Yubico Self-Issued Consulting This specification defines COSE algorithm identifiers for negotiating how to split a signature algorithm between two cooperating parties. Typically the first party hashes the data to be signed and the second party finishes the signature over the hashed data. This is a common technique, useful for example when the signing private key is held in a smart card or similar hardware component with limited processing power and communication bandwidth. The resulting signatures are identical in structure to those computed by a single party, and can be verified using the same verification algorithm without additional steps to preprocess the signed data.