IOHK | WHY WE ARE BUILDING CARDANO | 06/28/2017    The difference is that Ouroboros can be confirmed to permit both permissioned and permissionless ledgers via token distribution. With CSL, Ada has been distributed by a token generating event to purchasers throughout Asia who will eventually resell on a secondary market. This means that CSL’s consensus algorithm is controlled by a diverse and increasingly more decentralized set of actors or their delegated assigns. With CCL, it is possible to create a special purpose token held by delegates of that ledger who could be regulated entities, thereby creating a permissioned ledger. The flexibility of this approach allows for different instances of CCL to materialize with different rules about the evaluation of transactions. For example, gambling activities could be restricted unless KYC/AML data is present simply by blacklisting non-attributed transactions. Our final design focus is on adding trusted hardware security modules (HSM) to our protocol stack. These are two enormous advantages when introducing these capabilities into the protocol. First, HSMs provide massive boosts in performance without introducing security 14 concerns beyond trusting the vendor. Second, through the use of Sealed Glass Proofs (SGP), HSMs can provide assurances that data can be verified and then destroyed without being copied or leaked to malicious outsiders. Focusing on the second point, SGPs could have a revolutionary impact upon compliance. Ordinarily, when a consumer provides personally identifiable information (PII) to authenticate identity or prove the right to participate, this information is handed to a trusted third party with the hope it will not act maliciously. This activity is intrinsically centralized, the data provider loses control over their PII and is also subject to various regulations based on jurisdiction. The ability to select a set of trusted attestors and then warehouse PII in a hardware enclave means that any actor with a sufficiently capable HSM will be able to verify facts about an actor in an unforgeable way without the verifier knowing the identity of the actor. For example, Bob is not an US citizen. Alice is an accredited investor. James is a US taxpayer and one should send taxable profits to account X. Cardano’s HSM strategy will be to attempt implemented specialized protocols over the next two years using Intel SGX and ARM Trustzone . Both modules are built into billions of consumer devices from laptops to cellphones and require no additional effort on the consumer side to use. Both are also heavily vetted, well designed and based upon years of iteration from some of the largest and best funded hardware security teams. 14 See http://hackingdistributed.com/2016/12/22/scaling-bitcoin-with-secure-hardware/ from Cornell University WHY WE ARE BUILDING CARDANO  Creative Commons Attribution 4.0 International License Page 17 of 44