private static byte[] toLittleEndian(BigInteger n) {
    byte[] b = new byte[32];
    byte[] nBytes = n.toByteArray();
    System.arraycopy(nBytes, 0, b, 32 - nBytes.length, nBytes.length);
    for (int i = 0; i < b.length / 2; i++) {
      byte t = b[i];
      b[i] = b[b.length - i - 1];
      b[b.length - i - 1] = t;
    }
    return b;
  }
Base point for the Edwards twisted curve = (x, 4/5) and its exponentiations. B_TABLE[i][j] =
(j+1)*256^i*B for i in [0, 32) and j in [0, 8). Base point B = B_TABLE[0][0]

<p>See {@link Ed25519ConstantsGenerator}.
java_src/src/main/java/com/google/crypto/tink/internal/Ed25519Constants.java