SHA-1 Generator and Hash Lookup
Understanding SHA-1
SHA-1 produces a deterministic 160-bit digest, normally written as 40 hexadecimal characters. It was widely used for file integrity, signatures and password storage, but practical collisions mean it should not be selected for new security applications.
Digest size160 bits
Common format40 hexadecimal characters
Generation and database lookup
The generator hashes the exact bytes of your input. The lookup then compares each digest with our multi-hash corpus. It may recover a previously indexed plaintext, including values from our own research, but it cannot reconstruct arbitrary text from the digest.
Worked example
The SHA-1 digest of hello is aa f4 c6 1d dc c5 e8 a2 da be de 0f 3b 48 2c d9 ae a9 43 4d without spaces. Hello, hello and hello\n all produce different results.
How does the lookup work?
A miss only means the plaintext is not present in the currently queried corpus. Salted hashes, random strings, long inputs and unusual encodings are less likely to match. For multiple digests, the API provides batch lookup through the same logical database.
Security guidance
Do not use SHA-1 for new signatures, certificates or security designs. Passwords should use Argon2id, scrypt or bcrypt with a unique salt. Salting SHA-1 blocks precomputed tables but does not fix its excessive speed against offline guessing.
Reproduce the calculation
These examples hash exactly the text “hello” without a trailing newline. A space or line break would change the digest.
Shell
printf %s 'hello' | sha1sumPHP
echo hash('sha1', 'hello');JavaScript
const bytes = new TextEncoder().encode('hello');
const digest = await crypto.subtle.digest('SHA-1', bytes);Comparison with other SHA variants
SHA-1 is longer than MD5 but is no longer collision-resistant. SHA-256 and SHA-512 belong to SHA-2 and remain suitable for integrity when correctly used, although they are still not password-storage functions.
FAQ
How long is a SHA-1 hash?
SHA-1 produces 160 bits, which is 20 bytes or 40 hexadecimal characters.
Can SHA-1 be decrypted?
No. Md5Decrypt searches for an already calculated match in its corpus; it does not mathematically reverse SHA-1.
Why is SHA-1 no longer recommended?
Practical collisions show that different contents can be constructed with the same digest, invalidating modern hostile-integrity and signature use.
Is salted SHA-1 safe for passwords?
A salt prevents precomputed tables, but SHA-1 remains too fast. Use a configurable password KDF such as Argon2id, scrypt or bcrypt.
Why was my SHA-1 hash not found?
The plaintext may be absent, salted, long, random or encoded differently from what you expect.
Practical notes
The lookup compares exact SHA-1 digests with the database. The file checker is useful for integrity checks, but SHA-1 is no longer suitable for modern signatures or password storage.
Length160 bits / 40 hex
BatchUp to 20 digests
FileCalculate and compare
Frequently asked questions
Why is SHA-1 discouraged?
Practical collisions have been demonstrated. It should no longer protect signatures, certificates or new systems.
What is the file checksum used for?
It calculates a file digest so it can be compared with a published value. This verification is separate from a database lookup.
Why can a lookup fail?
The database can only return previously indexed text that exactly matches the digest.
Reproducible examples
These commands hash the five UTF-8 bytes in “hello”, without adding a trailing newline.
Terminal
printf %s "hello" | sha1sumPHP
hash('sha1', 'hello');JavaScript
const bytes = new TextEncoder().encode('hello');
const digest = await crypto.subtle.digest('SHA-1', bytes);