A first public key is generated based at least in part on a first plurality of signing keys and a second public key is generated based at least in part on a second plurality of signing keys. The signing keys may be used to generate digital signatures. The second public key may be made available to verify a digital signature generated using a signing key from the second plurality of signing keys. In some cases, a first Merkle tree may be formed by the first public key and the first plurality of signing keys, and a second Merkle tree may be formed by the second public key, the first public key, and the second plurality of signing keys.