Bitwarden and its Argon2id settings

  • SpinRite v6.1 Release #3
    The 3rd release of SpinRite v6.1 is published and may be obtained by all SpinRite v6.0 owners at the SpinRite v6.1 Pre-Release page. (SpinRite will shortly be officially updated to v6.1 so this page will be renamed.) The primary new feature, and the reason for this release, was the discovery of memory problems in some systems that were affecting SpinRite's operation. So SpinRite now incorporates a built-in test of the system's memory. For the full story, please see this page in the "Pre-Release Announcements & Feedback" forum.
  • Be sure to checkout “Tips & Tricks”
    Dear Guest Visitor → Once you register and log-in please checkout the “Tips & Tricks” page for some very handy tips!

  • BootAble – FreeDOS boot testing freeware

    To obtain direct, low-level access to a system's mass storage drives, SpinRite runs under a GRC-customized version of FreeDOS which has been modified to add compatibility with all file systems. In order to run SpinRite it must first be possible to boot FreeDOS.

    GRC's “BootAble” freeware allows anyone to easily create BIOS-bootable media in order to workout and confirm the details of getting a machine to boot FreeDOS through a BIOS. Once the means of doing that has been determined, the media created by SpinRite can be booted and run in the same way.

    The participants here, who have taken the time to share their knowledge and experience, their successes and some frustrations with booting their computers into FreeDOS, have created a valuable knowledgebase which will benefit everyone who follows.

    You may click on the image to the right to obtain your own copy of BootAble. Then use the knowledge and experience documented here to boot your computer(s) into FreeDOS. And please do not hesitate to ask questions – nowhere else can better answers be found.

    (You may permanently close this reminder with the 'X' in the upper right.)


Oct 4, 2020
Hooksett, NH
Hey all.
Just wanted to get the expert's take on what the settings should be for decent protection when using Bitwarden's new Argon2id KDF algorithm. I don't want to switch over just to find out I have my settings too low, and I don't want to crank it up and stall out my devices while unlocking.

Defaults for Argon2id seem to be 3 KDF iterations (wow that seems low!), 64 MB KDF memory, and 4 KDF Parallelism. @Steve hasn't mentioned these settings as of yet.

Are those defaults sufficient or should they be raised? if so.. by how much?

Thanks all!


  • BW Argon.jpg
    BW Argon.jpg
    11.2 KB · Views: 270
Well start with the fact that key stretching is NOT protection, it's just delay. For safety and security, you should start with a long and strong password to begin with. A passphrase of 25+ characters should be good enough protection for any situation, even one where a key stretching algorithm is not used.
  • Like
Reactions: Gilles
I think the ideal settings settings would probably depend on what devices you are using. For example, I was reading that the maximum you can really handle for Parallelism is double the number of CPU cores that you have.

So if all of your devices have 2 or more CPU cores, you can use 4 KDF parallelism. If you have single core devices, you have to drop that to 2. If all your devices are quad core or better, you can make it 8.

I get the impression that with these settings, you'd probably actually make Bitwarden outright on some of your devices not work if you set this stuff too strongly (vs PBKDF2 where it just slows it down a bit).
  • Like
Reactions: Gilles
Another fun note, it seems the way they did Argon2 in the browser extensions, they're signal threaded. It's possible browsers have yet to support enough WebAssembly to handle multiple threads, or the WebAssembly builds of Argon2 that Bitwarden can trust will work dependably at least can only run in single thread mode for now (I have seen test pages in which does have multi-thread support, and something else that at least Safari didn't support (SMID or something) which does speed things up)
  • Like
Reactions: Gilles
Interesting - that contradicts what I said before - if it's running single threaded, then what I read would suggest that it should never be higher than 2 KDF parallelism. But I've got mine set to 4, and it performs better on my desktop browser than it does with the app on either Android tablet or phone.
If your desktop run laps around your Android devices, then I assume that the way it's implemented, your desktop can run 4 parallel threads in a single tread faster.

Also, it's very much possible that what I read about the browser extensions being single threaded is wrong. Bitwarden might have used Web Workers to allow multi-threading in extensions anyway.
The KeePass article is indeed helpful. I also made a post regarding this in another thread here, though it's not as detailed as the KeePass article.

BitWarden adopted Argon2id as it's the most recommended variant, but the KeePass article is correct that 2d and 2id are a different and that client applications can choose 2d as they are less concerned with side-channel attacks. Servers have to worry more about side-channel attacks, so 2id has become fairly ubiquitous. BitWarden opted to go with 2id as it's the most recommended variant and is likely the safest choice to use across clients and servers. People like having 1 standard option and not multiples. AES-256 and SHA-256 became near-universal standards despite the existence of variants and I suspect that Argon2id will become the standard for Argon as it's a reasonable compromise between 2i and 2d.

I wouldn't worry too much about threading as requesting more threads than logical cores does not seem to slow performance to any substantial degree; I can't even measure an average difference. I cover this a bit more in the linked post.