Aside from the common mathematical approaches for breaking encryption methods a growing number of alternative attacks exist, which are referred to as side channel attacks. Those approaches are using alternative ways like measuring power consumption or computing time of a device. Using this information internal operations can be revealed and secret keys extracted. The asymmetric encryption RSA can be implemented in a field programmable gate array by using different kinds of algorithms, thus requiring different interpretations of the side-channel. This thesis is about methods to identify those algorithms in a blackbox. The analysed implementations consist of the Chinese remainder theorem, the binary exponentiation algorithm, the Montgomery- or the Blakley-Multiplication and were successfully attacked in this work to reveal the hidden key of the implementation. The results were used to develop generic detection methods. Many encryption implementations, which are proven as mathematically secure, do not worry about side-channel leakage. Also a lot of countermeasures were cracked through enhanced attacks and analyses in the past. Therefore, besides the prevention of the algorithm identification, focus is put on countermeasures, which complicate or even block those previously mentioned attacks.