Posts tagged: RC4

MS Office encryption: keep making the old mistake

In one of the last articles I considered in details the process of the encryption evolution in different MS Office versions and concluded that it became better and better with every next version. However, as it is often happens in a updating of a software version, the new problems can appear unexpectadly, proving that the best is the enemy of the good. Read more »

MS Office 40-bit key searching on GPU

In one of the first notes in this blog I have already spoken about the encryption details used in different versions of Microsoft Office. Certainly it was interesting for me whether it is possible to apply technology of general-purpose computations on video cards (CUDA) to speed up the process of key recovery for MS Office. The most important bottleneck was the RC4 algorithm which is basic in almost all Office versions encryption. In the Internet I saw responses that RC4 implementation on CUDA was almost more slowly than on CPU which meant that RC4 algorithm did not fit for optimized GPU implementation. Read more »

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