1. Hash Algorithm
Hash Algorithm can generate unique value to each unique input, and it's infeasible to reverse the process; that is, given a hash value, it should be computationally infeasible to find the original input.
Hash functions are widely used in various applications:
- Data Integrity: Verifying the integrity of data by comparing hash values.
- Password Hashing: Storing passwords securely by hashing them and storing the hash value.
| Algorithm Name | Input | Output | Security | Application |
|---|---|---|---|---|
| MD5 | Unlimited Length | 128-bit (16 bytes) | Not secure | MD5 can be used as a checksum to verify data integrity against unintentional corruption. |
| SHA-1 | bits | 160-bit (20 bytes) | Not secure | The same as MD5 |
| SHA-2 (SHA-256, SHA-384, SHA-512,SHA-224) | bits | Based on the suffix | Secure | |
| SHA-3 (Keccak) | Unlimited Length | Variable | Secure | |
| BLAKE | BLAKE2b-,BLAKE2s- | Variable | Secure |
Speed: MD5 > SHA1 > SHA2 > SHA3
If speed is a critical factor and security requirements allow, MD5 and BLAKE (especially BLAKE2) are among the fastest. However, given the security issues with MD5 and to a lesser extent SHA-1, BLAKE2 often represents the best balance of speed and security among these options.
2. Symmetric Encryption Algorithm
A symmetric encryption algorithm is a type of encryption where the same key is used for both encryption and decryption of data.
| Algorithm | Block Size (bits) | Key Size (bits) | Security Considerations | Typical Use Cases |
|---|---|---|---|---|
| AES | 128 | 128/192/256 | Highly secure, resistant to known attacks; standard for encryption | Data encryption in databases, software applications, and communication protocols |
| Blowfish | 64 | 32 to 448 | Secure, but has some theoretical vulnerabilities; faster than AES in some implementations | File encryption, legacy systems not supporting AES |
| Twofish | 128 | 128/192/256 | Considered secure, no effective attacks known; finalist in the AES competition | Alternative to AES where a non-NIST standard is desired |
| RC4 | Stream cipher | 40 to 2048 | Vulnerable to several serious attacks, not recommended for new systems | Formerly used in SSL and WEP, now largely replaced by stronger algorithms |
| ChaCha20 | Stream cipher | 256 | Considered very secure and fast, especially on platforms without AES-NI | Used in VPNs, TLS, and file encryption |
*DES and 3DES are obsolete due to their vulnerabilities, so we are not going to cover them here.
3. Asymmetric Algorithm
An asymmetric encryption algorithm, also known as public-key encryption, uses a pair of keys for encryption and decryption: a public key and a private key
| Algorithm | Key Size (bits) | Security Considerations | Typical Use Cases | Relative Speed |
|---|---|---|---|---|
| RSA | 1024 to 4096 | Secure at higher key sizes (2048+); susceptible to quantum attacks | Digital signatures, secure data transmission, encryption | Slow |
| ECC (Elliptic Curve Cryptography) | 160 to 521 | Provides higher security per bit than RSA; resistant to some attacks that affect RSA | Secure mobile communications, lightweight cryptography | Fast |
| DSA (Digital Signature Algorithm) | 1024 to 3072 | Primarily used for digital signatures; not for encryption | Digital signatures in software distribution, document signing | Moderate |
| ElGamal | Similar to DH | Provides both encryption and digital signature capabilities; computationally intensive | Secure email, file encryption | Slow |
4. Key Exchange
A key exchange algorithm is a cryptographic protocol designed to securely exchange cryptographic keys between parties over a public or insecure channel. Diffie–Hellman key exchange and Elliptic-curve Diffie–Hellman are common Key Exchange