From 55e4450a65eb47c74620ef11698618035faca985 Mon Sep 17 00:00:00 2001
From: Tony Arcieri <bascule@gmail.com>
Date: Wed, 17 Jan 2024 04:30:51 +0000
Subject: [PATCH] rfc6979: add P-521 + SHA-512 test vectors (#775)

These now work after #781
---
 rfc6979/src/lib.rs   | 33 +++++++++++++++++++++++++++++++--
 rfc6979/tests/lib.rs | 14 --------------
 2 files changed, 31 insertions(+), 16 deletions(-)
 delete mode 100644 rfc6979/tests/lib.rs

diff --git a/rfc6979/src/lib.rs b/rfc6979/src/lib.rs
index 4e718128..e6f62d04 100644
--- a/rfc6979/src/lib.rs
+++ b/rfc6979/src/lib.rs
@@ -161,9 +161,12 @@ where
 
 #[cfg(test)]
 mod tests {
-    use crate::{consts::U21, generate_k};
+    use crate::{
+        consts::{U21, U66},
+        generate_k, Array,
+    };
     use hex_literal::hex;
-    use sha2::Sha256;
+    use sha2::{Digest, Sha256, Sha512};
 
     /// "Detailed Example" from RFC6979 Appendix A.1.
     ///
@@ -181,4 +184,30 @@ mod tests {
         let k = generate_k::<Sha256, U21>(&x.into(), &q.into(), &h2.into(), aad);
         assert_eq!(k, hex!("023AF4074C90A02B3FE61D286D5C87F425E6BDD81B"));
     }
+
+    /// Example from RFC6979 Appendix A.2.7.
+    #[test]
+    fn p521_sha512() {
+        let q = hex!(
+            "01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFA51868783BF2F966B7FCC0148F709A5D03BB5C9B8899C47AEBB6FB71E91386409"
+        );
+
+        let x = hex!(
+            "00FAD06DAA62BA3B25D2FB40133DA757205DE67F5BB0018FEE8C86E1B68C7E75CAA896EB32F1F47C70855836A6D16FCC1466F6D8FBEC67DB89EC0C08B0E996B83538"
+        );
+
+        // Hash message and emulate `bits2octets` to produce the input digest
+        let message = "sample";
+        let mut h = Array::<u8, U66>::default();
+        h[2..].copy_from_slice(&Sha512::digest(message));
+
+        let aad = b"";
+        let k = generate_k::<Sha512, U66>(&x.into(), &q.into(), &h.into(), aad);
+
+        let expected_k = hex!(
+            "01DAE2EA071F8110DC26882D4D5EAE0621A3256FC8847FB9022E2B7D28E6F10198B1574FDD03A9053C08A1854A168AA5A57470EC97DD5CE090124EF52A2F7ECBFFD3"
+        );
+
+        assert_eq!(k, expected_k);
+    }
 }
diff --git a/rfc6979/tests/lib.rs b/rfc6979/tests/lib.rs
deleted file mode 100644
index 1b622f8b..00000000
--- a/rfc6979/tests/lib.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-//! Smoke tests which use `MockCurve`
-
-#![cfg(feature = "dev")]
-
-use elliptic_curve::dev::MockCurve;
-
-type Signature = ecdsa::Signature<MockCurve>;
-type SignatureBytes = ecdsa::SignatureBytes<MockCurve>;
-
-#[test]
-fn rejects_all_zero_signature() {
-    let all_zero_bytes = SignatureBytes::default();
-    assert!(Signature::try_from(all_zero_bytes.as_ref()).is_err());
-}