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Switch from i2p/eddsa to Bouncy Castle for Ed25519 

The i2p eddsa library produces non-standard Ed25519 signatures that
Node.js crypto doesn't accept. Bouncy Castle is more widely tested
and should produce standard-compliant signatures.
This commit is contained in:
James (ClawdBot) 2026-01-28 19:25:57 +00:00
parent 5b140362bf
commit 1f58f36470
2 changed files with 32 additions and 59 deletions
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4
app/build.gradle.kts
View File

@ -54,8 +54,8 @@ dependencies {
// Security - encrypted storage
implementation("androidx.security:security-crypto:1.1.0-alpha06")
// Ed25519 signatures (pure Java, works on all Android versions)
implementation("net.i2p.crypto:eddsa:0.3.0")
// Ed25519 signatures via Bouncy Castle (reliable, widely tested)
implementation("org.bouncycastle:bcprov-jdk18on:1.77")
// Networking - WebSocket
implementation("com.squareup.okhttp3:okhttp:4.12.0")

87
app/src/main/java/com/inou/clawdnode/security/DeviceIdentity.kt
View File

@ -5,21 +5,17 @@ import android.util.Base64
import android.util.Log
import androidx.security.crypto.EncryptedSharedPreferences
import androidx.security.crypto.MasterKey
import net.i2p.crypto.eddsa.EdDSAEngine
import net.i2p.crypto.eddsa.EdDSAPrivateKey
import net.i2p.crypto.eddsa.EdDSAPublicKey
import net.i2p.crypto.eddsa.KeyPairGenerator
import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable
import net.i2p.crypto.eddsa.spec.EdDSAPrivateKeySpec
import net.i2p.crypto.eddsa.spec.EdDSAPublicKeySpec
import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters
import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters
import org.bouncycastle.crypto.signers.Ed25519Signer
import java.security.MessageDigest
import java.security.SecureRandom
/**
* Manages device identity using Ed25519 keys.
* Manages device identity using Ed25519 keys via Bouncy Castle.
*
* Keys are stored in EncryptedSharedPreferences for security.
* Uses pure-Java Ed25519 implementation for compatibility with all Android versions.
* Uses Bouncy Castle's Ed25519 implementation for compatibility.
*
* The key format matches the Clawdbot gateway protocol:
* - Public key: 32 bytes raw, base64url-encoded
@ -33,8 +29,6 @@ class DeviceIdentity(context: Context) {
private val keyPrivate = "private_key"
private val keyPublic = "public_key"
private val ed25519Spec = EdDSANamedCurveTable.getByName("Ed25519")
private val prefs by lazy {
val masterKey = MasterKey.Builder(context)
.setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
@ -54,9 +48,8 @@ class DeviceIdentity(context: Context) {
*/
val publicKey: String by lazy {
ensureKeyPair()
val publicKeyBytes = prefs.getString(keyPublic, null)
prefs.getString(keyPublic, null)
?: throw IllegalStateException("No public key available")
publicKeyBytes // Already stored as base64url
}
/**
@ -67,22 +60,15 @@ class DeviceIdentity(context: Context) {
val publicKeyBase64 = prefs.getString(keyPublic, null)
?: throw IllegalStateException("No public key available")
// Decode the raw public key bytes
val publicKeyBytes = base64UrlDecode(publicKeyBase64)
// Create fingerprint using SHA-256 of the raw public key bytes
val digest = MessageDigest.getInstance("SHA-256")
val hash = digest.digest(publicKeyBytes)
// Return as hex string (full 32 bytes = 64 chars, matching gateway)
hash.joinToString("") { "%02x".format(it) }
}
/**
* Sign a challenge nonce for gateway authentication
*
* @param nonce The challenge nonce from the gateway
* @return Signature and timestamp
*/
fun signChallenge(nonce: String): SignedChallenge {
ensureKeyPair()
@ -92,36 +78,32 @@ class DeviceIdentity(context: Context) {
Log.d(tag, "Signing payload: $payload")
// Load private key
// Load private key (32-byte seed)
val privateKeyBase64 = prefs.getString(keyPrivate, null)
?: throw IllegalStateException("No private key available")
