sshnet / sshnet/SSH.NET

Investigate using BouncyCastle for bcrypt

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Dominant language
C#
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Description

We support encrypted OpenSSH keys (defined at https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key) for which we have a bcrypt implementation (from somewhere) for the key derivation (kdf).

Now that we depend on BouncyCastle and have replaced a lot of internal crypto with a BouncyCastle implementation, we may also be able to use https://github.com/bcgit/bc-csharp/blob/master/crypto/src/crypto/generators/BCrypt.cs

As far as I can tell, the OpenSSH kdf does a little bit on top of straight bcrypt, probably encapsulated here:

https://github.com/sshnet/SSH.NET/blob/fe827a529a002b679fa29d146029244340e21d3f/src/Renci.SshNet/Security/Cryptography/Bcrypt.cs#L853

It may be possible to replace all or some of our Bcrypt.cs with BouncyCastle

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the existing Bcrypt.cs implementation and comparing its OpenSSH key-derivation behavior with BouncyCastle's crypto/src/crypto/generators/BCrypt.cs. Check the OpenSSH PROTOCOL.key description and determine whether BouncyCastle can replace all or only part of Bcrypt.cs without changing the OpenSSH KDF behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp
Domain
cryptography
Issue type
Refactor
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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