This issue was reported on github by: GregoireG-C

see also; https://github.com/OPCFoundation/UA-.NETStandard/issues/1491

n CTT, the tests in Security User Name Password failed when I use a certificate with a key lenght of 4096 bits while it works when I use a certificate with a key lenght of 3072 bits. When I watch closely in the CTT debuger, it seems that the CTT is unable to encrypt the message with a key lenght of 4096.

To Reproduce
Steps to reproduce the behavior:
1.Create a certificate with the following settings :

sign Algorythm : sha256RSA
Hach sign algo : sha256
public key lenght 4096 bits
Configure your OPCUA server to use this certificate
Launch the server and launch the conformance unit : Security/Security UserName Password
Check that initialize and 001.js has failed
Expected behavior
The initialize and 001.js succeed

Screenshots

The first screenshot is obtained when using a keyLenght of 4096 while the second one is obtained with a keyLenght of 3072.
You can observe that the data in the debugger is on the first screenshot null and on the second one completed.
UserTokenCERTUA-SRV-CA1
UserTokenCertificatGenere

CTT version : 1.4.9.398