}
		// The static RSA key exchange works by decrypting a challenge with the
		// RSA private key, not by signing, so check the PrivateKey implements
		// crypto.Decrypter, like *rsa.PrivateKey does.
		if priv, ok := c.PrivateKey.(crypto.Decrypter); ok {
			if _, ok := priv.Public().(*rsa.PublicKey); !ok {
				return unsupported
			}
		} else {
			return unsupported
		}

	// full block's worth of padding, replace the final block with another
	// block. If the MAC check passed but the padding check failed, the
	// last byte of that block decrypted to the block size.
	//
	// See also macAndPaddingGood logic below.
	paddingLen &= good

	toRemove = int(paddingLen) + 1
	return
}

func roundUp(a, b int) int {
	return a + (b-a%b)%b
}