Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Cannot disable Cipher TLS_RSA_WITH_AES_128_GCM_SHA256 or TLS_RSA_WITH_AES_256_GCM_SHA384

  • 4 replies
  • 1 has this problem
  • 33 views
  • Last reply by Reuben

more options

Hi there,

I'm trying to disable insecure ciphers in TLS 1.2 since 1.3 isn't widely supported yet.

I'm using this to determine whats secure: https://browserleaks.com/ssl

I cant find any option to disable these two ciphers:

0x009c TLS_RSA_WITH_AES_128_GCM_SHA256 0x009d TLS_RSA_WITH_AES_256_GCM_SHA384

Thanks :)

Attached screenshots

Chosen solution

You can disable/enable those ciphers in about:config:

security.ssl3.rsa_aes_128_gcm_sha256 for TLS_RSA_WITH_AES_128_GCM_SHA256 and security.ssl3.rsa_aes_256_gcm_sha384 for TLS_RSA_WITH_AES_256_GCM_SHA384

This will only work in the latest version of Firefox.

Read this answer in context 👍 1

All Replies (4)

more options

Hi Reuben:

I personally don't know how to do this, but I've asked some developers to help!

And hopefully I'll be able to report back soon!

Cheers!

...Roland

Helpful?

more options

Chosen Solution

You can disable/enable those ciphers in about:config:

security.ssl3.rsa_aes_128_gcm_sha256 for TLS_RSA_WITH_AES_128_GCM_SHA256 and security.ssl3.rsa_aes_256_gcm_sha384 for TLS_RSA_WITH_AES_256_GCM_SHA384

This will only work in the latest version of Firefox.

Helpful?

more options

For reference, those new preferences were added in this bug:

https://bugzilla.mozilla.org/show_bug.cgi?id=1638369

Modified by Mike Kaply

Helpful?

more options

Thanks for that Mike.

Is this in the Beta/Nightly?

I cant seem to find it in the Win 10 standard release 78.0.2 (64-bit) or Dev edition 79.0b7 (64-bit)

EDIT: ignore me added the value in about:config and toggled to False worked. Does not appear if searched. Cheers, Reuben

Modified by Reuben

Helpful?

Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.