Initial commit

.gitignore

@@ -0,0 +1,45 @@
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Kotlin ###
+.kotlin
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

.idea/.gitignore

@@ -0,0 +1,3 @@
+# Default ignored files
+/shelf/
+/workspace.xml

.idea/gradle.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="GradleMigrationSettings" migrationVersion="1" />
+  <component name="GradleSettings">
+    <option name="linkedExternalProjectsSettings">
+      <GradleProjectSettings>
+        <option name="externalProjectPath" value="$PROJECT_DIR$" />
+        <option name="gradleHome" value="" />
+        <option name="modules">
+          <set>
+            <option value="$PROJECT_DIR$" />
+          </set>
+        </option>
+      </GradleProjectSettings>
+    </option>
+  </component>
+</project>

.idea/kotlinc.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="KotlinJpsPluginSettings">
+    <option name="version" value="2.2.20" />
+  </component>
+</project>

.idea/misc.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="21" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>

.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

build.gradle.kts

@@ -0,0 +1,42 @@
+plugins {
+    kotlin("multiplatform") version "2.2.21"
+}
+
+repositories {
+    mavenCentral()
+}
+
+kotlin {
+    val hostOs = System.getProperty("os.name")
+    val isArm64 = System.getProperty("os.arch") == "aarch64"
+    val isMingwX64 = hostOs.startsWith("Windows")
+    val nativeTarget = when {
+        hostOs == "Mac OS X" && isArm64 -> macosArm64("native")
+        hostOs == "Mac OS X" && !isArm64 -> macosX64("native")
+        hostOs == "Linux" && isArm64 -> linuxArm64("native")
+        hostOs == "Linux" && !isArm64 -> linuxX64("native")
+        isMingwX64 -> mingwX64("native")
+        else -> throw GradleException("Host OS is not supported in Kotlin/Native.")
+    }
+
+    nativeTarget.apply {
+        compilations.getByName("main") {
+            cinterops {
+                val gpgme by creating
+            }
+        }
+        binaries {
+            executable {
+                entryPoint = "dn42.m724.auth.main"
+            }
+        }
+    }
+
+    sourceSets {
+        nativeMain.dependencies {
+        }
+        nativeTest.dependencies {
+            implementation("io.kotest:kotest-assertions-core:6.0.4")
+        }
+    }
+}

gradle.properties

@@ -0,0 +1 @@
+kotlin.code.style=official

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Sat Oct 25 20:37:08 CEST 2025
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

settings.gradle.kts

@@ -0,0 +1,4 @@
+plugins {
+    id("org.gradle.toolchains.foojay-resolver-convention") version "0.8.0"
+}
+rootProject.name = "dn42-auth"

src/nativeInterop/cinterop/gpgme.def

@@ -0,0 +1,4 @@
+headers = gpgme.h
+
+compilerOpts = -I/usr/include
+linkerOpts = -L/usr/lib64 -lgpgme

src/nativeMain/kotlin/dn42/m724/auth/AuthenticationMethod.kt

@@ -0,0 +1,20 @@
+package dn42.m724.auth
+
+sealed interface AuthenticationMethod {
+    data class Pgp(val fingerprint: String) : AuthenticationMethod {
+        init {
+            // TODO validate
+        }
+    }
+
+    data class Ssh(val type: KeyType, val fingerprint: String) : AuthenticationMethod {
+        init {
+            // TODO validate
+        }
+
+        enum class KeyType {
+            Rsa,
+            Ed25519
+        }
+    }
+}

src/nativeMain/kotlin/dn42/m724/auth/Main.kt

@@ -0,0 +1,26 @@
+package dn42.m724.auth
+
+import dn42.m724.auth.pgp.PgpSignatureChecker
+
+// This is actually a library, below code is just showcase
+
+fun main() {
+    print("Message to sign (single line): ")
+    val message = readln()
+
+    print("Key fingerprint:")
+    val fingerprint = readln()
+
+    println("Please input signature below:")
+    val lines = mutableListOf<String>()
+    while (lines.lastOrNull() != "-----END PGP SIGNATURE-----") {
+        print(" ")
+        lines.add(readln())
+    }
+
+    val signature = lines.joinToString("\n")
+
+    val checker = PgpSignatureChecker()
+    checker.verify(message, fingerprint, signature)
+    println("Signature is valid")
+}

src/nativeMain/kotlin/dn42/m724/auth/SignatureChecker.kt

@@ -0,0 +1,18 @@
+package dn42.m724.auth
+
+interface SignatureChecker {
+    /**
+     * Verifies whether the signature matches the provided key fingerprint and the plain text.
+     *
+     * @param sourcePlainText The plain text.
+     * @param keyFingerprint The key fingerprint the plain text must be signed with.
+     * @param signature The signature to verify.
+     *
+     * @throws Exception If we were unable to verify that the signature satisfies the above requirements.
+     */
+    fun verify(
+        sourcePlainText: String,
+        keyFingerprint: String,
+        signature: String
+    )
+}

