hash value using a private key
Security Concern Vulnerable to collisions if weak hash function is used Requires secure key management
Example Algorithms MD5, SHA-256, SHA-3 RSA, DSA, ECDSA

Key Takeaways for CompTIA Security+

Hashing is used for verifying data integrity.

Digital signatures provide authentication, integrity, and non-repudiation.

Strong hashing algorithms (SHA-2, SHA-3) should be used for security.

Public and private keys are used in digital signatures.

Digital signatures are essential for secure communication, document signing, and software authentication.


Labels:

Post a Comment

Previous Post Next Post