# Any algorithm with a pair of master keys and multiple pairs of subkey for a secure key escrow?

Note: This question looks like my other question — Any algorithm with a master key for decrypting private key encrypted messages? — which is perfectly answered by @real-or-random, but this one is different in how subkeys are generated.

Assume the following:

1. Create a pair of master private/public key
2. Create a private/public subkey #1 based on the master public key
3. Create a private/public subkey #2 based on the master public key
4. Encrypt data #1 with public subkey #1
5. Encrypt data #2 with public subkey #2
6. Possible to decrypt data #1 with both private subkey #1 and master private key
7. Possible to decrypt data #2 with both private subkey #2 and master private key
8. Impossible to decrypt data #1 with private subkey #2
9. Impossible to decrypt data #2 with private subkey #1

Is there any algorithm out there that implements the above scenario?

• You can just use the scheme you are linking to? You could just double the private key value as secret input to a KDF. Then you can always keep or recalculate the keys of #1 and #2... Apr 10, 2018 at 11:05