I have a simple problem: I have a set of users' ECDSA key pairs, and say I want to encrypt them with a simple algorithm. I have access to one variable that uniquely identifies the user, so I hash it with a SHA-2 algorithm and have a string of bytes longer than each of the keys.
Is it safe to XOR a key pair, or XORing both of the keys together will make it easier to decode the original value?
What if I hash the entire key chain, does that make it much easier to get the data?