Add crypto-utils building block using Noble crypto libraries

building-blocks/README.md

@@ -55,14 +55,26 @@ Path: [`./read-data-feeds`](./read-data-feeds)
 - On a cron schedule, reads `decimals()` and `latestAnswer()` from **Chainlink Data Feeds** (example targets BTC/USD and ETH/USD on Arbitrum One).
 - Shows how to add an ABI, generate Go bindings, configure chain RPC, and log scaled answers.
 
-👉 See the block’s README for setup, config, and sample logs.
+👉 See the block's README for setup, config, and sample logs.
+
+---
+
+### 3) **Crypto Utils**
+Path: [`./crypto-utils`](./crypto-utils)
+
+- Demonstrates how to use **cryptographic operations** in CRE TypeScript workflows using the **Noble crypto libraries**.
+- Shows alternatives to Node.js `crypto` module for: hashing (SHA-256, SHA3, Keccak, BLAKE), HMAC, key derivation (PBKDF2, Scrypt, HKDF), symmetric encryption (AES-GCM, ChaCha20-Poly1305), digital signatures (ECDSA, Ed25519), and ECDH key exchange.
+- Includes practical examples for Bitcoin and Ethereum address derivation.
+
+👉 See the block's README for setup, Node.js-to-Noble mapping table, and code examples.
 
 ---
 
 ## When to Use Which Block
 
 * **kv-store**: You want to see an **off-chain write** pattern (AWS S3), secrets usage, SigV4 signing, and a **consensus read → single write** flow.
 * **read-data-feeds**: You want to **read on-chain data** via contract calls, manage ABIs/bindings, and configure **RPC** access.
+* **crypto-utils**: You need to perform **cryptographic operations** (hashing, signing, encryption, key derivation) in a TypeScript workflow.
 
 ---
 

building-blocks/crypto-utils/README.md

@@ -0,0 +1,85 @@
+<div style="text-align:center" align="center">
+    <a href="https://chain.link" target="_blank">
+        <img src="https://raw.githubusercontent.com/smartcontractkit/chainlink/develop/docs/logo-chainlink-blue.svg" width="225" alt="Chainlink logo">
+    </a>
+
+[![License](https://img.shields.io/badge/license-MIT-blue)](https://github.com/smartcontractkit/cre-templates/blob/main/LICENSE)
+[![CRE Home](https://img.shields.io/static/v1?label=CRE&message=Home&color=blue)](https://chain.link/chainlink-runtime-environment)
+[![CRE Documentation](https://img.shields.io/static/v1?label=CRE&message=Docs&color=blue)](https://docs.chain.link/cre)
+
+</div>
+
+# Crypto Utils - CRE Building Block
+
+This building block demonstrates how to perform cryptographic operations in CRE workflows using the **Noble crypto libraries** as an alternative to the Node.js `crypto` module.
+
+## The Problem
+
+The CRE TypeScript SDK runs on **QuickJS**, a lightweight JavaScript engine that does not support Node.js native modules. This means the standard `crypto` module from Node.js is **not available** in CRE workflows.
+
+## The Solution
+
+The [Noble crypto libraries](https://paulmillr.com/noble/) provide pure JavaScript implementations of common cryptographic algorithms. They are:
+
+- **Pure JavaScript** - No native dependencies, works in QuickJS
+- **Audited** - Security-audited implementations
+- **Minimal** - Small bundle size (~29KB gzipped for curves)
+- **Standards-compliant** - Implements widely-used cryptographic standards
+
+## Random Bytes
+
+Noble's `randomBytes()` won't work (needs Web Crypto API), but **CRE provides a `Math.random()` polyfill** using ChaCha8Rng that IS consensus-safe. You can build your own `randomBytes()`:
+
+```typescript
+function randomBytes(length: number): Uint8Array {
+  const bytes = new Uint8Array(length);
+  for (let i = 0; i < length; i++) {
+    bytes[i] = Math.floor(Math.random() * 256);
+  }
+  return bytes;
+}
+```
+
+See the [TypeScript README](./crypto-utils-ts/README.md#random-bytes-in-cre) for details.
+
+---
+
+## What's Covered
+
+This template demonstrates:
+
+| Category | Noble Package | Operations |
+|----------|---------------|------------|
+| **Hashing** | `@noble/hashes` | SHA-256, SHA-512, SHA3, Keccak-256, BLAKE2b, BLAKE3, RIPEMD-160 |
+| **HMAC** | `@noble/hashes` | HMAC with any hash function |
+| **Key Derivation** | `@noble/hashes` | PBKDF2, Scrypt, HKDF |
+| **Symmetric Encryption** | `@noble/ciphers` | AES-GCM, ChaCha20-Poly1305 |
+| **Digital Signatures** | `@noble/curves` | ECDSA (secp256k1), Ed25519 |
+| **Key Exchange** | `@noble/curves` | ECDH, X25519 |
+| **Utilities** | `@noble/hashes` | Hex encoding, UTF-8 encoding |
+| **Random Bytes** | `Math.random()` polyfill | Consensus-safe PRNG (ChaCha8Rng) |
+
+## Get Started
+
+- **TypeScript**: See the [TypeScript README](./crypto-utils-ts/README.md) for detailed setup, usage examples, and a complete Node.js-to-Noble mapping table.
+
+## Quick Example
+
+```typescript
+// Instead of Node.js crypto:
+// const hash = crypto.createHash('sha256').update('hello').digest('hex');
+
+// Use Noble:
+import { sha256 } from "@noble/hashes/sha2";
+import { bytesToHex, utf8ToBytes } from "@noble/hashes/utils";
+
+const hash = bytesToHex(sha256(utf8ToBytes("hello")));
+```
+
+## Reference Documentation
+
+- [Noble Crypto Libraries](https://paulmillr.com/noble/)
+- [Noble Hashes GitHub](https://github.com/paulmillr/noble-hashes)
+- [Noble Curves GitHub](https://github.com/paulmillr/noble-curves)
+- [Noble Ciphers GitHub](https://github.com/paulmillr/noble-ciphers)
+- [CRE Documentation](https://docs.chain.link/cre)

building-blocks/crypto-utils/crypto-utils-ts/.gitignore

@@ -0,0 +1 @@
+*.env