This paper introduces dynamic accumulators, which allow for efficient addition and deletion of values in an accumulator, with costs independent of the number of accumulated values. The authors provide a construction of a dynamic accumulator and an efficient zero-knowledge proof of knowledge of an accumulated value, proving their security under the strong RSA assumption. They demonstrate that this construction enables efficient revocation of anonymous credentials and membership revocation for recent group signature and identity escrow schemes. Dynamic accumulators are particularly useful in scenarios where users need to prove eligibility without revealing their identity. The authors show that using accumulators in combination with zero-knowledge proofs allows for efficient revocation of anonymous credentials. The construction can be applied to other schemes as well, by incorporating the public key for an accumulator scheme into the group manager's public key and the secret trapdoor into the corresponding secret key. The paper also discusses related work, including group signature schemes and identity escrow schemes, and highlights the challenges of revocation in these systems. The authors show that their dynamic accumulator construction provides an efficient mechanism for revoking group membership in the Ateniese et al. identity escrow/group signature scheme and for credential revocation in the Camenisch and Lysyanskaya credential system. The construction is secure under the strong RSA assumption and does not add significant communication or computation overhead to the underlying schemes.This paper introduces dynamic accumulators, which allow for efficient addition and deletion of values in an accumulator, with costs independent of the number of accumulated values. The authors provide a construction of a dynamic accumulator and an efficient zero-knowledge proof of knowledge of an accumulated value, proving their security under the strong RSA assumption. They demonstrate that this construction enables efficient revocation of anonymous credentials and membership revocation for recent group signature and identity escrow schemes. Dynamic accumulators are particularly useful in scenarios where users need to prove eligibility without revealing their identity. The authors show that using accumulators in combination with zero-knowledge proofs allows for efficient revocation of anonymous credentials. The construction can be applied to other schemes as well, by incorporating the public key for an accumulator scheme into the group manager's public key and the secret trapdoor into the corresponding secret key. The paper also discusses related work, including group signature schemes and identity escrow schemes, and highlights the challenges of revocation in these systems. The authors show that their dynamic accumulator construction provides an efficient mechanism for revoking group membership in the Ateniese et al. identity escrow/group signature scheme and for credential revocation in the Camenisch and Lysyanskaya credential system. The construction is secure under the strong RSA assumption and does not add significant communication or computation overhead to the underlying schemes.