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| author | Mirek Kratochvil <exa.exa@gmail.com> | 2018-04-12 10:17:14 +0200 |
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| committer | Mirek Kratochvil <exa.exa@gmail.com> | 2018-04-12 10:17:14 +0200 |
| commit | 3d52296670ee23339f6585ee3703ea18be31d4a5 (patch) | |
| tree | 369b621b8259a98ac8d583936e10361324d03ca5 | |
| parent | f73bc96360b385ad167d7f7e91b6b2a8e6266d0a (diff) | |
| download | ls47-3d52296670ee23339f6585ee3703ea18be31d4a5.tar.gz ls47-3d52296670ee23339f6585ee3703ea18be31d4a5.tar.bz2 | |
update the README
| -rw-r--r-- | README.md | 14 |
1 files changed, 7 insertions, 7 deletions
@@ -70,8 +70,8 @@ You may as well see the paper [1], there are also pictures. This is somewhat mor 3. Find the next letter you want to encrypt on the board, its position is `P`. 4. Look at the marker; numbers written on the marked tile are coordinates `M`. 5. Compute position of the ciphertext as `C := P + M mod (7,7)`. Output the letter found on position `C` as ciphertext. -6. Rotate the row that contains the plaintext letter one position to the right, carry the marker if present. -7. Rotate the column that now (after the first rotation) contains the ciphertext letter one position down, carry the marker if present. +6. Rotate the row that contains the plaintext letter one position to the right, but do not carry the marker if present (it should stay on the same coordinates). +7. Rotate the column that now (after the first rotation) contains the ciphertext letter one position down, also not carrying the marker. 8. Update the position of the marker: `M := M + C' mod (7,7)` where `C'` are the numbers written on the ciphertext tile. 9. Repeat from 3 as many times as needed to encrypt the whole plaintext. @@ -90,7 +90,7 @@ You may as well see the paper [1], there are also pictures. This is somewhat mor + * 7 8 9 , - 5. Ciphertext is 'w' 6. Rotate the plaintext 1 position - (='y' moved by (5,0)) right, possibly carrying the marker. + (='y' moved by (5,0)) right, keep marker coordinates. [e]f _ a b c d [e]f _ a b c d Output 'w'! l m g h i j k l m g h i j k @@ -102,7 +102,7 @@ You may as well see the paper [1], there are also pictures. This is somewhat mor 7. Rotate the ciphertext 1 Now look at the ciphertext tile: - position down, also carry. + position down. [e]f _ a b , d /-----\ l m g h i c k | | @@ -174,9 +174,9 @@ letters of a pre-negotiated length (e.g. N tiles drawn randomly from a bag, adviseable value of N is at least 10). You may also want to add a random number of spaces to the end of the ciphertext --- it prevents the enemy from seeing the difference between ciphertexts of -'yes please' and 'no', which would otherwise encrypt to easily measurable -gibberish like `qwc3w_cs'(` and `+v`. +-- it prevents the enemy from seeing the difference between ciphertexts of 'yes +please' and 'no', which would otherwise encrypt to gibberish that is easily +distinguishable by length, like `qwc3w_cs'(` and `+v`. ### Authenticated encryption |