diff --git a/grpc/gcp/handshaker.proto b/grpc/gcp/handshaker.proto
index cf4cad07..47a356be 100644
--- a/grpc/gcp/handshaker.proto
+++ b/grpc/gcp/handshaker.proto
@@ -113,7 +113,7 @@ message StartClientHandshakeReq {
   // ALTS connections. The access token that should be used to authenticate to
   // the peer. The access token MUST be strongly bound to the ALTS credentials
   // used to establish the connection that the token is sent over.
-  string access_token = 11;
+  string access_token = 11 [debug_redact = true];
 }
 
 message ServerHandshakeParameters {
@@ -129,7 +129,7 @@ message ServerHandshakeParameters {
   // ALTS connections. The token should be used to authenticate to
   // the peer. The token MUST be strongly bound to the ALTS credentials
   // used to establish the connection that the token is sent over.
-  optional string token = 3;
+  optional string token = 3 [debug_redact = true];
 }
 
 message StartServerHandshakeReq {