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Version: v3.x.x

Programmable Signing

Overview​

Lit’s distributed key management network can be used to produce programmable signatures and transaction automations. Functionally, this feature gives developers the capacity to build distributed serverless functions and applications that have the ability to sign data with their own private key. The signing keys generated by Lit are:

  1. Blockchain Agnostic: Lit keys can be used to sign transactions on any blockchains or state machines using ECDSA for digital signatures. Currently, the SDK provides easy-to-use methods for creating wallets on EVM and Cosmos based chains.
  2. Programmable: Lit keys can be programmed to sign based on pre-defined conditions, referred to as conditional signatures in the docs. This is useful for defining signing automations, handling authentication, or generating proofs over off-chain data.
  3. Fault-tolerant: Each key is generated collectively by the Lit nodes through a process called Distributed Key Generation (DKG). As a network, this allows Lit to generate a new key pair where no one node ever holds the key in its entirety.

To get started building with these tools right away, check out the Lit SDK install guide. Otherwise, keep reading to get a better understanding of how digital signatures work, why the technology is important, and potential ways this tooling can be implemented in the real world!

Introduction to Digital Signatures​

Based upon public key infrastructure (PKI), digital signatures provide a tamper-resistant means of verifying the authenticity and integrity of data on the Web. Data “signed” by an individual private key can be mathematically verified against the associated public key. It is this nature of mathematical verifiability that makes digital signatures so powerful. You can trust, with high confidence, that a particular signature is in fact authentic and hasn’t been forged or tampered with.

Digital signatures involve the following steps:

  1. The sender creates a digital signature by hashing a message and encrypting the hash using their private key.
  2. The recipient receives the message and signature.
  3. The recipient verifies the signature by decrypting the hash using the sender's public key and comparing it to the hash of the original message. If the hashes are equivalent, the signature is authentic.

Programmable Signatures with Lit​

The Lit network can be harnessed to program programmatic digital signatures. Some potential use cases for this functionality include:

  1. Event listening and condition-based transaction execution: Automate your interactions with blockchain ecosystems using condition-based execution, enabling use cases such as on-chain limit orders or recurring payments that don’t require manual input (i.e. signing off on the transaction) from the end user.
  2. Native cross-chain messaging and swaps: Seamlessly transfer assets and data across blockchain networks without relying on a trusted intermediary or centralized asset bridge.
  3. Automated verifiable credential issuance: Verifiable credentials are digital certifications attesting to particular user attributes or qualifications. Using condition-based signing, automate the issuance of these credentials and eliminate the possibility of fraud or human error.
  4. Enterprise “signed data” applications: There are numerous use cases for cryptographically-verifiable “signed data” in institutional and enterprise environments, such as using digital signatures to authenticate and track goods in physical supply chains.
  5. Generating signed proofs over arbitrary Web data: Using digital signatures to verify the provenance and integrity of data sourced from various locations on the open Web.
  6. Trustless vault applications: Each PKP is represented by an ERC-721 token on the blockchain (explored in more detail in subsequent sections). This means that any assets sent to the PKP can be traded or sold in a single transaction by selling the NFT that controls the underlying key pair. This facilitates potential trustless “vault” applications where an array of assets may be managed together according to the rules associated with the PKP itself.
  7. Authentication for AI generated content: A registry of identities and associated keys (which do the signing) in order to verify who made a given claim is neither ideal for privacy nor in line with the way that people use the Web. Threshold signing offers a unique solution to the data integrity problem, distributing trust among a set of parties to act as a “signer of last resort”.

Getting Started and Further Reading​

Some links to further reading and resources to help you get started building on the Lit network today: