Increase confidential transactions fee (#7063)

2026-06-03 08:46:46 +00:00 · 2026-05-06 17:15:39 -04:00
parent b831b661ed
commit ed6de36cb4
16 changed files with 275 additions and 30 deletions
--- a/include/xrpl/protocol/Protocol.h
+++ b/include/xrpl/protocol/Protocol.h
@@ -348,6 +348,9 @@ std::size_t constexpr kEC_CONVERT_BACK_PROOF_LENGTH = 816;
 /** Length of the ZKProof for ConfidentialMPTClawback. */
 std::size_t constexpr kEC_CLAWBACK_PROOF_LENGTH = 64;

+/** Extra base fee multiplier charged to confidential MPT transactions. */
+std::uint32_t constexpr kCONFIDENTIAL_FEE_MULTIPLIER = 9;
+
 /** Compressed EC point prefix for even y-coordinate */
 std::uint8_t constexpr kEC_COMPRESSED_PREFIX_EVEN_Y = 0x02;

--- a/include/xrpl/tx/transactors/token/ConfidentialMPTClawback.h
+++ b/include/xrpl/tx/transactors/token/ConfidentialMPTClawback.h
@@ -32,6 +32,9 @@ public:
    static NotTEC
    preflight(PreflightContext const& ctx);

+    static XRPAmount
+    calculateBaseFee(ReadView const& view, STTx const& tx);
+
    static TER
    preclaim(PreclaimContext const& ctx);

--- a/include/xrpl/tx/transactors/token/ConfidentialMPTConvert.h
+++ b/include/xrpl/tx/transactors/token/ConfidentialMPTConvert.h
@@ -34,6 +34,9 @@ public:
    static NotTEC
    preflight(PreflightContext const& ctx);

+    static XRPAmount
+    calculateBaseFee(ReadView const& view, STTx const& tx);
+
    static TER
    preclaim(PreclaimContext const& ctx);

--- a/include/xrpl/tx/transactors/token/ConfidentialMPTConvertBack.h
+++ b/include/xrpl/tx/transactors/token/ConfidentialMPTConvertBack.h
@@ -35,6 +35,9 @@ public:
    static NotTEC
    preflight(PreflightContext const& ctx);

+    static XRPAmount
+    calculateBaseFee(ReadView const& view, STTx const& tx);
+
    static TER
    preclaim(PreclaimContext const& ctx);

--- a/include/xrpl/tx/transactors/token/ConfidentialMPTMergeInbox.h
+++ b/include/xrpl/tx/transactors/token/ConfidentialMPTMergeInbox.h
@@ -36,6 +36,9 @@ public:
    static NotTEC
    preflight(PreflightContext const& ctx);

+    static XRPAmount
+    calculateBaseFee(ReadView const& view, STTx const& tx);
+
    static TER
    preclaim(PreclaimContext const& ctx);

--- a/include/xrpl/tx/transactors/token/ConfidentialMPTSend.h
+++ b/include/xrpl/tx/transactors/token/ConfidentialMPTSend.h
@@ -45,6 +45,9 @@ public:
    static NotTEC
    preflight(PreflightContext const& ctx);

+    static XRPAmount
+    calculateBaseFee(ReadView const& view, STTx const& tx);
+
    static TER
    preclaim(PreclaimContext const& ctx);

--- a/src/libxrpl/tx/transactors/token/ConfidentialMPTClawback.cpp
+++ b/src/libxrpl/tx/transactors/token/ConfidentialMPTClawback.cpp
@@ -2,12 +2,14 @@

 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/core/ServiceRegistry.h>
+#include <xrpl/ledger/ReadView.h>
 #include <xrpl/protocol/ConfidentialTransfer.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/LedgerFormats.h>
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/tx/Transactor.h>
@@ -45,6 +47,15 @@ ConfidentialMPTClawback::preflight(PreflightContext const& ctx)
    return tesSUCCESS;
 }

