diff --git a/src/schnorrsig.rs b/src/schnorrsig.rs index c369e23d2..195f0f965 100644 --- a/src/schnorrsig.rs +++ b/src/schnorrsig.rs @@ -76,6 +76,18 @@ impl str::FromStr for Signature { } /// Opaque data structure that holds a keypair consisting of a secret and a public key. +/// +/// # Serde support +/// [`Serialize`] and [`Deserialize`] are not implemented for this type, even with the `serde` +/// feature active. This is due to security considerations, see the [`serde_keypair`] documentation +/// for details. +/// +/// If the `serde` and `global-context[-less-secure]` features are active `KeyPair`s can be serialized and +/// deserialized by annotating them with `#[serde(with = "secp256k1::schnorrsig::serde_keypair")]` +/// inside structs or enums for which [`Serialize`] and [`Deserialize`] are being derived. +/// +/// [`Deserialize`]: serde::Deserialize +/// [`Serialize`]: serde::Serialize #[derive(Copy, Clone, PartialEq, Eq, Debug, PartialOrd, Ord, Hash)] pub struct KeyPair(ffi::KeyPair); @@ -596,6 +608,45 @@ impl Secp256k1 { } } +/// Serde implementation for the [`KeyPair`] type. +/// +/// Only the secret key part of the [`KeyPair`] is serialized using the [`SecretKey`] serde +/// implementation, meaning the public key has to be regenerated on deserialization. +/// +/// **Attention:** The deserialization algorithm uses the [global context] to generate the public key +/// belonging to the secret key to form a [`KeyPair`]. The typical caveats regarding use of the +/// [global context] with secret data apply. +/// +/// [`SecretKey`]: crate::SecretKey +/// [global context]: crate::SECP256K1 +#[cfg(all(feature = "global-context-less-secure", feature = "serde"))] +pub mod serde_keypair { + use serde::{Deserialize, Deserializer, Serialize, Serializer}; + use schnorrsig::KeyPair; + use SecretKey; + + #[allow(missing_docs)] + pub fn serialize(key: &KeyPair, serializer: S) -> Result + where + S: Serializer, + { + SecretKey::from_keypair(key).serialize(serializer) + } + + #[allow(missing_docs)] + pub fn deserialize<'de, D>(deserializer: D) -> Result + where + D: Deserializer<'de>, + { + let secret_key = SecretKey::deserialize(deserializer)?; + + Ok(KeyPair::from_secret_key( + &crate::SECP256K1, + secret_key, + )) + } +} + #[cfg(test)] mod tests { use super::super::Error::InvalidPublicKey; @@ -935,4 +986,50 @@ mod tests { assert_eq!(pk1.serialize()[..], kpk1.serialize()[1..]); assert_eq!(pk2.serialize()[..], kpk2.serialize()[1..]); } + + #[test] + #[cfg(all(feature = "global-context-less-secure", feature = "serde"))] + fn test_serde_keypair() { + use serde::{Deserialize, Deserializer, Serialize, Serializer}; + use serde_test::{Configure, Token, assert_tokens}; + use super::serde_keypair; + + // Normally users would derive the serde traits, but we can't easily enable the serde macros + // here, so they are implemented manually to be able to test the behaviour. + #[derive(Debug, Copy, Clone, Eq, PartialEq)] + struct KeyPairWrapper(KeyPair); + + impl<'de> Deserialize<'de> for KeyPairWrapper { + fn deserialize(deserializer: D) -> Result + where D: Deserializer<'de> { + serde_keypair::deserialize(deserializer).map(KeyPairWrapper) + } + } + + impl Serialize for KeyPairWrapper { + fn serialize(&self, serializer: S) -> Result where S: Serializer { + serde_keypair::serialize(&self.0, serializer) + } + } + + static SK_BYTES: [u8; 32] = [ + 1, 1, 1, 1, 1, 1, 1, 1, + 0, 1, 2, 3, 4, 5, 6, 7, + 0xff, 0xff, 0, 0, 0xff, 0xff, 0, 0, + 99, 99, 99, 99, 99, 99, 99, 99 + ]; + static SK_STR: &'static str = "\ + 01010101010101010001020304050607ffff0000ffff00006363636363636363\ + "; + + let sk = KeyPairWrapper(KeyPair::from_seckey_slice(&crate::SECP256K1, &SK_BYTES).unwrap()); + + assert_tokens(&sk.compact(), &[Token::BorrowedBytes(&SK_BYTES[..])]); + assert_tokens(&sk.compact(), &[Token::Bytes(&SK_BYTES)]); + assert_tokens(&sk.compact(), &[Token::ByteBuf(&SK_BYTES)]); + + assert_tokens(&sk.readable(), &[Token::BorrowedStr(SK_STR)]); + assert_tokens(&sk.readable(), &[Token::Str(SK_STR)]); + assert_tokens(&sk.readable(), &[Token::String(SK_STR)]); + } }