Fix base64 encoding for large byte arrays

packages/client/signers-cryptography/src/primitives/encoding/base64.test.ts

@@ -0,0 +1,12 @@
+import { describe, expect, it } from "vitest";
+import { decodeBase64, encodeBase64 } from "./base64";
+
+describe("base64 encoding", () => {
+    it("encodes large byte arrays without exceeding the call stack", () => {
+        const bytes = new Uint8Array(200_000);
+        bytes.fill(65);
+
+        expect(() => encodeBase64(bytes)).not.toThrow();
+        expect(decodeBase64(encodeBase64(bytes))).toEqual(bytes);
+    });
+});

packages/client/signers-cryptography/src/primitives/encoding/base64.ts

@@ -1,5 +1,12 @@
 export function encodeBase64(bytes: Uint8Array): string {
-    return btoa(String.fromCharCode.apply(null, Array.from(bytes)));
+    let binary = "";
+    const chunkSize = 0x8000;
+
+    for (let i = 0; i < bytes.length; i += chunkSize) {
+        binary += String.fromCharCode(...bytes.subarray(i, i + chunkSize));
+    }
+
+    return btoa(binary);
 }
 
 export function decodeBase64(base64: string): Uint8Array {