+XRPAmount
+ConfidentialMPTClawback::calculateBaseFee(ReadView const& view, STTx const& tx)
+{
+    // Transactor::calculateBaseFee = baseFee + (signerCount * baseFee).
+    // We charge kCONFIDENTIAL_FEE_MULTIPLIER extra base fees so the total is
+    // 10 * baseFee + (signerCount * baseFee).
+    return Transactor::calculateBaseFee(view, tx) + view.fees().base * kCONFIDENTIAL_FEE_MULTIPLIER;
+}
+
 TER
 ConfidentialMPTClawback::preclaim(PreclaimContext const& ctx)
 {
--- a/src/libxrpl/tx/transactors/token/ConfidentialMPTConvert.cpp
+++ b/src/libxrpl/tx/transactors/token/ConfidentialMPTConvert.cpp
@@ -3,11 +3,13 @@
 #include <xrpl/basics/Slice.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/core/ServiceRegistry.h>
+#include <xrpl/ledger/ReadView.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/ConfidentialTransfer.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/MPTIssue.h>
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/TER.h>
@@ -63,6 +65,15 @@ ConfidentialMPTConvert::preflight(PreflightContext const& ctx)
    return tesSUCCESS;
 }

+XRPAmount
+ConfidentialMPTConvert::calculateBaseFee(ReadView const& view, STTx const& tx)
+{
+    // Transactor::calculateBaseFee = baseFee + (signerCount * baseFee).
+    // We charge kCONFIDENTIAL_FEE_MULTIPLIER extra base fees so the total is
+    // 10 * baseFee + (signerCount * baseFee).
+    return Transactor::calculateBaseFee(view, tx) + view.fees().base * kCONFIDENTIAL_FEE_MULTIPLIER;
+}
+
 TER
 ConfidentialMPTConvert::preclaim(PreclaimContext const& ctx)
 {
--- a/src/libxrpl/tx/transactors/token/ConfidentialMPTConvertBack.cpp
+++ b/src/libxrpl/tx/transactors/token/ConfidentialMPTConvertBack.cpp
@@ -2,6 +2,7 @@

 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/core/ServiceRegistry.h>
+#include <xrpl/ledger/ReadView.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/ConfidentialTransfer.h>
 #include <xrpl/protocol/Feature.h>
@@ -48,6 +49,15 @@ ConfidentialMPTConvertBack::preflight(PreflightContext const& ctx)
    return tesSUCCESS;
 }

+XRPAmount
+ConfidentialMPTConvertBack::calculateBaseFee(ReadView const& view, STTx const& tx)
+{
+    // Transactor::calculateBaseFee = baseFee + (signerCount * baseFee).
+    // We charge kCONFIDENTIAL_FEE_MULTIPLIER extra base fees so the total is
+    // 10 * baseFee + (signerCount * baseFee).
+    return Transactor::calculateBaseFee(view, tx) + view.fees().base * kCONFIDENTIAL_FEE_MULTIPLIER;
+}
+
 /**
 * Verifies the cryptographic proofs for a ConvertBack transaction.
 *
--- a/src/libxrpl/tx/transactors/token/ConfidentialMPTMergeInbox.cpp
+++ b/src/libxrpl/tx/transactors/token/ConfidentialMPTMergeInbox.cpp
@@ -2,11 +2,13 @@

 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/core/ServiceRegistry.h>
+#include <xrpl/ledger/ReadView.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/ConfidentialTransfer.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/TER.h>
@@ -31,6 +33,15 @@ ConfidentialMPTMergeInbox::preflight(PreflightContext const& ctx)
    return tesSUCCESS;
 }

+XRPAmount
+ConfidentialMPTMergeInbox::calculateBaseFee(ReadView const& view, STTx const& tx)
+{
+    // Transactor::calculateBaseFee = baseFee + (signerCount * baseFee).
+    // We charge kCONFIDENTIAL_FEE_MULTIPLIER extra base fees so the total is
+    // 10 * baseFee + (signerCount * baseFee).
+    return Transactor::calculateBaseFee(view, tx) + view.fees().base * kCONFIDENTIAL_FEE_MULTIPLIER;
+}
+
 TER
 ConfidentialMPTMergeInbox::preclaim(PreclaimContext const& ctx)
 {
--- a/src/libxrpl/tx/transactors/token/ConfidentialMPTSend.cpp
+++ b/src/libxrpl/tx/transactors/token/ConfidentialMPTSend.cpp
@@ -1,6 +1,7 @@
 #include <xrpl/tx/transactors/token/ConfidentialMPTSend.h>

