Add pkix der encoded key parsing

sigstore-java/src/main/java/dev/sigstore/encryption/Keys.java

@@ -108,6 +108,24 @@ public static PublicKey parsePublicKey(byte[] keyBytes)
     return keyFactory.generatePublic(publicKeySpec);
   }
 
+  /**
+   * Takes a PKIX DER formatted public key in bytes and constructs a {@code PublicKey} with it.
+   *
+   * <p>This method is known to work with keys algorithms: RSA, EdDSA, EC.
+   *
+   * @param contents the public key bytes
+   * @param algorithm the key algorithm
+   * @return a PublicKey object
+   * @throws NoSuchAlgorithmException if we don't support the scheme provided
+   * @throws InvalidKeySpecException if the public key material is invalid
+   */
+  public static PublicKey parsePkixPublicKey(byte[] contents, String algorithm)
+      throws NoSuchAlgorithmException, InvalidKeySpecException {
+    X509EncodedKeySpec spec = new X509EncodedKeySpec(contents);
+    KeyFactory factory = KeyFactory.getInstance(algorithm);
+    return factory.generatePublic(spec);
+  }
+
   /**
    * Valid values for scheme are:
    *
@@ -127,16 +145,12 @@ public static PublicKey parsePublicKey(byte[] keyBytes)
    */
   public static PublicKey constructTufPublicKey(byte[] contents, String scheme)
       throws NoSuchAlgorithmException, InvalidKeySpecException {
-    PublicKey publicKey = null;
     switch (scheme) {
-      case "rsassa-pss-sha256":
-        throw new RuntimeException("rsassa-pss-sha256 not currently supported");
       case "ed25519":
         {
           final KeyFactory kf = KeyFactory.getInstance("Ed25519");
           final X509EncodedKeySpec keySpec = new X509EncodedKeySpec(contents);
-          publicKey = kf.generatePublic(keySpec);
-          break;
+          return kf.generatePublic(keySpec);
         }
       case "ecdsa-sha2-nistp256":
         {
@@ -157,11 +171,11 @@ public static PublicKey constructTufPublicKey(byte[] contents, String scheme)
               new ECNamedCurveSpec("P-256", spec.getCurve(), spec.getG(), spec.getN());
           ECPoint point = decodePoint(params.getCurve(), contents);
           ECPublicKeySpec pubKeySpec = new ECPublicKeySpec(point, params);
-          publicKey = kf.generatePublic(pubKeySpec);
-          break;
+          return kf.generatePublic(pubKeySpec);
         }
+      default:
+        throw new RuntimeException(scheme + " not currently supported");
     }
-    return publicKey;
   }
 
   // https://stackoverflow.com/questions/42911637/get-publickey-from-key-bytes-not-knowing-the-key-algorithm

sigstore-java/src/test/java/dev/sigstore/encryption/KeysTest.java

@@ -23,6 +23,7 @@
 import java.security.NoSuchProviderException;
 import java.security.PublicKey;
 import java.security.spec.InvalidKeySpecException;
+import org.bouncycastle.util.encoders.Base64;
 import org.bouncycastle.util.encoders.Hex;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
@@ -155,33 +156,56 @@ void parseTufPublicKey_ed25519_lteJava14()
 
   @Test
   void parseTufPublicKey_ed25519Bad() {
-
-    try {
-      PublicKey key =
-          Keys.constructTufPublicKey(
-              Hex.decode(
-                  "302b300506032b65700321008b2e369230c3b97f4627fd6a59eb054a83ec15ed929ab3d983a40ffd322a223d"),
-              "ed25519");
-      fail();
-    } catch (Exception e) {
-    }
+    Assertions.assertThrows(
+        InvalidKeySpecException.class,
+        () ->
+            Keys.constructTufPublicKey(
+                Hex.decode(
+                    "302b300506032b65700321008b2e369230c3b97f4627fd6a59eb054a83ec15ed929ab3d983a40ffd322a223d"),
+                "ed25519"));
   }
 
