1 files changed, 60 insertions, 0 deletions
diff --git a/packages/taler-util/src/rfc3548.ts b/packages/taler-util/src/rfc3548.ts
new file mode 100644
index 000000000..2dd18cdfc
--- /dev/null
+++ b/packages/taler-util/src/rfc3548.ts
@@ -0,0 +1,60 @@
+/*
+ This file is part of GNU Taler
+ (C) 2024 Taler Systems SA
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+import { getRandomBytes } from "./taler-crypto.js";
+
+const encTable = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
+
+/**
+ * base32 RFC 3548
+ */
+export function encodeRfc3548Base32(data: ArrayBuffer) {
+  const dataBytes = new Uint8Array(data);
+  let sb = "";
+  const size = data.byteLength;
+  let bitBuf = 0;
+  let numBits = 0;
+  let pos = 0;
+  while (pos < size || numBits > 0) {
+    if (pos < size && numBits < 5) {
+      const d = dataBytes[pos++];
+      bitBuf = (bitBuf << 8) | d;
+      numBits += 8;
+    }
+    if (numBits < 5) {
+      // zero-padding
+      bitBuf = bitBuf << (5 - numBits);
+      numBits = 5;
+    }
+    const v = (bitBuf >>> (numBits - 5)) & 31;
+    sb += encTable[v];
+    numBits -= 5;
+  }
+  return sb;
+}
+
+export function isRfc3548Base32Charset(s: string): boolean {
+  for (let idx = 0; idx < s.length; idx++) {
+    const c = s.charAt(idx);
+    if (encTable.indexOf(c) === -1) return false;
+  }
+  return true;
+}
+
+export function randomRfc3548Base32Key(): string {
+  const buf = getRandomBytes(20);
+  return encodeRfc3548Base32(buf);
+}