> ## Documentation Index
> Fetch the complete documentation index at: https://www.helius.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Confidential Fiat On-Ramp and Off-Ramp
> On-ramp and off-ramp fiat directly to and from a private balance, without revealing the asset or amount.
Users can onramp and offramp fiat balances directly to and from their confidential Solana balance.
Neither action deposits to a public balance, so neither reveals the asset or amount a user on-ramps or off-ramps.
| Field | Visibility | Why |
| ------------------------ | ----------- | --------------------------------------------------------------------- |
| Fiat balance and payment | Not onchain | The fiat payment is not onchain |
| Asset | Private | The asset is encrypted onchain |
| Amount | Private | The transferred amount is encrypted onchain |
| Onramp Provider | Public | In a confidential Ring the wallet address of the provider is visible. |
| User wallet address | Public | In a confidential Ring the user wallet address is visible onchain. |
| Field | Visibility | Why |
| ------------------- | ----------- | --------------------------------------------------------------------- |
| Fiat payout | Not onchain | The fiat payout is not onchain |
| Asset | Private | The asset is encrypted onchain |
| Amount | Private | The transferred amount is encrypted onchain |
| Offramp Provider | Public | In a confidential Ring the wallet address of the provider is visible. |
| User wallet address | Public | In a confidential Ring the user wallet address is visible onchain. |
## Prerequisites:
* The provider (for example, a centralized exchange or fiat-to-crypto processor) holds a private balance of the asset for private on-ramps and off-ramps (SOL or any SPL / Token 2022 token, such as USDC).
* Make sure the private on-ramp and off-ramp account has a sufficient balance to serve your users.
* The user has a Private Wallet.
## High-Level Flows
The fiat leg depends on your internal ledger.
Private on-ramps and off-ramps can be integrated into the Default Ring or a Custom Ring. A Custom Ring can be confidential or anonymous.
### 1. On-Ramp
An on-ramp credits a private balance: the user pays fiat offchain; the provider sends a private transfer onchain from its on-ramp account to the user's Private Wallet.
1. The user deposits fiat.
2. The provider matches the user's fiat deposit to a Private Wallet in the internal ledger.
3. The provider syncs the private balance of the on-ramp account to get its latest balance, then sends a private transfer to the user's Private Wallet.
```mermaid theme={"system"}
%%{init: {
'theme': 'base',
'themeVariables': {
'lineColor': '#FF6B35',
'primaryTextColor': '#737373',
'primaryBorderColor': '#9CA3AF',
'actorBkg': '#FFFFFF',
'actorBorder': '#9CA3AF',
'actorTextColor': '#737373',
'signalColor': '#FF6B35',
'signalTextColor': '#737373',
'labelBoxBkgColor': '#FF6B351F',
'labelBoxBorderColor': '#FF6B35',
'noteBkgColor': '#F5F5F5',
'noteTextColor': '#737373',
'noteBorderColor': '#9CA3AF'
}
}}%%
sequenceDiagram
participant User
participant UW as UserWallet
participant P as Provider OnOfframp
participant RPC as RPC
participant SPP as Solana
User->>P: onramp request (fiat amount)
P->>RPC: sync the on-ramp account balance
RPC-->>P: latest on-ramp account balance
Note over P: build and sign the private transfer
P->>RPC: request proof
RPC-->>P: proof
P->>SPP: submit private transfer (on-ramp account to user)
SPP-->>P: confirmed, transaction hash
UW->>RPC: sync private balance
RPC-->>UW: confirm private balance
```
### 2. Off-Ramp
An off-ramp is a private transfer from the user's Private Wallet to the off-ramp account and an update of the provider's internal ledger to pay out fiat to the user.
The steps to complete a private off-ramp include:
1. The user syncs their private balance and sends a private transfer to the provider's off-ramp account.
2. In a confidential Ring the provider can match the transfer by the visible user wallet address. In an anonymous Ring the public ledger does not reveal sender or recipient; match via the off-ramp request in the internal ledger.
```mermaid theme={"system"}
%%{init: {
'theme': 'base',
'themeVariables': {
'lineColor': '#FF6B35',
'primaryTextColor': '#737373',
'primaryBorderColor': '#9CA3AF',
'actorBkg': '#FFFFFF',
'actorBorder': '#9CA3AF',
'actorTextColor': '#737373',
'signalColor': '#FF6B35',
'signalTextColor': '#737373',
'labelBoxBkgColor': '#FF6B351F',
'labelBoxBorderColor': '#FF6B35',
'noteBkgColor': '#F5F5F5',
'noteTextColor': '#737373',
'noteBorderColor': '#9CA3AF'
}
}}%%
sequenceDiagram
participant User
participant UW as UserWallet
participant P as Provider OnOfframp
participant RPC as RPC
participant SPP as Solana
User->>P: send off-ramp request (amount)
UW->>RPC: sync private balance
Note over UW: build and sign the private transfer
UW->>RPC: request proof
RPC-->>UW: proof
UW->>SPP: submit private transfer (user to off-ramp account)
SPP-->>UW: confirmed, transaction hash
P->>RPC: sync off-ramp account
RPC-->>P: off-ramp request confirmed
Note over P: match sender to a user, credit fiat ledger
P->>User: pay out fiat
```
### 3. On-Ramp and Off-Ramp Account
The on-ramp and off-ramp account is a private balance of the provider to serve on-ramps and off-ramps of users. It can hold SOL or any SPL or Token-2022 token you want to support, such as USDC.
Make sure the on-ramp and off-ramp account has a sufficient balance to serve your users, similar to public on-ramps and off-ramps.
#### Funding the On-Ramp and Off-Ramp Account
To fund the account's private balance, deposit from a public Solana balance (Source public wallet) to a private balance. Users only interact with the account via private transfers, so the amounts and assets transferred to the user are never exposed.
| Field | Visibility | Why |
| -------------------------- | ---------- | -------------------------------------------------- |
| Source public wallet | Public | The source wallet address is visible onchain |
| Asset | Public | The asset is visible onchain |
| Amount | Public | The deposited amount is visible onchain |
| Destination wallet address | Public | The destination wallet address is visible onchain |
| Resulting private balance | Private | The resulting private balance is encrypted onchain |
## Start Integrating
Add privacy support with your own key management. For providers that want to manage encryption keys and run state sync.
Add privacy support to your app via REST API. For providers and apps that want to get started quickly without their own key management and state sync.
Add privacy support via REST API and configure a custom ring with policy and compliance controls.
For fintechs, payroll platforms, remittance companies, neobanks, and enterprises.
## Didn't find what you were looking for?
Reach out! [Telegram](https://t.me/tilo_light) | [E-Mail](mailto:sales@helius.xyz) | [Contact](https://www.helius.dev/contact)