 #include <xrpl/core/ServiceRegistry.h>
+#include <xrpl/ledger/ReadView.h>
 #include <xrpl/ledger/helpers/CredentialHelpers.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/ConfidentialTransfer.h>
@@ -88,6 +89,15 @@ ConfidentialMPTSend::preflight(PreflightContext const& ctx)
    return tesSUCCESS;
 }

+XRPAmount
+ConfidentialMPTSend::calculateBaseFee(ReadView const& view, STTx const& tx)
+{
+    // Transactor::calculateBaseFee = baseFee + (signerCount * baseFee).
+    // We charge kCONFIDENTIAL_FEE_MULTIPLIER extra base fees so the total is
+    // 10 * baseFee + (signerCount * baseFee).
+    return Transactor::calculateBaseFee(view, tx) + view.fees().base * kCONFIDENTIAL_FEE_MULTIPLIER;
+}
+
 TER
 verifySendProofs(
    PreclaimContext const& ctx,
--- a/src/test/app/ConfidentialTransfer_test.cpp
+++ b/src/test/app/ConfidentialTransfer_test.cpp
@@ -2900,7 +2900,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        ConfidentialEnv confEnv{
            env,
            alice,
-            {{.account = bob, .payAmount = 1000, .convertAmount = 60}, {carol, 1000, 50}}};
+            {{.account = bob, .payAmount = 1000, .convertAmount = 60},
+             {.account = carol, .payAmount = 1000, .convertAmount = 50}}};
        auto& mptAlice = confEnv.mpt;

        {
@@ -2972,7 +2973,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            ConfidentialEnv zeroEnv{
                env2,
                alice2,
-                {{.account = bob2, .payAmount = 100, .convertAmount = 0}, {carol2, 50, 0}}};
+                {{.account = bob2, .payAmount = 100, .convertAmount = 0},
+                 {.account = carol2, .payAmount = 50, .convertAmount = 0}}};
            auto& mptAlice2 = zeroEnv.mpt;

            // Trying to send any amount with 0 spending balance must fail:
@@ -6057,7 +6059,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        ConfidentialEnv confEnv{
            env,
            alice,
-            {{.account = bob, .payAmount = 100, .convertAmount = 100}, {carol, 50, 50}}};
+            {{.account = bob, .payAmount = 100, .convertAmount = 100},
+             {.account = carol, .payAmount = 50, .convertAmount = 50}}};
        auto& mptAlice = confEnv.mpt;

        // Bob sends 10 to carol.  The send amount (10) and Bob's remaining balance
@@ -6205,7 +6208,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            ConfidentialEnv confEnv{
                env,
                alice,
-                {{.account = bob, .payAmount = 100, .convertAmount = 60}, {carol, 50, 30}}};
+                {{.account = bob, .payAmount = 100, .convertAmount = 60},
+                 {.account = carol, .payAmount = 50, .convertAmount = 30}}};
            auto& mptAlice = confEnv.mpt;

            // sender's encrypted amount has an invalid coordinate
@@ -6284,7 +6288,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            ConfidentialEnv confEnv{
                env,
                alice,
-                {{.account = bob, .payAmount = 100, .convertAmount = 60}, {carol, 50, 30}}};
+                {{.account = bob, .payAmount = 100, .convertAmount = 60},
+                 {.account = carol, .payAmount = 50, .convertAmount = 30}}};
            auto& mptAlice = confEnv.mpt;

            Buffer badProof(kEC_SEND_PROOF_LENGTH);
@@ -6310,7 +6315,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            ConfidentialEnv confEnv{
                env,
                alice,
-                {{.account = bob, .payAmount = 100, .convertAmount = 60}, {carol, 50, 30}}};
+                {{.account = bob, .payAmount = 100, .convertAmount = 60},
+                 {.account = carol, .payAmount = 50, .convertAmount = 30}}};
            auto& mptAlice = confEnv.mpt;

