From c85d006887b6c6eaf8389a6448a68044083091ed Mon Sep 17 00:00:00 2001
From: Heiko Schaefer <heiko@schaefer.name>
Date: Sun, 18 Jul 2021 21:12:22 +0200
Subject: [PATCH] Support ECDSA signatures

---
 openpgp-card-sequoia/src/signer.rs | 11 +++++++++++
 openpgp-card/src/card_app.rs       |  1 +
 openpgp-card/src/lib.rs            |  3 +++
 3 files changed, 15 insertions(+)

diff --git a/openpgp-card-sequoia/src/signer.rs b/openpgp-card-sequoia/src/signer.rs
index e197caf..f9cabf7 100644
--- a/openpgp-card-sequoia/src/signer.rs
+++ b/openpgp-card-sequoia/src/signer.rs
@@ -138,6 +138,17 @@ impl<'a> crypto::Signer for CardSigner<'a> {
 
                 Ok(mpi::Signature::EdDSA { r, s })
             }
+            (PublicKeyAlgorithm::ECDSA, mpi::PublicKey::ECDSA { .. }) => {
+                let hash = Hash::ECDSA(digest);
+
+                let sig = self.ca.signature_for_hash(hash)?;
+
+                let len_2 = sig.len() / 2;
+                let r = mpi::MPI::new(&sig[..len_2]);
+                let s = mpi::MPI::new(&sig[len_2..]);
+
+                Ok(mpi::Signature::ECDSA { r, s })
+            }
 
             // FIXME: implement NIST etc
             (pk_algo, _) => Err(anyhow!(
diff --git a/openpgp-card/src/card_app.rs b/openpgp-card/src/card_app.rs
index ec0f66f..b34112a 100644
--- a/openpgp-card/src/card_app.rs
+++ b/openpgp-card/src/card_app.rs
@@ -543,6 +543,7 @@ impl CardApp {
                 tlv.serialize()
             }
             Hash::EdDSA(d) => d.to_vec(),
+            Hash::ECDSA(d) => d.to_vec(),
         };
 
         self.compute_digital_signature(data)
diff --git a/openpgp-card/src/lib.rs b/openpgp-card/src/lib.rs
index 42c5395..e804a35 100644
--- a/openpgp-card/src/lib.rs
+++ b/openpgp-card/src/lib.rs
@@ -61,6 +61,7 @@ pub enum Hash<'a> {
     SHA384([u8; 0x30]),
     SHA512([u8; 0x40]),
     EdDSA(&'a [u8]), // FIXME?
+    ECDSA(&'a [u8]), // FIXME?
 }
 
 impl Hash<'_> {
@@ -76,6 +77,7 @@ impl Hash<'_> {
                 Some(&[0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03])
             }
             Self::EdDSA(_) => None,
+            Self::ECDSA(_) => None,
         }
     }
 
@@ -85,6 +87,7 @@ impl Hash<'_> {
             Self::SHA384(d) => &d[..],
             Self::SHA512(d) => &d[..],
             Self::EdDSA(d) => d,
+            Self::ECDSA(d) => d,
         }
     }
 }