Import APK in tests

app/src/main/java/com/github/nacabaro/vbhelper/source/ApkSecretsImporter.kt

@@ -0,0 +1,25 @@
+package com.github.nacabaro.vbhelper.source
+
+import java.io.InputStream
+import java.util.zip.ZipInputStream
+
+class ApkSecretsImporter(private val dexFileSecretsImporter: DexFileSecretsImporter = DexFileSecretsImporter()) {
+
+    companion object {
+        const val DEX_FILE = "classes.dex"
+    }
+
+    fun importSecrets(inputStream: InputStream): Map<UShort, Secrets> {
+        ZipInputStream(inputStream).use { zip ->
+            var zipEntry = zip.nextEntry
+            while(zipEntry != null) {
+                println("Zip Entry: ${zipEntry.name}")
+                if(zipEntry.name == DEX_FILE) {
+                    return dexFileSecretsImporter.importSecrets(zip)
+                }
+                zipEntry = zip.nextEntry
+            }
+            throw IllegalArgumentException("File `$DEX_FILE` is missing from apk!")
+        }
+    }
+}

app/src/main/java/com/github/nacabaro/vbhelper/source/DexFileSecretsImporter.kt

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+package com.github.nacabaro.vbhelper.source
+
+import com.github.cfogrady.vbnfc.data.DeviceType
+import java.io.InputStream
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+import java.nio.charset.StandardCharsets
+
+
+class DexFileSecretsImporter {
+    companion object {
+
+        const val VBDM_SUBSTITUTION_CIPHER_IDX = 1080145
+        const val BE_SUBSTITUTION_CIPHER_IDX = 1080217
+
+        const val VBDM_HMAC_KEY_2_IDX = 1249063
+        const val VBDM_HMAC_KEY_1_IDX = 1494074
+        const val VBC_HMAC_KEY_1_IDX = 1241640
+        const val VBC_HMAC_KEY_2_IDX = 1466955
+        const val BE_HMAC_KEY_1_IDX = 1580157
+        const val BE_HMAC_KEY_2_IDX = 1593759
+        const val AES_KEY_IDX = 1277527
+    }
+
+    fun importSecrets(inputStream: InputStream): Map<UShort, Secrets> {
+        val dexFile = inputStream.readBytes()
+        val byteOrder = ByteOrder.BIG_ENDIAN
+        val vbdmSubstitutionCipher = dexFile.sliceArray(VBDM_SUBSTITUTION_CIPHER_IDX until VBDM_SUBSTITUTION_CIPHER_IDX+(16*4)).toIntArray(byteOrder)
+        val beSubstitutionCipher = dexFile.sliceArray(BE_SUBSTITUTION_CIPHER_IDX until BE_SUBSTITUTION_CIPHER_IDX+(16*4)).toIntArray(byteOrder)
+        val aesKey = dexFile.sliceArray(AES_KEY_IDX until AES_KEY_IDX+24).toString(StandardCharsets.UTF_8)
+        val cryptographicTransformerByDevices = mapOf(
+            Pair(DeviceType.VitalSeriesDeviceType, buildSecrets(dexFile, VBDM_HMAC_KEY_1_IDX, VBDM_HMAC_KEY_2_IDX, aesKey, vbdmSubstitutionCipher)),
+            Pair(DeviceType.VitalBraceletBEDeviceType, buildSecrets(dexFile, BE_HMAC_KEY_1_IDX, BE_HMAC_KEY_2_IDX, aesKey, beSubstitutionCipher)),
+            Pair(DeviceType.VitalCharactersDeviceType, buildSecrets(dexFile, VBC_HMAC_KEY_1_IDX, VBC_HMAC_KEY_2_IDX, aesKey, vbdmSubstitutionCipher)),
+        )
+        return cryptographicTransformerByDevices
+    }
+
+    private fun buildSecrets(dexFile: ByteArray, hmacKeyIdx1: Int, hmacKeyIdx2: Int, aesKey: String, substitutionCipher: IntArray): Secrets {
+        val hmacKey1 = dexFile.sliceArray(hmacKeyIdx1 until hmacKeyIdx1+24).toString(StandardCharsets.UTF_8)
+        val hmacKey2 = dexFile.sliceArray(hmacKeyIdx2 until hmacKeyIdx2+24).toString(StandardCharsets.UTF_8)
+        return Secrets(hmacKey1, hmacKey2, aesKey, substitutionCipher)
+    }
+}
+
+fun ByteArray.toIntArray(byteOrder: ByteOrder): IntArray {
+    require(this.size % 4 == 0) { "Number of bytes must be multiple of 4 to convert into 32-bit words" }
+    val values = IntArray(this.size / 4)
+    ByteBuffer.wrap(this).order(byteOrder).asIntBuffer()[values]
+    return values
+}

app/src/main/java/com/github/nacabaro/vbhelper/source/Secrets.kt

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+package com.github.nacabaro.vbhelper.source
+
+import com.github.cfogrady.vbnfc.CryptographicTransformer
+
+data class Secrets(val hmacKey1: String, val hmacKey2: String, val aesKey: String, val substitutionCipher: IntArray) {
+    fun toCryptographicTransformer(): CryptographicTransformer {
+        return CryptographicTransformer(hmacKey1, hmacKey2, aesKey, substitutionCipher)
+    }
+}