            // getTrivialCiphertext() has both C1 and C2 as valid (but trivial)
@@ -6402,7 +6408,10 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        Env env{*this, features};
        Account const alice("alice"), bob("bob"), carol("carol");
        ConfidentialEnv confEnv{
-            env, alice, {{.account = bob, .payAmount = 100, .convertAmount = 60}, {carol, 50, 30}}};
+            env,
+            alice,
+            {{.account = bob, .payAmount = 100, .convertAmount = 60},
+             {.account = carol, .payAmount = 50, .convertAmount = 30}}};
        auto& mptAlice = confEnv.mpt;

        // The x-coordinate of the NIST P-256 generator point — a real,
@@ -6586,7 +6595,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        ConfidentialEnv confEnv{
            env,
            alice,
-            {{.account = bob, .payAmount = 100, .convertAmount = 100}, {carol, 50, 50}}};
+            {{.account = bob, .payAmount = 100, .convertAmount = 100},
+             {.account = carol, .payAmount = 50, .convertAmount = 50}}};
        auto& mptAlice = confEnv.mpt;

        auto const bobSpendingBefore =
@@ -6733,6 +6743,125 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        submitWithDivergentC1(Participant::Auditor);
    }

+    void
+    testConfidentialMPTBaseFee(FeatureBitset features)
+    {
+        testcase("test confidential transactions fee");
+        using namespace test::jtx;
+
+        auto setup =
+            [&](MPTTester& mpt, Account const& alice, Account const& bob, Account const& carol) {
+                mpt.create({
+                    .ownerCount = 1,
+                    .flags = tfMPTCanLock | tfMPTCanConfidentialAmount | tfMPTCanTransfer |
+                        tfMPTCanClawback,
+                });
+                mpt.authorize({.account = bob});
+                mpt.authorize({.account = carol});
+                mpt.pay(alice, bob, 100);
+                mpt.pay(alice, carol, 50);
+                mpt.generateKeyPair(alice);
+                mpt.generateKeyPair(bob);
+                mpt.generateKeyPair(carol);
+                mpt.set({.account = alice, .issuerPubKey = mpt.getPubKey(alice)});
+            };
+
+        // test expected base fee for confidential transactions
+        {
+            Env env{*this, features};
+            Account const alice("alice"), bob("bob"), carol("carol");
+            MPTTester mptAlice(env, alice, {.holders = {bob, carol}});
+            setup(mptAlice, alice, bob, carol);
+
+            auto const baseFee = env.current()->fees().base;
+            auto const expectedFee = baseFee * 10;
+
+            // lambda function to submit confidential transaction and check fee charged to the
+            // account
+            auto checkFee = [&](Account const& acct, auto&& submitFn) {
+                auto const before = env.balance(acct);
+                submitFn();
+                auto const after = env.balance(acct);
+                BEAST_EXPECT(before - after == expectedFee);
+            };
+
+            checkFee(bob, [&]() {
+                mptAlice.convert(
+                    {.account = bob,
+                     .amt = 50,
+                     .holderPubKey = mptAlice.getPubKey(bob),
+                     .fee = expectedFee});
+            });
+            checkFee(carol, [&]() {
+                mptAlice.convert(
+                    {.account = carol,
+                     .amt = 10,
+                     .holderPubKey = mptAlice.getPubKey(carol),
+                     .fee = expectedFee});
+            });
+            checkFee(bob, [&]() { mptAlice.mergeInbox({.account = bob, .fee = expectedFee}); });
+            checkFee(carol, [&]() { mptAlice.mergeInbox({.account = carol, .fee = expectedFee}); });
+            checkFee(bob, [&]() {
+                mptAlice.send({.account = bob, .dest = carol, .amt = 5, .fee = expectedFee});
+            });
+            checkFee(bob, [&]() {
+                mptAlice.convertBack({.account = bob, .amt = 5, .fee = expectedFee});
+            });
+            checkFee(alice, [&]() {
+                mptAlice.confidentialClaw(
+                    {.account = alice, .holder = carol, .amt = 15, .fee = expectedFee});
+            });
+        }
+
+        // test insufficient fee for confidential transactions
+        {
+            Env env{*this, features};
+            Account const alice("alice"), bob("bob"), carol("carol");
+            MPTTester mptAlice(env, alice, {.holders = {bob, carol}});
+            setup(mptAlice, alice, bob, carol);
+            auto const baseFee = env.current()->fees().base;
+
+            mptAlice.convert(
+                {.account = bob,
+                 .amt = 1,
+                 .holderPubKey = mptAlice.getPubKey(bob),
+                 .fee = baseFee * 10 - 1,
+                 .err = telINSUF_FEE_P});
+            mptAlice.mergeInbox({.account = bob, .fee = baseFee, .err = telINSUF_FEE_P});
+            mptAlice.send(
+                {.account = bob,
+                 .dest = carol,
+                 .amt = 1,
+                 .fee = baseFee * 9,
+                 .err = telINSUF_FEE_P});
+            mptAlice.convertBack({.account = bob, .amt = 1, .fee = baseFee, .err = telINSUF_FEE_P});
+            mptAlice.confidentialClaw(
+                {.account = alice,
+                 .holder = carol,
+                 .amt = 1,
+                 .fee = baseFee,
+                 .err = telINSUF_FEE_P});
+        }
+
+        // test excessive fee for confidential transactions
+        {
+            Env env{*this, features};
+            Account const alice("alice"), bob("bob"), carol("carol");
+            MPTTester mptAlice(env, alice, {.holders = {bob, carol}});
+            setup(mptAlice, alice, bob, carol);
+
+            auto const baseFee = env.current()->fees().base;
+            auto const highFee = baseFee * 20;
+            auto const bobBefore = env.balance(bob);
+            mptAlice.convert(
+                {.account = bob,
+                 .amt = 1,
+                 .holderPubKey = mptAlice.getPubKey(bob),
+                 .fee = highFee});
+            BEAST_EXPECT(env.balance(bob) == bobBefore - highFee);
+        }
+    }
+
    // Exercises every Confidential Transfer transaction type (MPTokenIssuanceSet,
    // Convert, MergeInbox, Send, ConvertBack) using tickets instead of regular account
    // sequence numbers.
@@ -7082,7 +7211,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            auto const bobSeq = env.seq(bob);
            auto const carolSeq = env.seq(carol);
            // 3 signers, Bob, Carol, Dave
-            auto const batchFee = batch::calcBatchFee(env, 1, 3);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 1, 3);

