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#! /bin/bash | |
table=(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 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 0 1 2 3 4 5 6 7 8 9 - _ =) | |
#text="{\"alg\":\"RS256\",\"typ\":\"JWT\"}" | |
#text="{\"iss\":\"761326798069-r5mljlln1rd4lrbhg75efgigp36m78j5@developer.gserviceaccount.com\",\"scope\":\"https://www.googleapis.com/auth/prediction\",\"aud\":\"https://accounts.google.com/o/oauth2/token\",\"exp\":1328554385,\"iat\":1328550785}" | |
read text | |
# breaking binary represantation of $text in to 6-bit blocks | |
for line in $(echo -n "$text" | xxd -b -g 0 | cut -d ' ' -f 2 | paste -s -d '' | fold -w 6 -s) | |
do | |
length=$(echo ${#line}) | |
let padding=6-$length | |
s="0" | |
p="" | |
# padding 6-bit to 8-bit by adding zeros to the right | |
if (($padding > 0)); then | |
while ((${#p} < "$padding")); do | |
p="$p$s"; | |
done; | |
fi | |
# convert binary to decimal | |
n=$(echo "ibase=2;$line$p" | bc) | |
# output the table looked up character | |
echo -n ${table[n]} | |
done |
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