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Cannot disable Cipher TLS_RSA_WITH_AES_128_GCM_SHA256 or TLS_RSA_WITH_AES_256_GCM_SHA384

  • 4 replies
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  • Last reply by Reuben

Reuben
Reuben
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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 :)

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)

Roland Tanglao
Roland Tanglao
  • Moderator
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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

Mike Kaply
Mike Kaply
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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.

Mike Kaply
Mike Kaply
  • Moderator
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For reference, those new preferences were added in this bug:

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

Modified by Mike Kaply

Reuben
Reuben Question owner
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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