diff --git a/website/docs/cmixx/design-specs/end_to_end.md b/website/docs/cmixx/design-specs/end_to_end.md
index 3e6927611bff2eabb1e618fdb1b435fd3e42bf5d..2f0f83be70c022796bf8b5e5c295d299c6dd44d7 100644
--- a/website/docs/cmixx/design-specs/end_to_end.md
+++ b/website/docs/cmixx/design-specs/end_to_end.md
@@ -38,6 +38,10 @@ exchanged less frequently than every message.
 * [Diffie–Hellmen](https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange): Length is 3072 bits. Discrete log-based component of key negotiation.
 * [SIDH](https://sike.org/files/SIDH-spec.pdf): Length of public key is 3024 bits. Quantum resistant component of key negotiation.
 
+:::note
+In cMixx SIDH was later replaced by CSIDH
+:::
+
 ## Auth Request Response Protocol
 
 The Auth Request Response Protocol is similar a two way handshake