val privateKeyBytes = base64UrlDecode(privateKeyBase64)
// Create EdDSA private key from seed
val privateKeySpec = EdDSAPrivateKeySpec(privateKeyBytes, ed25519Spec)
val privateKey = EdDSAPrivateKey(privateKeySpec)
// Create Bouncy Castle Ed25519 private key from seed
val privateKey = Ed25519PrivateKeyParameters(privateKeyBytes, 0)
// Verify the derived public key matches stored public key
val derivedPubKey = privateKey.abyte
// Verify derived public key matches stored
val derivedPubKey = privateKey.generatePublicKey().encoded
val storedPubKeyBase64 = prefs.getString(keyPublic, null)
val storedPubKey = storedPubKeyBase64?.let { base64UrlDecode(it) }
val keysMatch = derivedPubKey.contentEquals(storedPubKey)
Log.d(tag, "Stored pubkey: ${storedPubKeyBase64?.take(20)}...")
Log.d(tag, "Derived pubkey: ${base64UrlEncode(derivedPubKey).take(20)}...")
Log.d(tag, "Keys match: ${derivedPubKey.contentEquals(storedPubKey)}")
Log.d(tag, "Keys match: $keysMatch")
// Sign the payload using standard Ed25519 (not prehashed Ed25519ph)
val signature = EdDSAEngine().apply {
initSign(privateKey)
update(payload.toByteArray(Charsets.UTF_8))
}
// Sign using Ed25519
val signer = Ed25519Signer()
signer.init(true, privateKey)
signer.update(payload.toByteArray(Charsets.UTF_8), 0, payload.length)
val signatureBytes = signer.generateSignature()
val signatureBytes = signature.sign()
val signatureBase64 = base64UrlEncode(signatureBytes)
Log.d(tag, "Generated signature: ${signatureBase64.take(20)}... (${signatureBytes.size} bytes)")
val keysMatch = derivedPubKey.contentEquals(storedPubKey)
val debugInfo = "Keys match: $keysMatch | Stored: ${storedPubKeyBase64?.take(12)}... | Derived: ${base64UrlEncode(derivedPubKey).take(12)}..."
return SignedChallenge(
@ -150,29 +132,26 @@ class DeviceIdentity(context: Context) {
}
/**
* Generate a new Ed25519 keypair and store it
* Generate a new Ed25519 keypair using Bouncy Castle
*/
private fun generateKeyPair() {
Log.i(tag, "Generating new Ed25519 device keypair")
Log.i(tag, "Generating new Ed25519 device keypair (Bouncy Castle)")
val keyPairGenerator = KeyPairGenerator()
keyPairGenerator.initialize(256, SecureRandom())
val keyPair = keyPairGenerator.generateKeyPair()
// Generate random 32-byte seed
val seed = ByteArray(32)
SecureRandom().nextBytes(seed)
val privateKey = keyPair.private as EdDSAPrivateKey
val publicKey = keyPair.public as EdDSAPublicKey
// Create keypair from seed
val privateKey = Ed25519PrivateKeyParameters(seed, 0)
val publicKey = privateKey.generatePublicKey()
// Get raw 32-byte keys (matching gateway format)
// For Ed25519, the "seed" is the 32-byte private key
val privateKeyBytes = privateKey.seed
// The "A" point is the 32-byte public key
val publicKeyBytes = publicKey.abyte
val publicKeyBytes = publicKey.encoded
Log.d(tag, "Generated keypair: private=${privateKeyBytes.size} bytes, public=${publicKeyBytes.size} bytes")
Log.d(tag, "Generated keypair: seed=${seed.size} bytes, public=${publicKeyBytes.size} bytes")
// Store as base64url
prefs.edit()
.putString(keyPrivate, base64UrlEncode(privateKeyBytes))
.putString(keyPrivate, base64UrlEncode(seed))
.putString(keyPublic, base64UrlEncode(publicKeyBytes))
.apply()
@ -190,16 +169,10 @@ class DeviceIdentity(context: Context) {
Log.i(tag, "Device keypair deleted")
}
/**
* Base64url encode (no padding, URL-safe)
*/
private fun base64UrlEncode(bytes: ByteArray): String {
return Base64.encodeToString(bytes, Base64.URL_SAFE or Base64.NO_WRAP or Base64.NO_PADDING)
}
/**
* Base64url decode (handles both padded and unpadded)
*/
private fun base64UrlDecode(input: String): ByteArray {
return Base64.decode(input, Base64.URL_SAFE or Base64.NO_WRAP or Base64.NO_PADDING)
}
@ -208,6 +181,6 @@ class DeviceIdentity(context: Context) {
val signature: String,
val signedAt: Long,
val nonce: String,
val debugInfo: String = "" // For debugging key derivation
val debugInfo: String = ""
)
}