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To verify a Linux ISO on a Ventoy USB, select the ISO in Ventoy’s main menu, press m, choose SHA256, and compare the displayed hash with the value published for that exact image and release. For stronger assurance, first verify the distribution’s signature on its checksum file using a signing key whose identity you have independently established. A matching hash confirms the USB copy matches the reference you supplied; it does not prove that reference is authentic unless you have authenticated its source.
What should you verify before booting?
There are two related checks, and they answer different questions:
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- Integrity comparison: Does the ISO on the Ventoy drive match a published checksum? This can detect a damaged download or an incomplete or altered copy to the USB.
- Authenticity verification: Was the checksum file genuinely published by the Linux distribution? Verifying its digital signature with a trusted signing key helps answer that.
A hash comparison is only as trustworthy as the reference hash. If you calculate a hash from the USB copy and compare it with another hash calculated from that same copy, you have not independently established that the ISO is genuine. Get the reference from the distribution and authenticate its checksum file when the distribution provides a signature.
Also verify the copy on the Ventoy drive, not just the file on your computer. The goal is to check the precise image you intend to boot after it has been copied.
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That distinction matters because verification has two stages. First, establish that the reference checksum is a trustworthy one. Then calculate a checksum for the stored ISO and compare the two complete values. If the source checksum is authentic but the USB copy differs, the specific file on the drive is not the image described by that reference. If the values match but the source checksum was not authenticated, you have established a match to that value—not who published it.
What do you need?
- A Ventoy USB drive and the Linux ISO you intend to boot.
- The checksum for the exact ISO filename, edition, and release from the distribution’s official source.
- If available, the checksum file’s digital signature and a signing key whose identity you have established.
- A safe way to finish copying and eject the drive. Installing Ventoy on a drive formats it and erases existing data, so back up that drive before installation.
Ventoy’s official start guide explains installation and warns about data loss. Copy the ISO to Ventoy’s first, main partition; Ventoy searches folders on that partition for image files and lists them when it starts.
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Make sure you are installing Ventoy on the intended USB drive, not a drive that contains files you still need. Installation is different from an ordinary update: the initial installation formats the target and loses its existing data, so copy anything important elsewhere first. If Ventoy is already installed, the verification workflow does not require you to reinstall it. You need a suitable drive with Ventoy and enough room for the ISO you plan to copy.
A USB flash drive is the usual medium if you do not already have a suitable Ventoy drive. Ventoy also lists SSDs as installation media, but the verification steps do not depend on buying a particular model or type of storage. A new device is not necessary if your existing Ventoy drive is suitable.
How do you get and authenticate the right checksum?
Download the checksum file from the Linux distribution’s official download or verification page, making sure it corresponds to the exact image you downloaded. If the distribution publishes a signature for that file, verify the signature before relying on the checksum.
For example, Debian says its official installation and live images have signed checksum files, and recommends SHA256 or SHA512 tools. See Debian’s image-verification guidance. Ubuntu provides SHA256SUMS and SHA256SUMS.gpg for installation media; its download-verification tutorial covers the process.
Match the checksum to the ISO precisely. Distribution download pages can list multiple editions, architectures, releases, or image types, and a checksum for one is not interchangeable with another. Compare the filename in the checksum list with the ISO you have, and check that the release and edition are the ones you intended to download. Do not use a sample value from a tutorial or a checksum for a similarly named image.
For Ubuntu, Canonical documents verifying the signing key and then checking the signed checksum list with commands such as:
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gpgv --keyring ./ubuntu.gpg ./SHA256SUMS.gpg ./SHA256SUMSAfter the signature check succeeds, you can check an ISO against the list on a Linux system with:
sha256sum -c --ignore-missing ./SHA256SUMSThe --ignore-missing option is useful when the published list names multiple images but you downloaded only one. These commands check the file available to that computer; they do not replace the Ventoy-menu check of the copy on the USB.
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Key trust matters. Canonical explicitly says you must verify the authenticity of the Ubuntu Image Signing public key before using it to verify signatures. Merely downloading a key alongside the ISO does not establish that it belongs to Ubuntu. Follow the distribution’s instructions for establishing trust in its key rather than assuming a signature is meaningful simply because a tool reports success.
