Fork and VM clone safety

Affected Versions
All Tink versions
Affected Key Types
Streaming AEAD, AES-GCM-HKDF

Description

In general, Tink does not aim to provide security if the program does calls to the UNIX fork() system call, or if the program is cloned on a virtual machine and then executed multiple times from the same state.

The only concrete problem is known for Streaming AEAD, key type AES-GCM-HKDF. In this case, such an attack can lead to Tink encrypting different plaintext with AES GCM using the same nonce, which is known to leak the authentication key.