The Book Architecture

The Book is Depa’s general ledger of record. It provides an immutable, double-entry accounting engine designed specifically for modern financial institutions that operate across fiat banking rails and digital assets simultaneously.

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Core Ledger PrinciplesCopy Anchor Link

1. Balanced Double-Entry SystemCopy Anchor Link

Every transaction recorded in Depa consists of balanced journal entries. For every debit, an equal and opposite credit is posted. The ledger balances continuously and deterministically—no phantom balances or floating discrepancies.

2. Multi-Asset by DesignCopy Anchor Link

Traditional core banking ledgers track currency units (e.g. cents). Crypto custodians track wallet balances. The Book unifies both:

• Fiat Balances: EUR, USD, GBP, and 20 other national currencies.
• Stablecoins & Crypto: USDC, EURC, USDT, ETH, BTC.
• Positions & FX: Gross transaction amounts, fee markups, and liquidity fills are recorded as discrete journal lines.

3. Separation of ConcernsCopy Anchor Link

• The Journal executes orders across banking and crypto rails.
• The Watch validates compliance policies before money moves.
• The Book holds the immutable record of truth.

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Entity RelationshipsCopy Anchor Link

• Client: The primary business entity contracted with Depa. Runs in its own isolated multi-tenant partition.
• User: Individuals or backend systems authenticated to perform actions. Users hold role-based access control (RBAC) permissions.
• Account: The core financial container. An account holds bank accounts, blockchain wallets, transaction histories, and balances.
• Identification: A verified KYC or KYB identity. One account can have multiple verified identities (e.g., corporate directors or family members), and one identity can own multiple accounts across personal and business treasuries.