.gitattributes

@@ -1,3 +1,4 @@
 /gradlew text eol=lf
 *.bat text eol=crlf
 *.jar binary
+*.java text eol=lf

build.gradle.kts

@@ -29,8 +29,10 @@ repositories {
 }
 
 dependencies {
-	implementation("org.springframework.boot:spring-boot-autoconfigure")
+	implementation("org.zeroturnaround:zt-exec:1.12")
+	implementation("org.apache.commons:commons-lang3:3.17.0")
 
+	implementation("org.springframework.boot:spring-boot-autoconfigure")
 	implementation("org.springframework.boot:spring-boot-starter-jdbc")
 	implementation("org.xerial:sqlite-jdbc")
 	implementation("org.springframework.boot:spring-boot-starter-data-jpa")
@@ -53,4 +55,5 @@ dependencies {
 
 tasks.withType<Test> {
 	useJUnitPlatform()
+	testLogging.showStandardStreams = true
 }

src/main/java/de/mlessmann/certassist/DeleteRecursiveFileVisitor.java

@@ -0,0 +1,46 @@
+package de.mlessmann.certassist;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.FileVisitor;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
+import org.slf4j.Logger;
+import org.springframework.lang.NonNull;
+
+public class DeleteRecursiveFileVisitor implements FileVisitor<Path> {
+
+    private static final Logger LOGGER = getLogger(DeleteRecursiveFileVisitor.class);
+
+    @NonNull
+    @Override
+    public FileVisitResult preVisitDirectory(Path dir, @NonNull BasicFileAttributes attrs) throws IOException {
+        return FileVisitResult.CONTINUE;
+    }
+
+    @NonNull
+    @Override
+    public FileVisitResult visitFile(Path file, @NonNull BasicFileAttributes attrs) throws IOException {
+        LOGGER.trace("Deleting file {}", file);
+        Files.delete(file);
+        return FileVisitResult.CONTINUE;
+    }
+
+    @NonNull
+    @Override
+    public FileVisitResult visitFileFailed(Path file, @NonNull IOException exc) throws IOException {
+        LOGGER.error("Could not delete file {}", file, exc);
+        throw exc;
+    }
+
+    @NonNull
+    @Override
+    public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
+        LOGGER.trace("Deleting directory {}", dir);
+        Files.delete(dir);
+        return FileVisitResult.CONTINUE;
+    }
+}

src/main/java/de/mlessmann/certassist/ExecutableResolver.java

@@ -0,0 +1,68 @@
+package de.mlessmann.certassist;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import de.mlessmann.certassist.except.UnresolvableCLIDependency;
+import java.io.File;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import org.apache.commons.lang3.SystemUtils;
+import org.slf4j.Logger;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Service;
+
+@Service
+public class ExecutableResolver {
+
+    private static final Logger LOGGER = getLogger(ExecutableResolver.class);
+
+    @Value("${openssl.path:#{null}}")
+    private String opensslPath;
+
+    public String getOpenSSLPath() throws UnresolvableCLIDependency {
+        if (opensslPath == null) {
+            LOGGER.atDebug().log("No openssl path configured, falling back to resolving by shell.");
+            var optSSLPath = searchCommandFromPath("openssl");
+            opensslPath = optSSLPath.orElseThrow(() -> new UnresolvableCLIDependency("openssl", "openssl.path"));
+        }
+
+        Path configuredPath = new File(opensslPath).toPath();
+        if (!Files.isRegularFile(configuredPath)) {
+            throw new UnresolvableCLIDependency("openssl", "openssl.path");
+        }
+
+        return opensslPath;
+    }
+
+    private Optional<String> searchCommandFromPath(String executableName) {
+        String envPath = System.getenv("PATH");
+        Objects.requireNonNull(envPath, "Environment variable 'PATH' is not set?!");
+        String[] pathEntries = envPath.split(File.pathSeparator);
+
+        for (String pathEntry : pathEntries) {
+            for (String fileExtension : getAllowedExtensions()) {
+                Path executablePath = Path.of(pathEntry, executableName + fileExtension);
+                if (Files.isRegularFile(executablePath) && Files.isExecutable(executablePath)) {
+                    return Optional.of(executablePath.toString());
+                }
+            }
+        }
+
+        LOGGER.error(
+            "Could not find executable '{}' in PATH. Make sure that it exists on the of the directory and is executable.",
+            executableName
+        );
+        return Optional.empty();
+    }
+
+    public List<String> getAllowedExtensions() {
+        if (SystemUtils.IS_OS_WINDOWS) {
+            return List.of(".exe", ".bat", ".cmd");
+        } else {
+            return List.of("", ".sh");
+        }
+    }
+}

