add anastasis skeleton, put crypto in taler-util

1 files changed, 19 insertions, 0 deletions

diff --git a/packages/taler-util/src/prng-browser.ts b/packages/taler-util/src/prng-browser.ts
new file mode 100644
index 000000000..79d399e03
--- /dev/null
+++ b/packages/taler-util/src/prng-browser.ts
@@ -0,0 +1,19 @@
+import { setPRNG } from "./nacl-fast.js";
+
+export function loadBrowserPrng() {
+  // Initialize PRNG if environment provides CSPRNG.
+  // If not, methods calling randombytes will throw.
+  // @ts-ignore-error
+  const cr = typeof self !== "undefined" ? self.crypto || self.msCrypto : null;
+
+  const QUOTA = 65536;
+  setPRNG(function (x: Uint8Array, n: number) {
+    let i;
+    const v = new Uint8Array(n);
+    for (i = 0; i < n; i += QUOTA) {
+      cr.getRandomValues(v.subarray(i, i + Math.min(n - i, QUOTA)));
+    }
+    for (i = 0; i < n; i++) x[i] = v[i];
+    for (i = 0; i < v.length; i++) v[i] = 0;
+  });
+}