HashOnClick Frequently Asked Questions
Frequently Asked Questions (FAQs)
These FAQs aim to help you understand HashOnClick better, and quickly solve any difficulties that you might encounter.
Q: What is an SHA-1 hash value?
A: An SHA-1 hash value is a 40-character string that identifies the contents of a file. If two files have the same contents then it's probable they will have the same SHA-1 hash value. However, please note that it is possible to create two completely different files that have the same SHA-1 hash value. To be sure you should use SHA-2 hashing.
Q: What is an SHA-2 hash value?
A: SHA-2 is an improvement on SHA-1 and is the recommended hashing method to use. HashOnClick supports all types of SHA-2, ranging from SHA-2 224 to SHA-2 512/256.
Q: What is an MD5 hash value?
A: An MD5 hash value is a 32-character string that identifies the contents of a file. If two files have the same contents then it's probable they will have the same MD5 hash value. However, please note that it is possible to create two completely different files that have the same MD5 hash value. It is not recommended that MD5 hashing be used to compare files. It is provided for backwards compatibility.
Q: What is a CRC32 hash value?
A: A CRC32 hash value is an 8-character string that identifies the contents of a file. If two files have the same contents then they will probably have the same CRC32 hash value. The Zip format uses CRC32 values to verify the contents of files. It is not recommended that CRC32 hashing be used to compare files. It is provided for backwards compatibility.
Q: What is a xxhash value?
A: xxHash is an extremely fast non-cryptographic hash algorithm, working at speeds close to RAM limits. If two files have the same contents then they will probably have the same xxhash32 hash value. If two files have the same contents then it's extremely probable they will have the same xxhash64 hash value.
Q: Why do you support several different ways of doing the same thing?
A: In some cases you may want the CRC32 value, e.g. when comparing with files in a Zip file or with files on an FTP server that can only return CRC32 values. MD5 values are commonly used on web sites and are supported by a few FTP servers. SHA-2 is an improvement over SHA-1 and is not yet widely used, but it is the best way to compare files.
Q: Is it possible that the hash values may be the same for two files even though the file contents are different?
A: With CRC32, MD5 and SHA-1 it is possible. With xxhash32 it is unlikely, but not impossible. With xxhash64 it's highly unlikely, but in some cases but may be possible. With SHA-2 it's impossible (at time of writing).
Q: What type of files can I get the hash values for?
A: Any type of file. Folders do not have contents so it cannot be used with folders.
Q: Why does your hash value not match the hash value I got from another program for the same file?
A: There are many hash calculation programs available, but unfortunately not all of them have been tested as much as HashOnClick. It may also be that they have incorrectly labeled the hash algorithm, e. g. they may say SHA when it may be SHA-2 512bits.
Q: I'm getting the error "Cannot open file" or "Failed" whenever I try and get the hash value of a file.
A: The most probable reason for this error is that you don't have access rights to the file, or it cannot be opened because it is being used by another program, process, or Windows itself.
Q: Windows File Explorer has stopped functioning. Why?
A: It is not possible to use Windows File Explorer when HashOnClick is in use. Simply close the HashOnClick window and Windows File Explorer will function normally.
Q: Does HashOnClick work with 64-bit versions of Windows?
Q: I have a multi-core/multi-CPU system. Does HashOnClick make full use of this?
A: Yes. HashOnClick V2.2 and later is multi-threaded, meaning it will read the file at the same time it is calculating its hash value. Also, when hash values are calculated on the Property Sheet then hash values are calculated in parallel. Because of this it is one of the fastest hash calculation programs available today on Windows systems.
Q: Some of the file names have a colon (:) and $DATA in their name. What are they?
A: On the NTFS file system a file can have alternate data streams (ADS). Think of alternate data streams as files attached to other files. Normally you do not see the alternate data streams because Windows File Explorer, for example, only shows you the size and details of the main stream (which is the file you see and use). If a file has alternate data streams (it can have one or several) then it will calculate the hash values for them.
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