src/nativeMain/kotlin/dn42/m724/auth/pgp/PgpSignatureChecker.kt

@@ -0,0 +1,150 @@
+package dn42.m724.auth.pgp
+
+import dn42.m724.auth.SignatureChecker
+import gpgme.*
+import kotlinx.cinterop.*
+import platform.posix.errno
+
+@OptIn(ExperimentalForeignApi::class)
+class PgpSignatureChecker : SignatureChecker {
+    override fun verify(sourcePlainText: String, keyFingerprint: String, signature: String) {
+        gpgme_check_version(null)?.let {
+            println("GPGME version: ${it.toKString()}")
+        } ?: throw RuntimeException("Failed to get GPGME version")
+
+        withGpgContextMemScoped { ctx ->
+            gpgme_set_protocol(ctx, GPGME_PROTOCOL_OPENPGP.toUInt())
+            gpgme_set_armor(ctx, 1)
+
+            val detached = signature.startsWith("-----BEGIN PGP SIGNATURE-----")
+            verifySignature(ctx, signature, sourcePlainText, detached)
+
+            val signature = gpgme_op_verify_result(ctx)?.let {
+                findMatchingKeyFingerprint(it, keyFingerprint)
+            } ?: throw RuntimeException("Did not find any signature with matching key fingerprint")
+
+            if (!signature.isGood()) {
+                throw RuntimeException("Bad signature for matching key fingerprint")
+            }
+        }
+    }
+
+    private fun _gpgme_signature.isGood(): Boolean {
+        return this.summary.and(GPGME_SIG_STAT_GOOD) != 0u
+    }
+
+    private fun findMatchingKeyFingerprint(
+        result: CPointer<_gpgme_op_verify_result>,
+        keyFingerprint: String
+    ): _gpgme_signature? {
+        var matchingSignature: _gpgme_signature? = null
+
+        result.pointed.signatures?.let { initialPointer ->
+            var signaturePointer: CPointer<_gpgme_signature>? = initialPointer
+            println("pointer is null: ${signaturePointer == null}")
+
+            while (signaturePointer != null) {
+                val signature = signaturePointer.pointed
+                println("Found signature with timestamp ${signature.timestamp} and fingerprint ${signature.fpr?.toKString()}")
+
+                assertGpg(signature.status) { "Failed to check signature" }
+
+                if (signature.fpr?.toKString() == keyFingerprint) {
+                    matchingSignature = signature
+                    break
+                }
+
+
+                signaturePointer = signature.next
+            }
+        }
+
+        return matchingSignature
+    }
+
+    private fun MemScope.verifySignature(
+        ctx: gpgme_ctx_t,
+        signedMessage: String,
+        sourcePlainText: String,
+        detached: Boolean
+    ) {
+        val sigData = alloc<gpgme_data_tVar>()
+        val textData = alloc<gpgme_data_tVar>()
+        val plainData = alloc<gpgme_data_tVar>()
+
+        try {
+            assertGpg(
+                gpgme_data_new_from_mem(sigData.ptr, signedMessage, signedMessage.length.toULong(), 1) // TODO idk if the 1 is good
+            ) { "Failed to read signature" }
+
+            assertGpg(
+                gpgme_data_new_from_mem(textData.ptr, sourcePlainText, sourcePlainText.length.toULong(), 1)
+            ) { "Failed to create text data object" }
+
+            assertGpg(
+                gpgme_data_new(plainData.ptr)
+            ) { "Failed to create data object" }
+
+            assertGpg(
+                gpgme_op_verify(ctx, sigData.value, textData.value, if (detached) null else plainData.value)
+            ) { "Failed to verify" }
+
+            assertGpg(
+                gpgme_data_seek(plainData.value, 0, SEEK_SET) != -1L
+            ) { "Failed to reset plain data for reading" } // TODO is this even necessary
+
+            if (!detached) {
+                var plainText = ""
+                allocArray<ByteVar>(512).let { buffer ->
+                    while (gpgme_data_read(plainData.value, buffer, 512u) > 0) {
+                        plainText += buffer.toKString()
+                    }
+                }
+
+                println(plainText.encodeToByteArray().toHexString())
+                println(sourcePlainText.encodeToByteArray().toHexString())
+
+                check(plainText.trim() == sourcePlainText.trim()) { "Plain text message doesn't match" }
+            }
+        } finally {
+            gpgme_data_release(sigData.value)
+            gpgme_data_release(textData.value)
+            gpgme_data_release(plainData.value)
+        }
+    }
+
+    private fun withGpgContextMemScoped(
+        block: MemScope.(gpgme_ctx_t) -> Unit
+    ) {
+        memScoped {
+            val ctxPointer = alloc<gpgme_ctx_tVar>()
+
+            assertGpg(gpgme_new(ctxPointer.ptr)) { "Error creating GPGME context" }
+
+            try {
+                block(ctxPointer.value!!)
+            } finally {
+                gpgme_release(ctxPointer.value)
+            }
+        }
+    }
+
+    private fun assertGpg(
+        errorCode: UInt,
+        message: () -> String
+    ) {
+        if (gpg_err_code(errorCode) != GPG_ERR_NO_ERROR) {
+            val causeMessage = gpgme_strerror(errorCode)!!.toKString()
+            throw RuntimeException("${message()}: $causeMessage")
+        }
+    }
+
+    private fun assertGpg(
+        success: Boolean,
+        message: () -> String
+    ) {
+        if (!success) {
+            assertGpg(gpgme_error_from_errno(errno), message)
+        }
+    }
+}

