If you are using checksums to verify that an attacker isn't screwing with your files, MD5 is a terrible idea. If the attacker knows what they're doing, they could theoretically find the right collision that'd enable them to execute their code without altering the file's checksum, thus eluding any checksum-based security verification. SHA algos perform well enough on modern CPUs and scale a lot better as file sizes get bigger, so too must our checksums.
No, it's less fast but not that slow For a backup program it's maybe necessary to have something even faster than MD5 All in all, I'd say that MD5 in addition to the file name is absolutely safe.
Peter Mortensen Genesis Rock Genesis Rock 2 2 gold badges 5 5 silver badges 15 15 bronze badges. Thank you, but the problem is I don't know what else I could use! Depends on the programming language and runtime environment you're using. You are able to checkout the following resources: Speed Comparison of Popular Crypto Algorithms Comparison of cryptographic hash functions.
SaidbakR SaidbakR Ah, and the link you have provided also shows other algorythms. I guess I need to find which ones are available to.
NET now and find the quickest. Thank you — Dave. DaveRook In addition, If you look arround for famous website such as Sun, Ubuntu and others, you may notice that they supply MD5 checksum for files integrity. This may support its value for such tasks.
See other answers here and the answers to this Stack Overflow questions. Here's a backup scenario where MD5 would not be appropriate: Your backup program hashes each file being backed up. It then stores each file's data by its hash, so if you're backing up the same file twice you only end up with one copy of it.
An attacker can cause the system to backup files they control. The attacker knows the MD5 hash of a file they want to remove from the backup. The attacker can then use the known weaknesses of MD5 to craft a new file that has the same hash as the file to remove.
When that file is backed up, it will replace the file to remove, and that file's backed up data will be lost. This backup system could be strengthened a bit and made more efficient by not replacing files whose hash it has previously encountered, but then an attacker could prevent a target file with a known hash from being backed up by preemptively backing up a specially constructed bogus file with the same hash.
Obviously most systems, backup and otherwise, do not satisfy the conditions necessary for this attack to be practical, but I just wanted to give an example of a situation where SHA would be preferable to MD5. Whether this would be the case for the system you're creating depends on more than just the characteristics of MD5 and SHA Happy hashing!
In the context of exchanging PGP public keys with people, hash values often called "fingerprints" or "thumbprints" are short enough to be transferred manually printed on a business card, spelled over phone Digital signatures expand on the concept, but they too begin with hash functions.
All digital signature algorithms sign not the message itself, but the hash of the message which is equally good as long as the hash function is secure, i. For many pieces of software, the providers of the files also provide the hash of the file that allows you to verify it's integrity. Instructions are also provided as well if one does not how to use the provided checksums. Generally, if the files are provided through the same medium as the checksums, there is very little real benefit as an attacker that manages to compromise the download will also have the capability to replace the provided checksum.
However, this is very useful in the case of the files being downloaded over an insecure connection like torrents or a CDN. In such a situation, the software provider can provided the small checksum on his server while serving the files through a higher bandwidth medium such as torrents or a CDN.
Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How can I check the integrity of the downloaded files?
Ask Question. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Privacy policy. We've also renamed Azure Defender plans to Microsoft Defender plans. Learn more about the recent renaming of Microsoft security services. File integrity monitoring FIM , also known as change monitoring, examines operating system files, Windows registries, application software, Linux system files, and more, for changes that might indicate an attack.
FIM informs you about suspicious activity such as:. The Log Analytics agent uploads data to the Log Analytics workspace. By comparing the current state of these items with the state during the previous scan, FIM notifies you if suspicious modifications have been made. When file integrity monitoring is enabled, you have a Change Tracking resource of type Solution. For data collection frequency details, see Change Tracking data collection details.
If you remove the Change Tracking resource, you will also disable the file integrity monitoring feature in Defender for Cloud. When choosing which files to monitor, consider the files that are critical for your system and applications.
If you choose files that are frequently changed by applications or operating system such as log files and text files it'll create a lot of noise, making it difficult to identify an attack. Defender for Cloud provides the following list of recommended items to monitor based on known attack patterns. From the Workload protections dashboard's Advanced protection area, select File integrity monitoring. Upgrade the workspace to use enhanced security features.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Privacy policy. A hash value is a numeric value of a fixed length that uniquely identifies data. Hash values represent large amounts of data as much smaller numeric values, so they are used with digital signatures. You can sign a hash value more efficiently than signing the larger value.
Hash values are also useful for verifying the integrity of data sent through insecure channels. The hash value of received data can be compared to the hash value of data as it was sent to determine whether the data was altered.
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