Project:Infrastructure/SSSS secret storage

This proposal addresses the problem of storing high-security secrets; that is, secrets that aren't necessary in daily Infra operations but need to be available for Infra members for special cases. Those secrets can include primary OpenPGP keys, admin account passwords etc. The proposal is based on the use of M-out-of-N secret sharing scheme to combine the two goals: reducing the exposure of secrets to individual Infra members while at the same time avoiding a low bus factor.

Goals
The goals of this proposal are:
 * 1) Infra member can only gain access to the secret if (M-1) other infra members agree with it.
 * 2) All secret accesses are logged in the audit log, by all infra members participating in the process. Each successive member taking part in secret decryption verifies the log entry of his predecessors, effectively requiring M compromised members to prevent the access from being logged.