Timeline for How to solve this decryption algorithm given the encryption algorithm?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 28, 2021 at 5:08 | comment | added | Manish Adhikari | Forget it, ponzo already gave a very good hint and much simple one at that | |
| Feb 28, 2021 at 4:57 | comment | added | Manish Adhikari | Sorry, I completely ignored the first question. My comment above was for second question, to check for solvability. Does any key (solution) exist for any arbitrary plain-text cipher-text pair can be checked by using key as variable vector instead. | |
| Feb 28, 2021 at 4:50 | comment | added | Manish Adhikari | I think the better idea will be to use key $(a,b,c,d,e,f)$ as the variable vector $x$ with the last element = 1 as in $[a,b,c,d,e,f,1]^T$. Create matrix $A$ using plain texts and ciphertext is solution matrix $B$ in $Ax=B$. It will be easier to check for solvability for any plaintext matrix of the given form and any ciphertext that way. | |
| Feb 27, 2021 at 23:03 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Jan 28, 2021 at 22:27 | answer | added | poncho♦ | timeline score: 1 | |
| Jan 28, 2021 at 21:46 | comment | added | kelalaka | \begin{array}{ccccc} a & 1 & 0 & 0 & 0 & C_1\\ b & c & 0 & 0 & 0 & C_2 \\ 0 & 0 & d & e & 0 & C_3 \\ 0 & 0 & 0 & 1 & f & C_4 \end{array} See dummies.com/education/math/calculus/… | |
| Jan 28, 2021 at 21:16 | comment | added | Joshua Leung | @kelalaka $$ \left[ \begin{array}{cccccc|c} a & 0 & 0 & 0 & 0 & 0 & P_1 \\ 0 & b & c & 0 & 0 & 0 & P_2 \\ 0 & 0 & 0 & d & e & 0 & P_3 \\ 0 & 0 & 0 & 0 & 0 & f & P_4 \end{array} \right] $$ something like this? | |
| Jan 28, 2021 at 21:09 | comment | added | kelalaka | Sorry, but, basic linear algebra. Setup the equations and solve by Gaussian Elimination on $GF(2)$ | |
| Jan 28, 2021 at 21:06 | history | asked | Joshua Leung | CC BY-SA 4.0 |