src/nativeTest/kotlin/dn42/m724/auth/pgp/PgpSignatureVerificationTest.kt

@@ -0,0 +1,82 @@
+package dn42.m724.auth.pgp
+
+import dn42.m724.auth.SignatureChecker
+import io.kotest.assertions.throwables.shouldNotThrowAny
+import io.kotest.assertions.throwables.shouldThrow
+import kotlin.experimental.ExperimentalNativeApi
+import kotlin.test.BeforeTest
+import kotlin.test.Test
+
+private const val fingerprint = "2DE81640E41DD84A9ED9B8F8FD4D7C6652E72E7B"
+private const val invalidFingerprint = "139F1460BC66A19A2F880D8D47BA020D8EBCC05E"
+
+private val clearTextSignature = """
+    -----BEGIN PGP SIGNED MESSAGE-----
+    Hash: SHA512
+
+    simple message
+    -----BEGIN PGP SIGNATURE-----
+
+    iJEEARYKADkWIQQt6BZA5B3YSp7ZuPj9TXxmUucuewUCaP4wchsUgAAAAAAEAA5t
+    YW51MiwyLjUrMS4xMSwyLDIACgkQ/U18ZlLnLnuM3AD+L0QBrn2pnGAemcJZDh+p
+    6oJnuTgeSMiMRkkbMgTOMFMBAPzhLKgyzx4YJcgrIinvZsgPowR9Pf0ryzxwQ5mo
+    qUwJ
+    =FYVj
+    -----END PGP SIGNATURE-----
+    """.trimIndent()
+
+val detachedSignature = """
+    -----BEGIN PGP SIGNATURE-----
+
+    iJEEABYKADkWIQQt6BZA5B3YSp7ZuPj9TXxmUucuewUCaP4wWxsUgAAAAAAEAA5t
+    YW51MiwyLjUrMS4xMSwyLDIACgkQ/U18ZlLnLnsaEgEA15uncZNWN6zV952vO6rG
+    mMIAG9X54X9Cfp5DEfG3hPcBAJypNGnlyHivk+ZKYDlKSZB2S53vKrA3q3J2yDqb
+    0SUF
+    =12FC
+    -----END PGP SIGNATURE-----
+""".trimIndent()
+
+@OptIn(ExperimentalNativeApi::class)
+class PgpSignatureVerificationTest {
+    private lateinit var checker: SignatureChecker
+
+    @BeforeTest
+    fun beforeTest() {
+        checker = PgpSignatureChecker()
+    }
+
+    @Test
+    fun `verify should succeed for valid signature`() {
+        shouldNotThrowAny {
+            checker.verify ("simple message", fingerprint, clearTextSignature)
+        }
+    }
+
+    @Test
+    fun `verify should succeed for valid detached signature`() {
+        shouldNotThrowAny {
+            checker.verify("simple message", fingerprint, detachedSignature)
+        }
+    }
+
+    @Test
+    fun `verify should fail for not matching message`() {
+        shouldThrow<Exception> { // "Plain text message doesn't match"
+            checker.verify("totally different", fingerprint, clearTextSignature)
+        }
+    }
+
+    @Test
+    fun `verify should fail for not matching detached message`() {
+        shouldThrow<Exception> { // "Failed to check signature: Bad signature"
+            checker.verify("totally different", fingerprint, detachedSignature)
+        }
+    }
+
+    @Test
+    fun `verify should fail for not matching fingerprint`() {
+        shouldThrow<Exception> { // Did not find any signature with matching key fingerprint
+            checker.verify("simple message", invalidFingerprint, detachedSignature)
+        }
+    }
+}