diff --git a/liblsl/include/lsl_security.h b/liblsl/include/lsl_security.h
index 7d88073..8fe9f9d 100644
--- a/liblsl/include/lsl_security.h
+++ b/liblsl/include/lsl_security.h
@@ -11,7 +11,7 @@
  *
  * Security Model:
  * - Ed25519 for device identity and signatures
- * - X25519 + HKDF for session key derivation
+ * - X25519 + BLAKE2b for session key derivation
  * - ChaCha20-Poly1305 for authenticated encryption
  * - Unified security: all-secure or all-insecure network
  *
diff --git a/liblsl/src/lsl_security.h b/liblsl/src/lsl_security.h
index 34096c5..a18987f 100644
--- a/liblsl/src/lsl_security.h
+++ b/liblsl/src/lsl_security.h
@@ -19,10 +19,7 @@ namespace lsl {
 namespace security {
 
 // Internal constants
-constexpr size_t HKDF_CONTEXT_SIZE = 8;
-constexpr char HKDF_CONTEXT[] = "lsl-sess";
-// Domain-separation context for the ephemeral-exchange session key, kept
-// distinct from HKDF_CONTEXT so the two derivations can never collide.
+// Domain-separation context for the ephemeral-exchange session key.
 constexpr char EPH_CONTEXT[] = "lsl-esk1";
 constexpr uint64_t SESSION_KEY_SUBKEY_ID = 1;