SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function, part of the SHA-2 family, designed by the NSA. It takes any input data (text, file, etc.) and produces a unique, fixed-length 256-bit (64-character hex) string called a 'hash' or 'digest'. It is a one-way function.

Is SHA-256 a form of encryption?

No. This is a common misconception. Encryption is a two-way process (encrypt/decrypt) and requires a key. SHA-256 is a *one-way hash function*. You cannot 'decode' or 'reverse' a SHA-256 hash to get the original input. It is used for *verification*, not *secrecy*.

What is SHA-256 used for?

The main uses for SHA-256 are: 1) **Data Integrity:** Verifying that a file has not been altered (by comparing hashes). 2) **Password Storage:** Storing a 'hash' of a user's password (with a 'salt') instead of the password itself. 3) **Blockchain (Bitcoin):** It is the foundation of Bitcoin's 'Proof-of-Work' mining and transaction verification.

What is the difference between SHA-256 and MD5?

SHA-256 is modern, secure, and has no known practical collision vulnerabilities. MD5 is an older hash function that is considered *broken* and *insecure*. MD5 is highly vulnerable to 'collisions' (where two different inputs produce the same hash) and should *never* be used for security purposes. Always use SHA-256 or SHA-512 instead.

SHA-256 Hash Generator

Secure online calculator for SHA-256 hashes.

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What is SHA-256? A Comprehensive Guide

SHA-256 (Secure Hash Algorithm 256-bit) is a **cryptographic hash function**. It is a member of the **SHA-2** family, which was designed by the NSA and published by NIST as a U.S. federal standard.

What is a Hash Function? A hash function is a mathematical algorithm that takes an input (like text, a file, or any data) and produces a fixed-size string of characters, known as a **"hash"** or **"digest"**.

One-Way: It is computationally infeasible to reverse the process (i.e., find the input from its hash). This is why it is **not encryption**, which is a two-way process.
Deterministic: The same input will *always* produce the same SHA-256 hash.
Avalanche Effect: Changing even one character in the input (e.g., 'Hello' vs 'hello') will produce a completely different hash.
Collision Resistant: It is extremely difficult to find two different inputs that produce the same hash.

The output of SHA-256 is *always* 256 bits long, which is commonly represented as a **64-character hexadecimal string**.

Key Use Cases for this Generator:

Password Storage: When you create an account, systems store the SHA-256 hash of your password (ideally with a "salt"), not the password itself. When you log in, the system hashes your input and compares it to the stored hash.
Data Integrity Check: Software downloads often provide a SHA-256 hash. After downloading, you can use this tool to hash the file and compare the result. If they match, the file is authentic and has not been corrupted or tampered with.
Blockchain & Cryptocurrencies: SHA-256 is the foundational algorithm for **Bitcoin**. It's used in the "Proof-of-Work" mining process to verify transactions and create new blocks.

SHA-256 Hash Examples

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SHA-256 Best Practices & Key Concepts

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Myth: SHA-256 is Encryption

This is the #1 misconception. Hashing is **one-way** (for verification). Encryption is **two-way** (for confidentiality) and can be reversed with a key. You cannot "decrypt" a SHA-256 hash. Never use it to "hide" data you need to get back.

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Always "Salt" Your Passwords

Never store a *raw* SHA-256 hash of a password (e.g., sha256("password123")). Attackers use "rainbow tables" (pre-computed hashes) to crack these instantly. You must use a "salt" — a unique, random string added to *each* password *before* hashing. E.g., sha256("password123" + "random_salt_here").

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SHA-256 vs. MD5 & SHA-1

MD5 and SHA-1 are older hash functions that are **considered broken and insecure**. They are vulnerable to "collisions" (finding two inputs with the same hash). Never use MD5 or SHA-1 for security. **SHA-256 (and SHA-512)** are the current industry standards.