Concepts

​

Introduction to Rings

• In confidential Rings, the asset and amount are private, while the sender and recipient stay visible.
• In anonymous Rings the asset, amount, sender, and recipient are private.

1. The Default Ring is permissionless and confidential. It encrypts asset and amount, can be used by anyone, and does not have custom policy controls.
2. Custom Rings are Solana programs that make privacy on Solana programmable, similar to Token-2022. A Custom Ring can be confidential or anonymous with custom policy, reporting, and visibility rules.

​

Custom Rings Are Programmable

​

User Flows and Privacy Guarantees

​

Deposit to a Private Balance: What Is Private

1. On-ramp from a fiat balance to a private crypto balance
2. Deposit from a public to a private crypto balance

​

Private Transfer: What Is Private

1. Transfer in the same Ring
2. Transfer to a different Ring

​

Withdraw from a Private Balance: What Is Private

1. Off-ramp from private crypto to a fiat balance
2. Withdraw from private crypto to a public crypto balance

​

High-Level Transaction Flow

​

Private Wallet

​

Creation of a Private Wallet

​

Transfers to a Private Wallet

​

Key Management

ShieldedAddress = (signing_pk, nullifier_pk, viewing_pk)

​

Creating a Shielded Keypair

1. Derive keys from the Seed phrase.
   • The recommended approach for seed based wallets.
   • Confidential Rings: the signing key is the same Ed25519 key a Solana wallet derives from that seed. The nullifier and viewing keys are additional keys derived from the same seed.
   • Custom Anonymous Rings: the signing key is an additional P-256 key derived from the wallet seed.
   • You can always recreate the shielded keypair the same way you recreate the Solana wallet.
2. Derive keys from a fixed message with the existing Solana key.
   • Solana signatures are deterministic, hence the same Solana keypair always produces the same shielded keypair. The app never receives the private key.
   • The recommended approach for tests and wallets that do not use a seed phrase. The integrating wallet must ensure that the signature is not exposed to third parties.

​

Integrating a Shielded Keypair

​

Decryption Modes and Wallet Sync

​

Local Decryption

​

Delegated Decryption

​

Indexer Serves Encrypted State

​

Private Wallet Balance

Balances in UTXOs vs Solana accounts

For the user experience, it does not matter whether the balance is held in UTXOs or Solana token accounts.At a technical level, spending a public balance reduces the amount in a Solana token account. Spending a Private Balance does not overwrite the amount field of a UTXO. Instead, private transactions take existing UTXOs as inputs (automatically chosen by the SDK), consume the inputs and create new outputs for the recipient and for the sender’s remaining balance.For example, Alice has 50 USDC and sends Bob 35.

• In a Solana token account, her amount field goes from 50 to 15, and Bob’s goes up by 35. The number changes in place.
• With UTXOs, Alice holds one 50 USDC note. The transaction spends it and creates two new notes: a 35 USDC note for Bob, and a 15 USDC change note for Alice. Her old 50 note is now spent.

• One input note
• Multiple input notes

	Solana token account	Private Solana token account (UTXO)
Holds	One balance number in the amount field	A set of notes, each a fixed amount of one asset
Balance	The number on the account	The sum of all unspent UTXOs
Spending	Subtracts from the amount field in place	Consumes input UTXOs and writes a new change UTXO
Visibility	Public onchain	Encrypted onchain

At deposit to a private balance of SOL and SPL assets, an interface PDA owned by the Solana Privacy Program escrows tokens and creates UTXOs with the user as owner.At withdrawal to a public balance, existing UTXOs are marked as spent, and tokens are released to the Solana token accounts.

​

Private Solana Token Accounts

• a Private Solana Token Account does not require rent-exemption upon creation, and
• its balance is encrypted onchain.

• Asset: the mint the UTXO holds units of. SOL is the default mint address. The asset can be SOL or any SPL or Token-2022 asset.
• Amount: the number of units of asset the note holds, in the asset’s smallest unit.
• Program and policy data: optional data for the configured ring policy to add Token-2022-like functionality

• Diagram
• Code

The full record stored for each Private Solana Token Account is a flat UTXO:

Private Solana Token Account (UTXO)

struct Utxo {
    /// Constant separating UTXOs from other Poseidon-hashed records.
    domain: u16,
    /// Recipient's `owner_hash` from their Shielded Address.
    /// Senders write this value directly; the spender supplies the preimage
    /// components as proof witness.
    owner: [u8; 32],
    /// Asset mint. SOL is Address::default().
    asset: Address,
    /// Amount in the smallest unit of `asset`.
    amount: u64,
    /// Random bytes ensuring distinct UTXO hashes for equal
    /// `(owner, asset, amount)` triples.
    blinding: [u8; 31],
    /// Arbitrary program data.
    program_data: Option<Vec<u8>>,
    /// Arbitrary policy data.
    policy_data: Option<Vec<u8>>,
    /// The policy program that authorizes spends of this UTXO.
    policy_program_id: Option<Address>,
}

View Solana token account

• Diagram
• Code

Solana Token Account

pub struct Account {
    /// The mint associated with this account
    pub mint: Pubkey,
    /// The owner of this account.
    pub owner: Pubkey,
    /// The amount of tokens this account holds.
    pub amount: u64,
    /// If `delegate` is `Some` then `delegated_amount` represents
    /// the amount authorized by the delegate
    pub delegate: COption<Pubkey>,
    /// The account's state
    pub state: AccountState,
    /// If is_native.is_some, this is a native token, and the value logs the
    /// rent-exempt reserve. An Account is required to be rent-exempt, so
    /// the value is used by the Processor to ensure that wrapped SOL
    /// accounts do not drop below this threshold.
    pub is_native: COption<u64>,
    /// The amount delegated
    pub delegated_amount: u64,
    /// Optional authority to close the account.
    pub close_authority: COption<Pubkey>,
}

​

On Concurrency

​

On Proof Generation Time

​

Terms

​

Didn’t find what you were looking for?