Cryprography: Difference between revisions
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(New page: This page just gathers miscellaneous remarks I collected on Cryptography in general. No effort is made to tidy things up. This will be done as soon as the page gets some volume... == Str...) |
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#REDIRECT [[Cryptography]] |
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This page just gathers miscellaneous remarks I collected on Cryptography in general. |
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No effort is made to tidy things up. This will be done as soon as the page gets some volume... |
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== Stream Cipher == |
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=== Security Properties === |
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* Stream cipher building block must be invertible, otherwise it is easy to create collisions. |
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== Hash Functions == |
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=== Security Attacks === |
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* Man-in-the-Middle pre-image attacks. |
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: Principle is to generate a message m = m<sub>1</sub>||m<sub>2</sub>, such that H(m)=h. If H(m)=g(F(IV,m<sub>1</sub>),m<sub>2</sub>), the MITM attacks consists in generate random m<sub>1</sub>, m<sub>2</sub> until one get G<sup>-1</sup>(h,m<sub>2</sub>) = F(IV,m<sub>1</sub>). Power of the attack relies on the fact that probability of finding a collision is inv. prop. to sqrt of the state size. |
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: ''''Countermeasures'''' - prevent attacker to exploit symmmetry properties between round so that he can't discard part of the state, or control part of the state. Make attacker to use too much memory. |
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Latest revision as of 11:02, 16 January 2014
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