dsa: capture error

Author: baloo

Cargo.lock

@@ -19,7 +19,7 @@ rust-version = "1.85"
 digest = "=0.11.0-pre.10"
 crypto-bigint = { version = "=0.7.0-pre.1", default-features = false, features = ["alloc", "zeroize"] }
 crypto-primes = { version = "=0.7.0-dev", default-features = false }
-pkcs8 = { version = "0.11.0-rc.1", default-features = false, features = ["alloc"] }
+pkcs8 = { version = "0.11.0-rc.3", default-features = false, features = ["alloc"] }
 rfc6979 = { version = "=0.5.0-pre.4" }
 sha2 = { version = "=0.11.0-pre.5", default-features = false }
 signature = { version = "=3.0.0-pre", default-features = false, features = ["alloc", "digest", "rand_core"] }
@@ -28,7 +28,7 @@ zeroize = { version = "1", default-features = false }
 [dev-dependencies]
 hex = "0.4.3"
 hex-literal = "1"
-pkcs8 = { version = "0.11.0-rc.1", default-features = false, features = ["pem"] }
+pkcs8 = { version = "0.11.0-rc.3", default-features = false, features = ["pem"] }
 proptest = "1"
 rand = "0.9"
 rand_chacha = "0.9"

dsa/Cargo.toml

@@ -185,8 +185,13 @@ impl TryFrom<&[u8]> for Signature {
     type Error = signature::Error;
 
     fn try_from(bytes: &[u8]) -> signature::Result<Self> {
-        // TODO(tarcieri): capture error source when `std` feature enabled
-        Self::from_der(bytes).map_err(|_| signature::Error::new())
+        let out = Self::from_der(bytes);
+
+        if cfg!(feature = "std") {
+            out.map_err(signature::Error::from_source)
+        } else {
+            out.map_err(|_| signature::Error::new())
+        }
     }
 }