Script + proto definition used to research the pageToken of the GCP IAM projects.serviceAccounts.list method

encode.sh

#!/bin/bash

project=$1
page_size=3
unknown4=0

# Magic

outer=$(echo -e "project: $project\npage_size: $page_size\nunknown4: $unknown4" | protoc --encode=Outer test.proto | base64 -w 0 | sed 's/+/-/g; s/\//_/g')
outer=${outer//=}

echo cg:$outer

test.proto

syntax = "proto2";

message Outer {
  optional uint64 project = 1;
  optional int32 page_size = 3;
  optional int32 unknown4 = 4;
  optional string inner_pb = 5;
}

message Inner {
  optional uint64 last_service_account = 1;
}