RFR: 8245545: Disable TLS_RSA cipher suites

[Sean Mullan]

On Fri, 15 Nov 2024 19:50:33 GMT, Artur Barashev <abarashev at openjdk.org> wrote:

> These cipher suites do not preserve forward-secrecy and are not commonly used. Other TLS implementations (ex: Rustls) do not support or enable these suites by default. RFC 9325 [1] states that these suites should not be used. The IETF Draft "Deprecating Obsolete Key Exchange Methods in TLS" [2] mandates that these suites not be used.
> 
> Some TLS_RSA_* cipher suites are already disabled because they use DES, 3DES, RC4, or NULL, which are disabled. This action will disable all remaining TLS_RSA cipher suites.
> 
> [1] RFC 9325, Recommendations for Secure Use of TLS and DTLS (https://www.rfc-editor.org/rfc/rfc9325.html#section-4.1-2.5.1): "Implementations SHOULD NOT negotiate cipher suites based on RSA key transport, a.k.a. "static RSA". Rationale: These cipher suites, which have assigned values starting with the string "TLS_RSA_WITH_*", have several drawbacks, especially the fact that they do not support forward secrecy."
> [2] IETF Draft, Deprecating Obsolete Key Exchange Methods in TLS (https://www.ietf.org/archive/id/draft-ietf-tls-deprecate-obsolete-kex-05.html#section-4): "Clients MUST NOT offer and servers MUST NOT select RSA cipher suites in TLS 1.2 connections. (Note that TLS 1.0 and 1.1 are deprecated by [RFC8996], and TLS 1.3 does not support static RSA [RFC8446].)"

test/jdk/javax/net/ssl/DTLS/CipherSuite.java line 71:

> 69: 
> 70:     public static void main(String[] args) throws Exception {
> 71:         SecurityUtils.removeFromDisabledTlsAlgs("TLS_RSA_*");

Instead, you can add the "re-enable" argument to the @run lines starting with "TLS_RSA_".

test/jdk/javax/net/ssl/TLSv11/GenericBlockCipher.java line 52:

> 50: import javax.net.ssl.SSLSocketFactory;
> 51: 
> 52: import jdk.test.lib.security.SecurityUtils;

Typically internal imports are listed after standard imports.

test/jdk/javax/net/ssl/TLSv11/GenericBlockCipher.java line 178:

> 176:         // Re-enable TLSv1.1 since test depends on it.
> 177:         SecurityUtils.removeFromDisabledTlsAlgs("TLSv1.1");
> 178:         SecurityUtils.removeFromDisabledTlsAlgs("TLS_RSA_*");

You can put more than one alg in the same call, i.e. `SecurityUtils.removeFromDisabledTlsAlgs("TLSv1.1", "TLS_RSA_*");`

test/jdk/javax/net/ssl/sanity/ciphersuites/CheckCipherSuites.java line 241:

> 239: 
> 240:     public static void main(String[] args) throws Exception {
> 241:         SecurityUtils.removeFromDisabledTlsAlgs("TLS_RSA_*");

This test verifies that only the enabled suites are what are expected, and we didn't accidentally re-enable a cipher suite. You should not be re-enabling any disabled suites. Instead remove TLS_RSA from the static String arrays.

test/jdk/javax/net/ssl/sanity/ciphersuites/SystemPropCipherSuitesOrder.java line 86:

> 84: 
> 85:     public static void main(String[] args) {
> 86:         SecurityUtils.removeFromDisabledTlsAlgs("TLS_RSA_*");

A suggestion - re-enable TLS_RSA only if you need to. You could check if `servercipherSuites` or `clientciphersuites` starts with "TLS_RSA".

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PR Review Comment: https://git.openjdk.org/jdk/pull/22163#discussion_r1847297410
PR Review Comment: https://git.openjdk.org/jdk/pull/22163#discussion_r1847310890
PR Review Comment: https://git.openjdk.org/jdk/pull/22163#discussion_r1847311819
PR Review Comment: https://git.openjdk.org/jdk/pull/22163#discussion_r1847308667
PR Review Comment: https://git.openjdk.org/jdk/pull/22163#discussion_r1847318221