feat(keys): add functionality to extract public key to KeyParsers

core/common/lib/keys-lib/src/main/java/org/eclipse/edc/keys/KeyParserRegistryImpl.java

@@ -37,4 +37,12 @@ public Result<Key> parse(String encoded) {
                 .map(kp -> kp.parse(encoded))
                 .orElseGet(() -> Result.failure("No parser found that can handle that format."));
     }
+
+    @Override
+    public Result<Key> parsePublic(String encoded) {
+        return parsers.stream().filter(kp -> kp.canHandle(encoded))
+                .findFirst()
+                .map(kp -> kp.parsePublic(encoded))
+                .orElseGet(() -> Result.failure("No parser found that can handle that format."));
+    }
 }

core/common/lib/keys-lib/src/main/java/org/eclipse/edc/keys/keyparsers/JwkParser.java

@@ -86,8 +86,9 @@ public boolean canHandle(String encoded) {
     @Override
     public Result<Key> parse(String encoded) {
         try {
-            var jwk = JWK.parse(encoded);
 
+
+            var jwk = JWK.parse(encoded);
             // OctetKeyPairs (OKP) need special handling, as they can't be easily converted to a Java PrivateKey
             if (jwk instanceof OctetKeyPair okp) {
                 return parseOctetKeyPair(okp).map(key -> key);
@@ -107,6 +108,26 @@ public Result<Key> parse(String encoded) {
         }
     }
 
+    @Override
+    public Result<Key> parsePublic(String encoded) {
+        try {
+            var jwk = JWK.parse(encoded).toPublicJWK();
+            // OctetKeyPairs (OKP) need special handling, as they can't be easily converted to a Java PrivateKey
+            if (jwk instanceof OctetKeyPair okp) {
+                return parseOctetKeyPair(okp.toPublicJWK()).map(key -> key);
+            }
+            var list = KeyConverter.toJavaKeys(List.of(jwk)); // contains an entry each for public and private key
+
+            return list.stream()
+                    .findFirst()
+                    .map(Result::success)
+                    .orElse(Result.failure(ERROR_NO_KEY));
+        } catch (ParseException | NoSuchAlgorithmException | IOException | InvalidKeySpecException e) {
+            monitor.warning("Parser error", e);
+            return Result.failure("Parser error: " + e.getMessage());
+        }
+    }
+
     private Result<? extends Key> parseOctetKeyPair(OctetKeyPair okp) throws NoSuchAlgorithmException, IOException, InvalidKeySpecException {
         var d = okp.getDecodedD();
         var x = okp.getDecodedX();

core/common/lib/keys-lib/src/main/java/org/eclipse/edc/keys/keyparsers/PemParser.java

@@ -62,11 +62,7 @@ public boolean canHandle(String encoded) {
     @Override
     public Result<Key> parse(String encoded) {
 
-        var matcher = PEM_FORMAT_REGEX.matcher(encoded);
-        if (!matcher.find()) {
-            return Result.failure("The given input is not valid PEM.");
-        }
-        var keypair = parseKeys(encoded);
+        var keypair = parsePem(encoded);
 
         if (keypair.succeeded()) {
 
@@ -83,7 +79,38 @@ public Result<Key> parse(String encoded) {
                     .orElseGet(() -> Result.failure("PEM-encoded structure did not contain a private key."));
         }
 
-        return keypair.mapTo();
+        return keypair.mapEmpty();
+    }
+
+    @Override
+    public Result<Key> parsePublic(String encoded) {
+
+        var keypair = parsePem(encoded);
+        if (keypair.succeeded()) {
+
+            var keyPairList = keypair.getContent();
+            if (keyPairList.size() > 1) {
+                monitor.warning("PEM expected to contain exactly 1 key(-pair), but contained %s. Will take the first one. Please consider re-structuring your PEM document.".formatted(keyPairList.size()));
+            }
+            return keyPairList
+                    .stream()
+                    .filter(Objects::nonNull) // PEM strings that only contain public keys would get eliminated here
+                    .map(keyPair -> (Key) keyPair.getPublic())
+                    .filter(Objects::nonNull)
+                    .findFirst()
+                    .map(Result::success)
+                    .orElseGet(() -> Result.failure("PEM-encoded structure did not contain a public key."));
+        }
+
+        return keypair.mapEmpty();
+    }
+
+    private Result<List<KeyPair>> parsePem(String pemEncoded) {
+        var matcher = PEM_FORMAT_REGEX.matcher(pemEncoded);
+        if (!matcher.find()) {
+            return Result.failure("The given input is not valid PEM.");
+        }
+        return parseKeys(pemEncoded);
     }
 
     /**

core/common/lib/keys-lib/src/test/java/org/eclipse/edc/keys/keyparsers/JwkParserTest.java

@@ -63,6 +63,23 @@ void parse_publicKey(JWK jwk) {
         assertThat(result).isSucceeded().isInstanceOf(PublicKey.class);
     }
 
+
+    @ParameterizedTest
+    @ArgumentsSource(KeyProvider.class)
+    void parsePublic_withPublicKey(JWK jwk) {
+        var publickey = jwk.toPublicJWK();
+        var result = parser.parsePublic(publickey.toJSONString());
+        assertThat(result).isSucceeded().isInstanceOf(PublicKey.class);
+    }
+
+
+    @ParameterizedTest
+    @ArgumentsSource(KeyProvider.class)
+    void parsePublic_withPrivateKey(JWK jwk) {
+        var result = parser.parsePublic(jwk.toJSONString());
+        assertThat(result).isSucceeded().isInstanceOf(PublicKey.class);
+    }
+
     private static class KeyProvider implements ArgumentsProvider {
         @Override
         public Stream<? extends Arguments> provideArguments(ExtensionContext context) {

core/common/lib/keys-lib/src/test/java/org/eclipse/edc/keys/keyparsers/PemParserTest.java

