feat: add cross-environment crypto adapter

- Create getCryptoRandomValues() utility
- Support both window.crypto (browser/Electron) and crypto.webcrypto (Node.js)
- Add comprehensive test coverage for adapter functionality

src/utils/crypto-adapter.ts

@@ -0,0 +1,36 @@
+/**
+ * Cross-environment crypto adapter
+ * Provides unified access to cryptographically secure random number generation
+ * Works in both browser/Electron (window.crypto) and Node.js (crypto.webcrypto)
+ */
+
+/**
+ * Gets the appropriate Crypto interface for the current environment
+ * @returns Crypto interface with getRandomValues method
+ * @throws Error if no crypto API is available
+ */
+function getCrypto(): Crypto {
+	// Browser/Electron environment
+	if (typeof window !== 'undefined' && window.crypto) {
+		return window.crypto;
+	}
+
+	// Node.js environment (15+) - uses Web Crypto API standard
+	if (typeof global !== 'undefined') {
+		const nodeCrypto = require('crypto');
+		if (nodeCrypto.webcrypto) {
+			return nodeCrypto.webcrypto;
+		}
+	}
+
+	throw new Error('No Web Crypto API available in this environment');
+}
+
+/**
+ * Fills a typed array with cryptographically secure random values
+ * @param array TypedArray to fill with random values
+ * @returns The same array filled with random values
+ */
+export function getCryptoRandomValues<T extends ArrayBufferView>(array: T): T {
+	return getCrypto().getRandomValues(array);
+}

tests/crypto-adapter.test.ts

@@ -0,0 +1,56 @@
+import { getCryptoRandomValues } from '../src/utils/crypto-adapter';
+
+describe('crypto-adapter', () => {
+	describe('getCryptoRandomValues', () => {
+		it('should fill Uint8Array with random values', () => {
+			const array = new Uint8Array(32);
+			const result = getCryptoRandomValues(array);
+
+			expect(result).toBe(array);
+			expect(result.length).toBe(32);
+			// Verify not all zeros (extremely unlikely with true random)
+			const hasNonZero = Array.from(result).some(val => val !== 0);
+			expect(hasNonZero).toBe(true);
+		});
+
+		it('should produce different values on subsequent calls', () => {
+			const array1 = new Uint8Array(32);
+			const array2 = new Uint8Array(32);
+
+			getCryptoRandomValues(array1);
+			getCryptoRandomValues(array2);
+
+			// Arrays should be different (extremely unlikely to be identical)
+			const identical = Array.from(array1).every((val, idx) => val === array2[idx]);
+			expect(identical).toBe(false);
+		});
+
+		it('should preserve array type', () => {
+			const uint8 = new Uint8Array(16);
+			const uint16 = new Uint16Array(8);
+			const uint32 = new Uint32Array(4);
+
+			const result8 = getCryptoRandomValues(uint8);
+			const result16 = getCryptoRandomValues(uint16);
+			const result32 = getCryptoRandomValues(uint32);
+
+			expect(result8).toBeInstanceOf(Uint8Array);
+			expect(result16).toBeInstanceOf(Uint16Array);
+			expect(result32).toBeInstanceOf(Uint32Array);
+		});
+
+		it('should work with different array lengths', () => {
+			const small = new Uint8Array(8);
+			const medium = new Uint8Array(32);
+			const large = new Uint8Array(128);
+
+			getCryptoRandomValues(small);
+			getCryptoRandomValues(medium);
+			getCryptoRandomValues(large);
+
+			expect(small.every(val => val >= 0 && val <= 255)).toBe(true);
+			expect(medium.every(val => val >= 0 && val <= 255)).toBe(true);
+			expect(large.every(val => val >= 0 && val <= 255)).toBe(true);
+		});
+	});
+});