refactor: rename modules

Closes #75

crypto-toolbox/README.md

@@ -0,0 +1,113 @@
+# KeyLoader
+
+KeyLoader provides utility methods to load keys from pem-formatted key texts.
+
+## ECDSA-based algorithm
+
+### Generate key pair
+
+#### Generate private key
+
+Generate a private key by `genpkey` command provided by OpenSSL:
+
+```shell
+openssl genpkey -algorithm EC -pkeyopt ec_paramgen_curve:P-256 -out ec_private_key.pem
+```
+
+The output of this command is a file called `ec_private_key.pem` and its content looks like the
+following:
+
+```text
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgs79JlARgXEf6EDV7
++PHQCTHEMtqIoHOy1GZ1+ynQJ6yhRANCAARkA7GRY2i4gg8qx0XViAXUP9cPw9pn
+Jg1wfrQ41FaMyqVBejNYxvaLtamErF/ySimnjafMJ+VZCh34lBj6Ez8R
+-----END PRIVATE KEY-----
+```
+
+#### Generate public key by private key
+
+Export public key from private key with `ec` command provided by OpenSSL:
+
+```shell
+openssl ec -in ec_private_key.pem -pubout -out ec_public_key.pem
+```
+
+The output of this command is a file called `ec_public_key.pem` and its content looks like the
+following:
+
+```text
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEZAOxkWNouIIPKsdF1YgF1D/XD8Pa
+ZyYNcH60ONRWjMqlQXozWMb2i7WphKxf8kopp42nzCflWQod+JQY+hM/EQ==
+-----END PUBLIC KEY-----
+```
+
+## RSA-based algorithm
+
+### Generate key pair
+
+#### Generate private key
+
+Generate a private key by `genpkey` command provided by OpenSSL:
+
+```shell
+openssl genpkey -algorithm RSA -out rsa_private_key.pem -pkeyopt rsa_keygen_bits:2048
+```
+
+The output of this command is a file called `rsa_private_key.pem` and its content looks like the
+following:
+
+```text
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----
+```
+
+#### Generate public key by private key
+
+Export public key from private key by OpenSSL:
+
+```shell
+openssl pkey -in rsa_private_key.pem -pubout -out rsa_public_key.pem
+```
+
+The output of this command is a file called `rsa_public_key.pem` and its content looks like the
+following:
+
+```text
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA+FSBWCRTALNeYyd1dyIn
+B3e7CNkyBak2TBONM5TpVQJTyi2Zk0L2RSzYGlAALLz4uYtQ0dssMCugJQX58FZ8
+75g1wuZihzs+KMTkFQOjZadslWkDM4nZn2DUpDLXL/+B0T7GrXOyvzOZeqQj9tA1
+UY5IpAXSMvHvcPsegayBaeUPD2XP19gRjQFDDGAAnXmB+UfwNAsapDQ9d3rHOIJM
+pzDq72a2Rhws+dbrH0gqsg1lsLDfhhui2FomuBpDZUtHq0Jz/IEvd3X45XvegSH8
+t8+yL/pFK3+YpDVtj/IzMSwL+izvnXFALvZOO+8CABeyKuSjLh/6LbAzrvoftql5
+gQIDAQAB
+-----END PUBLIC KEY-----
+```