A signature check and a checksum check are separate operations. The signature authenticates the checksum list when it verifies against a key you trust. The checksum calculation then determines whether a particular ISO matches an entry in that list. A successful signature check alone does not tell you that the ISO on the Ventoy drive matches; likewise, a matching ISO hash does not authenticate an unsigned or untrusted list.
How do you check the ISO in Ventoy before booting?
Ventoy calculates the selected image’s checksum from its boot menu. Match the algorithm to the distribution’s published checksum—SHA256 in the steps below—and compare the complete resulting value.
- Finish copying the ISO. Copy the image to Ventoy’s main partition, wait for the file transfer to finish, and safely eject the USB from the computer. Avoid checking while a write is still in progress.
- Start the computer from the Ventoy USB. Stop at Ventoy’s main menu; do not launch the Linux image yet.
- Highlight the intended ISO. Check its displayed filename against the release and edition for which you obtained the checksum.
- Press m. Ventoy documents this hotkey for file checksums. Choose SHA256 from the available options if that is the algorithm used by the distribution’s reference.
- Compare the full hash. Compare Ventoy’s displayed value with the authenticated published checksum for that exact filename. Do not rely on only the first few characters.
- Boot only if it matches. If the values differ, do not boot the image. Follow the recovery steps below.
Ventoy recommends checking from its menu so the calculation is performed on the file on the USB, rather than mistakenly relying on a cached copy on the host system. Its checksum documentation describes the hotkey and supported comparison methods.
This is a manual comparison: Ventoy displays a hash, and you compare it with the separately obtained reference. It is straightforward when you have one ISO to check and want to see exactly which value Ventoy calculated. Be careful when transcribing a long hash: compare all characters, not just the opening sequence, and ensure you are comparing like algorithms. A SHA256 value cannot be compared meaningfully with a SHA512 value simply because both are checksums.
The menu check also answers a specific question: does the file currently stored at that Ventoy path match the reference? It is not a check of the downloaded copy still on your computer, and it is not a test of whether the operating system will boot on your hardware. Let the copy complete before checking, then use the Ventoy menu on the same drive you intend to boot.
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Can Ventoy compare a checksum automatically?
Yes. You can place a sidecar checksum file beside an ISO or use a VENTOY_CHECKSUM file to let Ventoy compare the image with a supplied value. These methods are convenient, but they still depend on you supplying a checksum obtained from a trustworthy, authenticated reference.
The choice is between displaying a hash for a manual comparison and preparing a sidecar or list for Ventoy to compare. Neither approach changes the trust question: automatic comparison can save a manual step, but it does not authenticate the checksum value. Authenticate the distributor’s checksum file first when authenticity is your goal, then use the value from that file.
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Put a plain-text file next to the ISO, using the ISO’s full original filename followed by the checksum suffix. For example, for example.iso, use example.iso.sha256. Do not rename the ISO itself to example.sha256.
Ventoy’s documentation says the sidecar can contain a bare hash, a conventional hash-and-filename line, or a line in the form SHA256 (filename) = hash. Use the format shown in Ventoy’s documented checksum instructions, and ensure the hash is the one from the trusted distributor reference—not one first calculated from the potentially damaged USB copy.
The sidecar belongs alongside the image it describes, and the filename convention helps Ventoy associate the reference with that image. Preserve the ISO’s full original filename before adding the suffix. If the ISO is called debian-example.iso, the corresponding SHA256 sidecar would be debian-example.iso.sha256, not a renamed ISO or a sidecar for another release.
VENTOY_CHECKSUM file
Alternatively, place a file named VENTOY_CHECKSUM in the image’s directory or use one at the partition root. A local file applies to images in its directory and subdirectories; a root-level file uses full paths, such as ISO/example.iso. Ventoy checks a matching per-image sidecar first, then a local VENTOY_CHECKSUM, and then the global file at the partition root.
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Ventoy lists .md5, .sha1, .sha256, and .sha512 sidecar suffixes. Prefer the algorithm the distribution publishes, and use SHA256 or SHA512 when available rather than choosing an older algorithm just because Ventoy supports it.
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Automatic comparison is useful when you want a prepared reference next to an image or when using a list for multiple files. Manual display is useful when you want to make a direct comparison without preparing those files. In either case, the reference must come from the correct release’s distributor checksum file, and a sidecar or list should not be populated with a value calculated from the same USB copy you are trying to check.
