[apkverify] Skip DSA SHA256 during apk verification

Test: libapkverify.integration_test
Bug: 197052981
Change-Id: Ia42864ab609b1dbe59e260bd330cbdc4079982d6
diff --git a/libs/apkverify/src/algorithms.rs b/libs/apkverify/src/algorithms.rs
index a1cf368..ecca7ed 100644
--- a/libs/apkverify/src/algorithms.rs
+++ b/libs/apkverify/src/algorithms.rs
@@ -97,14 +97,6 @@
         &self,
         public_key: &'a PKey<pkey::Public>,
     ) -> Result<Verifier<'a>> {
-        ensure!(
-            !matches!(
-                self,
-                SignatureAlgorithmID::DsaWithSha256 | SignatureAlgorithmID::VerityDsaWithSha256
-            ),
-            "TODO(b/197052981): Algorithm '{:?}' is not implemented.",
-            self
-        );
         ensure!(public_key.id() == self.pkey_id(), "Public key has the wrong ID");
         let mut verifier = Verifier::new(self.new_message_digest(), public_key)?;
         if public_key.id() == pkey::Id::RSA {
@@ -130,6 +122,14 @@
         }
     }
 
+    /// DSA is not directly supported in openssl today. See b/197052981.
+    pub(crate) fn is_supported(&self) -> bool {
+        !matches!(
+            self,
+            SignatureAlgorithmID::DsaWithSha256 | SignatureAlgorithmID::VerityDsaWithSha256,
+        )
+    }
+
     fn pkey_id(&self) -> pkey::Id {
         match self {
             SignatureAlgorithmID::RsaPssWithSha256
diff --git a/libs/apkverify/src/v3.rs b/libs/apkverify/src/v3.rs
index 05694ff..80ef687 100644
--- a/libs/apkverify/src/v3.rs
+++ b/libs/apkverify/src/v3.rs
@@ -141,7 +141,7 @@
         Ok(self
             .signatures
             .iter()
-            .filter(|sig| sig.signature_algorithm_id.is_some())
+            .filter(|sig| sig.signature_algorithm_id.map_or(false, |algo| algo.is_supported()))
             .max_by_key(|sig| sig.signature_algorithm_id.unwrap().content_digest_algorithm())
             .context("No supported signatures found")?)
     }
diff --git a/libs/apkverify/tests/apkverify_test.rs b/libs/apkverify/tests/apkverify_test.rs
index 5bd901d..f2018a1 100644
--- a/libs/apkverify/tests/apkverify_test.rs
+++ b/libs/apkverify/tests/apkverify_test.rs
@@ -40,22 +40,11 @@
 }
 
 #[test]
-fn test_verify_v3_dsa_sha256() {
+fn apks_signed_with_v3_dsa_sha256_are_not_supported() {
     for key_name in KEY_NAMES_DSA.iter() {
         let res = verify(format!("tests/data/v3-only-with-dsa-sha256-{}.apk", key_name));
-        assert!(res.is_err());
-        assert_contains(&res.unwrap_err().to_string(), "not implemented");
-    }
-}
-
-/// TODO(b/197052981): DSA algorithm is not yet supported.
-#[test]
-fn apks_signed_with_v3_dsa_sha256_have_valid_apk_digest() {
-    for key_name in KEY_NAMES_DSA.iter() {
-        validate_apk_digest(
-            format!("tests/data/v3-only-with-dsa-sha256-{}.apk", key_name),
-            SignatureAlgorithmID::DsaWithSha256,
-        );
+        assert!(res.is_err(), "DSA algorithm is not supported for verification. See b/197052981.");
+        assert_contains(&res.unwrap_err().to_string(), "No supported signatures found");
     }
 }
 
@@ -102,7 +91,6 @@
 #[test]
 fn test_verify_v3_sig_does_not_verify() {
     let path_list = [
-        "tests/data/v3-only-with-dsa-sha256-2048-sig-does-not-verify.apk",
         "tests/data/v3-only-with-ecdsa-sha512-p521-sig-does-not-verify.apk",
         "tests/data/v3-only-with-rsa-pkcs1-sha256-3072-sig-does-not-verify.apk",
     ];
@@ -118,16 +106,9 @@
 
 #[test]
 fn test_verify_v3_digest_mismatch() {
-    let path_list = [
-        "tests/data/v3-only-with-dsa-sha256-3072-digest-mismatch.apk",
-        "tests/data/v3-only-with-rsa-pkcs1-sha512-8192-digest-mismatch.apk",
-    ];
-    for path in path_list.iter() {
-        let res = verify(path);
-        assert!(res.is_err());
-        let error_msg = &res.unwrap_err().to_string();
-        assert!(error_msg.contains("Digest mismatch") || error_msg.contains("not implemented"));
-    }
+    let res = verify("tests/data/v3-only-with-rsa-pkcs1-sha512-8192-digest-mismatch.apk");
+    assert!(res.is_err());
+    assert_contains(&res.unwrap_err().to_string(), "Digest mismatch");
 }
 
 #[test]
diff --git a/libs/apkverify/tests/data/v3-only-with-dsa-sha256-1024.apk.apk_digest b/libs/apkverify/tests/data/v3-only-with-dsa-sha256-1024.apk.apk_digest
deleted file mode 100644
index c5aec18..0000000
--- a/libs/apkverify/tests/data/v3-only-with-dsa-sha256-1024.apk.apk_digest
+++ /dev/null
Binary files differ
diff --git a/libs/apkverify/tests/data/v3-only-with-dsa-sha256-2048.apk.apk_digest b/libs/apkverify/tests/data/v3-only-with-dsa-sha256-2048.apk.apk_digest
deleted file mode 100644
index c5aec18..0000000
--- a/libs/apkverify/tests/data/v3-only-with-dsa-sha256-2048.apk.apk_digest
+++ /dev/null
Binary files differ
diff --git a/libs/apkverify/tests/data/v3-only-with-dsa-sha256-3072.apk.apk_digest b/libs/apkverify/tests/data/v3-only-with-dsa-sha256-3072.apk.apk_digest
deleted file mode 100644
index c5aec18..0000000
--- a/libs/apkverify/tests/data/v3-only-with-dsa-sha256-3072.apk.apk_digest
+++ /dev/null
Binary files differ