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#!/bin/sh
set -e
usage() {
echo "usage:"
echo "$ cat secret_key | $0 challenge n k /path/to/data >challenge"
echo "$ $0 solve challenge >solution"
echo "$ cat secret_key | $0 verify /path/to/challenge /path/to/solution"
exit 0
}
challenge() {
[ "${#}" -ne 3 ] && usage
secret_key="$(cat)"
n=$1
k=$2
data="$(cat "$3")"
ts="$(date +%s)"
sig=$(printf "%s %s %s %s" "$n" "$k" "$ts" "$data" | openssl dgst -sha256 -binary -hmac "$secret_key")
printf "%s%s %s %s %s" "$sig" "$n" "$k" "$ts" "$data"
}
solve() {
[ "${#}" -ne 1 ] && usage
puzzle="$1"
tail -c +33 "$puzzle" | {
read -r n k ts data || true
ehwait equihash solve -n "$n" -k "$k" -f "$puzzle" -s /dev/stdout
}
}
const_cmp() {
res=0
for i in $(seq 0 31); do
res=$((res | ($(printf "%d" "'${1:i:1}") ^ $(printf "%d" "'${2:i:1}") ) ))
done
return $res
}
#const_cmp "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" && echo ok || echo meh
#const_cmp "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAb" && echo ok || echo meh
#const_cmp "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" && echo ok || echo meh
verify() {
[ "${#}" -ne 2 ] && usage
secret_key="$(cat)"
puzzle="$1"
solution="$2"
sig="$(head -c 32 "$puzzle")"
msg="$(tail -c +33 "$puzzle")"
echo "$msg" | {
read -r n k ts data || true
sig2=$(printf "%s" "$msg" | openssl dgst -sha256 -binary -hmac "$secret_key")
const_cmp "$sig" "$sig2" || {
echo "error: invalid challenge"
exit 1
}
equihash verify -v -n "$n" -k "$k" -f "$puzzle" -s "$solution"
exit $?
}
}
case "$1" in
challenge) shift; challenge "${@}";;
solve) shift; solve "${@}";;
verify) shift; verify "${@}";;
*) usage;;
esac
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