Solana to Zcash

Bridging zoZEC from Solana to Zcash is pretty straightforward here.

1. User burns zoZEC with ZEC recipient specified

#![allow(unused)]
fn main() {
struct BridgeToZcash {
    /// The amount of the transaction
    amount: u64,

    /// The zcash recipient address (orchard unified address, 110 chars)
    recipient: String,
}
}

User calls the burn instruction on the Solana program. This is a public action - anyone can burn their own zoZEC.

The program:

1. Burns the zoZEC from the user’s token account
2. Emits a BurnEvent with sender, amount, and Zcash recipient
3. Collectors watch these events to trigger the bridge process

2. Collectors detect and submit bridge requests

Collectors subscribe to Solana program logs and detect BurnEvent emissions:

1. Listen to Solana program logs for burn events
2. Parse the event to extract sender, amount, and Zcash recipient
3. Submit bridge request to zosh mempool

#![allow(unused)]
fn main() {
struct Bridge {
    coin: Coin::Zec,
    recipient: Vec<u8>,  // Zcash orchard address
    amount: u64,
    txid: Vec<u8>,       // Solana burn transaction signature
    source: Chain::Solana,
    target: Chain::Zcash,
}
}

Anyone can run a collector - it’s permissionless.

3. Validators create and sign Zcash transaction

Validators collect bridge requests in the mempool and create Zcash transactions:

1. Bridge requests enter the mempool
2. Validators create a Zcash orchard transaction bundle
3. FROST threshold signing: Validators perform 2-round signature aggregation to sign the Zcash transaction
4. The finalized Zcash transaction is committed to a zosh block

#![allow(unused)]
fn main() {
struct BridgeBundle {
    target: Chain::Zcash,
    bridge: Vec<Bridge>,           // Burn requests
    data: Vec<u8>,                 // Zcash transaction data
    signatures: Vec<Vec<u8>>,      // FROST threshold signatures
}
}

The Zcash transaction is created using the bridge’s orchard wallet. Unspent funds (UTXO change) are sent back to the bridge’s orchard address.

4. The recipient receives ZEC on Zcash

After validators sign the Zcash transaction with FROST, anyone can submit it to the Zcash network:

• The user themselves
• A collector/relayer service
• Any third party (permissionless)

The signed Zcash transaction is stored in the zosh block and can be broadcast by anyone with access to a Zcash node.

No on-chain verification on Zcash is needed - the FROST signature already proves validator consensus. Recipients receive ZEC directly to their orchard shielded address.