  Redactable signature allows anyone to remove parts of a signed message
without invalidating the signature. The need to prove the validity of digital
documents issued by governments is increasing. When governments disclose
documents, they must remove private information concerning individuals.
Redactable signature is useful for such a situation. However, in most
redactable signature schemes, to remove parts of the signed message, we need
pieces of information for each part we want to remove. If a signed message
consists of l elements, the number of elements in an original signature is at
least linear in l. As far as we know, in some redactable signature schemes, the
number of elements in an original signature is constant, regardless of the
number of elements in a message to be signed. However, these constructions have
drawbacks in that the use of the random oracle model or generic group model. In
this paper, we construct an efficient redactable signature to overcome these
drawbacks. Our redactable signature is obtained by combining set-commitment
proposed in the recent work by Fuchsbauer et al. (JoC 2019) and digital
signatures.
