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chopchoptheory [2007/02/28 22:05] darkaudax |
chopchoptheory [2010/11/21 15:46] (current) sleek typos |
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* D0 to D4 remain the same. | * D0 to D4 remain the same. | ||
* R5 = I3 + K5 = I3 + (D5+D5) + K5 = (I3+D5) + (D5+K5) = X + S5. | * R5 = I3 + K5 = I3 + (D5+D5) + K5 = (I3+D5) + (D5+K5) = X + S5. | ||
- | * R6 to R8 are computed by reversing one crc step based on the value of X. There's a correspondence among I2-I0 and J3-J1 because crc shiftes them back but D5 "pushes" them forward again. They are not necessarily keeping the same values, but their difference depends only on X, which we have guessed. | + | * R6 to R8 are computed by reversing one crc step based on the value of X. There's a correspondence among I2-I0 and J3-J1 because crc shifts them back but D5 "pushes" them forward again. They are not necessarily keeping the same values, but their difference depends only on X, which we have guessed. |
* J0 depends only on X. K9 = S9 + J0. We have guessed the last message byte and the last byte of keystream. | * J0 depends only on X. K9 = S9 + J0. We have guessed the last message byte and the last byte of keystream. | ||