# ICP Building Blocks

What are the unique ICP technical building blocks enabling the creation of OISY?

* **Chain-key signatures:** the world's best threshold ECDSA signature [protocol suite](https://eprint.iacr.org/2022/506) (only available on ICP) enables smart contracts to perform cryptographic signatures without a single entity having full access to the private key. Read more about [chain-key cryptography](https://internetcomputer.org/how-it-works/chain-key-technology/) or start building based on [chain-key signature sample code](https://github.com/dfinity/examples/tree/master/rust/threshold-ecdsa).
* **Internet Identity (II):** based on ICP's threshold BLS signature schemes and WebAuthn, Internet Identity (II) is an authentication and key management system with strong privacy and security guarantees. Using [WebAuthn](https://www.w3.org/TR/webauthn-3), users can conveniently create secure sessions with their fingerprint or other biometric identifiers. Read more about [Internet Identity technology](https://internetcomputer.org/internet-identity) or [start integrating II](https://internetcomputer.org/docs/current/developer-docs/integrations/internet-identity/integrate-identity) into your canister smart contract.
* **Web applications served from chain:** ICP is not only designed to run *backends*, such as ledgers, on chain, its low storage cost and low latency allow it to serve *frontends*, such as HTML files and images, from chain, too. Read more about [smart contracts serving web applications](https://internetcomputer.org/how-it-works/smart-contracts-serve-the-web/) or directly start [building your first decentralized web frontend](https://internetcomputer.org/docs/current/developer-docs/frontend/).
* (Upcoming) **HTTP outcalls:** for now, OISY calls centralized Ethereum endpoints, such as Infura or Alchemy, from the frontend. In the future, OISY might be improved to use [HTTP outcalls](https://internetcomputer.org/https-outcalls) to call these endpoints in a decentralized fashion. Check out the [HTTP outcalls sample code](https://internetcomputer.org/docs/current/developer-docs/integrations/https-outcalls/https-outcalls-how-to-use) to explore how to use Web 2.0 services on ICP.

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[Build and Run Yourself](/for-developers/icp-building-blocks/build-and-run-yourself.md)
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