TLS key log fallback: decrypting Envoy, Istio and rustls workloads
Gocipher captures TLS secrets by hooking the TLS library of the application: OpenSSL, Go's crypto/tls, and now the
JDK's JSSE. Some runtimes give it nothing to hook. Envoy, and so every Istio sidecar, ships its own BoringSSL inside a
static binary. A Rust service using rustls has no libssl at all. For these, Spider showed a TCP session whose content
could not be read.
Those runtimes can still be asked to write their TLS key log, the same NSS format that SSLKEYLOGFILE produces for
Wireshark. The key log fallback reads that log, without any file.