Testing of MS Office password recovery programs with GPU support

Password recovery software developers actively introduce general purpose computations on GPU (GPGPU) into their products. Today I will test three products, which already have support of NVIDIA and/or ATI cards for password recovery of Microsoft Office files. Read more »

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 »

About CPU and GPU usage for password recovery

Ivan Golubev, the author of very fast programs ighashgpu and igrargpu, which were mentioned in my block, wrote an interesting article “About CPU and GPU usage for password recovery“.

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 »

RAR Password Recovery on GPU

Recently at least two RAR password recovery programs with GPU acceleration were released. The first was new 3.2 version of cRARk supporting CUDA technology. The second was a new igrargpu program written by Ivan Golubev. Read more »

Encryption evolution in Microsoft Office

In the conclusion of my article ‘On cryptosystems untrustworthiness’, written in 1998, I specified that the using the strong cryptography in application is gradually changing for the better. Lets consider evolution of cryptographic capabilities used by the one of the most popular applications for personal computers – MS Office, šespecially because recently Microsoft has officially opened specifications of this software, including encryption algorithms used. Here below I will speak only about passwords for file opening, because when using any other passwords (read-only access etc.) the text of the document is not encrypted and that is why they can be easily bypassed. Read more »

In the beginning there was the word

… and the word was 4 bits, because the first microprocessor Intel 4004, produced in 1971, was 4-bit. We will repeatedly return to the processors, its characteristics and evolution in this blog, but let me introduce myself.

My name is Pavel Semjanov and more than 15 years I practice the computer security and work at St. Petersburg Technical University. šThe cryptography, particularly its practical application in various computer systems, became one of my hobbies from the very beginning. Another my hobby closely connected with work became the software developing for analysis of cryptographic system vulnerability and mainly password cracking (or in other words, password recovery).

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