crypto-toolbox/build.gradle.kts

@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+import java.net.URI
+
+plugins {
+    java
+    id("java-library")
+    id("maven-publish")
+    id("signing")
+}
+
+val artefactVersion: String by project
+val projectUrl: String by project
+val projectGithubUrl: String by project
+val licenseName: String by project
+val licenseUrl: String by project
+
+group = "com.onixbyte"
+version = artefactVersion
+
+repositories {
+    mavenCentral()
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
+    withSourcesJar()
+    withJavadocJar()
+}
+
+tasks.withType<JavaCompile> {
+    options.encoding = "UTF-8"
+}
+
+tasks.withType<Jar> {
+    exclude("logback.xml")
+}
+
+dependencies {
+    compileOnly(libs.slf4j)
+    implementation(libs.logback)
+    testImplementation(libs.jwt.core)
+    testImplementation(platform(libs.junit.bom))
+    testImplementation(libs.junit.jupiter)
+}
+
+tasks.test {
+    useJUnitPlatform()
+    testLogging {
+        events("passed", "skipped", "failed")
+    }
+}
+
+publishing {
+    publications {
+        create<MavenPublication>("cryptoToolbox") {
+            groupId = group.toString()
+            artifactId = "crypto-toolbox"
+            version = artefactVersion
+
+            pom {
+                name = "OnixByte Crypto Toolbox"
+                description =
+                    "This module can easily load key pairs from a PEM content."
+                url = projectUrl
+
+                licenses {
+                    license {
+                        name = licenseName
+                        url = licenseUrl
+                    }
+                }
+
+                scm {
+                    connection = "scm:git:git://github.com:OnixByte/JDevKit.git"
+                    developerConnection = "scm:git:git://github.com:OnixByte/JDevKit.git"
+                    url = projectGithubUrl
+                }
+
+                developers {
+                    developer {
+                        id = "zihluwang"
+                        name = "Zihlu Wang"
+                        email = "really@zihlu.wang"
+                        timezone = "Asia/Hong_Kong"
+                    }
+
+                    developer {
+                        id = "siujamo"
+                        name = "Siu Jam'o"
+                        email = "jamo.siu@outlook.com"
+                        timezone = "Asia/Shanghai"
+                    }
+                }
+            }
+
+            from(components["java"])
+
+            signing {
+                sign(publishing.publications["cryptoToolbox"])
+            }
+        }
+
+        repositories {
+            maven {
+                name = "sonatypeNexus"
+                url = URI(providers.gradleProperty("repo.maven-central.host").get())
+                credentials {
+                    username = providers.gradleProperty("repo.maven-central.username").get()
+                    password = providers.gradleProperty("repo.maven-central.password").get()
+                }
+            }
+        }
+    }
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/PrivateKeyLoader.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto;
+
+import java.security.PrivateKey;
+
+/**
+ * The {@code PrivateKeyLoader} interface provides utility methods for loading keys pairs from
+ * PEM-formatted key text. This class supports loading both private and public keys.
+ *
+ * @author zihluwang
+ * @author siujamo
+ * @version 2.0.0
+ * @since 1.6.0
+ */
+public interface PrivateKeyLoader {
+
+    /**
+     * Load private key from pem-formatted key text.
+     *
+     * @param pemKeyText pem-formatted key text
+     * @return loaded private key
+     */
+    PrivateKey loadPrivateKey(String pemKeyText);
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/PublicKeyLoader.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto;
+
+import com.onixbyte.crypto.exception.KeyLoadingException;
+
+import java.security.PublicKey;
+import java.security.interfaces.ECPublicKey;
+import java.security.interfaces.RSAPublicKey;
+
+/**
+ *
+ * @author siujamo
+ * @version 3.0.0
+ */
+public interface PublicKeyLoader {
+
+    /**
+     * Load public key from pem-formatted key text.
+     *
+     * @param pemKeyText pem-formatted key text
+     * @return loaded private key
+     */
+    PublicKey loadPublicKey(String pemKeyText);
+
+    /**
+     * Loads an EC public key using the provided x and y coordinates together with the curve name.
+     * <p>
+     * This default implementation throws a {@link KeyLoadingException} to signify that this key
+     * loader does not support loading an EC public key. Implementing classes are expected to
+     * override this method to supply their own loading logic.
+     *
+     * @param xHex      the hexadecimal string representing the x coordinate of the EC point
+     * @param yHex      the hexadecimal string representing the y coordinate of the EC point
+     * @param curveName the name of the elliptic curve
+     * @return the loaded {@link ECPublicKey} instance
+     * @throws KeyLoadingException if loading is not supported or fails
+     */
+    default ECPublicKey loadPublicKey(String xHex, String yHex, String curveName) {
+        throw new KeyLoadingException("This key loader does not support loading an EC public key.");
+    }
+
+    /**
+     * Loads an RSA public key using the provided modulus and exponent.
+     * <p>
+     * This default implementation throws a {@link KeyLoadingException} to signify that this key
+     * loader does not support loading an RSA public key. Implementing classes are expected to
+     * override this method to supply their own loading logic.
+     *
+     * @param modulus  the modulus value of the RSA public key, usually represented in hexadecimal
+     *                 or Base64 string format
+     * @param exponent the public exponent value of the RSA public key, usually represented in
+     *                 hexadecimal or Base64 string format
+     * @return the loaded {@link RSAPublicKey} instance
+     * @throws KeyLoadingException if loading is not supported or fails
+     */
+    default RSAPublicKey loadPublicKey(String modulus, String exponent) {
+        throw new KeyLoadingException("This key loader does not support loading an RSA public key.");
+    }
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/algorithm/ecdsa/ECPrivateKeyLoader.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto.algorithm.ecdsa;
+
+import com.onixbyte.crypto.PrivateKeyLoader;
+import com.onixbyte.crypto.exception.KeyLoadingException;
+import com.onixbyte.crypto.util.CryptoUtil;
+
+import java.math.BigInteger;
+import java.security.AlgorithmParameters;
+import java.security.KeyFactory;
+import java.security.NoSuchAlgorithmException;
+import java.security.interfaces.ECPrivateKey;
+import java.security.interfaces.ECPublicKey;
+import java.security.spec.*;
+import java.util.Base64;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Key pair loader for loading key pairs for ECDSA-based algorithms.
+ * <p>
+ *
+ * <b>Example usage for ECDSA:</b>
+ * <pre>{@code
+ * PrivateKeyLoader keyLoader = new EcKeyLoader();
+ * String pemPrivateKey = """
+ *                        -----BEGIN EC PRIVATE KEY-----
+ *                        ...
+ *                        -----END EC PRIVATE KEY-----""";
+ * ECPrivateKey privateKey = PrivateKeyLoader.loadEcdsaPrivateKey(pemPrivateKey);
+ *
+ * String pemPublicKey = """
+ *                       -----BEGIN EC PUBLIC KEY-----
+ *                       ...
+ *                       -----END EC PUBLIC KEY-----""";
+ * ECPublicKey publicKey = PrivateKeyLoader.loadPublicKey(pemPublicKey);
+ * }</pre>
+ *
+ * @author zihluwang
+ * @version 2.0.0
+ * @since 2.0.0
+ */
+public class ECPrivateKeyLoader implements PrivateKeyLoader {
+
+    private final KeyFactory keyFactory;
+
+    private final Base64.Decoder decoder;
+
+    /**
+     * Initialise a key loader for EC-based algorithms.
+     */
+    public ECPrivateKeyLoader() {
+        try {
+            this.keyFactory = KeyFactory.getInstance("EC");
+            this.decoder = Base64.getDecoder();
+        } catch (NoSuchAlgorithmException e) {
+            throw new KeyLoadingException(e);
+        }
+    }
+
+    /**
+     * Load ECDSA private key from pem-formatted key text.
+     *
+     * @param pemKeyText pem-formatted key text
+     * @return loaded private key
+     * @throws KeyLoadingException if the generated key is not a {@link ECPrivateKey} instance,
+     *                             or EC Key Factory is not loaded, or key spec is invalid
+     */
+    @Override
+    public ECPrivateKey loadPrivateKey(String pemKeyText) {
+        try {
+            pemKeyText = CryptoUtil.getRawContent(pemKeyText);
+            var decodedKeyString = decoder.decode(pemKeyText);
+            var keySpec = new PKCS8EncodedKeySpec(decodedKeyString);
+
+            var _key = keyFactory.generatePrivate(keySpec);
+            if (_key instanceof ECPrivateKey privateKey) {
+                return privateKey;
+            } else {
+                throw new KeyLoadingException("Unable to load private key from pem-formatted key text.");
+            }
+        } catch (InvalidKeySpecException e) {
+            throw new KeyLoadingException("Key spec is invalid.", e);
+        }
+    }
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/algorithm/ecdsa/ECPublicKeyLoader.java

