Timing attacks on RSA: revealing your secrets through the fourth dimension

Do you think your computer system is secure because you use strong cryptography? Do you think your system is impenetrable because you use a long secret value in the cryptographic computation that attackers cannot guess by brute force? If so, you should know that attackers may be able to exploit your system in an unexpected manner by surreptitiously invading it rather than by directly attempting to break the cryptography.