Make to_inner on public key types pub(super)
What the developer wrote
Authored by Mitchell Bagot
Make to_inner on public key types pub(super)
The to_inner function was introduced as a stop-gap to eliminate the
public access to inner secp types on the public key types. Now that
the key types have been adjusted such that inner access is no longer
needed outside of crypto, these conversion methods can be made private.
Make to_inner on all public key types pub(super).
What changed, and why it matters
This commit narrows the visibility of internal helper methods named to_inner on Bitcoin public-key types. Previously any outside code could call these methods to extract the raw underlying secp256k1 key objects; now only code inside the same module can do so. This is a defensive encapsulation change that reduces the public API surface and makes future misuse or accidental exposure of internal cryptographic details less likely. It is not a fix for an active vulnerability.
No urgent action required. Downstream users relying on `to_inner` should migrate to the supported public APIs (e.g., `with_compressedness`). Monitor release notes for API-breaking changes.
Security signals we found
Reduction of public API surface for cryptographic key types
Encapsulation of inner secp256k1 key objects
Defensive hardening against misuse of raw public-key internals
No memory-safety, cryptographic, or authentication bug is fixed
Evidence from the diff
The patch changes pub fn to_inner(...) to pub(super) fn to_inner(...) on XOnlyPublicKey, PublicKey, and LegacyPublicKey in crypto/src/key.rs, and updates one test in bitcoin/src/crypto/key.rs to use a new public with_compressedness API instead of from_secp(pk.to_inner()). The change restricts access to the inner secp256k1 types to the parent module, continuing an earlier effort to stop exposing raw secp256k1 types publicly. It is a hardening/API-cleanup commit, not a patch for a known exploit.
Changed components
crypto/src/key.rsbitcoin/src/crypto/key.rsXOnlyPublicKeyPublicKeyLegacyPublicKeyInspect captured patch +4 / −4
diff --git a/bitcoin/src/crypto/key.rs b/bitcoin/src/crypto/key.rs
index 3bcd92ba..bb0bd457 100644
--- a/bitcoin/src/crypto/key.rs
+++ b/bitcoin/src/crypto/key.rs
@@ -238,7 +238,7 @@ mod tests {
.parse::<LegacyPublicKey>().unwrap());
let addr = Address::p2pkh(pk, sk.network_kind);
assert_eq!(&addr.to_string(), "1GhQvF6dL8xa6wBxLnWmHcQsurx9RxiMc8");
- pk = LegacyPublicKey::from_secp(pk.to_inner());
+ pk = pk.with_compressedness(true);
assert_eq!(
&pk.to_string(),
"032e58afe51f9ed8ad3cc7897f634d881fdbe49a81564629ded8156bebd2ffd1af"
diff --git a/crypto/src/key.rs b/crypto/src/key.rs
index ecf1973b..57dc5a74 100644
--- a/crypto/src/key.rs
+++ b/crypto/src/key.rs
@@ -85,7 +85,7 @@ mod encapsulate {
/// Returns the inner secp256k1 x-only public key.
#[inline]
- pub fn to_inner(self) -> secp256k1::XOnlyPublicKey { self.inner }
+ pub(super) fn to_inner(self) -> secp256k1::XOnlyPublicKey { self.inner }
/// Returns the inner secp256k1 x-only public key.
#[inline]
@@ -147,7 +147,7 @@ mod encapsulate {
/// Returns the inner secp256k1 public key.
#[inline]
- pub fn to_inner(self) -> secp256k1::PublicKey { self.inner }
+ pub(super) fn to_inner(self) -> secp256k1::PublicKey { self.inner }
/// Returns whether this public key should be serialized as compressed.
#[inline]
@@ -165,7 +165,7 @@ mod encapsulate {
/// Returns the inner [`secp256k1::PublicKey`].
#[inline]
- pub fn to_inner(self) -> secp256k1::PublicKey { self.0 }
+ pub(super) fn to_inner(self) -> secp256k1::PublicKey { self.0 }
}
/// A Bitcoin ECDSA private key.
Why this scored 23/100
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