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Diffstat (limited to 'taler-kotlin-android/src/main/java/net/taler/common/CryptoUtils.kt')
| -rw-r--r-- | taler-kotlin-android/src/main/java/net/taler/common/CryptoUtils.kt | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/taler-kotlin-android/src/main/java/net/taler/common/CryptoUtils.kt b/taler-kotlin-android/src/main/java/net/taler/common/CryptoUtils.kt new file mode 100644 index 0000000..0dba7aa --- /dev/null +++ b/taler-kotlin-android/src/main/java/net/taler/common/CryptoUtils.kt @@ -0,0 +1,97 @@ +/* + * 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 CryptoUtils { + private const val encTable = "0123456789ABCDEFGHJKMNPQRSTVWXYZ" + + 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 encodeCrock(bytes: ByteArray): String { + var sb = "" + val size = bytes.size + var bitBuf = 0 + var numBits = 0 + var pos = 0 + while (pos < size || numBits > 0) { + if (pos < size && numBits < 5) { + val d = bytes[pos++] + bitBuf = bitBuf.shl(8).or(d.toInt()) + numBits += 8 + } + if (numBits < 5) { + // zero-padding + bitBuf = bitBuf.shl(5 - numBits) + numBits = 5 + } + val v = bitBuf.ushr(numBits - 5).and(31) + sb += encTable[v] + numBits -= 5 + } + return sb + } + + 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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