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fix: num sig zero is invalid #1966

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Merged
thesimplekid merged 2 commits into from
May 17, 2026
Merged

fix: num sig zero is invalid #1966

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9215f28
fix: num sig zero is invalid
thesimplekid May 14, 2026
b3e5de8
fix: reject impossible empty refund tags
thesimplekid May 14, 2026
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223 changes: 194 additions & 29 deletions crates/cashu/src/nuts/nut10/spending_conditions.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -110,15 +110,19 @@ impl TryFrom<Nut10Secret> for SpendingConditions {
conditions: secret
.secret_data()
.tags()
.and_then(|t| t.clone().try_into().ok()),
.cloned()
.map(Conditions::try_from)
.transpose()?,
}),
Kind::HTLC => Ok(Self::HTLCConditions {
data: Sha256Hash::from_str(secret.secret_data().data())
.map_err(|_| Error::NUT14(nut14::Error::InvalidHash))?,
conditions: secret
.secret_data()
.tags()
.and_then(|t| t.clone().try_into().ok()),
.cloned()
.map(Conditions::try_from)
.transpose()?,
}),
}
}
Expand All @@ -142,6 +146,7 @@ impl From<SpendingConditions> for super::Secret {
impl TryFrom<SpendingConditions> for Secret {
type Error = Error;
fn try_from(conditions: SpendingConditions) -> Result<Secret, Self::Error> {
conditions.validate()?;
let secret: Nut10Secret = conditions.into();
Secret::try_from(secret)
}
Expand Down Expand Up @@ -176,6 +181,61 @@ pub struct Conditions {
}

impl Conditions {
fn validate(&self, primary_key_count: u64) -> Result<(), Error> {
if let Some(n) = self.num_sigs {
if n == 0 {
return Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired));
}

let available_keys =
primary_key_count + self.pubkeys.as_ref().map(Vec::len).unwrap_or(0) as u64;
if n > available_keys {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleMultisigConfiguration {
required: n,
available: available_keys,
},
));
}
}

match (&self.refund_keys, self.num_sigs_refund) {
(Some(_), Some(0)) => {
return Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired));
}
(Some(refund_keys), Some(required)) if required > refund_keys.len() as u64 => {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleRefundMultisigConfiguration {
required,
available: refund_keys.len() as u64,
},
));
}
(None, Some(0)) => {
return Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired));
}
(None, Some(required)) => {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleRefundMultisigConfiguration {
required,
available: 0,
},
));
}
(Some(refund_keys), None) if refund_keys.is_empty() => {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleRefundMultisigConfiguration {
required: 1,
available: 0,
},
));
}
_ => {}
}

Ok(())
}

/// Create new Spending [`Conditions`]
pub fn new(
locktime: Option<u64>,
Expand All @@ -192,40 +252,39 @@ impl Conditions {
);
}

if let Some(n) = num_sigs {
let available_keys = 1 + pubkeys.as_ref().map(Vec::len).unwrap_or(0);
if n > available_keys as u64 {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleMultisigConfiguration {
required: n,
available: available_keys as u64,
},
));
}
}

if let Some(n) = num_sigs_refund {
let refund_key_count = refund_keys.as_ref().map(Vec::len).unwrap_or(0);
if n > refund_key_count as u64 {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleMultisigConfiguration {
required: n,
available: refund_key_count as u64,
},
));
}
}

Ok(Self {
let conditions = Self {
locktime,
pubkeys,
refund_keys,
num_sigs,
sig_flag: sig_flag.unwrap_or_default(),
num_sigs_refund,
})
};
conditions.validate(1)?;

Ok(conditions)
}
}

impl SpendingConditions {
fn validate(&self) -> Result<(), Error> {
match self {
Self::P2PKConditions { conditions, .. } => {
if let Some(conditions) = conditions {
conditions.validate(1)?;
}
}
Self::HTLCConditions { conditions, .. } => {
if let Some(conditions) = conditions {
conditions.validate(0)?;
}
}
}

Ok(())
}
}

impl From<Conditions> for Vec<Vec<String>> {
fn from(conditions: Conditions) -> Vec<Vec<String>> {
let Conditions {
Expand All @@ -251,7 +310,7 @@ impl From<Conditions> for Vec<Vec<String>> {
tags.push(Tag::NSigs(num_sigs).as_vec());
}

if let Some(refund_keys) = refund_keys {
if let Some(refund_keys) = refund_keys.filter(|keys| !keys.is_empty()) {
tags.push(Tag::Refund(refund_keys).as_vec())
}

