srecord MD5(long a, long b) {
  *(byte[] data) {
    loadDigest(md5AsByteArray(data));
  }
  
  *(File f) {
    loadDigest(md5OfFileAsByteArray(f));
  }
  
  // md5 is the digest, not the data being checksummed
  static MD5 ofDigest(byte[] digest) {
    ret new MD5().loadDigest(digest);
  }
  
  selfType loadDigest(byte[] digest) {
    assertEquals("MD5 digest", 16, l(digest));
    a = longFromBytes_bigEndian(digest, 0);
    b = longFromBytes_bigEndian(digest, 8);
    this;
  }
  
  *(S md5) {
    this(parseHexBytes(md5));
  }
  
  toString { ret "MD5=" + longToHex(a) + longToHex(b); }
}