Blowfish Cipher Encrypt Decrypt Online

Encrypt and decrypt data using the Blowfish symmetric block cipher. Fast, secure, and widely supported encryption algorithm with variable key length from 32 to 448 bits.

Mode:

Blowfish Configuration

Key length: 0 characters (0 bits)

Choose how encrypted data should be encoded for display and storage.

Length: 0 characters

Encrypted data will appear here...

Output length: 0 characters

About Blowfish Cipher

What is Blowfish?

Blowfish is a symmetric-key block cipher designed by Bruce Schneier in 1993. It's known for its speed, simplicity, and strong security, making it ideal for applications where both security and performance are important.

Key Features

  • • Block Size: 64-bit blocks
  • • Key Length: Variable from 32 to 448 bits
  • • Rounds: 16 rounds of Feistel network
  • • Speed: Fast encryption and decryption
  • • Memory: Large key-dependent S-boxes

Algorithm Structure

Blowfish consists of two parts: key expansion and data encryption. The key expansion converts a variable-length key into several subkey arrays totaling 4,168 bytes.

Common Applications

  • • File and disk encryption
  • • Network protocol encryption
  • • Database encryption
  • • Password manager applications
  • • Secure communication systems

Blowfish Algorithm Implementation Details

Feistel Network Structure:

  • 16-round Feistel cipher with complex F-function
  • Each round uses 32-bit subkeys from P-array
  • F-function combines four S-boxes with 256 entries each
  • Data flows through alternating left-right processing
  • Final swap and XOR with last two P-array entries

Key Expansion Process:

  • Initialize P-array and S-boxes with fixed values
  • XOR P-array entries with key material cyclically
  • Encrypt all-zero blocks to generate new P-array
  • Continue encryption to fill all S-box entries
  • Total of 521 encryptions needed for key setup

Security Analysis & Cryptographic Properties

Strengths:

  • No known practical attacks against full Blowfish
  • Fast performance in software implementations
  • Variable key length provides flexibility
  • Large memory requirements deter hardware attacks
  • Patent-free and public domain algorithm
  • Extensively analyzed by cryptographic community
  • Simple structure aids in verification

Considerations:

  • 64-bit block size limits secure data volume
  • Slow key setup makes it less suitable for frequent key changes
  • Sweet32 attack affects all 64-bit block ciphers
  • Not recommended for new applications (use AES instead)
  • Weak keys exist but are extremely rare
  • Memory requirements may be challenging on constrained devices

Performance Characteristics & Benchmarks

Speed Advantages:

  • Optimized for 32-bit processors
  • Simple operations: XOR, addition, table lookups
  • No multiplication or complex bit operations
  • Excellent performance on older hardware
  • Minimal code size requirements
  • Cache-friendly memory access patterns

Memory Usage:

  • P-array: 18 × 32-bit entries (72 bytes)
  • S-boxes: 4 × 256 × 32-bit entries (4,096 bytes)
  • Total memory: 4,168 bytes per key schedule
  • Key setup time: ~521 encryption operations
  • Memory access intensive during encryption

Implementation Variants & Standards

Standard Implementations:

  • OpenSSL Blowfish implementation
  • GnuPG uses Blowfish for symmetric encryption
  • bcrypt password hashing (Blowfish-based)
  • SSH protocol cipher support
  • TLS/SSL cipher suite inclusion

Related Algorithms:

  • Twofish: Blowfish successor by same author
  • Threefish: Part of Skein hash function
  • bcrypt: Adaptive password hashing
  • Eksblowfish: Expensive key schedule variant

Tool Capabilities:

  • Full Blowfish implementation
  • Variable key length support (8-56 chars)
  • PKCS7 padding for arbitrary data lengths
  • Hex and Base64 output encoding
  • Secure random key generation
  • Client-side processing for privacy

Historical Context & Legacy

Development History:

  • 1993: Published by Bruce Schneier
  • 1994: First cryptanalysis attempts
  • 1996: Incorporated into various software
  • 1998: Twofish (successor) submitted to AES
  • 2000s: Widespread adoption in applications
  • 2016: Sweet32 attack affects 64-bit ciphers

Current Status:

  • Still secure for most practical purposes
  • Gradually being replaced by AES
  • Remains popular for legacy system support
  • Educational value for understanding Feistel ciphers
  • Important milestone in cipher design history
  • Influence on modern cipher development

Best Practices & Security Guidelines

Key Management:

  • Use minimum 128-bit (16-character) keys
  • Generate keys using cryptographically secure RNG
  • Avoid predictable or dictionary-based keys
  • Consider key derivation functions for password-based keys
  • Implement proper key rotation policies
  • Secure key storage and transmission

Usage Recommendations:

  • Limit data encrypted with single key (64GB max)
  • Use appropriate block cipher modes (CBC, CTR)
  • Implement proper initialization vectors
  • Consider authenticated encryption modes
  • Migrate to AES for new applications
  • Regular security assessment and updates