Section 3 presents a new group signature scheme based on a shared secret key and a smart card. Section 4.1 presents a solution to the problem of revocation that adds to the general group signature an ordinary signature that depends on a group-shared key. If one wants to apply this revocation method to this group signature, each signer will have a priori to compute two different signatures. But the two signatures can easily be merged into a single one, since they both use a group-shared secret key. This leads to a very attractive method which allows revocation while generating only one signature. More precisely, only one signature is necessary because it is possible to replace the (fixed) group-shared key of section 3 with a dynamic group-shared key, as explained in section 4.1. The group-shared key used in the group signature scheme only needs to be modified by the group manager after each revocation (see. section 4.1.2) and the rest is unchanged. Figure 1 shows the mechanism carried out by the smart card during the signature phase to which must be added the key updating phase illustrated in Figure 3.