src/main/java/de/mlessmann/certassist/except/CommandLineOperationException.java

@@ -0,0 +1,16 @@
+package de.mlessmann.certassist.except;
+
+public class CommandLineOperationException extends Exception {
+
+    public CommandLineOperationException(String message) {
+        super(message);
+    }
+
+    public CommandLineOperationException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public CommandLineOperationException(Throwable cause) {
+        super(cause);
+    }
+}

src/main/java/de/mlessmann/certassist/except/UnresolvableCLIDependency.java

@@ -0,0 +1,21 @@
+package de.mlessmann.certassist.except;
+
+import lombok.Getter;
+
+@Getter
+public class UnresolvableCLIDependency extends Exception {
+
+    private final String executableName;
+    private final String propertyName;
+
+    public UnresolvableCLIDependency(String executableName, String propertyName) {
+        super(
+            "Could not resolve executable for '%s'. (Use property '%s' to point the application directly to the executable.)".formatted(
+                    executableName,
+                    propertyName
+                )
+        );
+        this.executableName = executableName;
+        this.propertyName = propertyName;
+    }
+}

src/main/java/de/mlessmann/certassist/openssl/CertificateRequest.java

@@ -0,0 +1,47 @@
+package de.mlessmann.certassist.openssl;
+
+import java.util.UUID;
+import lombok.Builder;
+import lombok.Data;
+
+@Data
+@Builder
+public class CertificateRequest {
+
+    @Builder.Default
+    private String oid = UUID.randomUUID().toString();
+
+    private RequestType type;
+    private String commonName;
+    private String trustingAuthority;
+
+    @Builder.Default
+    private int requestedKeyLength = 4096;
+
+    @Builder.Default
+    private int requestedValidityDays = 365;
+
+    private CertificateSubject subject;
+    private CertificateRequestExtension extension;
+
+    public enum RequestType {
+        ROOT_AUTHORITY,
+        STANDALONE_CERTIFICATE,
+        NORMAL_CERTIFICATE,
+    }
+
+    public static class CertificateRequestBuilder {
+
+        public CertificateRequestBuilder subject(CertificateSubject.CertificateSubjectBuilder builder) {
+            this.subject = builder.build();
+            return this;
+        }
+
+        public CertificateRequestBuilder extension(
+            CertificateRequestExtension.CertificateRequestExtensionBuilder builder
+        ) {
+            this.extension = builder.build();
+            return this;
+        }
+    }
+}

src/main/java/de/mlessmann/certassist/openssl/CertificateRequestExtension.java

@@ -0,0 +1,20 @@
+package de.mlessmann.certassist.openssl;
+
+import java.util.List;
+import lombok.Builder;
+import lombok.Getter;
+
+@Getter
+@Builder
+public class CertificateRequestExtension {
+
+    private List<String> alternativeNames;
+
+    public static class CertificateRequestExtensionBuilder {
+
+        public CertificateRequestExtensionBuilder alternativeNames(String... altNames) {
+            this.alternativeNames = List.of(altNames);
+            return this;
+        }
+    }
+}

