### Payment Proof: Derive and Share Daily TVK

Source: https://docs.umbraprivacy.com/docs/core-concepts/selective-transparency

Example of deriving a specific daily TVK to prove a payment on a particular date. This involves deriving yearly, monthly, and then daily TVKs.

```plaintext
TVK2025 = Poseidon(MVK, 2025)
TVK2025-03 = Poseidon(TVK2025, 3)
TVK2025-03-15 = Poseidon(TVK2025-03, 15)
```

--------------------------------

### Ongoing Audit: Share Monthly TVKs

Source: https://docs.umbraprivacy.com/docs/core-concepts/selective-transparency

Example for an ongoing audit requiring monthly access. Individual monthly TVKs are derived and shared, allowing the auditor rolling visibility for each month.

```plaintext
TVK2025-01 = Poseidon(TVK2025, 1)
TVK2025-02 = Poseidon(TVK2025, 2)
TVK2025-03 = Poseidon(TVK2025, 3)
```

--------------------------------

### Tax Compliance: Share Yearly TVK

Source: https://docs.umbraprivacy.com/docs/core-concepts/selective-transparency

Example of deriving and sharing a yearly TVK for tax compliance. The accountant can view all transactions for the specified year but cannot derive the MVK or spend funds.

```plaintext
TVK2024 = Poseidon(MVK, 2024)
```

--------------------------------

### Derive Daily TVK from Monthly TVK

Source: https://docs.umbraprivacy.com/docs/core-concepts/selective-transparency

Derive a daily TVK by hashing the monthly TVK with the day. This provides daily transaction visibility.

```plaintext
TVKday = Poseidon(TVKmonth, Day)
```

--------------------------------

### Derive Hourly TVK from Daily TVK

Source: https://docs.umbraprivacy.com/docs/core-concepts/selective-transparency

Derive an hourly TVK by hashing the daily TVK with the hour. This offers the most granular time-based access.

```plaintext
TVKhour = Poseidon(TVKday, Hour)
```