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3

Can someone explain me how the t actually affects the outcome of the procedure (which, as far as I understand, just calculates the eight 64-bit words xor with "a5a5a5a5a5a5a5a5")? That's not right. Both hex 5 and A are encoded setting two bits out of 4; a5 translates to 1010 0101 in bits. I.e. half the bits are flipped. This kind of XOR value is often ...


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TL;DR: Using words instead of strings / images may be a good solution for short, easy-to-verify codes and using locality / time dependent verification codes strengthens short hashes as would using password-hashes. Additionally to the improvements to comparability of the hash proposed by A. Toumantsev, I will propose three extra measures which I believe may ...


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First use the TID as input for a KDF to generate one or more tag specific keys, using a static, symmetric master key stored in the initialization software and gadget. Use one of these keys to obtain access. Use another for verification of the tag. During initialization derive and set the access key (s). Then create a HMAC over a static value (or multiple ...


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It is quite practical to deliberately generate two different files with the same MD5 hash; if you were handed these files by someone else, it is possible that they did this. However, MD5 will collide only if someone deliberately crafts the files to do so; if you modified the files somehow, then this is unlikely to happen. Instead, it would be a strong ...


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I'm not commenting on the security side of the solution, there are real experts here who can help with this (or turn your idea right down ;) ). However, assuming your solution (with SHA256) is acceptable and secure, your main problem seems to be that "carefully comparing all the digits of a SHA-256 hash .. takes a while". Indeed, comparing a string of 64 ...


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The main question about this topic is: Guarding against cryptanalytic breakthroughs: combining multiple hash functions. There you will find some better combiners for multiple hash functions. I would generally recommend against the extra complexity - a single good hash ought to be enough. Now, regarding your way of combining them: Does this make sense? ...



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