## What is Blowfish encryption, and how does it work?

**Block cipher.** A block cipher in Blowfish encrypts data in 64-bit blocks. **Symmetric key algorithm.** The Blowfish algorithm uses the same symmetric encryption key to encrypt and decrypt data. **Variable length key.** Blowfish offers different key lengths, from 32 bits to 448 bits. The longer the key, the safer the data. However, longer keys usually require more processing time and resources. **Feistel cipher.** The Feistel cipher structure splits the plaintext into two halves and scrambles each half separately using a chain of mathematical operations.

**Key expansion.** Blowfish begins with a secret key, which can be from 32 bits to 448 bits long. The encryption key is then prepared and stretched out using the P-array and S-boxes precomputation to generate a series of subkeys. **Subkeys generation.** The stretched-out key is divided into smaller parts: the 64-bit blocks are divided into two 32-bit chunks. These pieces are mixed with some predefined values to create a new set of subkeys. **Data encryption.** Here comes the main part. Those two 32-bit halves pass through 16 rounds of encryption. Each round involves a complex sequence of substitutions and transpositions (XOR operations, additions, and lookups in the S-boxes). **Post-processing.** After the 16 rounds, the scrambled pieces of 32-bits are rejoined to form 64-bit ciphertext blocks. **Decryption.** Decryption in Blowfish uses the same process as encryption but in reverse. So it all goes backward until the ciphertext is reversed into plaintext.

**Network protocols.** The Blowfish algorithm has been used in network{‘ ‘} protocols like Secure Shell (SSH) and IPSec to secure internet communications. **Password hashing.** Some{‘ ‘} password managers use the{‘ ‘} bcrypt password hashing function based on Blowfish. **File encryption.** Certain file encryption software provides the option to use Blowfish for encryption to prevent unauthorized access. **Disk encryption.** Some disk encryption software uses Blowfish to safeguard your sensitive data from digital pirates and snoops. **Embedded systems.** Due to its simplicity and speed, Blowfish has been used in some embedded systems, such as devices with limited processing power. **Email encryption.** Blowfish has been used in some email encryption software to keep your messages under wraps.

The post What is Blowfish encryption, and how does it work? first appeared on NordVPN.

AES blowfish Cybersecurity encryption password hashing symmetric cryptography twofish