67 lines
2.5 KiB
Markdown
67 lines
2.5 KiB
Markdown
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# Before start
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`AES-128-CFB8`, `RSA1024` and `SHA1` has been implemented in `libmc-protocol-context` module, it uses
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`cryptography-kotlin`(and its platform based provider)
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> All impl example below are based on Java's built-in security & cryptography API
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# AES-128-CFB8
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```kotlin
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class JavaAesCipher(sharedKey: ByteArray) : NetworkCipher {
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private val encryptCipher = Cipher.getInstance("AES/CFB8/NoPadding").apply {
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init(Cipher.ENCRYPT_MODE, SecretKeySpec(sharedKey, "AES"), IvParameterSpec(sharedKey))
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}
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private val decryptCipher = Cipher.getInstance("AES/CFB8/NoPadding").apply {
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init(Cipher.DECRYPT_MODE, SecretKeySpec(sharedKey, "AES"), IvParameterSpec(sharedKey))
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}
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override fun encrypt(buffer: ByteArray, offset: Int, length: Int) {
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encryptCipher.update(buffer, offset, length, buffer, offset)
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}
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override fun decrypt(buffer: ByteArray, offset: Int, length: Int) {
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decryptCipher.update(buffer, offset, length, buffer, offset)
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}
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}
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```
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# RSA1024
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```kotlin
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private fun encrypt(publicKeyBytes: ByteArray, data: ByteArray): ByteArray {
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val keySpec = X509EncodedKeySpec(publicKeyBytes)
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val keyFactory = KeyFactory.getInstance("RSA")
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val publicKey = keyFactory.generatePublic(keySpec)
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val cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding")
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cipher.init(Cipher.ENCRYPT_MODE, publicKey)
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return cipher.doFinal(data)
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}
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public val CustomProtocolContext: ProtocolContextBuilder.() -> Unit = {
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rsaEncryptor = RSA1024Encryptor { key: ByteArray, data: ByteArray -> encrypt(key, data) }
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}
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```
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# SHA1
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```kotlin
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private fun minecraftServerIdHash(serverId: String, secretKey: ByteArray, publicKey: ByteArray): String {
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val serverIdBytes: ByteArray = serverId.encodeToByteArray()
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for (b in serverIdBytes) require((b.toInt() and 0xFF) <= 0x7F) { "serverId contains non-US-ASCII character" }
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val data = ByteArray(serverIdBytes.size + secretKey.size + publicKey.size)
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System.arraycopy(serverIdBytes, 0, data, 0, serverIdBytes.size)
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System.arraycopy(secretKey, 0, data, serverIdBytes.size, secretKey.size)
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System.arraycopy(publicKey, 0, data, serverIdBytes.size + secretKey.size, publicKey.size)
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val digest = MessageDigest.getInstance("SHA-1")
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val hash = digest.digest(data)
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return BigInteger(hash).toString(16)
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}
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public val CustomProtocolContext: ProtocolContextBuilder.() -> Unit = {
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sha1Hasher = Sha1Hasher { serverId: String, secretKey: ByteArray, publicKey: ByteArray ->
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minecraftServerIdHash(serverId, secretKey, publicKey)
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}
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}
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```
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