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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.lib.wallet.crypto
import net.taler.lib.common.Amount
import net.taler.lib.crypto.Crypto
import net.taler.lib.crypto.EddsaKeyPair
import net.taler.lib.wallet.crypto.Signature.PurposeBuilder
import net.taler.lib.crypto.Base32Crockford
import net.taler.lib.wallet.toByteArray
internal class Planchet(private val crypto: Crypto) {
data class CreationRequest(
val value: Amount,
val feeWithdraw: Amount,
val denomPub: String,
val reservePub: String,
val reservePriv: String
)
data class CreationResult(
val coinPub: String,
val coinPriv: String,
val reservePub: String,
val denomPubHash: String,
val denomPub: String,
val blindingKey: String,
val withdrawSig: String,
val coinEv: String,
val coinValue: Amount,
val coinEvHash: String
)
internal fun create(req: CreationRequest, coinKeyPair: EddsaKeyPair, blindingFactor: ByteArray): CreationResult {
val reservePub = Base32Crockford.decode(req.reservePub)
val reservePriv = Base32Crockford.decode(req.reservePriv)
val denomPub = Base32Crockford.decode(req.denomPub)
val coinPubHash = crypto.sha512(coinKeyPair.publicKey)
val ev = crypto.rsaBlind(coinPubHash, blindingFactor, denomPub)
val amountWithFee = req.value + req.feeWithdraw
val denomPubHash = crypto.sha512(denomPub)
val evHash = crypto.sha512(ev)
val withdrawRequest = PurposeBuilder(Signature.RESERVE_WITHDRAW)
.put(reservePub)
.put(amountWithFee.toByteArray())
.put(req.feeWithdraw.toByteArray())
.put(denomPubHash)
.put(evHash)
.build()
val sig = crypto.eddsaSign(withdrawRequest, reservePriv)
return CreationResult(
blindingKey = Base32Crockford.encode(blindingFactor),
coinEv = Base32Crockford.encode(ev),
coinPriv = Base32Crockford.encode(coinKeyPair.privateKey),
coinPub = Base32Crockford.encode(coinKeyPair.publicKey),
coinValue = req.value,
denomPub = req.denomPub,
denomPubHash = Base32Crockford.encode(denomPubHash),
reservePub = req.reservePub,
withdrawSig = Base32Crockford.encode(sig),
coinEvHash = Base32Crockford.encode(evHash),
)
}
/**
* Create a pre-coin ([Planchet]) of the given [CreationRequest].
*/
fun create(req: CreationRequest): CreationResult {
val coinKeyPair = crypto.createEddsaKeyPair()
val blindingFactor = crypto.getRandomBytes(32)
return create(req, coinKeyPair, blindingFactor)
}
}
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