// base64 получил при помощи btoa()
  // создаем хэш по base64 от бинарника
  function createFileHashByBase64(sBase64) {
    var CADESCOM_HASH_ALGORITHM_CP_GOST_3411 = 100;
    var CADESCOM_BASE64_TO_BINARY            = 1;
    var oHashedData = createObject("CAdESCOM.HashedData");
    oHashedData.Algorithm    = CADESCOM_HASH_ALGORITHM_CP_GOST_3411;
    oHashedData.DataEncoding = CADESCOM_BASE64_TO_BINARY;
    oHashedData.Hash(sBase64);
    return oHashedData;
  }