Secure Obfuscation for Tightly Structure-Preserving Encrypted Proxy Signatures

In recent years, the obfuscation has been one of the most intriguing open problems in cryptography. Loosely speaking, an obfuscation O(P) of a program P should preserve P´s functionality and its code remains ``unintelligent´´. However, few positive results have been proposed. Hada et. al in EUROCRYPT´10 demonstrated an obfuscation of encrypted signature. Inspired by their work, We construct a structure-preserving encrypted proxy signature. Alice wants to make encrypted signatures to Bob, but she will be absent. During this period, she wants to delegate her signing authority to a proxy without sending him her secret signing key. We run a step for obfuscation and then successfully solve the problem. Our proposed structure satisfies the virtual box property of obfuscation. We show its security in the sequel. The whole proof is under the standard model.