Generate local signatures with additional randomness

[rust-lightning] / lightning / src / util / crypto.rs

diff --git a/lightning/src/util/crypto.rs b/lightning/src/util/crypto.rs
index 2f2d33b29f7ea53c0a2dda084ac7a139583c6345..d4d15cfa3045a9fb09b4400b12302b9984d5d49f 100644 (file)
--- a/lightning/src/util/crypto.rs
+++ b/lightning/src/util/crypto.rs
@@ -3,6 +3,10 @@ use bitcoin::hashes::hmac::{Hmac, HmacEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::secp256k1::{Message, Secp256k1, SecretKey, ecdsa::Signature, Signing};
 
+use crate::chain::keysinterface::EntropySource;
+
+use core::ops::Deref;
+
 macro_rules! hkdf_extract_expand {
        ($salt: expr, $ikm: expr) => {{
                let mut hmac = HmacEngine::<Sha256>::new($salt);
@@ -46,3 +50,19 @@ pub fn sign<C: Signing>(ctx: &Secp256k1<C>, msg: &Message, sk: &SecretKey) -> Si
        let sig = ctx.sign_ecdsa(msg, sk);
        sig
 }
+
+#[inline]
+pub fn sign_with_aux_rand<C: Signing, ES: Deref>(
+       ctx: &Secp256k1<C>, msg: &Message, sk: &SecretKey, entropy_source: &ES
+) -> Signature where ES::Target: EntropySource {
+       #[cfg(feature = "grind_signatures")]
+       let sig = loop {
+               let sig = ctx.sign_ecdsa_with_noncedata(msg, sk, &entropy_source.get_secure_random_bytes());
+               if sig.serialize_compact()[0] < 0x80 {
+                       break sig;
+               }
+       };
+       #[cfg(not(feature = "grind_signatures"))]
+       let sig = ctx.sign_ecdsa_with_noncedata(msg, sk, &entropy_source.get_secure_random_bytes());
+       sig
+}