> ## Documentation Index
> Fetch the complete documentation index at: https://docs.skale.space/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Smart contracts with secrets. Control who sees what and when — all in Solidity, no trusted third parties

## What Is Programmable Privacy?

SKALE's Programmable Privacy suite brings **composable onchain confidentiality** to smart contracts. Built on threshold encryption and integrated at the protocol layer, it lets contracts define *who* can see *what* and *when* — all while staying fully EVM compatible.

Unlike simple encryption schemes that act as an all-or-nothing blanket, Programmable Privacy is **composable**: decryption rules, access controls, and confidentiality policies are expressed in Solidity, enabling private state, selective disclosure, conditional execution, and confidential token logic.

## Why Programmable Privacy?

Public blockchains expose everything — transaction amounts, contract calls, user intent. This creates problems for real-world applications:

* **Confidentiality** — Payroll, supply chain, lending, and gaming all handle data that shouldn't be public
* **Competition** — Competitors can monitor contract interactions, extract positions, and front-run strategies
* **Compliance** — Regulated use cases (e.g., securities, identity) require controlled disclosure, not full transparency
* **User experience** — Public balances and transaction histories deter adoption for consumer and enterprise use

Programmable Privacy solves these at the protocol layer — no trusted third parties, no L2s with sequencer backdoors, no breaking EVM compatibility.

## Features

| Feature                                                                               | Status    | Chain Availability             |
| ------------------------------------------------------------------------------------- | --------- | ------------------------------ |
| [Encrypted Transactions](/developers/programmable-privacy/encrypted-transactions)     | Available | SKALE Base, SKALE Base Sepolia |
| [Conditional Transactions](/developers/programmable-privacy/conditional-transactions) | Available | SKALE Base, SKALE Base Sepolia |
| [Re-encryption](/developers/programmable-privacy/re-encryption)                       | Beta      | SKALE Base Sepolia             |
| [Confidential Tokens](/developers/programmable-privacy/confidential-tokens)           | Beta      | SKALE Base Sepolia             |

> **Note:** Encrypted Transactions and Conditional Transactions are available on SKALE Base mainnet. Re-encryption and Confidential Tokens are in Beta on SKALE Base Sepolia (testnet) — mainnet deployment is coming soon. For questions or early mainnet access to Beta features, reach out to the SKALE team on [Discord](https://discord.gg/skale).

## How It Works

Programmable Privacy extends SKALE with threshold encryption built into consensus:

1. **Encrypt** — Your wallet or contract encrypts data using SKALE's threshold public key
2. **Submit** — Encrypted data is sent to a precompile or smart contract
3. **Finalize** — Consensus finalizes the encrypted data without seeing contents
4. **Decrypt** — After finality, the validator committee runs threshold decryption
5. **Execute** — Decrypted data executes normally in the EVM

This is **commit-then-reveal** at the protocol level — inclusion happens before anyone can read the data.

## Key Properties

### Threshold Decryption

No single node can decrypt data. The validator committee jointly decrypts using threshold BLS — a minimum number of validators must collaborate. Keys rotate each epoch using onchain DKG.

### Zero Trust

You don't need to trust any single party. The cryptography ensures:

* **No early decryption** — Requires threshold of validators
* **No selective decryption** — All or nothing per epoch
* **No single point of failure** — Distributed key generation

### EVM Compatible

Programmable Privacy works with existing tooling:

* MetaMask, WalletConnect, and other wallets
* Foundry, Hardhat, and other development frameworks
* Ethers.js, Viem, and other web3 libraries
* Existing Solidity contracts (no changes needed for encrypted transactions)

### MEV Resistance (Secondary Benefit)

Encrypting transaction fields also removes the information MEV bots need to front-run or sandwich users — intent is hidden until finality, and validators can't filter by content. This is a useful side effect of protocol-level encryption, not the primary design goal.

## Learn More

* [Encrypted Transactions](/developers/programmable-privacy/encrypted-transactions) — Hide transaction payloads during mempool and consensus
* [Conditional Transactions](/developers/programmable-privacy/conditional-transactions) — Smart contracts that request decryption on-demand
* [Re-encryption](/developers/programmable-privacy/re-encryption) — Encrypt data for specific viewers or private onchain state
* [Confidential Tokens](/developers/programmable-privacy/confidential-tokens) — ERC20 tokens with encrypted balances