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/*
* This file is part of GNU Taler
* (C) 2020 Taler Systems S.A.
*
* GNU Taler is free software; you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation; either version 3, or (at your option) any later version.
*
* GNU Taler 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with
* GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
package net.taler.wallet.kotlin.crypto
import net.taler.wallet.kotlin.Base32Crockford
import net.taler.wallet.kotlin.crypto.CryptoImpl.Companion.toByteArray
import net.taler.wallet.kotlin.exchange.DenominationRecord
import net.taler.wallet.kotlin.exchange.WireFee
internal class Signature(private val crypto: Crypto) {
@Suppress("unused")
companion object {
const val RESERVE_WITHDRAW = 1200
const val WALLET_COIN_DEPOSIT = 1201
const val MASTER_DENOMINATION_KEY_VALIDITY = 1025
const val MASTER_WIRE_FEES = 1028
const val MASTER_WIRE_DETAILS = 1030
const val WALLET_COIN_MELT = 1202
const val TEST = 4242
const val MERCHANT_PAYMENT_OK = 1104
const val WALLET_COIN_RECOUP = 1203
const val WALLET_COIN_LINK = 1204
const val EXCHANGE_CONFIRM_RECOUP = 1039
const val EXCHANGE_CONFIRM_RECOUP_REFRESH = 1041
}
internal class PurposeBuilder(private val purposeNum: Int) {
private val chunks = ArrayList<ByteArray>()
fun put(bytes: ByteArray): PurposeBuilder {
chunks.add(bytes)
return this
}
fun build(): ByteArray {
var payloadLen = 0
for (c in chunks) payloadLen += c.size
val size = 4 + 4 + payloadLen
val bytes = ByteArray(size)
size.toByteArray().copyInto(bytes, 0)
purposeNum.toByteArray().copyInto(bytes, 4)
var offset = 8
for (c in chunks) {
c.copyInto(bytes, offset)
offset += c.size
}
return bytes
}
}
private fun verifyPayment(sig: ByteArray, contractHash: ByteArray, merchantPub: ByteArray): Boolean {
val p = PurposeBuilder(MERCHANT_PAYMENT_OK)
.put(contractHash)
.build()
return crypto.eddsaVerify(p, sig, merchantPub)
}
/**
* Verifies an EdDSA payment signature made with [MERCHANT_PAYMENT_OK].
*
* @param merchantPub an EdDSA public key, usually belonging to a merchant.
*
* @return true if the signature is valid, false otherwise
*/
fun verifyPayment(sig: String, contractHash: String, merchantPub: String): Boolean {
val sigBytes = Base32Crockford.decode(sig)
val hashBytes = Base32Crockford.decode(contractHash)
val pubBytes = Base32Crockford.decode(merchantPub)
return verifyPayment(sigBytes, hashBytes, pubBytes)
}
/**
* Verifies an EdDSA wire fee signature made with [MASTER_WIRE_FEES].
*
* @param masterPub an EdDSA public key
*
* @return true if the signature is valid, false otherwise
*/
fun verifyWireFee(type: String, wireFee: WireFee, masterPub: String): Boolean {
val p = PurposeBuilder(MASTER_WIRE_FEES)
.put(crypto.sha512("$type\u0000".encodeToByteArray()))
.put(wireFee.startStamp.roundedToByteArray())
.put(wireFee.endStamp.roundedToByteArray())
.put(wireFee.wireFee.toByteArray())
.put(wireFee.closingFee.toByteArray())
.build()
val sig = Base32Crockford.decode(wireFee.signature)
val pub = Base32Crockford.decode(masterPub)
return crypto.eddsaVerify(p, sig, pub)
}
/**
* Verifies an EdDSA denomination record signature made with [MASTER_DENOMINATION_KEY_VALIDITY].
*
* @param masterPub an EdDSA public key
*
* @return true if the signature is valid, false otherwise
*/
fun verifyDenominationRecord(d: DenominationRecord, masterPub: String): Boolean {
val pub = Base32Crockford.decode(masterPub)
val p = PurposeBuilder(MASTER_DENOMINATION_KEY_VALIDITY)
.put(pub)
.put(d.stampStart.roundedToByteArray())
.put(d.stampExpireWithdraw.roundedToByteArray())
.put(d.stampExpireDeposit.roundedToByteArray())
.put(d.stampExpireLegal.roundedToByteArray())
.put(d.value.toByteArray())
.put(d.feeWithdraw.toByteArray())
.put(d.feeDeposit.toByteArray())
.put(d.feeRefresh.toByteArray())
.put(d.feeRefund.toByteArray())
.put(Base32Crockford.decode(d.denomPubHash))
.build()
val sig = Base32Crockford.decode(d.masterSig)
return crypto.eddsaVerify(p, sig, pub)
}
/**
* Verifies an EdDSA wire account signature made with [MASTER_WIRE_DETAILS].
*
* @param masterPub an EdDSA public key
*
* @return true if the signature is valid, false otherwise
*/
fun verifyWireAccount(paytoUri: String, signature: String, masterPub: String): Boolean {
val h = crypto.kdf(
64,
"exchange-wire-signature".encodeToByteArray(),
"$paytoUri\u0000".encodeToByteArray(),
ByteArray(0)
)
val p = PurposeBuilder(MASTER_WIRE_DETAILS)
.put(h)
.build()
val sig = Base32Crockford.decode(signature)
val pub = Base32Crockford.decode(masterPub)
return crypto.eddsaVerify(p, sig, pub)
}
}
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