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refactor(noise/protocol): migrate AESGCMOnCtrCipherState to Kotlin
- Override CipherState properties; tighten `initializeKey` parameter type to non-null `ByteArray`. - Promote the constructor to a `@Throws(NoSuchAlgorithmException)` primary constructor with the `Cipher` instance assigned once as a non-null `val`, removing the bogus `cipher: Cipher? = null` initializer the IDE emitted. - Replace `Arrays.fill(arr, 0.toByte())` with `arr.fill(0)`. - Inline-byte XOR loop in `encryptWithAd` now casts back to `Byte` explicitly to satisfy Kotlin's stricter type rules. - `fork()` rethrows the (impossible) NoSuchAlgorithmException as IllegalStateException instead of returning null — matches the non-null contract on `CipherState.fork`. - AES/CTR keystream and GHASH paths preserved byte-for-byte. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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@ -27,7 +27,6 @@ import com.bitchat.android.noise.southernstorm.protocol.Noise.throwBadTagExcepti
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import java.security.InvalidAlgorithmParameterException
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import java.security.InvalidKeyException
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import java.security.NoSuchAlgorithmException
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import java.util.Arrays
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import javax.crypto.BadPaddingException
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import javax.crypto.Cipher
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import javax.crypto.IllegalBlockSizeException
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@ -43,33 +42,23 @@ import javax.crypto.spec.SecretKeySpec
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* This class is used on platforms that don't have "AES/GCM/NoPadding",
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* but which do have the older "AES/CTR/NoPadding".
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*/
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internal class AESGCMOnCtrCipherState : CipherState {
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private val cipher: Cipher? = null
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private var keySpec: SecretKeySpec?
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private var n: Long
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private val iv: ByteArray
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private val hashKey: ByteArray
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private val ghash: GHASH
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internal class AESGCMOnCtrCipherState
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@Throws(NoSuchAlgorithmException::class)
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constructor() : CipherState {
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private val cipher: Cipher
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private var keySpec: SecretKeySpec? = null
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private var n: Long = 0
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private val iv: ByteArray = ByteArray(16)
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private val hashKey: ByteArray = ByteArray(16)
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private val ghash: GHASH = GHASH()
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/**
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* Constructs a new cipher state for the "AESGCM" algorithm.
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*
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* @throws NoSuchAlgorithmException The system does not have a
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* provider for this algorithm.
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*/
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init {
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try {
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cipher = Cipher.getInstance("AES/CTR/NoPadding")
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cipher = try {
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Cipher.getInstance("AES/CTR/NoPadding")
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} catch (e: NoSuchPaddingException) {
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// AES/CTR is available, but not the unpadded version? Huh?
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throw NoSuchAlgorithmException("AES/CTR/NoPadding not available", e)
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}
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keySpec = null
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n = 0
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iv = ByteArray(16)
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hashKey = ByteArray(16)
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ghash = GHASH()
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// Try to set a 256-bit key on the cipher. Some JCE's are
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// configured to disallow 256-bit AES if an extra policy
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@ -95,7 +84,7 @@ internal class AESGCMOnCtrCipherState : CipherState {
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keySpec = SecretKeySpec(ByteArray(32), "AES")
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val params = IvParameterSpec(iv)
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try {
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cipher!!.init(Cipher.ENCRYPT_MODE, keySpec, params)
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cipher.init(Cipher.ENCRYPT_MODE, keySpec, params)
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} catch (e: InvalidKeyException) {
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// Shouldn't happen.
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} catch (e: InvalidAlgorithmParameterException) {
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@ -103,25 +92,20 @@ internal class AESGCMOnCtrCipherState : CipherState {
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}
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}
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val cipherName: String
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get() = "AESGCM"
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override val cipherName: String get() = "AESGCM"
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override val keyLength: Int get() = 32
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override val macLength: Int get() = if (keySpec != null) 16 else 0
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val keyLength: Int
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get() = 32
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val mACLength: Int
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get() = if (keySpec != null) 16 else 0
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override fun initializeKey(key: ByteArray?, offset: Int) {
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override fun initializeKey(key: ByteArray, offset: Int) {
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// Set the encryption key.
