🔐 Hash Generator (MD5, SHA, HMAC)
Generate cryptographic hashes and HMAC: MD5, SHA-1, SHA-256, SHA-384, SHA-512. Free online hash generator with auto-hash and export options.
✓ SHA256 is secure and recommended.
What is a Hash Function?
A hash function is a mathematical algorithm that takes an input (or "message") and returns a fixed-size string of bytes. The output, known as the hash value or digest, is typically a hexadecimal string that appears random. Hash functions are one-way functions - it's easy to compute the hash from the input, but nearly impossible to reverse the process.
Hash functions are widely used in cryptography, data integrity verification, password storage, digital signatures, and blockchain technology. Different hash algorithms offer different levels of security and output sizes.
Hash Algorithms Explained
MD5 (128 bits)
MD5 produces a 128-bit hash value. It's fast but cryptographically broken and vulnerable to collision attacks. Not recommended for security purposes.
Use for: Checksums, non-security applications
SHA-1 (160 bits)
SHA-1 produces a 160-bit hash value. It's deprecated due to security vulnerabilities and collision attacks. Not recommended for new applications.
Use for: Legacy systems, non-security applications
SHA-256 (256 bits)
SHA-256 is part of the SHA-2 family and produces a 256-bit hash. It's secure, widely used, and recommended for most applications including blockchain and digital signatures.
Use for: Security, blockchain, digital signatures
SHA-384 (384 bits)
SHA-384 is part of the SHA-2 family and produces a 384-bit hash. It offers higher security than SHA-256 and is suitable for applications requiring enhanced security.
Use for: High-security applications
SHA-512 (512 bits)
SHA-512 is part of the SHA-2 family and produces a 512-bit hash. It offers the highest security level among SHA-2 algorithms and is suitable for applications requiring maximum security.
Use for: Maximum security, cryptographic applications
Common Use Cases
🔐 Password Storage
Hash passwords before storing them in databases. Use SHA-256 or SHA-512 with salt for secure password hashing (though bcrypt or Argon2 are preferred).
✅ Data Integrity
Verify file integrity by comparing hash values. Generate hashes for files and compare them to detect corruption or tampering.
🔗 Digital Signatures
Hash messages before signing them digitally. This ensures the signature applies to the entire message and provides integrity verification.
⛓️ Blockchain
Hash blocks and transactions in blockchain systems. SHA-256 is commonly used in Bitcoin and many other cryptocurrencies.
Key Features
Multiple Algorithms
Generate hashes using MD5, SHA-1, SHA-256, SHA-384, or SHA-512. Choose the algorithm that best fits your security requirements.
Auto-Hash
Enable auto-hashing to generate hashes automatically as you type. Real-time hash generation for faster workflow.
Hash Information
View hash length, bit size, and algorithm details. Understand the characteristics of your generated hash.
Export Options
Copy hash values to clipboard or export to text files. Easy integration into your applications or documentation.
Privacy First
All hashing happens locally in your browser using Web Crypto API. We never see, store, or have access to your input or generated hashes.
Understanding Cryptographic Hash Functions
What Are Hash Functions?
A cryptographic hash function is a mathematical algorithm that takes an input (or "message") and returns a fixed-size string of bytes. The output, called a hash value or digest, appears random and is unique to the input data. Even a tiny change in the input produces a completely different hash.
Hash functions are one-way functions - you can easily compute the hash from the input, but it's computationally infeasible to reverse the process and determine the original input from the hash. This property makes them ideal for password storage, data integrity verification, and digital signatures.
Key Properties of Hash Functions
Deterministic
The same input always produces the same hash output. This allows verification of data integrity by comparing hashes before and after transmission or storage.
Fast Computation
Hash functions are designed to compute quickly, making them practical for real-time applications like password verification and file integrity checks.
Avalanche Effect
A small change in input (even a single bit) produces a dramatically different hash. This ensures that similar inputs don't produce similar hashes, preventing pattern-based attacks.
Collision Resistance
It should be extremely difficult to find two different inputs that produce the same hash. While collisions are theoretically possible (due to fixed output size), finding them should be computationally infeasible for secure hash functions.
