From 0ef14ef5a257c794b51440dfaf16d44797f08778 Mon Sep 17 00:00:00 2001
From: Thomas HUET <thomas.huet@acinq.fr>
Date: Fri, 3 Oct 2025 11:48:15 +0200
Subject: [PATCH] Offers in EUR

---
 .../kotlin/fr/acinq/lightning/NodeParams.kt          |  2 +-
 .../fr/acinq/lightning/payment/OfferManager.kt       | 12 ++++--------
 .../kotlin/fr/acinq/lightning/wire/OfferTypes.kt     |  5 +++--
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt
index fd2bcc079..9563cd2d7 100644
--- a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt
+++ b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt
@@ -283,7 +283,7 @@ data class NodeParams(
     fun randomOffer(trampolineNodeId: PublicKey, amount: MilliSatoshi?, description: String?): Pair<OfferTypes.Offer, PrivateKey> {
         // We generate a random nonce to ensure that this offer is unique.
         val nonce = randomBytes32()
-        return OfferManager.deterministicOffer(chainHash, nodePrivateKey, trampolineNodeId, amount, description, nonce)
+        return OfferManager.deterministicOffer(chainHash, nodePrivateKey, trampolineNodeId, amount?.toLong(), description, nonce)
     }
 
 }
diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/payment/OfferManager.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/payment/OfferManager.kt
index 9760ebbde..3ee21b6d4 100644
--- a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/payment/OfferManager.kt
+++ b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/payment/OfferManager.kt
@@ -20,6 +20,7 @@ import fr.acinq.lightning.message.OnionMessages.buildMessage
 import fr.acinq.lightning.utils.currentTimestampMillis
 import fr.acinq.lightning.utils.toByteVector
 import fr.acinq.lightning.wire.*
+import fr.acinq.lightning.wire.OfferTypes.OfferAmount
 import kotlinx.coroutines.flow.MutableSharedFlow
 
 sealed class OnionMessageAction {
@@ -232,7 +233,7 @@ class OfferManager(val nodeParams: NodeParams, val walletParams: WalletParams, v
     private fun isOurOffer(offer: OfferTypes.Offer, pathId: ByteVector?, blindedPrivateKey: PrivateKey): Boolean = when {
         pathId != null && pathId.size() != 32 -> false
         else -> {
-            val expected = deterministicOffer(nodeParams.chainHash, nodeParams.nodePrivateKey, walletParams.trampolineNode.id, offer.amountMsat, offer.description, pathId?.let { ByteVector32(it) })
+            val expected = deterministicOffer(nodeParams.chainHash, nodeParams.nodePrivateKey, walletParams.trampolineNode.id, offer.records.get<OfferAmount>()?.amount, offer.description, pathId?.let { ByteVector32(it) })
             expected == Pair(offer, blindedPrivateKey)
         }
     }
@@ -246,7 +247,7 @@ class OfferManager(val nodeParams: NodeParams, val walletParams: WalletParams, v
             chainHash: BlockHash,
             nodePrivateKey: PrivateKey,
             trampolineNodeId: PublicKey,
-            amount: MilliSatoshi?,
+            amount: Long?,
             description: String?,
             pathId: ByteVector32?,
         ): Pair<OfferTypes.Offer, PrivateKey> {
@@ -255,15 +256,10 @@ class OfferManager(val nodeParams: NodeParams, val walletParams: WalletParams, v
             //  - the offer parameters (amount, description and pathId)
             //  - our trampoline node, which is used as an introduction node for the offer's blinded path
             //  - our private key, which ensures that nobody else can generate the same path key secret
-            val tweak = when {
-                amount == null && description == null && pathId == null -> "bolt 12 default offer".encodeToByteArray().byteVector()
-                else -> {
+            val tweak =
                     "bolt 12 deterministic offer".encodeToByteArray().byteVector() +
-                            Crypto.sha256("offer amount".encodeToByteArray() + (amount?.let { Pack.writeInt64BE(it.msat) } ?: ByteArray(0))) +
                             Crypto.sha256("offer description".encodeToByteArray() + (description?.encodeToByteArray() ?: ByteArray(0))) +
                             Crypto.sha256("offer path_id".encodeToByteArray().byteVector() + (pathId ?: ByteVector.empty))
-                }
-            }
             val sessionKey = PrivateKey(Crypto.sha256(tweak + trampolineNodeId.value + nodePrivateKey.value).byteVector32())
             return OfferTypes.Offer.createBlindedOffer(chainHash, nodePrivateKey, trampolineNodeId, amount, description, Features.empty, sessionKey, pathId)
         }
diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/wire/OfferTypes.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/wire/OfferTypes.kt
index 7b11a5d73..7df84cd60 100644
--- a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/wire/OfferTypes.kt
+++ b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/wire/OfferTypes.kt
@@ -797,7 +797,7 @@ object OfferTypes {
                 chainHash: BlockHash,
                 nodePrivateKey: PrivateKey,
                 trampolineNodeId: PublicKey,
-                amount: MilliSatoshi?,
+                amount: Long?,
                 description: String?,
                 features: Features,
                 blindedPathSessionKey: PrivateKey,
@@ -811,7 +811,8 @@ object OfferTypes {
                 )
                 val tlvs = setOfNotNull(
                     if (chainHash != Block.LivenetGenesisBlock.hash) OfferChains(listOf(chainHash)) else null,
-                    amount?.let { OfferAmount(it.toLong()) },
+                    amount?.let { OfferAmount(it) },
+                    amount?.let { OfferCurrency("EUR") },
                     description?.let { OfferDescription(it) },
                     features.bolt12Features().let { if (it != Features.empty) OfferFeatures(it.toByteArray().toByteVector()) else null },
                     // Note that we don't include an offer_node_id since we're using a blinded path.