            auto const jv1 = mpt.sendJV({.account = bob, .dest = carol, .amt = 100}, bobSeq + 1);
            auto const jv2 = mpt.mergeInboxJV({.account = carol});
@@ -7119,7 +7248,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            // tfAllOrNothing — rejects the whole batch as 2nd txn proof is incorrect
            {
                auto const bobSeq = env.seq(bob);
-                auto const batchFee = batch::calcBatchFee(env, 0, 2);
+                auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

                auto const jv1 = mpt.sendJV({.account = bob, .dest = carol, .amt = 50}, bobSeq + 1);
                auto const jv2 = mpt.sendJV({.account = bob, .dest = dave, .amt = 60}, bobSeq + 2);
@@ -7140,7 +7269,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            // If we change batch mode to be tfIndependent — txn 1 applies, inner 2 fails.
            {
                auto const bobSeq = env.seq(bob);
-                auto const batchFee = batch::calcBatchFee(env, 0, 2);
+                auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

                auto const jv1 = mpt.sendJV({.account = bob, .dest = carol, .amt = 50}, bobSeq + 1);
                auto const jv2 = mpt.sendJV({.account = bob, .dest = dave, .amt = 60}, bobSeq + 2);
@@ -7176,7 +7305,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite

            {
                auto const bobSeq = env.seq(bob);
-                auto const batchFee = batch::calcBatchFee(env, 0, 2);
+                auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

