CORDA-3175 Remove dependency on 3rd party javax.xml.bind library for simple hex parsing/printing. (#5412)

* Remove dependency on 2rd party javax.xml.bind library for simple hex parsing/printing.

* Added unit test.

core/src/main/kotlin/net/corda/core/utilities/ByteArrays.kt

@@ -10,7 +10,6 @@ import java.io.OutputStream
 import java.lang.Math.max
 import java.lang.Math.min
 import java.nio.ByteBuffer
-import javax.xml.bind.DatatypeConverter
 
 /**
  * An abstraction of a byte array, with offset and size that does no copying of bytes unless asked to.
@@ -179,13 +178,60 @@ fun ByteArray.sequence(offset: Int = 0, size: Int = this.size) = ByteSequence.of
 /**
  * Converts this [ByteArray] into a [String] of hexadecimal digits.
  */
-fun ByteArray.toHexString(): String = DatatypeConverter.printHexBinary(this)
+fun ByteArray.toHexString(): String = printHexBinary(this)
+
+private val hexCode = "0123456789ABCDEF".toCharArray()
+private fun printHexBinary(data: ByteArray): String {
+    val r = StringBuilder(data.size * 2)
+    for (b in data) {
+        r.append(hexCode[(b.toInt() shr 4) and 0xF])
+        r.append(hexCode[b.toInt() and 0xF])
+    }
+    return r.toString()
+}
 
 /**
  * Converts this [String] of hexadecimal digits into a [ByteArray].
  * @throws IllegalArgumentException if the [String] contains incorrectly-encoded characters.
  */
-fun String.parseAsHex(): ByteArray = DatatypeConverter.parseHexBinary(this)
+fun String.parseAsHex(): ByteArray = parseHexBinary(this)
+
+private fun parseHexBinary(s: String): ByteArray {
+    val len = s.length
+
+    // "111" is not a valid hex encoding.
+    if (len % 2 != 0) {
+        throw IllegalArgumentException("hexBinary needs to be even-length: $s")
+    }
+
+    val out = ByteArray(len / 2)
+
+    fun hexToBin(ch: Char): Int {
+        if (ch in '0'..'9') {
+            return ch - '0'
+        }
+        if (ch in 'A'..'F') {
+            return ch - 'A' + 10
+        }
+        return if (ch in 'a'..'f') {
+            ch - 'a' + 10
+        } else -1
+    }
+
+    var i = 0
+    while (i < len) {
+        val h = hexToBin(s[i])
+        val l = hexToBin(s[i + 1])
+        if (h == -1 || l == -1) {
+            throw IllegalArgumentException("contains illegal character for hexBinary: $s")
+        }
+
+        out[i / 2] = (h * 16 + l).toByte()
+        i += 2
+    }
+
+    return out
+}
 
 /**
  * Class is public for serialization purposes.

core/src/main/kotlin/net/corda/core/utilities/EncodingUtils.kt

@@ -10,7 +10,6 @@ import net.corda.core.internal.hash
 import java.nio.charset.Charset
 import java.security.PublicKey
 import java.util.*
-import javax.xml.bind.DatatypeConverter
 
 // This file includes useful encoding methods and extension functions for the most common encoding/decoding operations.
 
@@ -31,7 +30,7 @@ fun ByteArray.toBase58(): String = Base58.encode(this)
 fun ByteArray.toBase64(): String = Base64.getEncoder().encodeToString(this)
 
 /** Convert a byte array to a hex (Base16) capitalized encoded [String]. */
-fun ByteArray.toHex(): String = DatatypeConverter.printHexBinary(this)
+fun ByteArray.toHex(): String = toHexString()
 
 // [String] encoders and decoders
 
@@ -49,7 +48,7 @@ fun String.base58ToByteArray(): ByteArray = Base58.decode(this)
 fun String.base64ToByteArray(): ByteArray = Base64.getDecoder().decode(this)
 
 /** Hex-String to [ByteArray]. Accept any hex form (capitalized, lowercase, mixed). */
-fun String.hexToByteArray(): ByteArray = DatatypeConverter.parseHexBinary(this)
+fun String.hexToByteArray(): ByteArray = parseAsHex()
 
 // Encoding changers
 

core/src/test/kotlin/net/corda/core/utilities/ByteArraysTest.kt

@@ -1,7 +1,10 @@
 package net.corda.core.utilities
 
+import net.corda.core.contracts.StateRef
+import net.corda.core.crypto.SecureHash
 import net.corda.core.internal.declaredField
 import org.assertj.core.api.Assertions.catchThrowable
+import org.junit.Assert
 import org.junit.Assert.assertSame
 import org.junit.Test
 import java.nio.ByteBuffer
@@ -42,4 +45,17 @@ class ByteArraysTest {
         check(byteArrayOf(), seq.slice(2, 2))
         check(byteArrayOf(), seq.slice(2, 1))
     }
+
+    @Test
+    fun `test hex parsing strictly uppercase`() {
+        val HEX_REGEX = "^[0-9A-F]+\$".toRegex()
+
+        val privacySalt = net.corda.core.contracts.PrivacySalt()
+        val privacySaltAsHexString = privacySalt.bytes.toHexString()
+        Assert.assertTrue(privacySaltAsHexString.matches(HEX_REGEX))
+
+        val stateRef = StateRef(SecureHash.randomSHA256(), 0)
+        val txhashAsHexString = stateRef.txhash.bytes.toHexString()
+        Assert.assertTrue(txhashAsHexString.matches(HEX_REGEX))
+    }
 }