About SHA-1 Hash Generator
This SHA-1 hash generator computes the SHA-1 digest of your text or file. SHA-1 produces a 160-bit value, written as 40 hexadecimal characters. It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
SHA-1 is no longer safe against a determined attacker. A team from Google and CWI published the first practical collision, called SHAttered, in 2017, and later work made chosen-prefix attacks affordable. Browsers and certificate authorities stopped accepting SHA-1 certificates years ago, and NIST plans to retire it by 2030. For new work use SHA-256 or SHA-3.
You will still meet SHA-1 in older systems. Git has long named commits and files by their SHA-1, legacy APIs sign requests with HMAC-SHA1, and some Linux ISOs still publish a SHA1SUMS file. In those places the hash identifies content rather than defending against an attacker, so it keeps working.
The SHA-1 digest here comes from the Web Crypto API of your browser. HMAC-SHA1 is available by ticking HMAC with secret key. The SHA-1 of "hello" is aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d.
How to use SHA-1 Hash Generator
- Choose an algorithm from the row of buttons: MD5, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA3-256, SHA3-512 or CRC32. SHA-256 is a good default.
- Choose Text and type or paste your input, or choose File and pick a file from your device. The hash updates as you type.
- Read the digest in the result box. Tick Uppercase for capital hex letters, or Base64 output to show the digest in Base64 instead of hex.
- For a keyed hash, tick HMAC with secret key and enter the key. The result is then labelled HMAC-SHA-256 (or whichever algorithm you chose).
- To verify a download or a value from documentation, paste the expected hash into Compare with a known hash. The tool says Match or No match.
- Use Copy to put the digest on your clipboard.
Features
- Nine algorithms: MD5, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA3-256, SHA3-512 and CRC32.
- Hashes text as UTF-8, so accented letters, other scripts and emoji hash the same way as on a server or in a command-line tool.
- Hashes a file you choose from your device. The file is read in your browser and never uploaded.
- HMAC with a secret key for every algorithm except CRC32, following RFC 2104.
- Hex output in lowercase or uppercase, or Base64 output.
- Compare with a known hash. Case, spaces and a leading 0x are ignored, and the expected value can be hex or Base64.
- SHA-1, SHA-256, SHA-384 and SHA-512 use the Web Crypto API in your browser, which is fast and well tested.
- A warning appears when you pick MD5, SHA-1 or CRC32, because they are not safe for security purposes.
- One-click copy of the result.
Worked examples
SHA-1 of "abc" gives a9993e364706816aba3e25717850c26c9cd0d89d
The FIPS 180 test vector.
SHA-1 of an empty input gives da39a3ee5e6b4b0d3255bfef95601890afd80709
SHA-1 of "The quick brown fox jumps over the lazy dog" gives 2fd4e1c67a2d28fced849ee1bb76e7391b93eb12
Privacy: how it works
- The text, the file and the HMAC key stay in your browser tab. Nothing is sent to Ulkaa or to any other server, which you can confirm in the Network tab of your browser developer tools.
- Because the work happens on your own device, large files are limited by your browser memory rather than by an upload limit.
Tips
- To verify a download, choose File, pick the downloaded file, and paste the publisher hash into the compare box. A match means the bytes are identical to what the publisher hashed.
- Hash the same text twice with a trailing space added once. Seeing two unrelated digests is the quickest way to understand the avalanche effect.
- A hash you found on the same page as the download only protects against corruption. It cannot protect you if the page itself was altered.
- HMAC takes the key as plain text. If your key is hex or Base64, decode it first, or the result will not match another system.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial and no credit card. Ulkaa Tool does the work with your own device, so there is no server bill to pass on to you.
Do I need an account?
No. There is no sign-up and no login. Open the page and use it. An Ulkaa account is not needed for anything on this tool.
Does it run in my browser?
Yes. Your text and files are processed by code running in your browser tab, on your own device.
Is my data uploaded?
No. Your text and files are never sent to Ulkaa or to anyone else. You can check this yourself by watching the Network tab in your browser developer tools while you use the tool.
Is SHA-1 secure?
Not for security uses. Practical collisions have been demonstrated, so it should not be used for signatures, certificates or integrity checks against an attacker. It is acceptable only where compatibility forces it, such as old tools.
How long is a SHA-1 hash?
It is 160 bits, which is 40 hexadecimal characters, or 28 characters in Base64 including the padding.
Does Git still use SHA-1?
Git repositories default to SHA-1 object names, with hardened collision detection added in 2017. Git also supports SHA-256 repositories as an option. The hash of a Git object is not the plain SHA-1 of the file, because Git adds a short header first.
More Hash Generator pages
- Hash GeneratorHash text or a file with MD5, SHA-1, SHA-2, SHA-3 or CRC32, add an HMAC key, and check the result against a known hash.
- MD5 Hash GeneratorGet the 128-bit MD5 hash of text or a file as 32 hexadecimal characters.
- SHA-224 Hash GeneratorGet the 224-bit SHA-224 hash of text or a file as 56 hexadecimal characters.
- SHA-256 Hash GeneratorGet the 256-bit SHA-256 hash of text or a file as 64 hexadecimal characters.
- SHA-384 Hash GeneratorGet the 384-bit SHA-384 hash of text or a file as 96 hexadecimal characters.
- SHA-512 Hash GeneratorGet the 512-bit SHA-512 hash of text or a file as 128 hexadecimal characters.
- SHA3-256 Hash GeneratorGet the 256-bit SHA3-256 hash of text or a file as 64 hexadecimal characters.
- SHA3-512 Hash GeneratorGet the 512-bit SHA3-512 hash of text or a file as 128 hexadecimal characters.
- CRC32 Checksum CalculatorCalculate the 32-bit CRC32 checksum of text or a file as 8 hexadecimal characters.
- HMAC-SHA256 GeneratorSign a message with a secret key using HMAC-SHA256 and read the result as hex or Base64.
- File Checksum CalculatorHash a file on your device and compare it with the checksum the publisher gave you.