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FAQ

FAQ​

  • Q: Is it OK that all of my files are encrypted using the same DR public key? Don't keys need to be rotated?
    A: As this is an elliptic curve public key, and the DR-DEK ciphertexts are created using ECIES (which creates an independent ephemeral symmetric key for each ciphertext) there is no degradation in security over time. This is unlike, for example, symmetric keys, where it is important to not re-use the same symmetric key for too many ciphertexts.

    The other reason that keys are sometimes rotated is to reduce the impact if the private key is accidentally leaked by a system with access to it. In the case of Antimatter DR, none of the libraries nor the backend servers ever have access to the private key so cannot ever leak it. In fact, even when using the DR system and creating an open DR event permitting recovery of files, we recommend using the "Usage" DR event type which keeps the private key secure on the key card and prevents any possibility of leakage.

    An informal but easy way to prove the above claims is to imagine that an attacker had some way to compromise your data given sufficient time and knowledge of just the DR public key. This mechanism would in turn allow them to attack the Elliptic Curve Discrete Log Problem, which is currently believed to be secure to non-quantum adversaries. Thus, there is no concern that using the same public key indefinitely (when the private key is not known) will reduce the security of the system.

  • Q: Will enabling disaster recovery make my capsules larger?
    A: Yes, enabling DR will make capsules slightly larger (by about 170 bytes), but will not otherwise impact performance

  • Q: What happens if a member of the delegation loses their card?
    A: As long as you can still form a quorum with the remaining members, you can use the Migrate event type to securely move the disaster recovery private key to a new delegation. Once you delete the old delegation from the remaining cards (so that less than a quorum of shards remains), the existence of old key shards on the lost/stolen card no longer poses any security threat. Documentation covering this will be added soon.