Group signatures allow any member of the group sign the message on behalf of the group anonymously using his own secret-key. Only group manager can reveal the identity of the signer. Verifier Local Revocation (VLR) is an efficient approach of membership revocation.
In VLR group signatures, revocation-token is generated for each user and is placed in Revocation List (RL) whenever the user is revoked. VLR group signature schemes consist of three algorithms: KeyGen, Sign and Verify
KeyGen algorithm outputs public-key, secret-key for each user and revocation-token for each user
Sign algorithm generates the signature on a message using the secret-key of a group member.
Verify algorithm returns 1 if it is a valid signature that is signer is valid group member and he is not revoked. Otherwise, returns 0.
If a group member "i" is revoked then its revocation token in placed RL. Therefore, he cannot generate a valid signature. But, the verify algorithm returns invalid for all the signatures generated by user "i" before revocation if we verify the signatures using the RL where revocation-token of user "i" is placed. Is my understanding correct?