                // jv1 is built against the current ledger state (spending=200).
                auto const jv1 =
@@ -7215,7 +7344,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
                setupBatchEnv(mpt2, alice2, bob2, carol2, dave2, 150, 0);

                auto const bobSeq = env2.seq(bob2);
-                auto const batchFee = batch::calcBatchFee(env2, 0, 2);
+                auto const batchFee = batch::calcConfidentialBatchFee(env2, 0, 2);

                auto const jv1 =
                    mpt2.sendJV({.account = bob2, .dest = carol2, .amt = 100}, bobSeq + 1);
@@ -7261,7 +7390,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        {
            auto const bobSeq = env.seq(bob);
            auto const carolSeq = env.seq(carol);
-            auto const batchFee = batch::calcBatchFee(env, 1, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 1, 2);

            auto const jv1 = mpt.sendJV({.account = bob, .dest = dave, .amt = 10}, bobSeq + 1);
            auto const jv2 = mpt.sendJV({.account = carol, .dest = dave, .amt = 5}, carolSeq);
@@ -7300,7 +7429,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        {
            auto const bobSeq = env.seq(bob);
            auto const carolSeq = env.seq(carol);
-            auto const batchFee = batch::calcBatchFee(env, 1, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 1, 2);

            // Both proofs fail range check (amount > balance)
            auto const jv1 = mpt.sendJV({.account = bob, .dest = dave, .amt = 200}, bobSeq + 1);
@@ -7323,7 +7452,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        {
            auto const bobSeq = env.seq(bob);
            auto const carolSeq = env.seq(carol);
-            auto const batchFee = batch::calcBatchFee(env, 1, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 1, 2);

            auto jv1 = mpt.sendJV({.account = bob, .dest = dave, .amt = 200}, bobSeq + 1);
            auto jv2 = mpt.sendJV({.account = carol, .dest = dave, .amt = 5}, carolSeq);
@@ -7363,7 +7492,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        {
            auto const bobSeq = env.seq(bob);
            auto const carolSeq = env.seq(carol);
-            auto const batchFee = batch::calcBatchFee(env, 1, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 1, 2);

            auto const jv1 = mpt.sendJV({.account = bob, .dest = dave, .amt = 200}, bobSeq + 1);
            auto const jv2 = mpt.sendJV({.account = carol, .dest = dave, .amt = 5}, carolSeq);
@@ -7383,7 +7512,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        {
            auto const bobSeq = env.seq(bob);
            auto const carolSeq = env.seq(carol);
-            auto const batchFee = batch::calcBatchFee(env, 1, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 1, 2);

            auto const jv1 = mpt.sendJV({.account = bob, .dest = dave, .amt = 10}, bobSeq + 1);
            auto const jv2 = mpt.sendJV({.account = carol, .dest = dave, .amt = 5}, carolSeq);
@@ -7424,7 +7553,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        {
            auto const bobSeq = env.seq(bob);
            auto const carolSeq = env.seq(carol);
-            auto const batchFee = batch::calcBatchFee(env, 1, 3);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 1, 3);

            auto const jv1 = mpt.sendJV({.account = bob, .dest = dave, .amt = 10}, bobSeq + 1);

@@ -7482,7 +7611,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            mpt.pay(alice, bob, 50);

            auto const bobSeq = env.seq(bob);
-            auto const batchFee = batch::calcBatchFee(env, 0, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

            // jv1: convert 50 regular MPT into confidential inbox
            auto const jv1 = mpt.convertJV({.account = bob, .amt = 50}, bobSeq + 1);
@@ -7523,7 +7652,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            mpt.pay(alice, bob, 50);

            auto const bobSeq = env.seq(bob);
-            auto const batchFee = batch::calcBatchFee(env, 0, 3);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 3);

            auto const jv1 = mpt.convertJV({.account = bob, .amt = 50}, bobSeq + 1);
            auto const jv2 = mpt.mergeInboxJV({.account = bob});
@@ -7586,7 +7715,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            auto const carolSeq = env.seq(carol);
            auto const daveSeq = env.seq(dave);
            // 2 extra signers (carol, dave), 4 inner txns
-            auto const batchFee = batch::calcBatchFee(env, 2, 4);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 2, 4);

            // jv1: bob sends 30 to carol
            auto const jv1 = mpt.sendJV({.account = bob, .dest = carol, .amt = 30}, bobSeq + 1);
@@ -7633,7 +7762,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            setupBatchEnv(mpt, alice, bob, carol, dave, 100, 0);

            auto const bobSeq = env.seq(bob);
-            auto const batchFee = batch::calcBatchFee(env, 0, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

