message: update paper with official title
diff: Research
  ========
  -`PAC: Practical Accountability for CCF <https://arxiv.org/abs/2105.13116>`_
  - Permissioned ledger systems execute transactions on a set of replicas governed by members of a consortium. They use Byzantine fault tolerance protocols to distribute trust among the replicas, and thus can ensure linearizability if fewer than 1/3 of the replicas misbehave. With more misbehaving replicas, current systems provide no guarantees, and all replicas and members share the blame.
  -
  - We describe PAC, a permissioned ledger system that assigns blame to misbehaving replicas while supporting governance transactions to change the consortium membership and the set of replicas. PAC signs and stores protocol messages in the ledger and provides clients with signed, universally-verifiable receipts as evidence that a transaction executed at a certain ledger position. If clients obtain a sequence of receipts that violate linearizability, anyone can audit the ledger and the sequence of receipts to assign blame to at least 1/3 of the replicas, even if all replicas and members misbehave. Auditing assigns blame by finding contradictory statements signed by the same replica. Since the set of replicas changes, PAC determines the valid signing keys at any point in the ledger using a shorter sub-ledger of governance transactions. PAC provides a strong disincentive to misbehavior at low cost: it can execute more than 48,000 transactions per second, and clients receive receipts in two network round trips.
  +`IA-CCF: Individual Accountability for Permissioned Ledgers <https://arxiv.org/abs/2105.13116>`_
  + Permissioned ledger systems allow a consortium of members that do not trust one another to execute transactions safely on a set of replicas. Such systems typically use Byzantine fault tolerance (BFT) protocols to distribute trust, which only ensures safety when fewer than 1/3 of the replicas misbehave. Providing guarantees beyond this threshold is a challenge: current systems assume that the ledger is corrupt and fail to identify misbehaving replicas or hold the members that operate them accountable---instead all members share the blame.
  + We describe IA-CCF, a new permissioned ledger system that provides individual accountability. It can assign blame to the individual members that operate misbehaving replicas regardless of the number of misbehaving replicas or members. IA-CCF achieves this by signing and logging BFT protocol messages in the ledger, and by using Merkle trees to provide clients with succinct, universally-verifiable receipts as evidence of successful transaction execution. Anyone can audit the ledger against a set of receipts to discover inconsistencies and identify replicas that signed contradictory statements. IA-CCF also supports changes to consortium membership and replicas by tracking signing keys using a sub-ledger of governance transactions. IA-CCF provides strong disincentives to misbehavior with low overhead: it executes 47,000 tx/s while providing clients with receipts in two network round trips.
  `CCF: A Framework for Building Confidential Verifiable Replicated Service <https://github.com/microsoft/CCF/blob/main/CCF-TECHNICAL-REPORT.pdf>`_
  This paper presents CCF, a framework to build permissioned confidential blockchains. CCF provides a simple programming
  @@ -17,5 +16,5 @@ Research
  .. toctree::
  :hidden:
  - PAC: Practical Accountability for CCF <https://arxiv.org/abs/2105.13116>
  + IA-CCF: Individual Accountability for Permissioned Ledgers <https://arxiv.org/abs/2105.13116>
  CCF whitepaper <https://github.com/microsoft/CCF/blob/main/CCF-TECHNICAL-REPORT.pdf>
  