MOBUSD
MOB / United States dollar
crypto

MobileCoin is a privacy-focused cryptocurrency designed to be used as digital cash on a phone. The MobileCoin protocol allows for easy key management and private near-instantaneous transactions. The four fundamental issues that MobileCoin aims to address are privacy, transaction speed, energy consumption, and optimization for mobile devices. Transactions The MobileCoin ledger is implemented as a blockchain, in which each block contains transactions that include transaction outputs (TXOs) that might be spent in the future by their owners. Each transaction also includes a proof that all value spent in the transaction has never been spent before. The underlying design is based on the privacy-preserving CryptoNote ledger protocol, which obscures the identity of all TXO owners using one-time recipient addresses. The link between sender and recipient is protected through the use of input rings that guard the actually-spent TXO in a large set of possibly-spent TXOs. The monetary value of each TXO is encrypted using the method of Ring Confidential Transactions (RingCT). RingCT is implemented using bulletproofs for improved performance. Only the receiver of the transaction can reveal the encrypted monetary value and spend the new TXOs that are written to the ledger. The recipient's cryptographic control over spending ensures that all transactions in MobileCoin are irreversible, similar to cash transactions in the real world. Each TXO in the input ring of a transaction is annotated with a Merkle proof of inclusion in the MobileCoin Ledger blockchain. This allows new transactions to be validated with fewer blockchain read operations, improving efficiency and reducing information leaked to data-access side channels. Additionally, MobileCoin Ledger improves on the baseline privacy offered by CryptoNote and RingCT by requiring that the input rings for every transaction are deleted before the new payment is added to the public ledger. Digital signatures are added to the ledger in place of the full transaction records to provide a basis for auditing. SGX All MobileCoin full validator nodes run in an Intel Software Guard Extension (SGX) which provides an additional layer of security to the blockchain on top of CryptoNote and RingCT. An SGX enclave is isolated from the host OS in hardware-encrypted RAM, which prevents the node operator from being able to "see" into the enclave, although care must be taken to avoid information leaks through memory access patterns. SGX also supports a feature known as remote attestation, which allows a remote client to determine that a server is running a specific piece of software inside an SGX enclave over a network. By doing remote attestation before establishing encrypted communication channels between nodes, the entire MobileCoin ledger always remains sealed within SGX enclaves across the entire network, which means that the ledger, while "public" and distributed to all MobileCoin nodes, can never be accessed or viewed by humans (even the operators of the MobileCoin nodes) so long as SGX and the MobileCoin software remains secure. In addition to the full validator nodes, watcher nodes also exist which perform an essential role in the MobileCoin network by verifying the signatures that the full validator nodes attach to each block. In this way the watcher nodes continuously monitor the integrity of the decentralized MobileCoin network. A watcher node, which does not require SGX to run, also maintains a complete local copy of the blockchain and provides an API for wallet or exchange clients. FOG MobileCoin Fog is a suite of microservices designed to enable MobileCoin payments on mobile devices, which can use Fog to check their balance and send payments, without syncing the ledger. Fog is designed so that the MobileCoin and Fog service operators have no nontrivial insight into your payment. For MobileCoin payments to be practical, it cannot require the mobile device to sync the ledger or download the entire blockchain. However, a so-called "thin wallet" won't work either, because the types of queries made by a thin wallet generally reveal to the server the user's balance, when they got paid, etc. In typical thin wallet designs, the server is trusted by the user. Because of this, off-the-shelf solutions to wallet services simply don't work and Fog had to be developed. Fog makes heavy use of SGX enclaves and Oblivious RAM data structures to serve such queries privately and without compromising scalability. Although such use of SGX may create potential operational challenges, the MobileCoin system has been carefully designed to navigate these challenges.