mirror of
https://github.com/mollyim/monero-wallet-sdk.git
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lib: add base58 decoder
This commit is contained in:
Oscar Mira
parent
41050d28ed
commit
36be1d209a
70
lib/android/src/main/kotlin/im/molly/monero/util/Base58.kt
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70
lib/android/src/main/kotlin/im/molly/monero/util/Base58.kt
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package im.molly.monero.util
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import java.nio.ByteBuffer
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import java.nio.charset.Charset
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const val ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
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object Decoder {
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private val decodingTable = IntArray(128) { ALPHABET.indexOf(it.toChar()) }
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private val blockSizes = listOf(0, -1, 1, 2, -1, 3, 4, 5, -1, 6, 7, 8)
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fun decode(input: ByteArray): ByteBuffer {
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val size = input.size
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val needed = 8 * (size / 11) + findOutputBlockSize(size % 11)
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val out = ByteBuffer.allocate(needed)
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var pos = 0
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while (pos + 11 <= size) {
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decodeBlock(input, pos, 11, out)
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pos += 11
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}
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val remain = size - pos
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if (remain > 0) {
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decodeBlock(input, pos, remain, out)
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}
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out.flip()
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return out
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}
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private fun decodeBlock(block: ByteArray, offset: Int, len: Int, out: ByteBuffer) {
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val blockSize = findOutputBlockSize(len)
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val newOutPos = out.position() + blockSize
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var num = 0uL
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var base = 1uL
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var zeroes = 0
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for (i in (offset + len - 1) downTo offset) {
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val c = block[i].toInt()
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val digit = decodingTable.getOrElse(c) { -1 }.toULong()
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require(digit >= 0uL) { "Invalid symbol" }
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if (digit == 0uL) {
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zeroes++
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} else {
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while (zeroes > 0) {
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base *= 58u
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zeroes--
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}
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val prod = digit * base
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val lastNum = num
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num += prod
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require((prod / base == digit) && (num > lastNum)) { "Overflow" }
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base *= 58u // Never overflows, 58^10 < 2^64
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}
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}
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for (j in 1..blockSize) {
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out.put(newOutPos - j, num.toByte())
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num = num shr 8
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}
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require(num == 0uL) { "Overflow" }
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out.position(newOutPos)
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}
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private fun findOutputBlockSize(blockSize: Int): Int = blockSizes[blockSize].also {
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require(it >= 0) { "Invalid block size" }
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}
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}
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fun String.decodeBase58(): ByteArray =
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Decoder.decode(this.toByteArray(Charset.defaultCharset())).array()
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168
lib/android/src/test/kotlin/im/molly/monero/util/Base58Test.kt
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168
lib/android/src/test/kotlin/im/molly/monero/util/Base58Test.kt
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package im.molly.monero.util
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import com.google.common.truth.Truth.assertThat
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import org.junit.Assert
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import org.junit.Test
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class Base58Test {
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// Test cases from monero unit_tests/base58.cpp
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private val base58ToHex = mapOf(
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// 2-bytes block
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"11" to "00",
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"1z" to "39",
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"5Q" to "FF",
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// 3-bytes block
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"111" to "0000",
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"11z" to "0039",
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"15R" to "0100",
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"LUv" to "FFFF",
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// 5-bytes block
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"11111" to "000000",
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"1111z" to "000039",
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"11LUw" to "010000",
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"2UzHL" to "FFFFFF",
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// 6-bytes block
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"11111z" to "00000039",
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"7YXq9G" to "FFFFFFFF",
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// 7-bytes block
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"111111z" to "0000000039",
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"VtB5VXc" to "FFFFFFFFFF",
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// 9-bytes block
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"11111111z" to "000000000039",
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"3CUsUpv9t" to "FFFFFFFFFFFF",
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// 10-bytes block
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"111111111z" to "00000000000039",
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"Ahg1opVcGW" to "FFFFFFFFFFFFFF",
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// 11-bytes block
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"1111111111z" to "0000000000000039",
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"jpXCZedGfVQ" to "FFFFFFFFFFFFFFFF",
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"11111111111" to "0000000000000000",
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"11111111112" to "0000000000000001",
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"11111111119" to "0000000000000008",
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"1111111111A" to "0000000000000009",
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"11111111121" to "000000000000003A",
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"1Ahg1opVcGW" to "00FFFFFFFFFFFFFF",
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"22222222222" to "06156013762879F7",
