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/*
* This file is part of GNU Taler
* (C) 2022 Taler Systems S.A.
*
* GNU Taler is free software; you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation; either version 3, or (at your option) any later version.
*
* GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with
* GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
package net.taler.common
import kotlin.math.floor
object CyptoUtils {
internal fun getValue(c: Char): Int {
val a = when (c) {
'o','O' -> '0'
'i','I','l','L' -> '1'
'u','U' -> 'V'
else -> c
}
if (a in '0'..'9') {
return a - '0'
}
val A = if (a in 'a'..'z') a.uppercaseChar() else a
var dec = 0
if (A in 'A'..'Z') {
if ('I' < A) dec++
if ('L' < A) dec++
if ('O' < A) dec++
if ('U' < A) dec++
return A - 'A' + 10 - dec
}
throw Error("encoding error")
}
fun decodeCrock(e: String): ByteArray {
val size = e.length
var bitpos = 0
var bitbuf = 0
var readPosition = 0
val outLen = floor((size * 5f) / 8).toInt()
val out = ByteArray(outLen)
var outPos = 0
while (readPosition < size || bitpos > 0) {
if (readPosition < size) {
val v = getValue(e[readPosition++])
bitbuf = bitbuf.shl(5).or(v)
bitpos += 5
}
while (bitpos >= 8) {
val d = bitbuf.shr(bitpos -8).and(0xff).toByte()
out[outPos++] = d
bitpos -= 8
}
if (readPosition == size && bitpos > 0) {
bitbuf = bitbuf.shl( 8 - bitpos).and(0xff)
bitpos = if (bitbuf == 0) 0 else 8
}
}
return out
}
}
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