> For the complete documentation index, see [llms.txt](https://docs.zama.org/tfhe-rs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zama.org/tfhe-rs/tfhe-rs/0.1-1/js-on-wasm-api/tutorial.md). # Tutorial ## Using the JS on WASM API Welcome to this TFHE-rs JS on WASM API tutorial! TFHE-rs uses WASM to expose a JS binding to the client-side primitives, like key generation and encryption, of the Boolean and shortint modules. There are several limitations at this time. Due to a lack of threading support in WASM, key generation can be too slow to be practical for bigger parameter sets. Some parameter sets lead to FHE keys that are too big to fit in the 2GB memory space of WASM. This means that some parameters sets are virtually unusable. ## First steps using TFHE-rs JS on WASM API ### Setting-up TFHE-rs JS on WASM API for use in nodejs programs. To build the JS on WASM bindings for TFHE-rs, you will first need to install [`wasm-pack`](https://rustwasm.github.io/wasm-pack/) in addition to a compatible (>= 1.65) [`rust toolchain`](https://rustup.rs/). Then, in a shell run the following to clone the TFHE-rs repo (one may want to checkout a specific tag, here the default branch is used for the build): ```shell $ git clone https://github.com/zama-ai/tfhe-rs.git Cloning into 'tfhe-rs'... ... Resolving deltas: 100% (3866/3866), done. $ cd tfhe-rs $ cd tfhe $ rustup run wasm-pack build --release --target=nodejs --features=boolean-client-js-wasm-api,shortint-client-js-wasm-api [INFO]: Compiling to Wasm... ... [INFO]: :-) Your wasm pkg is ready to publish at ... ``` The command above targets nodejs. A binding for a web browser can be generated as well using `--target=web`. This use case will not be discussed in this tutorial. Both Boolean and shortint features are enabled here but it's possible to use one without the other. After the build, a new directory ***pkg*** is present in the `tfhe` directory. ```shell $ ls pkg LICENSE index.html package.json tfhe.d.ts tfhe.js tfhe_bg.txt tfhe_bg.wasm tfhe_bg.wasm.d.ts $ ``` ### Commented code to generate keys for shortint and encrypt a ciphertext {% hint style="info" %} Be sure to update the path of the required clause in the example below for the TFHE package that was just built. {% endhint %} ```javascript // Here import assert to check the decryption went well and panic otherwise const assert = require('node:assert').strict; // Import the Shortint module from the TFHE-rs package generated earlier const { Shortint } = require("/path/to/built/tfhe/pkg"); function shortint_example() { // Get pre-defined parameters from the shortint module to manage messages with 4 bits of useful // information in total (2 bits of "message" and 2 bits of "carry") let params = Shortint.get_parameters(2, 2); // Create a new secret ClientKey, this must not be shared console.log("Generating client keys...") let cks = Shortint.new_client_key(params); // Encrypt 3 in a ciphertext console.log("Encrypting 3...") let ct = Shortint.encrypt(cks, BigInt(3)); // Demonstrate ClientKey serialization (for example saving it on disk on the user device) let serialized_cks = Shortint.serialize_client_key(cks); // Deserialization let deserialized_cks = Shortint.deserialize_client_key(serialized_cks); // Demonstrate ciphertext serialization to send over the network let serialized_ct = Shortint.serialize_ciphertext(ct); // Deserialize a ciphertext received over the network for example let deserialized_ct = Shortint.deserialize_ciphertext(serialized_ct); // Decrypt with the deserialized objects console.log("Decrypting ciphertext...") let decrypted = Shortint.decrypt(deserialized_cks, deserialized_ct); // Check decryption works as expected assert.deepStrictEqual(decrypted, BigInt(3)); console.log("Decryption successful!") // Generate public evaluation keys, also called ServerKey console.log("Generating compressed ServerKey...") let sks = Shortint.new_compressed_server_key(cks); // Can be serialized to send over the network to the machine doing the evaluation let serialized_sks = Shortint.serialize_compressed_server_key(sks); let deserialized_sks = Shortint.deserialize_compressed_server_key(serialized_sks); console.log("All done!") } shortint_example(); ``` The `example.js` script can then be run using [`node`](https://nodejs.org/) like so: ```shell $ node example.js Generating client keys... Encrypting 3... Decrypting ciphertext... Decryption successful! Generating compressed ServerKey... All done! $ ``` --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.zama.org/tfhe-rs/tfhe-rs/0.1-1/js-on-wasm-api/tutorial.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. 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