   @Test
-  void parseTufPublicKey_rsa()
-      throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchProviderException {
+  void parseTufPublicKey_rsa() throws NoSuchAlgorithmException, InvalidKeySpecException {
     // {@code step crypto keypair ed25519.pub /dev/null --kty OKP --curve Ed25519}
     // copy just the key part out of ed25519.pub removing PEM header and footer
     // {@code echo $(copied content) | base64 -d | hexdump -v -e '/1 "%02x" '}
-    try {
-      PublicKey key =
-          Keys.constructTufPublicKey(
-              Hex.decode(
-                  "302a300506032b65700321008b2e369230c3b97f4627fd6a59eb054a83ec15ed929ab3d983a40ffd322a223d"),
-              "rsassa-pss-sha256");
-      fail();
-    } catch (RuntimeException e) {
-    }
+    Assertions.assertThrows(
+        RuntimeException.class,
+        () ->
+            Keys.constructTufPublicKey(
+                Hex.decode(
+                    "302a300506032b65700321008b2e369230c3b97f4627fd6a59eb054a83ec15ed929ab3d983a40ffd322a223d"),
+                "rsassa-pss-sha256"));
+  }
+
+  @Test
+  void parsePkixPublicKey_rsa() throws NoSuchAlgorithmException, InvalidKeySpecException {
+    var base64Key =
+        "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAghWkDAnX9F5QZZ9NxIWg9vcjULtD/kkbQwlcSm22e06FrgOdiFy1fKN/Ng32qEk1ZIKyi0HFzZxzPIcvg7eaFTRb7+AQiG6eMDmUzPGr67Jp0Di2ncH9+uOZmv4PVKovvQLq7qnEwbDk0HttxUscLQ2e36Lfv/2lpGW7apVmHVMoC5kwZ3KTiAk/DUtDhD4VQjU2rBy6OneO6pm6vdNzG4Jktjc0uUKFCRRUzydGEh05PgC9vSQu/EOiU+7aQPV1ZDUGpjg9tOM0SgaTOU3YSUfGiXZNHoiS2HwLyQPaxiHR2NPVH75bwnUFBHhdMxT1rhU+yLhXaweDQW6GQ0ti8wIDAQAB";
+    Assertions.assertNotNull(Keys.parsePkixPublicKey(Base64.decode(base64Key), "RSA"));
+  }
+
+  @Test
+  void parsePkixPublicKey_rsaKeyButWrongAlgorithm() {
+    var base64Key =
+        "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAghWkDAnX9F5QZZ9NxIWg9vcjULtD/kkbQwlcSm22e06FrgOdiFy1fKN/Ng32qEk1ZIKyi0HFzZxzPIcvg7eaFTRb7+AQiG6eMDmUzPGr67Jp0Di2ncH9+uOZmv4PVKovvQLq7qnEwbDk0HttxUscLQ2e36Lfv/2lpGW7apVmHVMoC5kwZ3KTiAk/DUtDhD4VQjU2rBy6OneO6pm6vdNzG4Jktjc0uUKFCRRUzydGEh05PgC9vSQu/EOiU+7aQPV1ZDUGpjg9tOM0SgaTOU3YSUfGiXZNHoiS2HwLyQPaxiHR2NPVH75bwnUFBHhdMxT1rhU+yLhXaweDQW6GQ0ti8wIDAQAB";
+    Assertions.assertThrows(
+        InvalidKeySpecException.class,
+        () -> Keys.parsePkixPublicKey(Base64.decode(base64Key), "EC"));
+  }
+
+  @Test
+  void parsePkixPublicKey_eddsa() throws NoSuchAlgorithmException, InvalidKeySpecException {
+    var base64Key = "MCowBQYDK2VwAyEAixzZOnx34hveTZ69J5iBCkmerK5Oh7EzJqTh3YY55jI=";
+    Assertions.assertNotNull(Keys.parsePkixPublicKey(Base64.decode(base64Key), "EdDSA"));
+  }
+
+  @Test
+  void parsePkixPublicKey_ecdsa() throws NoSuchAlgorithmException, InvalidKeySpecException {
+    var base64Key =
+        "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEVqBnvab9XEVlTLW4iGKBIdrL6Sxf0x5vclZyXtR6hl79/o+RSgyr1ZQKLLCUC20imDWUgFMmfLu4UUiKNcI2uQ==";
+    Assertions.assertNotNull(Keys.parsePkixPublicKey(Base64.decode(base64Key), "EC"));
   }
 
   @Test