Hash Algorithms Explained
MD5 (Message Digest 5)
Produces a 128-bit (16-byte) hash. MD5 is now considered cryptographically broken and unsuitable for security purposes due to collision vulnerabilities discovered in 2004. However, it's still useful for non-cryptographic purposes like checksums and data integrity verification in non-adversarial environments.
⚠️ Not recommended for security-sensitive applications
SHA-1 (Secure Hash Algorithm 1)
Produces a 160-bit (20-byte) hash. SHA-1 was deprecated by NIST in 2011 due to theoretical collision attacks. While still widely used, it's being phased out in favor of SHA-2 and SHA-3 for new applications.
⚠️ Deprecated - use SHA-256 or higher for new projects
SHA-256 (SHA-2 Family)
Produces a 256-bit (32-byte) hash. Part of the SHA-2 family, SHA-256 is currently the most widely used secure hash algorithm. It's recommended by security experts and used in Bitcoin, SSL/TLS certificates, and many other security-critical applications. SHA-256 provides excellent security and performance balance.
SHA-384 (SHA-2 Family)
Produces a 384-bit (48-byte) hash. Also part of the SHA-2 family, SHA-384 offers higher security than SHA-256, though SHA-256 is generally sufficient for most applications. SHA-384 is often used when additional security margin is desired.
SHA-512 (SHA-2 Family)
Produces a 512-bit (64-byte) hash. The largest output in the SHA-2 family, SHA-512 provides the highest level of security. While computationally more expensive than SHA-256, it's still fast enough for most applications and offers maximum security for sensitive data.
Common Use Cases for Hash Functions
- Password Storage: Websites store password hashes instead of plain text passwords. When you log in, your password is hashed and compared to the stored hash.
- Data Integrity: Verify that files haven't been corrupted or tampered with by comparing their hashes before and after transmission.
- Digital Signatures: Hash functions are used in digital signature algorithms to create compact, verifiable signatures.
- Blockchain: Cryptocurrencies like Bitcoin use hash functions extensively for mining, transaction verification, and maintaining the blockchain.
- Deduplication: Identify duplicate files or data by comparing their hashes.
- Commitment Schemes: Commit to a value without revealing it, then later prove what the value was.
Security Considerations
Salt for Passwords
When hashing passwords, always use a salt - a random value added to each password before hashing. Salting prevents rainbow table attacks and ensures that identical passwords produce different hashes. Modern password hashing uses specialized algorithms like bcrypt, Argon2, or PBKDF2 that incorporate salting and are computationally expensive to slow down brute force attacks.
Algorithm Selection
For security-sensitive applications, always use SHA-256 or higher. Avoid MD5 and SHA-1 for new projects. Consider the computational cost vs. security trade-off - SHA-256 is usually the sweet spot for most applications.
Hash Length
Longer hashes provide more security but require more storage and computation. SHA-256 (256 bits) is generally sufficient for most applications. SHA-512 provides maximum security for highly sensitive applications.
Frequently Asked Questions
Which hash algorithm should I use?
For security purposes, use SHA-256 or SHA-512. SHA-256 is widely used and provides excellent security. SHA-512 offers even higher security. Avoid MD5 and SHA-1 for security-critical applications as they're vulnerable to attacks.
Can I reverse a hash to get the original text?
No, hash functions are one-way functions. You cannot reverse a hash to get the original input. However, attackers can use rainbow tables or brute force to find inputs that produce the same hash.
Is MD5 secure?
No, MD5 is not secure for cryptographic purposes. It's vulnerable to collision attacks and should not be used for security-sensitive applications. Use SHA-256 or SHA-512 instead.
What's the difference between hash and encryption?
Hashing is one-way - you can't get the original data back. Encryption is two-way - you can decrypt encrypted data with the key. Use hashing for passwords and data integrity. Use encryption for data that needs to be recovered.
Do you store my hashed data?
No, absolutely not. All hashing happens entirely in your browser using the Web Crypto API. We never see, store, transmit, or have any access to your input text or generated hashes. Your privacy is completely protected.