SHA-1 was designed by the NSA and published in 1995. It produces 160-bit (40 hex) hashes. For two decades it secured SSL/TLS certificates, Git commits, and digital signatures worldwide.

Is SHA-1 still secure?

No. The SHAttered attack (2017) created two different PDFs with the same SHA-1 hash, proving practical collisions. All major browsers and certificate authorities have deprecated SHA-1.

Where is SHA-1 still used?

Git internally uses SHA-1 for commit hashes. While transitioning to SHA-256, most repositories still use SHA-1. Some legacy systems and hardware security modules also retain it.

SHA-256 is the direct replacement. All modern TLS certificates, code signing, and digital signatures use SHA-256 or stronger variants.

What was the SHAttered attack?

A 2017 Google/CWI Amsterdam collaboration that created two different PDF files with identical SHA-1 hashes after 9.2 billion billion SHA-1 computations — equivalent to 6,500 years of single-CPU time.

Tools

SHA-1|40 hex chars

Input

Output

Hash result will appear here...

0 chars|0 bytes

SHA1 Hash Generator — Online SHA-1 Checksum Tool

Once the backbone of internet security, now broken by the SHAttered collision attack. 160-bit output, deprecated by all major browsers. Still found in legacy Git repositories.

Features

✓Compute SHA-1 hashes online — the algorithm that secured the internet for two decades
✓Real-time 160-bit hash computation with 40 hex character output
✓One-click copy, download as .txt, and uppercase/lowercase toggle
✓Still found in legacy Git repositories and old SSL certificates
✓Hash verification against known SHA-1 checksums
✓100% browser-based — zero server uploads

How to Use

1Type or paste your text into the input box above.
2Your hash digest appears instantly — no page reload needed.
3Toggle UPPERCASE / lowercase to change the hex output format.
4Click the copy icon to copy the hash to clipboard, or use Download to save as .txt.
5Paste an expected hash into the Verify field to check for a match.

Frequently Asked Questions

Related Tools

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The global industry standard — powers Bitcoin, HTTPS certificates, and digital signatures worldwide. 256-bit output, 128-bit security. The most trusted SHA-2 variant by far.

SHA-512 Hash Calculator — 512-bit Maximum Security

The highest-output SHA-2 variant at 512 bits. Paradoxically faster than SHA-256 on 64-bit CPUs. 256-bit security level for long-term data protection.