Abstract: Disclosed are various embodiments for generating and verifying stateful hash-based signatures. A message hash of a message is generated using a cryptographic hash function. Then, the message hash is split into a predefined number of parts of equal size. Next, a value of a signature debt is calculated for each of the predefined number of parts of the message hash. Subsequently, a respective signature part is calculated for each of the predefined number of parts of the message hash by applying the cryptographic hash function to a respective portion of a private key for a number of times equal to the value of the signature debt. Next, the respective signature parts are concatenated to generate a signature for the message.