Signcryption is a public key cryptography primitive that provides all of the functions of a digital signature and encryption. Yuliang Zheng invented signcryption, and it is now an ISO standard, ISO/IEC 29150:2011. Traditionally, sign then encrypt or encrypt then sign schemes are used to provide unforgeability, authentication, and non-repudiation, but with signcryption, all services of digital signatures and encryption are provided at a cost that is less than that of the sign then encrypt scheme.
Signcryption enables Cost (signature & encryption) << Cost (signature) + Cost (Encryption) in a single logical step.
