Secure Cryptographic Workflow in the Standard Model.
Manuel Barbosa, Pooya Farshim · 2006
Abstract. Following the work of Al-Riyami et al. we define the notion of key encapsulation mechanism supporting cryptographic workflow (WF-KEM) and prove a KEM-DEM composition theorem which extends the notion of hybrid encryption to cryptographic workflow. We then generically construct a WF-KEM from an identity-based encryption (IBE) scheme and a secret sharing scheme. Chosen ciphertext security is achieved using one-time signatures. Adding a public-key encryption scheme we are able to modify the construction to obtain escrow-freeness. We prove all our constructions secure in the standard model. Keywords. Cryptographic Workflow. Key Encapsulation. Secret Sharing. Identity-Based Encryption.