Fix curve25519 endianness

CHANGELOG.md

@@ -17,12 +17,14 @@ SPDX-License-Identifier: CC0-1.0
 
 - Fix the length of the Digital signature counter DO 0x93 ([#76][])
 - PSO:CDS: Increment the signature counter ([#78][])
+- Fix endianness of curve25519 key import([#89][])
 
 [#64]: https://github.com/Nitrokey/opcard-rs/pull/64
 [#60]: https://github.com/Nitrokey/opcard-rs/pull/60
 [#63]: https://github.com/Nitrokey/opcard-rs/pull/63
 [#76]: https://github.com/Nitrokey/opcard-rs/pull/76
 [#78]: https://github.com/Nitrokey/opcard-rs/pull/78
+[#89]: https://github.com/Nitrokey/opcard-rs/pull/89
 
 ## v0.1.0 (2022-10-12)
 

src/command/private_key_template.rs

@@ -128,9 +128,27 @@ fn put_ec<const R: usize, T: trussed::Client>(
         Status::IncorrectDataParameter
     })?;
 
+    // GPG stores scalars as big endian when X25519 specifies them to be little endian
+    // See https://lists.gnupg.org/pipermail/gnupg-devel/2018-February/033437.html
+    let mut data: [u8; 32];
+    let message;
+    if matches!(curve, CurveAlgo::X255) {
+        data = private_key_data.try_into().map_err(|_| {
+            warn!(
+                "Bad private key length for x25519: {}",
+                private_key_data.len()
+            );
+            Status::IncorrectDataParameter
+        })?;
+        data.reverse();
+        message = data.as_slice();
+    } else {
+        message = private_key_data;
+    }
+
     let key = try_syscall!(ctx.backend.client_mut().unsafe_inject_key(
         curve.mechanism(),
-        private_key_data,
+        message,
         Location::Internal,
         KeySerialization::Raw
     ))

tests/crypto-gpg-import.rs

@@ -187,17 +187,24 @@ fn gpg_255() {
         let custom2 = format!(r"{temp_name} \(no comment\) <{temp_email}>");
         gnupg_test(
             &[DEFAULT_PW1],
-            &[vec![
-                r"\[GNUPG:\] ENC_TO [a-fA-F0-9]{16} \d* \d*",
-                r"\[GNUPG:\] DECRYPTION_KEY [a-fA-F0-9]{40} [a-fA-F0-9]{40} u",
-                r"\[GNUPG:\] BEGIN_DECRYPTION",
-                r"\[GNUPG:\] DECRYPTION_INFO \d \d \d",
-                r"\[GNUPG:\] PLAINTEXT \d* \d* Cargo.toml",
-                r"\[GNUPG:\] PLAINTEXT_LENGTH \d*",
-                r"\[GNUPG:\] DECRYPTION_OKAY",
-                r"\[GNUPG:\] GOODMDC",
-                r"\[GNUPG:\] END_DECRYPTION",
-            ]]
+            &[
+                vec![
+                    r"\[GNUPG:\] ENC_TO [a-fA-F0-9]{16} \d* \d*",
+                    &custom1,
+                    r"\[GNUPG:\] NEED_PASSPHRASE [a-fA-F0-9]{16} [a-fA-F0-9]{16} 18 0",
+                ],
+                virt::gpg_inquire_pin(),
+                vec![
+                    r"\[GNUPG:\] DECRYPTION_KEY [a-fA-F0-9]{40} [a-fA-F0-9]{40} u",
+                    r"\[GNUPG:\] BEGIN_DECRYPTION",
+                    r"\[GNUPG:\] DECRYPTION_INFO \d \d \d",
+                    r"\[GNUPG:\] PLAINTEXT \d* \d* Cargo.toml",
+                    r"\[GNUPG:\] PLAINTEXT_LENGTH \d*",
+                    r"\[GNUPG:\] DECRYPTION_OKAY",
+                    r"\[GNUPG:\] GOODMDC",
+                    r"\[GNUPG:\] END_DECRYPTION",
+                ],
+            ]
             .into_iter()
             .flatten()
             .collect::<Vec<&str>>(),