I read some materials about MS u-prove and IBM Idemix.
But according to these materials, the opinion about revocation is different.
Some materials say that u-prove and idemix do not provide revocation, but others say that they provide.
I tried to read technical papers about both but it was too hard to read.
Am I correct in understanding that only a user (not issuer or IdP) of both schemes can revoke it voluntarily?
Can anyone explain about specific details of revocation in u-prove and idemix?