Expand Down Expand Up @@ -311,6 +370,32 @@ impl TryFrom<Vec<Vec<String>>> for Conditions {
}
}

if let Some(0) = num_sigs {
return Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired));
}
if let Some(0) = num_sigs_refund {
return Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired));
}

if let Some(refund_keys) = &refund_keys {
let required = num_sigs_refund.unwrap_or(1);
if required > refund_keys.len() as u64 {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleRefundMultisigConfiguration {
required,
available: refund_keys.len() as u64,
},
));
}
} else if let Some(required) = num_sigs_refund {
return Err(Error::NUT11(
crate::nut11::Error::ImpossibleRefundMultisigConfiguration {
required,
available: 0,
},
));
}

Ok(Conditions {
locktime,
pubkeys,
Expand Down Expand Up @@ -362,4 +447,84 @@ mod tests {
Some(vec![PublicKey::from_str(pk1).unwrap()])
);
}

#[test]
fn test_empty_refund_tag_is_rejected() {
let tags = vec![
vec!["refund".to_string()],
vec!["sigflag".to_string(), "SIG_INPUTS".to_string()],
];

let result = Conditions::try_from(tags);

assert!(matches!(
result,
Err(Error::NUT11(
crate::nut11::Error::ImpossibleRefundMultisigConfiguration {
required: 1,
available: 0
}
))
));
}

#[test]
fn test_empty_refund_keys_are_not_serialized() {
let conditions = Conditions {
locktime: Some(1),
pubkeys: None,
refund_keys: Some(vec![]),
num_sigs: None,
sig_flag: crate::SigFlag::default(),
num_sigs_refund: None,
};

let tags = Vec::<Vec<String>>::from(conditions);

assert!(!tags
.iter()
.any(|tag| tag.first() == Some(&"refund".to_string())));
}

#[test]
fn test_n_sigs_refund_without_refund_keys_is_rejected() {
let tags = vec![
vec!["n_sigs_refund".to_string(), "1".to_string()],
vec!["sigflag".to_string(), "SIG_INPUTS".to_string()],
];

let result = Conditions::try_from(tags);

assert!(matches!(
result,
Err(Error::NUT11(
crate::nut11::Error::ImpossibleRefundMultisigConfiguration {
required: 1,
available: 0
}
))
));
}

#[test]
fn test_spending_conditions_try_from_propagates_invalid_tags() {
let pubkey = PublicKey::from_str(
"026562efcfadc8e86d44da6a8adf80633d974302e62c850774db1fb36ff4cc7198",
)
.unwrap();
let nut10_secret = Nut10Secret::new(
Kind::P2PK,
crate::nuts::nut10::SecretData::new(
pubkey.to_string(),
Some(vec![vec!["n_sigs".to_string(), "0".to_string()]]),
),
);

let result = SpendingConditions::try_from(nut10_secret);

assert!(matches!(
result,
Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired))
));
}
}
26 changes: 18 additions & 8 deletions crates/cashu/src/nuts/nut10/tag.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -116,12 +116,17 @@ where
TagKind::SigFlag => Ok(Tag::SigFlag(SigFlag::from_str(
tag.get(1).ok_or(Error::TagValueNotFound)?.as_ref(),
)?)),
TagKind::NSigs => Ok(Tag::NSigs(
tag.get(1)
TagKind::NSigs => {
let sigs = tag
.get(1)
.ok_or(Error::TagValueNotFound)?
.as_ref()
.parse()?,
)),
.parse()?;
if sigs == 0 {
return Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired));
}
Ok(Tag::NSigs(sigs))
}
TagKind::Locktime => Ok(Tag::LockTime(
tag.get(1)
.ok_or(Error::TagValueNotFound)?
Expand All @@ -146,12 +151,17 @@ where

Ok(Self::PubKeys(pubkeys))
}
TagKind::NSigsRefund => Ok(Tag::NSigsRefund(
tag.get(1)
TagKind::NSigsRefund => {
let sigs = tag
.get(1)
.ok_or(Error::TagValueNotFound)?
.as_ref()
.parse()?,
)),
.parse()?;
if sigs == 0 {
return Err(Error::NUT11(crate::nut11::Error::ZeroSignaturesRequired));
}
Ok(Tag::NSigsRefund(sigs))
}
TagKind::Custom(name) => {
let tags = tag
.iter()
Expand Down
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