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"1z111111111" to "05E022BA374B2A00",
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// Multiple blocks
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"1111111111111" to "000000000000000000",
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"11111111111111" to "00000000000000000000",
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"1111111111111111" to "0000000000000000000000",
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"11111111111111111" to "000000000000000000000000",
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"111111111111111111" to "00000000000000000000000000",
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"11111111111111111111" to "0000000000000000000000000000",
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"111111111111111111111" to "000000000000000000000000000000",
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"1111111111111111111111" to "00000000000000000000000000000000",
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"jpXCZedGfVQ5Q" to "FFFFFFFFFFFFFFFFFF",
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"jpXCZedGfVQLUv" to "FFFFFFFFFFFFFFFFFFFF",
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"jpXCZedGfVQ2UzHL" to "FFFFFFFFFFFFFFFFFFFFFF",
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"jpXCZedGfVQ7YXq9G" to "FFFFFFFFFFFFFFFFFFFFFFFF",
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"22222222222VtB5VXc" to "06156013762879F7FFFFFFFFFF",
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"jpXCZedGfVQVtB5VXc" to "FFFFFFFFFFFFFFFFFFFFFFFFFF",
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"jpXCZedGfVQ3CUsUpv9t" to "FFFFFFFFFFFFFFFFFFFFFFFFFFFF",
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"jpXCZedGfVQAhg1opVcGW" to "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
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"jpXCZedGfVQjpXCZedGfVQ" to "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
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)
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private val overflows = listOf(
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"5R",
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"zz",
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"LUw",
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"zzz",
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"2UzHM",
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"zzzzz",
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"7YXq9H",
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"zzzzzz",
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"VtB5VXd",
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"zzzzzzz",
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"3CUsUpv9u",
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"zzzzzzzzz",
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"Ahg1opVcGX",
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"zzzzzzzzzz",
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"jpXCZedGfVR",
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"zzzzzzzzzzz",
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"123456789AB5R",
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"123456789ABzz",
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"123456789ABLUw",
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"123456789ABzzz",
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"123456789AB2UzHM",
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"123456789ABzzzzz",
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"123456789AB7YXq9H",
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"123456789ABzzzzzz",
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"123456789ABVtB5VXd",
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"123456789ABzzzzzzz",
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"123456789AB3CUsUpv9u",
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"123456789ABzzzzzzzzz",
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"123456789ABAhg1opVcGX",
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"123456789ABzzzzzzzzzz",
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"123456789ABjpXCZedGfVR",
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"123456789ABzzzzzzzzzzz",
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"zzzzzzzzzzz11",
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)
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private val invalidSymbols = listOf(
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"10",
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"11I",
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"11O11",
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"11l111",
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"11_11111111",
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"1101111111111",
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"11I11111111111111",
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"11O1111111111111111111",
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"1111111111110",
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"111111111111l1111",
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"111111111111_111111111",
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)
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private val invalidLengths = listOf(
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"1",
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"z",
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"1111",
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"zzzz",
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"11111111",
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"zzzzzzzz",
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"123456789AB1",
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"123456789ABz",
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"123456789AB1111",
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"123456789ABzzzz",
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"123456789AB11111111",
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"123456789ABzzzzzzzz",
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)
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@Test
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fun `decode valid base58 strings`() {
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base58ToHex.forEach { (input, expected) ->
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assertThat(input.decodeBase58()).isEqualTo(expected.parseHex())
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}
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}
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@Test
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fun `empty string decodes to zero length`() {
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assertThat("".decodeBase58()).hasLength(0)
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}
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@Test
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fun `error on overflows`() {
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overflows.forEach {
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val thrown =
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Assert.assertThrows(IllegalArgumentException::class.java) { it.decodeBase58() }
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assertThat(thrown.message).ignoringCase().contains("overflow")
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}
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}
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@Test
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fun `error decoding invalid lengths`() {
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invalidLengths.forEach {
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Assert.assertThrows(IllegalArgumentException::class.java) { it.decodeBase58() }
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}
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}
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@Test
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fun `error decoding invalid symbols`() {
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invalidSymbols.forEach {
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Assert.assertThrows(IllegalArgumentException::class.java) { it.decodeBase58() }
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}
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}
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}
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