Add Taler common multiplatform library to project

1 files changed, 55 insertions, 0 deletions

diff --git a/wallet/src/commonMain/kotlin/net/taler/wallet/kotlin/crypto/CryptoImpl.kt b/wallet/src/commonMain/kotlin/net/taler/wallet/kotlin/crypto/CryptoImpl.kt
new file mode 100644
index 0000000..0780e45
--- /dev/null
+++ b/wallet/src/commonMain/kotlin/net/taler/wallet/kotlin/crypto/CryptoImpl.kt
@@ -0,0 +1,55 @@
+/*
+ * 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.crypto.CryptoImpl.Companion.toByteArray
+
+abstract class CryptoImpl : Crypto {
+
+    companion object {
+        fun Int.toByteArray(): ByteArray {
+            val bytes = ByteArray(4)
+            bytes[3] = (this and 0xFFFF).toByte()
+            bytes[2] = ((this ushr 8) and 0xFFFF).toByte()
+            bytes[1] = ((this ushr 16) and 0xFFFF).toByte()
+            bytes[0] = ((this ushr 24) and 0xFFFF).toByte()
+            return bytes
+        }
+
+        fun Long.toByteArray() = ByteArray(8).apply {
+            var l = this@toByteArray
+            for (i in 7 downTo 0) {
+                this[i] = (l and 0xFF).toByte()
+                l = l shr 8
+            }
+        }
+    }
+
+    override fun kdf(outputLength: Int, ikm: ByteArray, salt: ByteArray, info: ByteArray): ByteArray {
+        return Kdf.kdf(outputLength, ikm, salt, info, { sha256(it) }, { sha512(it) })
+    }
+
+    override fun setupRefreshPlanchet(secretSeed: ByteArray, coinNumber: Int): FreshCoin {
+        val info = "taler-coin-derivation".encodeToByteArray()
+        val salt = coinNumber.toByteArray()
+        val out = kdf(64, secretSeed, salt, info)
+        val coinPrivateKey = out.copyOfRange(0, 32)
+        val bks = out.copyOfRange(32, 64)
+        return FreshCoin(eddsaGetPublic(coinPrivateKey), coinPrivateKey, bks)
+    }
+
+}