  Cryptocurrencies, led by bitcoin launched in 2009, have obtained wide
attention due to the emerging Blockchain in recent years. Anonymous
cryptocurrencies are highly essential since users want to preserve their
privacy when conducting transactions. However, some users might misbehave with
the cover of anonymity such as rampant trafficking and extortion. Thus, it is
important to balance anonymity and accountability of anonymous
cryptocurrencies. In this paper, we solve this issue by proposing a linkable
group signature (LGS) for signing cryptocurrency transactions, which can be
used to trace a payer's identity in consortium blockchain based anonymous
cryptocurrencies, in case the payer tries illegal activities. A payer keeps
anonymous if he/she behaves honestly. We prove that the proposed scheme
achieves full-anonymity, full-traceability and linkability in the random
oracle. Implementation of the proposed LGS scheme demonstrates its high
efficiency thus, can be adopted in anonymous cryptocurrencies in reality.
