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Merged
benma merged 1 commit into from
Aug 24, 2026
Merged

Require antiklepto for signing #176

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97 changes: 42 additions & 55 deletions api/firmware/btc.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -353,6 +353,9 @@ func (device *Device) nonAtomicBTCSign(
formatUnit messages.BTCSignInitRequest_FormatUnit,
) (*BTCSignResult, error) {
generatedOutputs := map[int][]byte{}
if !device.version.AtLeast(semver.NewSemVer(9, 4, 0)) {
return nil, UnsupportedError("9.4.0")
}
if !device.version.AtLeast(semver.NewSemVer(9, 10, 0)) {
for _, sc := range scriptConfigs {
if isTaproot(sc) {
Expand All @@ -369,8 +372,6 @@ func (device *Device) nonAtomicBTCSign(
}
}

supportsAntiklepto := device.version.AtLeast(semver.NewSemVer(9, 4, 0))

containsSilentPaymentOutputs := false
for _, output := range tx.Outputs {
if output.SilentPayment != nil {
Expand Down Expand Up @@ -415,7 +416,7 @@ func (device *Device) nonAtomicBTCSign(
inputIsSchnorr := isTaproot(scriptConfigs[input.ScriptConfigIndex])

// Anti-Klepto protocol not supported yet for Schnorr signatures.
performAntiklepto := supportsAntiklepto && isInputsPass2 && !inputIsSchnorr
performAntiklepto := isInputsPass2 && !inputIsSchnorr

var hostNonce []byte
if performAntiklepto {
Expand Down Expand Up @@ -555,8 +556,9 @@ func (device *Device) nonAtomicBTCSign(
}
}

// BTCSign signs a bitcoin or bitcoin-like transaction. The previous transactions of the inputs
// need to be provided if `BTCSignNeedsPrevTxs()` returns true.
// BTCSign signs a bitcoin or bitcoin-like transaction. Firmware v9.4.0 or newer is required to

@bznein bznein Aug 24, 2026

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Suggested change
// BTCSign signs a bitcoin or bitcoin-like transaction. Firmware v9.4.0 or newer is required to
// BTCSign signs a bitcoin or bitcoin-like transaction. Firmware v9.5.0 or newer is required to

@benma benma Aug 24, 2026

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Why? It's actually v9.4.0 for btc tx signing.

// ensure anti-klepto protection for ECDSA signatures. The previous transactions of the inputs need
// to be provided if `BTCSignNeedsPrevTxs()` returns true.
func (device *Device) BTCSign(
coin messages.BTCCoin,
scriptConfigs []*messages.BTCScriptConfigWithKeypath,
Expand Down Expand Up @@ -655,23 +657,16 @@ func (device *Device) nonAtomicBTCSignMessage(
if isTaproot(scriptConfig) {
return nil, errp.New("taproot not supported")
}
if !device.version.AtLeast(semver.NewSemVer(9, 2, 0)) {
return nil, UnsupportedError("9.2.0")
if !device.version.AtLeast(semver.NewSemVer(9, 5, 0)) {
return nil, UnsupportedError("9.5.0")
}

supportsAntiklepto := device.version.AtLeast(semver.NewSemVer(9, 5, 0))
var hostNonceCommitment *messages.AntiKleptoHostNonceCommitment
var hostNonce []byte

if supportsAntiklepto {
var err error
hostNonce, err = generateHostNonce()
if err != nil {
return nil, err
}
hostNonceCommitment = &messages.AntiKleptoHostNonceCommitment{
Commitment: antikleptoHostCommit(hostNonce),
}
hostNonce, err := generateHostNonce()
if err != nil {
return nil, err
}
hostNonceCommitment := &messages.AntiKleptoHostNonceCommitment{
Commitment: antikleptoHostCommit(hostNonce),
}

request := &messages.BTCRequest{
Expand All @@ -689,42 +684,33 @@ func (device *Device) nonAtomicBTCSignMessage(
return nil, err
}

