Ověřování kontrolních součtů

(Dokumentace v angličtině)

What it does

The

ChecksumChecksumA short digest computed from a block of data, compared after transfer or storage to detect corruption. Changing one bit changes the checksum.

Verifier computes the MD5, SHA-1, SHA-256, and SHA-512 checksums of any file you drop on it, then lets you verify the file against a published

hashhashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

. Software vendors, ISO mirrors, and package registries publish these hashes next to their downloads; recomputing the digest on your copy proves the bytes you received are exactly the bytes they shipped. A single flipped bit - from a corrupted download or a deliberately tampered file - produces a completely different hash, so a mismatch is unambiguous evidence of alteration. Everything runs 100% client-side: your file is read locally with the File API and never uploaded anywhere.

How to use it

1. Drop a file on the upload zone (or click it to browse). The file name and size appear, with a progress bar while large files are read in chunks.
2. Read the four

   checksumschecksumsA short digest computed from a block of data, compared after transfer or storage to detect corruption. Changing one bit changes the checksum.

   in the

   hashhashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

   table - each row has a Copy button for pasting into a report or ticket.
3. Paste the expected

   checksumchecksumA short digest computed from a block of data, compared after transfer or storage to detect corruption. Changing one bit changes the checksum.

   (from the vendor’s download page) into the verify field. The algorithm is auto-detected from the

   hashhashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

   length: 32 hex chars = MD5, 40 = SHA-1, 64 = SHA-256, 128 = SHA-512.
4. A green Match badge means the file is intact; a red Mismatch badge means it differs from the published

   hashhashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

   - re-download and try again before trusting it.

Examples

Verify a download against its published SHA-256

Expected (from the vendor’s page): 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

A file containing exactly hello hashes to:

MD5:      5d41402abc4b2a76b9719d911017c592
SHA-1:    aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d
SHA-256:  2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

→ green Match badge, algorithm detected as SHA-256.

Catch a tampered file

Expected: 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 Actual file contains hellO (one character changed) → its SHA-256 is a completely different digest → red Mismatch badge.

Paste formatted hashes

Uppercase and grouped input is normalized automatically: D41D 8CD9 8F00 B204 E980 0998 ECF8 427E is detected as MD5 and compared byte-for-byte.

Good to know

• Private: the file never leaves your browser -

  hashinghashingA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

  happens locally, so it is safe for confidential artifacts.
• MD5 and SHA-1 are integrity checks only - both have known collision attacks, so use SHA-256 or SHA-512 when the goal is tamper resistance rather than corruption detection.
• Shareable: the expected

  hashhashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

  is encoded in the URL (?expected=…), so a link reproduces the exact verification view (drop the same file to complete it).
• Related tools:

  HashHashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

  ,

  HMACHMACA construction that combines a hash function with a secret key to prove a message is intact and came from someone holding the key.

  Generator, Hash Type Identifier.