Why is SHA-1 considered broken?

In 2017, researchers produced the first practical collision attack on SHA-1, meaning they created two different files with the same SHA-1 hash. While finding a collision still requires significant computing power, the theoretical vulnerability means SHA-1 can no longer be trusted for digital signatures, certificate authorities, or any application where collision resistance matters.

Can I reverse a hash back to the original text?

No. SHA hash functions are one-way: there is no mathematical operation that can reverse a hash back to its input. The only way to find the original text is through brute force (trying every possible input), which is computationally infeasible for SHA-256 and stronger algorithms with inputs longer than a few characters.

Why does the same text always produce the same hash?

Hash functions are deterministic - the same input always produces the same output. This is a feature, not a bug. It is what makes hashes useful for verification: you can hash a file now and hash it again later, and if the hashes match, the file has not changed.

Generate SHA Hashes from Any Text: All Four Algorithms at Once

Hash generator to calculate MD5, SHA-1, SHA-256, SHA-512 hashes. SHA256 hash generator, MD5 hash generator, checksum calculator. Free online hash tool.

Hash functions support data integrity verification, password storage, digital signatures, and blockchain technology. This generator produces four different SHA-family hashes - SHA-1, SHA-256, SHA-384, and SHA-512 - simultaneously from any text you enter, so you can compare outputs and choose the right algorithm for your use case. The tool uses your browser's built-in Web Crypto API, which implements these algorithms according to the official FIPS standards. Your input never leaves your device.

SHA-1 vs SHA-256 vs SHA-384 vs SHA-512: Which One Should You Use?

Not all hash algorithms are equal. Some are fast but compromised. Some are slower but more secure. A practical comparison to help you pick the right one for your specific need.

SHA-1 (160-bit, 40 hex characters)

Deprecated for security purposes since 2017, when Google and CWI Amsterdam demonstrated a collision attack (two different inputs producing the same hash). SHA-1 is still found in legacy systems and Git commit hashes, but you should never use it for new security-sensitive applications. Included here for legacy comparison only.

SHA-256 (256-bit, 64 hex characters)

The current standard for general-purpose hashing. Used in TLS certificates, Bitcoin, most password hashing schemes, and the vast majority of modern APIs. No practical collision attacks exist. If you are unsure which algorithm to use, SHA-256 is almost certainly the right choice.

SHA-384 (384-bit, 96 hex characters)

A middle ground between SHA-256 and SHA-512. Uses the same internal algorithm as SHA-512 but truncates the output to 384 bits. Required by some government and financial standards (FIPS 140-2, PCI DSS) that mandate algorithms stronger than SHA-256. Not commonly used outside of compliance requirements.

SHA-512 (512-bit, 128 hex characters)

The strongest SHA-2 variant. Produces the longest hash, making collision attacks even more theoretically difficult than SHA-256. Often used in security-critical applications, blockchain systems, and environments where maximum hash length is not a concern. Slightly faster than SHA-256 on 64-bit hardware due to operating on 64-bit words.

Common Questions About Hash Functions

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