A print substance cartridge for a printing device includes a supply of print substance for the printing device, a non-volatile memory, and logic. The memory store authentication values by which the print substance cartridge is authenticated by the printing device, and/or a cryptographic key from which authentication values are able to be generated within the print substance cartridge. The memory stores hash values corresponding to authentication values and by which the authentication values are verified by the printing device. The logic is to, in response to a request from the printing device for an authentication value, provide the requested authentication value to the printing device. The logic is to, in response to a request from the printing device for the hash value corresponding to the authentication value, provide the hash value corresponding to the authentication value to the printing device.