Aggregate Proxy Signature and Verifiably Encrypted Proxy Signature
A proxy signature protocol allows an original signer to delegate its signing power to another entity, called proxy signer, to sign messages on its behalf. The dele-gated proxy signer can compute a proxy signature that can be verified by anyone with access to the original signer's public key. Proxy signatures have many practical applications such as in distributed system etc. and are one of important cryptographic protocols. The concept of proxy signature was first introduced by Mambo, Usuda, and Okamoto in 1996.