Abstract:
In proxy re-encryption (PRE) scheme the
message is sent by a delegator to a delegatee with a
help of the trusted third party proxy without knowing
the existing plaintext. PRE schemes are widely used
in various applications. However, the standard PRE
scheme has some proxy problems called private key
generator (PKG) despotism problem. This means that
PKG can make re-encryption key without getting
permission from the delegator. And also, most of the
PRE schemes have the key-escrow problem. If
someone can attack PKG in PRE scheme, they can
decrypt both the original ciphertext and the reencrypted
ciphertext which means the key-escrow
problem. A solution for these two problems is to use
non-transferable PRE scheme. Non-transferable PRE
scheme solved the above PKG despotism problem
and key-escrow problem. We would like to introduce
our PRE scheme with a new approach. In our
scheme, there are three sub-processes, which are
based on non-transferable PRE scheme and group
signature. Our scheme will provide the security for
delegator i, delegatee j (who is in the same group
with delegator i), and delegatee k (who is in a
different group from delegator i).
