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/*
* This file is part of LibEuFin.
* Copyright (C) 2023 Stanisci and Dold.
* LibEuFin is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation; either version 3, or
* (at your option) any later version.
* LibEuFin is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General
* Public License for more details.
* You should have received a copy of the GNU Affero General Public
* License along with LibEuFin; see the file COPYING. If not, see
* <http://www.gnu.org/licenses/>
*/
package tech.libeufin.nexus
import kotlinx.serialization.Contextual
import kotlinx.serialization.KSerializer
import kotlinx.serialization.Serializable
import kotlinx.serialization.descriptors.PrimitiveKind
import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
import kotlinx.serialization.descriptors.SerialDescriptor
import kotlinx.serialization.encodeToString
import kotlinx.serialization.encoding.Decoder
import kotlinx.serialization.encoding.Encoder
import kotlinx.serialization.json.Json
import kotlinx.serialization.modules.SerializersModule
import tech.libeufin.common.Base32Crockford
import tech.libeufin.common.crypto.CryptoUtil
import java.nio.file.*
import java.security.interfaces.RSAPrivateCrtKey
import java.security.interfaces.RSAPublicKey
import kotlin.io.path.*
val JSON = Json {
this.serializersModule = SerializersModule {
contextual(RSAPrivateCrtKey::class) { RSAPrivateCrtKeySerializer }
contextual(RSAPublicKey::class) { RSAPublicKeySerializer }
}
}
/**
* Converts base 32 representation of RSA public keys and vice versa.
*/
object RSAPublicKeySerializer : KSerializer<RSAPublicKey> {
override val descriptor: SerialDescriptor =
PrimitiveSerialDescriptor("RSAPublicKey", PrimitiveKind.STRING)
override fun serialize(encoder: Encoder, value: RSAPublicKey) {
encoder.encodeString(Base32Crockford.encode(value.encoded))
}
// Caller must handle exceptions here.
override fun deserialize(decoder: Decoder): RSAPublicKey {
val fieldValue = decoder.decodeString()
val bytes = Base32Crockford.decode(fieldValue)
return CryptoUtil.loadRsaPublicKey(bytes)
}
}
/**
* Converts base 32 representation of RSA private keys and vice versa.
*/
object RSAPrivateCrtKeySerializer : KSerializer<RSAPrivateCrtKey> {
override val descriptor: SerialDescriptor =
PrimitiveSerialDescriptor("RSAPrivateCrtKey", PrimitiveKind.STRING)
override fun serialize(encoder: Encoder, value: RSAPrivateCrtKey) {
encoder.encodeString(Base32Crockford.encode(value.encoded))
}
// Caller must handle exceptions here.
override fun deserialize(decoder: Decoder): RSAPrivateCrtKey {
val fieldValue = decoder.decodeString()
val bytes = Base32Crockford.decode(fieldValue)
return CryptoUtil.loadRsaPrivateKey(bytes)
}
}
/**
* Structure of the JSON file that contains the client
* private keys on disk.
*/
@Serializable
data class ClientPrivateKeysFile(
@Contextual val signature_private_key: RSAPrivateCrtKey,
@Contextual val encryption_private_key: RSAPrivateCrtKey,
@Contextual val authentication_private_key: RSAPrivateCrtKey,
var submitted_ini: Boolean,
var submitted_hia: Boolean
)
/**
* Structure of the JSON file that contains the bank
* public keys on disk.
*/
@Serializable
data class BankPublicKeysFile(
@Contextual val bank_encryption_public_key: RSAPublicKey,
@Contextual val bank_authentication_public_key: RSAPublicKey,
var accepted: Boolean
)
/**
* Generates new client private keys.
