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2018-12-15 12:16:38 -0600 | commented answer | How to express unknown coefficients in GF(2^8)? thank you so much! this is exactly what I need |

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2018-12-15 10:32:46 -0600 | asked a question | How to express unknown coefficients in GF(2^8)? I want to make computations in GF(2^8) using the Rijndael modulus X^8+X^4+X^3+X+1 and with unknown elements of GF(2^8). For example, I need a polynomial x which is defined as x = x_7 * X^7 + x_6 * X^6 + x_5 * X^7 + ... + x_0 x.coefficients() should return [x_0, x_1, x_2, x_3, x_4, ...] If I for example add x to y, I would expect that the result would be a term like (x_7+y_7) * X^7 + (x_6+y_6)*X^6 + ... I tried the following: (which is very much like I found it in the sources of sage.crypto.mq.rijndael_gf.RijndaelGF) But the coefficients of poly_x and poly_y are not the variables x_0, x_1 etc. but the X^0, X^1, etc... I also tried: which is also not what I want. Also, expressions like the follow lead to an error: How can I express unknown elements with unknown coefficients? |

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2018-11-05 15:26:24 -0600 | asked a question | how to get the transformation matrix for a transformation over 4x4 matrices? I have the following transformation: This is not working - but I can't figure out what linear_transformation is expecting. How can I get this to work? Is this even possible? |

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