var signature []byte
if supportsAntiklepto {
signerCommitment, ok := response.Response.(*messages.BTCResponse_AntikleptoSignerCommitment)
if !ok {
return nil, errp.New("unexpected response")
}
response, err := device.nonAtomicQueryBTC(&messages.BTCRequest{
Request: &messages.BTCRequest_AntikleptoSignature{
AntikleptoSignature: &messages.AntiKleptoSignatureRequest{
HostNonce: hostNonce,
},
signerCommitment, ok := response.Response.(*messages.BTCResponse_AntikleptoSignerCommitment)
if !ok {
return nil, errp.New("unexpected response")
}
response, err = device.nonAtomicQueryBTC(&messages.BTCRequest{
Request: &messages.BTCRequest_AntikleptoSignature{
AntikleptoSignature: &messages.AntiKleptoSignatureRequest{
HostNonce: hostNonce,
},
})
if err != nil {
return nil, err
}
},
})
if err != nil {
return nil, err
}

signResponse, ok := response.Response.(*messages.BTCResponse_SignMessage)
if !ok {
return nil, errp.New("unexpected response")
}
signature = signResponse.SignMessage.Signature
err = antikleptoVerify(
hostNonce,
signerCommitment.AntikleptoSignerCommitment.Commitment,
signature[:64],
)
if err != nil {
return nil, err
}
} else {
signResponse, ok := response.Response.(*messages.BTCResponse_SignMessage)
if !ok {
return nil, errp.New("unexpected response")
}
signature = signResponse.SignMessage.Signature
signResponse, ok := response.Response.(*messages.BTCResponse_SignMessage)
if !ok {
return nil, errp.New("unexpected response")
}
signature := signResponse.SignMessage.Signature
err = antikleptoVerify(
hostNonce,
signerCommitment.AntikleptoSignerCommitment.Commitment,
signature[:64],
)
if err != nil {
return nil, err
}

sig, recID := signature[:64], signature[64]
Expand All @@ -738,7 +724,8 @@ func (device *Device) nonAtomicBTCSignMessage(
}, nil
}

// BTCSignMessage signs a Bitcoin message.
// BTCSignMessage signs a Bitcoin message. Firmware v9.5.0 or newer is required to ensure
// anti-klepto protection.
func (device *Device) BTCSignMessage(
coin messages.BTCCoin,
scriptConfig *messages.BTCScriptConfigWithKeypath,
Expand Down
4 changes: 2 additions & 2 deletions api/firmware/btc_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -474,13 +474,13 @@ func TestBTCSignMessage(t *testing.T) {
},
[]byte("message"),
)
if env.version.AtLeast(semver.NewSemVer(9, 2, 0)) {
if env.version.AtLeast(semver.NewSemVer(9, 5, 0)) {
require.NoError(t, err)
require.Equal(t, expectedSig[:64], result.Signature)
require.Equal(t, byte(0), result.RecID)
require.Equal(t, result.ElectrumSig65, append([]byte{31}, expectedSig[:64]...))
} else {
require.EqualError(t, err, UnsupportedError("9.2.0").Error())
require.EqualError(t, err, UnsupportedError("9.5.0").Error())
}
})
}
Expand Down
72 changes: 23 additions & 49 deletions api/firmware/eth.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -191,8 +191,8 @@ func ETHIdentifyCase(recipientAddress string) messages.ETHAddressCase {
}

// ETHSign signs an ethereum transaction. It returns a 65 byte signature (R, S,
// and 1 byte recID). If len(data) > 6144, firmware v9.26.0 or newer is
// required.
// and 1 byte recID). Firmware v9.5.0 or newer is required to ensure anti-klepto protection. If
// len(data) > 6144, firmware v9.26.0 or newer is required.
func (device *Device) ETHSign(
chainID uint64,
keypath []uint32,
Expand Down Expand Up @@ -229,21 +229,17 @@ func (device *Device) nonAtomicETHSign(
data []byte,
recipientAddressCase messages.ETHAddressCase,
) ([]byte, error) {
supportsAntiklepto := device.version.AtLeast(semver.NewSemVer(9, 5, 0))
if !device.version.AtLeast(semver.NewSemVer(9, 5, 0)) {
return nil, UnsupportedError("9.5.0")
}
useStreaming := len(data) > ethStreamingThreshold
if useStreaming && !device.version.AtLeast(semver.NewSemVer(9, 26, 0)) {
return nil, UnsupportedError("9.26.0")
}