*
* @return [ClientPrivateKeysFile]
*/
fun generateNewKeys(): ClientPrivateKeysFile =
ClientPrivateKeysFile(
authentication_private_key = CryptoUtil.generateRsaKeyPair(2048).private,
encryption_private_key = CryptoUtil.generateRsaKeyPair(2048).private,
signature_private_key = CryptoUtil.generateRsaKeyPair(2048).private,
submitted_hia = false,
submitted_ini = false
)
private inline fun <reified T> persistJsonFile(obj: T, path: Path, name: String) {
val content = try {
JSON.encodeToString(obj)
} catch (e: Exception) {
throw Exception("Could not encode $name", e)
}
val parent = try {
path.parent ?: path.absolute().parent
} catch (e: Exception) {
throw Exception("Could not write $name at '$path'", e)
}
try {
// Write to temp file then rename to enable atomicity when possible
val tmp = Files.createTempFile(parent, "tmp_", "_${path.fileName}")
tmp.writeText(content)
tmp.moveTo(path, StandardCopyOption.REPLACE_EXISTING)
} catch (e: Exception) {
when {
!parent.isWritable() -> throw Exception("Could not write $name at '$path': permission denied on '$parent'")
!path.isWritable() -> throw Exception("Could not write $name at '$path': permission denied")
else -> throw Exception("Could not write $name at '$path'", e)
}
}
}
/**
* Persist the bank keys file to disk
*
* @param location the keys file location
*/
fun persistBankKeys(keys: BankPublicKeysFile, location: Path) = persistJsonFile(keys, location, "bank public keys")
/**
* Persist the client keys file to disk
*
* @param location the keys file location
*/
fun persistClientKeys(keys: ClientPrivateKeysFile, location: Path) = persistJsonFile(keys, location, "client private keys")
private inline fun <reified T> loadJsonFile(path: Path, name: String): T? {
val content = try {
path.readText()
} catch (e: Exception) {
when (e) {
is NoSuchFileException -> return null
is AccessDeniedException -> throw Exception("Could not read $name at '$path': permission denied")
else -> throw Exception("Could not read $name at '$path'", e)
}
}
return try {
JSON.decodeFromString(content)
} catch (e: Exception) {
throw Exception("Could not decode $name at '$path'", e)
}
}
/**
* Load the bank keys file from disk.
*
* @param location the keys file location.
* @return the internal JSON representation of the keys file,
* or null if the file does not exist
*/
fun loadBankKeys(location: Path): BankPublicKeysFile? = loadJsonFile(location, "bank public keys")
/**
* Load the client keys file from disk.
*
* @param location the keys file location.
* @return the internal JSON representation of the keys file,
* or null if the file does not exist
*/
fun loadClientKeys(location: Path): ClientPrivateKeysFile? = loadJsonFile(location, "client private keys")
/**
* Load client and bank keys from disk.
* Checks that the keying process has been fully completed.
*
* Helps to fail before starting to talk EBICS to the bank.
*
* @param cfg configuration handle.
* @return both client and bank keys
*/
fun expectFullKeys(
cfg: EbicsSetupConfig
): Pair<ClientPrivateKeysFile, BankPublicKeysFile> {
val clientKeys = loadClientKeys(cfg.clientPrivateKeysFilename)
if (clientKeys == null) {
throw Exception("Missing client private keys file at '${cfg.clientPrivateKeysFilename}', run 'libeufin-nexus ebics-setup' first")
} else if (!clientKeys.submitted_ini || !clientKeys.submitted_hia) {
throw Exception("Unsubmitted client private keys, run 'libeufin-nexus ebics-setup' first")
}
val bankKeys = loadBankKeys(cfg.bankPublicKeysFilename)
if (bankKeys == null) {
throw Exception("Missing bank public keys at '${cfg.bankPublicKeysFilename}', run 'libeufin-nexus ebics-setup' first")
} else if (!bankKeys.accepted) {
throw Exception("Unaccepted bank public keys, run 'libeufin-nexus ebics-setup' until accepting the bank keys")
}
return Pair(clientKeys, bankKeys)
}
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