var data = new Uint32Array(1024); window.crypto.getRandomValues(data); var dataBuffer = new Uint8Array(data); data = String.fromCharCode.apply(null, dataBuffer); // src: https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest function hex(buffer) { var hexCodes = []; var view = new DataView(buffer); for (var i = 0; i < view.byteLength; i += 4) { // Using getUint32 reduces the number of iterations needed (we process 4 bytes each time) var value = view.getUint32(i) // toString(16) will give the hex representation of the number without padding var stringValue = value.toString(16) // We use concatenation and slice for padding var padding = '00000000' var paddedValue = (padding + stringValue).slice(-padding.length) hexCodes.push(paddedValue); } // Join all the hex strings into one return hexCodes.join(""); }