src/main/java/de/mlessmann/certassist/openssl/CertificateSubject.java

@@ -0,0 +1,16 @@
+package de.mlessmann.certassist.openssl;
+
+import lombok.Builder;
+import lombok.Getter;
+
+@Getter
+@Builder
+public class CertificateSubject {
+
+    private String emailAddress;
+    private String organization;
+    private String organizationalUnit;
+    private String country;
+    private String state;
+    private String locality;
+}

src/main/java/de/mlessmann/certassist/openssl/OpenSSLCertificateCreator.java

@@ -0,0 +1,224 @@
+package de.mlessmann.certassist.openssl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import de.mlessmann.certassist.ExecutableResolver;
+import de.mlessmann.certassist.except.CommandLineOperationException;
+import de.mlessmann.certassist.except.UnresolvableCLIDependency;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.ExecutionException;
+import org.apache.commons.lang3.StringUtils;
+import org.slf4j.Logger;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.lang.Nullable;
+import org.springframework.stereotype.Service;
+import org.zeroturnaround.exec.ProcessExecutor;
+import org.zeroturnaround.exec.StartedProcess;
+import org.zeroturnaround.exec.stream.slf4j.Slf4jStream;
+
+@Service
+public class OpenSSLCertificateCreator {
+
+    public static final String OPENSSL_CERT_SUBJECT_TEMPLATE =
+        "/C=ISO-COUNTRY/ST=STATE/L=LOCALITY/O=ORGANIZATION/CN=COMMON-NAME";
+    private static final Logger LOGGER = getLogger(OpenSSLCertificateCreator.class);
+    private static final String CSR_EXT_TEMPLATE =
+        """
+        authorityKeyIdentifier=keyid,issuer
+        basicConstraints=CA:FALSE
+        keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
+        subjectAltName = @alt_names
+
+        [alt_names]
+        """;
+
+    private final ExecutableResolver executableResolver;
+
+    @Autowired
+    public OpenSSLCertificateCreator(ExecutableResolver executableResolver) {
+        this.executableResolver = executableResolver;
+    }
+
+    private static String buildSubjectArg(CertificateRequest request) {
+        String certSubject = OPENSSL_CERT_SUBJECT_TEMPLATE
+            .replace("ISO-COUNTRY", request.getSubject().getCountry())
+            .replace("STATE", request.getSubject().getState())
+            .replace("LOCALITY", request.getSubject().getLocality())
+            .replace("ORGANIZATION", request.getSubject().getOrganization())
+            .replace("COMMON-NAME", request.getCommonName());
+
+        if (StringUtils.isNotBlank(request.getSubject().getOrganizationalUnit())) {
+            certSubject += "/OU=" + request.getSubject().getOrganizationalUnit();
+        }
+
+        if (StringUtils.isNotBlank(request.getSubject().getEmailAddress())) {
+            certSubject += "/emailAddress=" + request.getSubject().getEmailAddress();
+        }
+        return certSubject;
+    }
+
+    @Nullable
+    public OpenSSLCertificateResult createCertificate(CertificateRequest request)
+        throws CommandLineOperationException, InterruptedException {
+        Path tmpDir;
+        try {
+            tmpDir = Files.createTempDirectory("certassist");
+        } catch (IOException e) {
+            throw new CommandLineOperationException("Could not create temporary directory for certificate creation", e);
+        }
+
+        Path keyFile = createKeyfile(request, tmpDir.resolve("root.key"));
+        Path rootCert = createCertificate(request, keyFile, tmpDir.resolve("root.crt"));
+
+        Path childKey = createKeyfile(request, tmpDir.resolve("child.key"));
+        Path unsignedCert = createCertificate(request, childKey, tmpDir.resolve("child.csr"));
+        Path signedCert = signCertificate(request, rootCert, keyFile, unsignedCert);
+        return new OpenSSLCertificateResult(tmpDir);
+    }
+
+    private Path createKeyfile(CertificateRequest request, Path outFile)
+        throws CommandLineOperationException, InterruptedException {
+        Path keyFile = outFile.toAbsolutePath();
+        LOGGER.atDebug().log("Writing new certificate key to {}", keyFile);
+
+        try {
+            StartedProcess keygenProc = new ProcessExecutor()
+                .command(
+                    resolveOpenSSL(),
+                    "genrsa",
+                    "-out",
+                    keyFile.toString(),
+                    "-passout",
+                    "env:KEY_PASS",
+                    Integer.toString(request.getRequestedKeyLength())
+                )
+                .environment("KEY_PASS", request.getOid())
+                .redirectOutput(Slf4jStream.ofCaller().asDebug())
+                .redirectError(Slf4jStream.ofCaller().asError())
+                .start();
+            keygenProc.getFuture().get();
+        } catch (IOException e) {
