Implementation of butterfly key extension scheme. The present disclosure relates to methods, computer programs and
registration authority modules for implementing butterfly key extension scheme. The present disclosure also relates to a security
credential management system using these methods, computer programs or
registration authority modules for implementing butterfly key extension scheme. In a first step, a public
larva signature key and a first pseudo-random function in a private / public
larva signature key pair are received (S1) from a requesting device. The public
larva signature key is expanded (S2) to a public cocoon signature key using the first pseudo-random function. Then, based on the public cocoon signature key, a
certificate signing request is generated (S4), for example, by creating (S3) a public butterfly signature key from each public cocoon signature key and inserting each public butterfly signature key into a corresponding
certificate signing request. Subsequently, the
certificate signing request is sent (S5) to a
certificate authority module. In response, a signed pseudonym certificate is received (S6) from the
certificate authority module. Then, the signed pseudonym certificate is encrypted (S7) to generate a response packet. The generated response packet can be further signed (S8) and provided (S9) for downloading by the requesting device.