What should you do if the checksum does not match?
Stop. A mismatch means the image on the USB does not match the reference value you are checking against, so do not boot it.
- Recheck the reference. Confirm that the checksum belongs to the exact filename, edition, and release on the USB, and that you selected the same algorithm in Ventoy.
- Obtain a fresh ISO. Download it again from a known-good distribution source. Ubuntu’s guidance recommends a fresh download after a failed verification.
- Copy it again and repeat the USB check. Finish the copy, safely eject the drive, then calculate the checksum from Ventoy’s menu once more.
- Consider the USB separately if failures persist. Ventoy’s FAQ identifies faulty or counterfeit USB sticks as possible causes of boot problems. A matching image checksum does not prove that the drive hardware or the computer’s boot configuration is trouble-free.
Do not “fix” a mismatch by replacing the official checksum with a value calculated from the file that failed. That would only confirm the file agrees with itself, not with the distribution’s release.
Before repeating the download, check that the ISO and the reference actually refer to the same release and edition. A valid checksum for a different image will not match, even if both files came from the same distribution. Also check that Ventoy calculated the algorithm corresponding to the published value. If the reference and algorithm are correct and the result still differs, treat the ISO on the drive as unverified and replace it with a fresh copy rather than booting it.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What does a matching checksum prove—and what does it not?
If Ventoy’s hash for the USB copy matches a checksum you have authenticated, you have evidence that the selected ISO matches the image represented by that signed checksum list. That addresses file integrity and ties the image to a distributor-authenticated reference.
A match against an unauthenticated checksum proves only that the two values agree. It does not establish who published the reference. And even a valid checksum match does not guarantee that the ISO will boot on a particular computer, that the USB hardware is reliable, or that the boot configuration is correct. Ventoy’s checksum feature checks the selected image file; it is not a guarantee of successful installation or a substitute for signed-release verification.
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Frequently Asked Questions
Can I verify an ISO with Ventoy if I only have a checksum on my computer?
Yes. You can compare Ventoy’s displayed hash with a value on another screen or in a trusted note; the reference does not need to be stored on the USB. Keep track of which release and filename the value belongs to, since a correct hash for a different image will still produce a mismatch.
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Why did Ventoy report a different hash after I changed an ISO?
A checksum describes the exact file contents, so even a modified or incomplete image has a different hash. If you intentionally replaced or remastered an ISO, the distributor’s original checksum no longer verifies that modified file.
Does a checksum tell me whether an ISO is safe to install?
A checksum alone does not make that judgment: it only compares file contents with a reference. The signature check helps establish that the reference came from the distribution, but it is still sensible to obtain the image and verification files through the distribution’s official channels.
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Yes, provided you select the matching algorithm in Ventoy and compare the complete SHA512 value. The algorithm used for the calculation and the algorithm named by the reference must agree.
Do I need to install Ventoy again just to verify an ISO?
No. If Ventoy is already installed on the USB, copy the image to its main partition and use the menu checksum feature. A fresh installation formats the target drive and erases its contents, so back up the drive before installing Ventoy.
Does Ventoy verify the checksum file’s signature when I press m?
No. The menu hotkey calculates a checksum for the selected image. You must separately authenticate the distribution’s checksum file and its signing key if you want to establish the reference’s authenticity.
What if the hash matches but the ISO will not boot?
A matching hash checks the selected image file against the reference; it does not guarantee that the USB hardware, computer boot configuration, or image compatibility is trouble-free. If repeated boot issues persist, consider those as separate possible causes.
Which checksum algorithm should I choose?
Use the same algorithm named by the distribution’s published checksum, preferably SHA256 or SHA512 when available. Ventoy also lists older MD5 and SHA1 sidecar suffixes, but their availability is not a reason to choose them over a stronger published option.
The Bottom Line
Before booting, verify the ISO stored on the Ventoy USB: highlight it, press m, select the algorithm used by the distribution, and compare the complete hash with the exact release’s checksum. Authenticate the checksum file’s signature with a key you trust when you need assurance of origin. If the values do not match, do not boot the image; download and copy it again, then check the USB copy once more.