var hostNonceCommitment *messages.AntiKleptoHostNonceCommitment
var err error
var hostNonce []byte

if supportsAntiklepto {
hostNonceCommitment, hostNonce, err = handleHostNonceCommitment()
if err != nil {
return nil, err
}
hostNonceCommitment, hostNonce, err := handleHostNonceCommitment()
if err != nil {
return nil, err
}

coin, err := device.ethCoin(chainID)
Expand Down Expand Up @@ -285,14 +281,7 @@ func (device *Device) nonAtomicETHSign(
}
}

if supportsAntiklepto {
return device.nonAtomicHandleSignerNonceCommitment(response, hostNonce)
}
signResponse, ok := response.Response.(*messages.ETHResponse_Sign)
if !ok {
return nil, errp.New("unexpected response")
}
return signResponse.Sign.Signature, nil
return device.nonAtomicHandleSignerNonceCommitment(response, hostNonce)
}

// ETHSignEIP1559 signs an ethereum EIP1559 transaction. It returns a 65 byte
Expand Down Expand Up @@ -395,7 +384,8 @@ func (device *Device) nonAtomicETHSignEIP1559(
// ETHSignMessage signs an Ethereum message. The provided msg will be prefixed with "\x19Ethereum
// Signed Message\n" + len(msg) in the hardware, e.g. "\x19Ethereum Signed dMessage\n5hello" (yes, the len prefix is the
// ascii representation with no fixed size or delimiter, WTF).
// 27 is added to the recID to denote an uncompressed pubkey.
// 27 is added to the recID to denote an uncompressed pubkey. Firmware v9.5.0 or newer is required
// to ensure anti-klepto protection.
func (device *Device) ETHSignMessage(
chainID uint64,
keypath []uint32,
Expand All @@ -414,20 +404,16 @@ func (device *Device) nonAtomicETHSignMessage(
if len(msg) > 1024 {
return nil, errp.New("message too large")
}
if !device.version.AtLeast(semver.NewSemVer(9, 5, 0)) {
return nil, UnsupportedError("9.5.0")
}

supportsAntiklepto := device.version.AtLeast(semver.NewSemVer(9, 5, 0))
var hostNonceCommitment *messages.AntiKleptoHostNonceCommitment
var hostNonce []byte

if supportsAntiklepto {
var err error
hostNonce, err = generateHostNonce()
if err != nil {
return nil, err
}
hostNonceCommitment = &messages.AntiKleptoHostNonceCommitment{
Commitment: antikleptoHostCommit(hostNonce),
}
hostNonce, err := generateHostNonce()
if err != nil {
return nil, err
}
hostNonceCommitment := &messages.AntiKleptoHostNonceCommitment{
Commitment: antikleptoHostCommit(hostNonce),
}

coin, err := device.ethCoin(chainID)
Expand All @@ -450,24 +436,12 @@ func (device *Device) nonAtomicETHSignMessage(
return nil, err
}

if supportsAntiklepto {
signature, err := device.nonAtomicHandleSignerNonceCommitment(response, hostNonce)
if err != nil {
return nil, err
}
// 27 is the magic constant to add to the recoverable ID to denote an uncompressed pubkey.
signature[64] += 27
return signature, nil
}

signResponse, ok := response.Response.(*messages.ETHResponse_Sign)
if !ok {
return nil, errp.New("unexpected response")
signature, err := device.nonAtomicHandleSignerNonceCommitment(response, hostNonce)
if err != nil {
return nil, err
}
signature := signResponse.Sign.Signature
// 27 is the magic constant to add to the recoverable ID to denote an uncompressed pubkey.
signature[64] += 27

return signature, nil
}

Expand Down