b2 := b1>>2&0x33 | b1<<2&0xcc
	b3 := b2>>1&0x55 | b2<<1&0xaa
	return b3
}

// asn1BitLength returns the bit-length of bitString by considering the
// most-significant bit in a byte to be the "first" bit. This convention
// matches ASN.1, but differs from almost everything else.
func asn1BitLength(bitString []byte) int {
	bitLen := len(bitString) * 8

	for i := range bitString {

		{[]byte{0xf0}, 4},
		{[]byte{0x88}, 5},
		{[]byte{0xff}, 8},
		{[]byte{0xff, 0x80}, 9},
		{[]byte{0xff, 0x81}, 16},
	}

	for i, test := range tests {
		if got := asn1BitLength(test.bytes); got != test.bitLen {
			t.Errorf("#%d: calculated bit-length of %d for %x, wanted %d", i, got, test.bytes, test.bitLen)
		}
	}
}

func TestVerifyEmptyCertificate(t *testing.T) {