The aim of this project was development of proof of concept software that could assist in fight against dangerous and illegal attachments in e-mail traffic. Implemented software was tested in few different hardware configurations and was found to work well even with large transmissions. Due to the timescale of the project and the fact that produced software is only a proof of concept implementation, full testes have been postponed till appropriate founding is source. However, the results obtained until now are very promising, especially that the probability of false positives in the system is equivalent to the likeness of two different files producing identical signatures (collision). This varies for different hashing algorithms and strongly depends on the size of the signature. MD5 is one of the most commonly used algorithms. It produces 128 bit signatures, which means that at most 264 combinations would need to be used before collision was found (Atreya et al, 2002)*. Thus, probability of the implementation to produce false positives is extremely low and could be further lowered by employing more sophisticated hashing algorithm with longer signatures.

*Atreya, M., Hammond, B., Paine, S., Starrett, P. and Wu, S. 2002, Digital Signatures. Berkeley, California: RSAPress.