From d78d695c46db16d6c8769ba9f6d8e3a70dfaeb59 Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Wed, 4 Dec 2024 18:04:55 +0100 Subject: [PATCH] FFDH in TLS: it's only a limitation for TLS 1.2, not TLS 1.3 Signed-off-by: Gilles Peskine --- docs/driver-only-builds.md | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/docs/driver-only-builds.md b/docs/driver-only-builds.md index 6bd92623a1..e85496a053 100644 --- a/docs/driver-only-builds.md +++ b/docs/driver-only-builds.md @@ -278,9 +278,11 @@ The same holds for the associated algorithm: removing builtin support (i.e. `MBEDTLS_DHM_C`). Note that the PSA API only supports FFDH with RFC 7919 groups, whereas the -Mbed TLS legacy API supports custom groups. As a consequence, the TLS layer -of Mbed TLS only supports DHE cipher suites if built-in FFDH +Mbed TLS legacy API supports custom groups. As a consequence, the TLS 1.2 +layer of Mbed TLS only supports DHE cipher suites if built-in FFDH (`MBEDTLS_DHM_C`) is present, even when `MBEDTLS_USE_PSA_CRYPTO` is enabled. +(The TLS 1.3 layer uses PSA, and this is not a limitation because the +protocol does not allow custom FFDH groups.) RSA ---