@@ -17,6 +17,7 @@
 import org.assertj.core.api.Assertions;
 import org.eclipse.edc.junit.testfixtures.TestUtils;
 import org.junit.jupiter.api.Named;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
@@ -74,6 +75,38 @@ void parse_publicKey(String pem) {
                 .isInstanceOf(PublicKey.class);
     }
 
+
+    @ParameterizedTest
+    @ArgumentsSource(PemConvertiblePrivateKeyProvider.class)
+    void parsePublic_withPrivateKey(String pem) {
+        var result = parser.parsePublic(pem);
+        assertThat(result)
+                .isSucceeded()
+                .isNotNull()
+                .isInstanceOf(PublicKey.class);
+
+    }
+
+    @Test
+    void parsePublic_withPrivateKey_whenEd25519_shouldFail() {
+        var pem = TestUtils.getResourceFileContentAsString("ed25519.pem");
+        var result = parser.parsePublic(pem);
+        assertThat(result)
+                .isFailed()
+                .detail().isEqualTo("PEM-encoded structure did not contain a public key.");
+    }
+
+
+    @ParameterizedTest
+    @ArgumentsSource(PemPublicKeyProvider.class)
+    void parsePublic_withPublicKey(String pem) {
+
+        assertThat(parser.parsePublic(pem))
+                .isSucceeded()
+                .isNotNull()
+                .isInstanceOf(PublicKey.class);
+    }
+
     private static class PemPrivateKeyProvider implements ArgumentsProvider {
 
         @Override
@@ -88,6 +121,19 @@ public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
         }
     }
 
+    private static class PemConvertiblePrivateKeyProvider implements ArgumentsProvider {
+
+        @Override
+        public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
+            return Stream.of(
+                    Arguments.of(Named.named("RSA PrivateKey", TestUtils.getResourceFileContentAsString("rsa_2048.pem"))),
+                    Arguments.of(Named.named("EC PrivateKey (P256)", TestUtils.getResourceFileContentAsString("ec_p256.pem"))),
+                    Arguments.of(Named.named("EC PrivateKey (P384)", TestUtils.getResourceFileContentAsString("ec_p384.pem"))),
+                    Arguments.of(Named.named("EC PrivateKey (P512)", TestUtils.getResourceFileContentAsString("ec_p512.pem")))
+            );
+        }
+    }
+
     private static class PemPublicKeyProvider implements ArgumentsProvider {
 
         @Override

spi/common/keys-spi/src/main/java/org/eclipse/edc/keys/spi/KeyParser.java

@@ -49,4 +49,20 @@ public interface KeyParser {
      * @return Either a {@link java.security.PrivateKey}, a {@link java.security.PublicKey} or a failure.
      */
     Result<Key> parse(String encoded);
+
+    /**
+     * Parses the encoded key as public key. If the encoded string is invalid, or the parser can't handle the input,
+     * it must return a {@link Result#failure(String)}, it must never throw an exception.
+     * <p>
+     * If the given key material contains public and private key data, the parser attempts to remove the private key data,
+     * returning only the public part of the key as {@link java.security.PublicKey}.
+     * If the given key material does not contain private key data, just public key data, returns a {@link java.security.PublicKey}. In all
+     * other cases, a {@link Result#failure(String)} is returned, for example, when a private key cannot be converted into a public key.
+     *
+     * @param encoded serialized/encoded key material.
+     * @return Either a {@link java.security.PublicKey} or a failure.
+     */
+    default Result<Key> parsePublic(String encoded) {
+        return parse(encoded);
+    }
 }

spi/common/keys-spi/src/main/java/org/eclipse/edc/keys/spi/KeyParserRegistry.java

@@ -17,7 +17,6 @@
 import org.eclipse.edc.spi.result.Result;
 
 import java.security.Key;
-import java.security.PrivateKey;
 
 /**
  * Registry that holds multiple {@link KeyParser} instances that are used to deserialize a private key from their
@@ -30,11 +29,21 @@ public interface KeyParserRegistry {
     void register(KeyParser parser);
 
     /**
-     * Attempts to parse the String representation of a private key into a {@link PrivateKey}. If no parser can handle
+     * Attempts to parse the String representation of a private key into a {@link Key}. If no parser can handle
      * the encoded format, or it is corrupt etc. then a failure is returned.
      *
      * @param encoded The private key in encoded format (PEM, OpenSSH, JWK, PKCS8,...)
      * @return a success result containing the private key, a failure if the encoded private key could not be deserialized.
      */
     Result<Key> parse(String encoded);
+
+    /**
+     * Attempts to parse the String representation of a public or private key into a {@link Key}. If no parser can handle
+     * the encoded format, if the encoded format contains a private key that cannot be converted to a public key,
+     * or if the input is corrupt etc. then a failure is returned.
+     *
+     * @param encoded The private key in encoded format (PEM, OpenSSH, JWK, PKCS8,...)
+     * @return a success result containing the public key, a failure if the encoded public key could not be deserialized.
+     */
+    Result<Key> parsePublic(String encoded);
 }