# On average, what % of my private key is compromised on the first address re-use, and what exponential effect does it have on security?

Each time we use an address, 50% of your private key is revealed at random.

When 50% of the private key is revealed, a computer would have to do 2^256 computations to crack it, similar to the SHA-256 standard, which is considered cryptographically secure.

Mathematically, what % of my private key is revealed on average after the first key re-use, and in terms of exponents similar to 2^256, what level of computational security do I have now, on average?

We assume that you re-use your key for a transaction that is new and different from the previous (aka `hash(tx1) != hash(tx2)`)
Average case: assuming on average half of the bits from the hash will match bits from the private key that were used before, that means only 25% of the key will be left to guess. Since `512 * 0.25` = 128 bits will need to be discovered for the private key to be cracked, requiring at most 2^128 computations.