Cryptographic Solutions

🔐 Cryptography Basics

Cryptography is the art and science of securing data. It includes techniques for hiding data (encryption), verifying data (hashing), and proving identities (digital signatures).

🔁 Hashing Algorithms

• ▸ SHA-256: Secure Hash Algorithm used to verify data integrity.
• ▸ MD5: Produces 128-bit digest, vulnerable to collisions.
• ▸ Birthday attack: Exploits hash collisions for forgery.

🔑 Symmetric & Asymmetric Encryption

Symmetric encryption uses the same key to encrypt and decrypt (e.g., AES, DES). It is fast and good for bulk data.

Asymmetric encryption uses a key pair: public and private keys. It is used for authentication, digital signatures, and key exchange (e.g., RSA).

⚙️ Cipher Modes & Suites

Cipher suites combine key exchange, encryption, and hashing algorithms. Common cipher modes include ECB, CBC, and GCM. Asymmetric systems like PKI support authentication and integrity.

📦 Certificates & PKI

• ▸ PKI: Uses Certificate Authorities (CAs) to issue digital certificates and bind public keys to identities.
• ▸ Digital Certificate: Contains subject info, public key, issuer, validity period, etc. Learn more on Wikipedia.
• ▸ CSR: Certificate Signing Request submitted to a CA. Learn more from DigiCert.
• ▸ Certificate Lifecycle: Includes generation, renewal, suspension, and revocation. Learn more from SSL.com.

🧠 Cryptographic Use Cases

• ▸ Confidentiality: Encrypting sensitive files or communications. Learn more about encryption on Wikipedia.
• ▸ Integrity: Verifying files with checksums or hashes. Learn more about hashing on Wikipedia.
• ▸ Authentication: Digital certificates prove identity. Learn more about authentication on Wikipedia.
• ▸ Non-repudiation: Digital signatures prevent denial of authorship. Learn more about digital signatures on Wikipedia.

🔒 Advanced Techniques

• ▸ Salting: Random data added to passwords before hashing to resist attacks. Learn more about salting on Wikipedia.
• ▸ Key stretching: PBKDF2 increases complexity of brute-force attacks. Learn more about PBKDF2 on Wikipedia.
• ▸ Homomorphic encryption: Enables computation on encrypted data. Learn more about homomorphic encryption on Wikipedia.
• ▸ Steganography: Hides information within other media (e.g., images). Learn more about steganography on Wikipedia.