International Association for Cryptologic Research (IACR)
Abstract
In 1998, Blaze, Bleumer, and Strauss proposed a kind of
cryptographic primitive called proxy re-encryption.
In proxy re-encryption, a proxy can transform a ciphertext computed
under Alice\u27s public key into one that can be opened under Bob\u27s
decryption key. In 2007, Matsuo proposed the concept of four types
of proxy re-encryption schemes: CBE(Certificate Based Public
Key Encryption) to IBE(Identity Based Encryption)(type 1),
IBE to IBE(type 2), IBE to CBE (type 3),
CBE to CBE (type 4). Now CBE to
IBE and IBE to IBE proxy re-encryption schemes are being
standardized by IEEEP1363.3 working group. In this
paper, based on we pay attention to the role of
PKG for proxy re-encryption in identity based setting. We find
that if we allow the PKG to use its master-key in the
process of generating re-encryption key for proxy re-encryption in
identity based setting, many open problems can be solved. Our main
results are as following: We construct the first proxy re-encryption
scheme from CBE to IBE which can resist malicious PKG
attack, the first proxy re-encryption scheme from IBE to CBE,
the second proxy re-encryption scheme based on a variant of
BB_1 IBE, the first proxy re-encryption scheme based on BB_2 IBE, the
first proxy re-encryption scheme based on SK IBE, we also
prove their security in their corresponding security models