3 ms·
> A key cutting scheme may be useful in the case of mutli tenancy No. Cutting a key in half doesn't halve its security, but it reduces it exponentially. 256 b
by danuker 4y ago
> A key cutting scheme may be useful in the case of mutli tenancy
No. Cutting a key in half doesn't halve its security, but it reduces it exponentially.
256 bits = 2^256 possibilities for bruteforcing
255 bits = 2^255 possibilities for bruteforcing, or half
128 bits = 2^128 possibilities, or 1/(2^128) the security
- vageli 4y agoYou can split up a key using something like https://en.m.wikipedia.org/wiki/Shamir%27s_Secret_Sharing https://en.m.wikipedia.org/wiki/Shamir%27s_Secret_Sharing
- AgentME 4y agoYou could instead construct a key by appending two securely-long passphrases together (which will then go through a KDF in any good encryption software). Give each passphrase half to one person. Recombining them is as simple as typing both of them into the passphrase input in the decryption software.
- kilotaras 4y ago1. Key is 256 bits K 2. Half of K is a random 256 bit X 3. Other half is (K xor X), still 256 bit Having half of key is still 256 bit bruteforcing.