            // jv1: bob sends 30 to carol (spending 100->70, version V->V+1)
            auto const jv1 = mpt.sendJV({.account = bob, .dest = carol, .amt = 30}, bobSeq + 1);
@@ -7679,7 +7808,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite

            auto const bobSeq = env.seq(bob);
            // 0 extra signers: all inner txns are from bob;
-            auto const batchFee = batch::calcBatchFee(env, 0, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

            // When the outer uses a ticket (seq=0), inner txns start from bobSeq, bobSeq+1.
            // jv2 must use chain state predicted after jv1 since both sends are from bob.
@@ -7721,7 +7850,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            env.close();

            auto const bobSeq = env.seq(bob);
-            auto const batchFee = batch::calcBatchFee(env, 0, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

            // jv1: proof bound to ticketSeq1.
            auto const jv1 = mpt.sendJV({.account = bob, .dest = carol, .amt = 40}, ticketSeq1);
@@ -7758,7 +7887,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            env.close();

            auto const bobSeq = env.seq(bob);
-            auto const batchFee = batch::calcBatchFee(env, 0, 2);
+            auto const batchFee = batch::calcConfidentialBatchFee(env, 0, 2);

            // Proof intentionally built with account seq (bobSeq+1) instead of ticketSeq.
            auto const badJV = mpt.sendJV({.account = bob, .dest = carol, .amt = 40}, bobSeq + 1);
@@ -8501,7 +8630,8 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        ConfidentialEnv confEnv{
            env,
            alice,
-            {{.account = bob, .payAmount = 1000, .convertAmount = 10}, {carol, 1000, 50}}};
+            {{.account = bob, .payAmount = 1000, .convertAmount = 10},
+             {.account = carol, .payAmount = 1000, .convertAmount = 50}}};
        auto& mptAlice = confEnv.mpt;

        uint64_t const sendAmount = 10;
@@ -8683,7 +8813,7 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
            alice,
            {{.account = bob},
             {.account = carol, .payAmount = 1000, .convertAmount = 50},
-             {dan, 1000, 50}}};
+             {.account = dan, .payAmount = 1000, .convertAmount = 50}}};
        auto& mptAlice = confEnv.mpt;

        uint64_t const sendAmount = 10;
@@ -9768,6 +9898,9 @@ class ConfidentialTransfer_test : public beast::unit_test::Suite
        // Crafted-proof Tests
        testSendSharedRandomnessViolation(features);

+        // Fee Tests
+        testConfidentialMPTBaseFee(features);
+
        // Ticket Tests
        testWithTickets(features);
        testConvertTicketProofBinding(features);
--- a/src/test/jtx/batch.h
+++ b/src/test/jtx/batch.h
@@ -21,6 +21,10 @@ namespace xrpl::test::jtx::batch {
 XRPAmount
 calcBatchFee(jtx::Env const& env, uint32_t const& numSigners, uint32_t const& txns = 0);

+/** Calculate Batch Fee with Confidential MPT inner transactions. */
+XRPAmount
+calcConfidentialBatchFee(jtx::Env const& env, uint32_t const& numSigners, uint32_t const& txns = 0);
+
 /** Batch. */
 json::Value
 outer(jtx::Account const& account, uint32_t seq, STAmount const& fee, std::uint32_t flags);
--- a/src/test/jtx/impl/batch.cpp
+++ b/src/test/jtx/impl/batch.cpp
@@ -37,6 +37,16 @@ calcBatchFee(test::jtx::Env const& env, uint32_t const& numSigners, uint32_t con
    return ((numSigners + 2) * feeDrops) + feeDrops * txns;
 }

