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Change indexing to make card ordering more intuitive

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Update the indexing so that the table starts at "1". This way the ordered card layout (used for key generation) starts with the Ace of Diamonds and proceeds through the cards and suits as normal. This seems cleaner than awkwardly prepending the 10 of Spades. However, it involves a slight tweak to the key key_derive function to support the change in card order.
This commit is contained in:
Trevor Terris 2021-04-22 18:58:23 -04:00
parent 8e4e169a39
commit 2076f1b57b
2 changed files with 20 additions and 17 deletions

29
README.md
View file

@ -206,16 +206,17 @@ cards could be more innocuous and easily explainable to the secret police than
a set of peculiar numbered tiles.
```
0 a b c d e f
g h i j k l m
n o p q r s t
u v w x y z _
. , - + * / :
? ! ' ( ) 1 2
3 4 5 6 7 8 9
a b c d e f g
h i j k l m n
o p q r s t u
v w x y z _ .
, - + * / : ?
! ' ( ) 1 2 3
4 5 6 7 8 9 0
```
With this layout, the following mapping to playing cards is used:
**This board uses a 1-based index**, so `a=1`, `b=2`, and so on. With this layout,
the following mapping to playing cards is used:
| **Character** | Card | Index | **Character** | Card | Index | **Character** | Card | Index | **Character** | Card | Index |
|-----------|------|-------|-----------|------|-------|-----------|------|-------|-----------|------|--------|
@ -242,12 +243,12 @@ Heart is left as an exercise for the reader.
For LC4, the following board could be used:
```
# a b c d e
f g h i j k
l m n o p q
r s t u v w
x y z _ 2 3
4 5 6 7 8 9
a b c d e f
g h i j k l
m n o p q r
s t u v w x
y z _ 2 3 4
5 6 7 8 9 #
```
The "Hearts" suit would be ommitted from the card mapping table, and the index

8
lc4.py
View file

@ -151,9 +151,11 @@ def rotate_marker_down(m, col, n):
return ((m[0] + n) % size, m[1])
def derive_key(password):
def derive_key(password, one_indexed):
i = 0
k = letters
# if using one-indexed arrays, moves the zero element to the end
if one_indexed: k = k[1:]+k[0]
for c in password:
(row, col) = find_ix(c)
k = rotate_down(rotate_right(k, i, col), i, row)
@ -295,7 +297,7 @@ def test1(size, fixednonce):
else:
keyword = 's3cret_p4ssw0rd/31337'
szkeyword = keyword # This statement needed to show keyword in printinfo() [don't change args.keywordstring within test1()!]
key = derive_key(keyword)
key = derive_key(keyword, false)
else:
key = letters
initialkey = key
@ -433,7 +435,7 @@ if __name__ == '__main__':
if args.keywordfile: args.keywordstring = open(args.keywordfile, 'r').read().rstrip('\r\n')
if args.keywordstring:
szkeyword = args.keywordstring
key = derive_key(args.keywordstring)
key = derive_key(args.keywordstring, args.playingcard)
if args.keyfile: args.keystring = open(args.keyfile, 'r').read().rstrip('\r\n')
if args.keystring: key = args.keystring;