+            throw new CommandLineOperationException("Failure running OpenSSL keygen command.", e);
+        } catch (ExecutionException e) {
+            throw new RuntimeException(e);
+        }
+        return keyFile;
+    }
+
+    private Path createCertificate(CertificateRequest request, Path keyFile, Path outFile)
+        throws CommandLineOperationException, InterruptedException {
+        LOGGER.atDebug().log("Writing new certificate file {}", outFile);
+
+        String certSubject = buildSubjectArg(request);
+        try {
+            StartedProcess certGenProc = new ProcessExecutor()
+                .command(
+                    resolveOpenSSL(),
+                    "req",
+                    "-new",
+                    "-passin",
+                    "env:KEY_PASS",
+                    "-key",
+                    keyFile.toString(),
+                    "-sha256",
+                    "-days",
+                    Integer.toString(request.getRequestedValidityDays()),
+                    "-out",
+                    outFile.toString(),
+                    "-passout",
+                    "env:KEY_PASS",
+                    "-utf8",
+                    "-subj",
+                    certSubject
+                )
+                .environment("KEY_PASS", request.getOid())
+                .redirectOutput(Slf4jStream.ofCaller().asDebug())
+                .redirectError(Slf4jStream.ofCaller().asError())
+                .start();
+            certGenProc.getFuture().get();
+        } catch (IOException e) {
+            throw new CommandLineOperationException("Failure running OpenSSL req command.", e);
+        } catch (ExecutionException e) {
+            throw new RuntimeException(e);
+        }
+        return outFile;
+    }
+
+    private Path signCertificate(CertificateRequest request, Path caCert, Path caKey, Path csrFile)
+        throws CommandLineOperationException, InterruptedException {
+        Path outFile = csrFile.resolveSibling(csrFile.getFileName().toString().replace(".csr", ".crt"));
+        LOGGER.atDebug().log("Writing new signed certificate file {}", outFile);
+        Path extFile = csrFile.resolveSibling(csrFile.getFileName().toString().replace(".csr", ".ext"));
+
+        try {
+            String extContent = CSR_EXT_TEMPLATE;
+            List<String> altNames = Optional
+                .ofNullable(request.getExtension())
+                .map(CertificateRequestExtension::getAlternativeNames)
+                .orElse(List.of());
+            if (!altNames.isEmpty()) {
+                String altNamesContent = String.join("\n", altNames);
+                extContent = extContent.replaceAll("\\[alt_names]\n?, ", "[alt_names]\n" + altNamesContent);
+            } else {
+                extContent = extContent.replaceAll("\\s*subjectAltName\\s+=\\s+@alt_names\n?", "");
+                extContent = extContent.replaceAll("\\[alt_names]\n?, ", "");
+            }
+
+            LOGGER.debug("Writing extension file content: \n {}", extContent);
+            Files.writeString(
+                extFile,
+                extContent,
+                StandardCharsets.UTF_8,
+                StandardOpenOption.CREATE,
+                StandardOpenOption.TRUNCATE_EXISTING
+            );
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        try {
+            StartedProcess certGenProc = new ProcessExecutor()
+                .command(
+                    resolveOpenSSL(),
+                    "x509",
+                    "-req",
+                    "-days",
+                    Integer.toString(request.getRequestedValidityDays()),
+                    "-in",
+                    csrFile.toString(),
+                    "-CA",
+                    caCert.toString(),
+                    "-CAkey",
+                    caKey.toString(),
+                    "-CAcreateserial",
+                    "-out",
+                    outFile.toString(),
+                    "-extfile",
+                    extFile.toString()
+                )
+                .redirectOutput(Slf4jStream.ofCaller().asDebug())
+                .redirectError(Slf4jStream.ofCaller().asError())
+                .start();
+            certGenProc.getFuture().get();
+        } catch (IOException e) {
+            throw new CommandLineOperationException("Failure running OpenSSL x509 command.", e);
+        } catch (ExecutionException e) {
+            throw new RuntimeException(e);
+        }
+        return outFile;
+    }
+
+    private String resolveOpenSSL() throws CommandLineOperationException {
+        try {
+            return executableResolver.getOpenSSLPath();
+        } catch (UnresolvableCLIDependency e) {
+            throw new CommandLineOperationException(e);
+        }
+    }
+}