+XRPAmount
+calcConfidentialBatchFee(
+    test::jtx::Env const& env,
+    uint32_t const& numSigners,
+    uint32_t const& txns)
+{
+    XRPAmount const feeDrops = env.current()->fees().base;
+    return ((numSigners + 2) * feeDrops) + feeDrops * 10 * txns;
+}
+
 // Batch.
 json::Value
 outer(jtx::Account const& account, uint32_t seq, STAmount const& fee, std::uint32_t flags)
--- a/src/test/jtx/impl/utility.cpp
+++ b/src/test/jtx/impl/utility.cpp
@@ -57,7 +57,22 @@ fillFee(json::Value& jv, ReadView const& view)
 {
    if (jv.isMember(jss::Fee))
        return;
-    jv[jss::Fee] = to_string(view.fees().base);
+
+    auto const base = view.fees().base;
+
+    // For confidential transactions, the fee higher because confidential
+    // transaction processing is more expensive.
+    auto const txType = jv[jss::TransactionType].asString();
+    if (txType == jss::ConfidentialMPTConvert || txType == jss::ConfidentialMPTConvertBack ||
+        txType == jss::ConfidentialMPTSend || txType == jss::ConfidentialMPTMergeInbox ||
+        txType == jss::ConfidentialMPTClawback)
+    {
+        jv[jss::Fee] = to_string(base * 10);
+    }
+    else
+    {
+        jv[jss::Fee] = to_string(base);
+    }
 }

 void
--- a/src/test/jtx/mpt.h
+++ b/src/test/jtx/mpt.h
@@ -12,6 +12,7 @@
 #include <xrpl/protocol/ConfidentialTransfer.h>
 #include <xrpl/protocol/TxFlags.h>
 #include <xrpl/protocol/UintTypes.h>
+#include <xrpl/protocol/XRPAmount.h>

 #include <cstdint>

@@ -208,6 +209,7 @@ struct MPTConvert
    std::optional<std::uint32_t> ownerCount = std::nullopt;
    std::optional<std::uint32_t> holderCount = std::nullopt;
    std::optional<std::uint32_t> flags = std::nullopt;
+    std::optional<XRPAmount> fee = std::nullopt;
    std::optional<TER> err = std::nullopt;
 };

@@ -220,6 +222,7 @@ struct MPTMergeInbox
    std::optional<std::uint32_t> ownerCount = std::nullopt;
    std::optional<std::uint32_t> holderCount = std::nullopt;
    std::optional<std::uint32_t> flags = std::nullopt;
+    std::optional<XRPAmount> fee = std::nullopt;
    std::optional<TER> err = std::nullopt;
 };

@@ -247,6 +250,7 @@ struct MPTConfidentialSend
    std::optional<std::uint32_t> ownerCount = std::nullopt;
    std::optional<std::uint32_t> holderCount = std::nullopt;
    std::optional<std::uint32_t> flags = std::nullopt;
+    std::optional<XRPAmount> fee = std::nullopt;
    std::optional<TER> err = std::nullopt;
 };

@@ -268,6 +272,7 @@ struct MPTConvertBack
    std::optional<std::uint32_t> ownerCount = std::nullopt;
    std::optional<std::uint32_t> holderCount = std::nullopt;
    std::optional<std::uint32_t> flags = std::nullopt;
+    std::optional<XRPAmount> fee = std::nullopt;
    std::optional<TER> err = std::nullopt;
 };

@@ -283,6 +288,7 @@ struct MPTConfidentialClawback
    std::optional<std::uint32_t> ownerCount = std::nullopt;
    std::optional<std::uint32_t> holderCount = std::nullopt;
    std::optional<std::uint32_t> flags = std::nullopt;
+    std::optional<XRPAmount> fee = std::nullopt;
    std::optional<TER> err = std::nullopt;
 };

@@ -599,11 +605,17 @@ private:

    template <typename A>
    TER
-    submit(A const& arg, json::Value const& jv)
+    submit(A const& arg, json::Value jv)
    {
        auto const expectedFlags = Txflags(arg.flags.value_or(0));
        auto const expectedTer = Ter(arg.err.value_or(tesSUCCESS));

+        if constexpr (requires { arg.fee; })
+        {
+            if (arg.fee)
+                jv[jss::Fee] = to_string(*arg.fee);
+        }
+
        std::optional<std::uint32_t> ticketSeq;
        if constexpr (requires { arg.ticketSeq; })
            ticketSeq = arg.ticketSeq;