Author: raymo at riseup.net 2021-06-27 11:05:04
Published on: 2021-06-27T11:05:04+00:00
The Sabu protocol is designed with several restrictions to prevent fraudulent transactions. The Gazin wallet controls all Sabu transaction restrictions to ensure that they are valid before considering them as a legitimate deal. This means that the creditor wallet controls the MT and GT at first, and if the transactions meet the criteria, the creditor considers the entire process to be a valid deal and provides goods or services in exchange for received Satoshis.The issuer must sign an MT transaction in which a UTXO worth at least 40,000 Sat is spent, and the issuer can issue a maximum of 20,000 Sat debt-document. A transaction can have one or more outputs for creditors, but they must be worth in total less than 20,000 Sat. Each transaction must pay a fixed 10,000 Sat BTC-transaction-fee, regardless of the transaction length or the inputs/outputs amounts. The issuer always pays at least 4,000 Sat of BTC-transaction-fee, and the remaining 6,000 Sat fee must be paid by the issuer and creditors in proportion to their output amounts. Finally, the transaction can have one change-back output to the issuer address (same as input address) worth less than (40,000 – 4,000 = 36,000) Sat to the issuer.All these transactions are relative and depend on each other, limiting arbitrary UTXO spending by the issuer or self-paying transactions that could provide more output and benefits to the issuer than respecting the already issued MT. ZmnSCPxj raises concerns about the UX of the Sabu protocol, stating that the largest safe payment will vary depending on the on-chain mempool state. Additionally, there is a risk of fraudulent transactions where a single signer can sign anything, including a transaction that is not an MT or GT, but has arbitrary numbers that are neither a valid GT nor a valid MT. Thus, every trust-minimized off-chain system requires 2-of-2 to countercheck the validity of a protocol that is not directly on the blockchain. ZmnSCPxj raises a scenario where the issuer can create a self-paying transaction by itself that is neither a valid MT nor a valid GT, which is not checked by the blockchain layer. ZmnSCPxj argues that this makes Sabu a trusted system where every creditor trusts every issuer to only sign GTs and MTs, making it uninteresting compared to using Coinbase as an off-chain solution if you are going to inject trust.
Updated on: 2023-06-14T22:54:09.981848+00:00