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keySpec = SecretKeySpec(key, offset, 32, "AES")
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// Generate the hashing key by encrypting a block of zeroes.
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Arrays.fill(iv, 0.toByte())
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Arrays.fill(hashKey, 0.toByte())
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iv.fill(0)
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hashKey.fill(0)
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try {
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cipher!!.init(Cipher.ENCRYPT_MODE, keySpec, IvParameterSpec(iv))
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cipher.init(Cipher.ENCRYPT_MODE, keySpec, IvParameterSpec(iv))
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} catch (e: InvalidKeyException) {
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// Shouldn't happen.
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throw IllegalStateException(e)
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@ -185,12 +169,12 @@ internal class AESGCMOnCtrCipherState : CipherState {
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// Initialize the CTR mode cipher with the key and IV.
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cipher!!.init(Cipher.ENCRYPT_MODE, keySpec, IvParameterSpec(iv))
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cipher.init(Cipher.ENCRYPT_MODE, keySpec, IvParameterSpec(iv))
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// Encrypt a block of zeroes to generate the hash key to XOR
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// the GHASH tag with at the end of the encrypt/decrypt operation.
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Arrays.fill(hashKey, 0.toByte())
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hashKey.fill(0)
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try {
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cipher.update(hashKey, 0, 16, hashKey, 0)
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} catch (e: ShortBufferException) {
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@ -232,7 +216,7 @@ internal class AESGCMOnCtrCipherState : CipherState {
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try {
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setup(ad)
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val result =
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cipher!!.update(plaintext, plaintextOffset, length, ciphertext, ciphertextOffset)
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cipher.update(plaintext, plaintextOffset, length, ciphertext, ciphertextOffset)
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cipher.doFinal(ciphertext, ciphertextOffset + result)
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} catch (e: InvalidKeyException) {
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// Shouldn't happen.
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@ -250,8 +234,10 @@ internal class AESGCMOnCtrCipherState : CipherState {
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ghash.update(ciphertext, ciphertextOffset, length)
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ghash.pad((if (ad != null) ad.size else 0).toLong(), length.toLong())
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ghash.finish(ciphertext, ciphertextOffset + length, 16)
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for (index in 0..15) ciphertext[ciphertextOffset + length + index] =
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ciphertext[ciphertextOffset + length + index].toInt() xor hashKey[index].toInt()
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for (index in 0..15) {
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ciphertext[ciphertextOffset + length + index] =
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(ciphertext[ciphertextOffset + length + index].toInt() xor hashKey[index].toInt()).toByte()
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}
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return length + 16
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}
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@ -303,7 +289,7 @@ internal class AESGCMOnCtrCipherState : CipherState {
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if ((temp and 0xFF) != 0) throwBadTagException()
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try {
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val result =
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cipher!!.update(ciphertext, ciphertextOffset, dataLen, plaintext, plaintextOffset)
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cipher.update(ciphertext, ciphertextOffset, dataLen, plaintext, plaintextOffset)
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cipher.doFinal(plaintext, plaintextOffset + result)
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} catch (e: IllegalBlockSizeException) {
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// Shouldn't happen.
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@ -316,12 +302,11 @@ internal class AESGCMOnCtrCipherState : CipherState {
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}
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override fun fork(key: ByteArray, offset: Int): CipherState {
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val cipher: CipherState
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try {
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cipher = AESGCMOnCtrCipherState()
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val cipher: CipherState = try {
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AESGCMOnCtrCipherState()
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} catch (e: NoSuchAlgorithmException) {
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// Shouldn't happen.
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return null
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// Shouldn't happen — this state already exists, so the algorithm is available.
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throw IllegalStateException(e)
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}
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cipher.initializeKey(key, offset)
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return cipher
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