src/main/java/de/mlessmann/certassist/openssl/OpenSSLCertificateResult.java

@@ -0,0 +1,28 @@
+package de.mlessmann.certassist.openssl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import de.mlessmann.certassist.DeleteRecursiveFileVisitor;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Set;
+import org.slf4j.Logger;
+
+public class OpenSSLCertificateResult implements AutoCloseable {
+
+    private static final Logger LOGGER = getLogger(OpenSSLCertificateResult.class);
+
+    private final Path tmpDir;
+
+    OpenSSLCertificateResult(Path tmpDir) {
+        this.tmpDir = tmpDir;
+    }
+
+    @Override
+    public void close() throws IOException {
+        LOGGER.info("Cleaning up temporary output directory {}", tmpDir);
+        Files.walkFileTree(tmpDir, Set.of(), Integer.MAX_VALUE, new DeleteRecursiveFileVisitor());
+        Files.deleteIfExists(tmpDir);
+    }
+}

src/main/resources/application.properties

@@ -9,3 +9,7 @@ spring.jpa.database-platform=org.hibernate.community.dialect.SQLiteDialect
 #TODO: Use flyway for db setup
 hibernate.hbm2ddl.auto=create-drop
 hibernate.show_sql=true
+
+# Logging
+logging.level.root=INFO
+logging.level.de.mlessmann.certassist=DEBUG

src/test/java/de/mlessmann/certassist/TestOpenSSLCertificateCreator.java

@@ -0,0 +1,35 @@
+package de.mlessmann.certassist;
+
+import de.mlessmann.certassist.openssl.CertificateRequest;
+import de.mlessmann.certassist.openssl.CertificateRequest.RequestType;
+import de.mlessmann.certassist.openssl.CertificateRequestExtension;
+import de.mlessmann.certassist.openssl.CertificateSubject;
+import de.mlessmann.certassist.openssl.OpenSSLCertificateCreator;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class TestOpenSSLCertificateCreator {
+
+    private OpenSSLCertificateCreator openSSLCertificateCreator;
+
+    @BeforeEach
+    void setUp() {
+        ExecutableResolver executableResolver = new ExecutableResolver();
+        openSSLCertificateCreator = new OpenSSLCertificateCreator(executableResolver);
+    }
+
+    @Test
+    void testCertificateCreation() throws Exception {
+        CertificateRequest certRequest = CertificateRequest
+            .builder()
+            .commonName("test.home")
+            .type(RequestType.STANDALONE_CERTIFICATE)
+            .subject(CertificateSubject.builder().country("DE").state("SH").locality("HH").organization("Crazy-Cats"))
+            .extension(CertificateRequestExtension.builder().alternativeNames("test2.home", "test3.home"))
+            .build();
+
+        try (var cert = openSSLCertificateCreator.createCertificate(certRequest)) {
+            System.out.println("Certificate created: " + cert);
+        }
+    }
+}