feat(ext): base32 encode/decode for TOTP secret parse

extension/src/shared/__tests__/base32.test.ts

@@ -0,0 +1,33 @@
+// extension/src/shared/__tests__/base32.test.ts
+import { describe, expect, it } from 'vitest';
+import { base32Decode, base32Encode } from '../base32';
+
+describe('base32', () => {
+  // RFC 4648 § 10 test vectors
+  it('encodes empty', () => expect(base32Encode(new Uint8Array())).toBe(''));
+  it('encodes "f"',   () => expect(base32Encode(new TextEncoder().encode('f'))).toBe('MY'));
+  it('encodes "fo"',  () => expect(base32Encode(new TextEncoder().encode('fo'))).toBe('MZXQ'));
+  it('encodes "foo"', () => expect(base32Encode(new TextEncoder().encode('foo'))).toBe('MZXW6'));
+  it('encodes "foob"',  () => expect(base32Encode(new TextEncoder().encode('foob'))).toBe('MZXW6YQ'));
+  it('encodes "fooba"', () => expect(base32Encode(new TextEncoder().encode('fooba'))).toBe('MZXW6YTB'));
+  it('encodes "foobar"',() => expect(base32Encode(new TextEncoder().encode('foobar'))).toBe('MZXW6YTBOI'));
+
+  it('decodes round-trip', () => {
+    const bytes = new Uint8Array([0x12, 0x34, 0x56, 0x78, 0x9a]);
+    expect(base32Decode(base32Encode(bytes))).toEqual(bytes);
+  });
+
+  it('decodes case-insensitively', () => {
+    expect(base32Decode('mzxw6')).toEqual(new TextEncoder().encode('foo'));
+  });
+
+  it('decodes ignoring whitespace and padding', () => {
+    expect(base32Decode('JBSW Y3DP EHPK 3PXP==')).toEqual(
+      base32Decode('JBSWY3DPEHPK3PXP'),
+    );
+  });
+
+  it('throws on invalid characters', () => {
+    expect(() => base32Decode('MZ!W6')).toThrow();
+  });
+});

extension/src/shared/base32.ts

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+/// Minimal RFC 4648 base32 encode/decode for TOTP secret parsing.
+///
+/// Mirrors the encoder in crates/relicario-core/src/item.rs:base32_encode.
+/// Decode is case-insensitive, tolerates whitespace and `=` padding.
+
+const ALPHA = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
+
+export function base32Encode(bytes: Uint8Array): string {
+  let out = '';
+  let buffer = 0;
+  let bits = 0;
+  for (const b of bytes) {
+    buffer = (buffer << 8) | b;
+    bits += 8;
+    while (bits >= 5) {
+      const idx = (buffer >> (bits - 5)) & 0x1f;
+      out += ALPHA[idx];
+      bits -= 5;
+    }
+  }
+  if (bits > 0) {
+    const idx = (buffer << (5 - bits)) & 0x1f;
+    out += ALPHA[idx];
+  }
+  return out;
+}
+
+export function base32Decode(input: string): Uint8Array {
+  const cleaned = input.replace(/\s+/g, '').replace(/=+$/g, '').toUpperCase();
+  const out: number[] = [];
+  let buffer = 0;
+  let bits = 0;
+  for (const ch of cleaned) {
+    const idx = ALPHA.indexOf(ch);
+    if (idx === -1) throw new Error(`base32: invalid character "${ch}"`);
+    buffer = (buffer << 5) | idx;
+    bits += 5;
+    if (bits >= 8) {
+      out.push((buffer >> (bits - 8)) & 0xff);
+      bits -= 8;
+    }
+  }
+  return new Uint8Array(out);
+}