A concrete implementation of a secure obfuscator for a special encrypted ring signature (ERS) functionality is constructed. This ERS functionality is the sequential composition of Waterss ring signature scheme and linear encryption scheme. In the standard model

the proposed obfuscator satisfies average-case virtual black-box property (ACVBP)

which guarantees the preservation of the anonymity and unforgeability of the ring signature even if an obfuscated program is given to the adversaries.