@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto.algorithm.ecdsa;
+
+import com.onixbyte.crypto.PublicKeyLoader;
+import com.onixbyte.crypto.exception.KeyLoadingException;
+import com.onixbyte.crypto.util.CryptoUtil;
+
+import java.math.BigInteger;
+import java.security.AlgorithmParameters;
+import java.security.KeyFactory;
+import java.security.NoSuchAlgorithmException;
+import java.security.interfaces.ECPrivateKey;
+import java.security.interfaces.ECPublicKey;
+import java.security.spec.*;
+import java.util.Base64;
+import java.util.HashSet;
+import java.util.Set;
+
+public class ECPublicKeyLoader implements PublicKeyLoader {
+
+    /**
+     * Supported curves.
+     */
+    public static final Set<String> SUPPORTED_CURVES = new HashSet<>(Set.of(
+        "secp256r1", "secp384r1", "secp521r1", "secp224r1"
+    ));
+
+    private final KeyFactory keyFactory;
+
+    private final Base64.Decoder decoder;
+
+    /**
+     * Initialise a key loader for EC-based algorithms.
+     */
+    public ECPublicKeyLoader() {
+        try {
+            this.keyFactory = KeyFactory.getInstance("EC");
+            this.decoder = Base64.getDecoder();
+        } catch (NoSuchAlgorithmException e) {
+            throw new KeyLoadingException(e);
+        }
+    }
+
+    /**
+     * Load public key from pem-formatted key text.
+     *
+     * @param pemKeyText pem-formatted key text
+     * @return loaded private key
+     * @throws KeyLoadingException if the generated key is not a {@link ECPrivateKey} instance,
+     *                             or EC Key Factory is not loaded, or key spec is invalid
+     */
+    @Override
+    public ECPublicKey loadPublicKey(String pemKeyText) {
+        try {
+            pemKeyText = CryptoUtil.getRawContent(pemKeyText);
+            var keyBytes = decoder.decode(pemKeyText);
+            var spec = new X509EncodedKeySpec(keyBytes);
+            var key = keyFactory.generatePublic(spec);
+            if (key instanceof ECPublicKey publicKey) {
+                return publicKey;
+            } else {
+                throw new KeyLoadingException("Unable to load public key from pem-formatted key text.");
+            }
+        } catch (InvalidKeySpecException e) {
+            throw new KeyLoadingException("Key spec is invalid.", e);
+        }
+    }
+
+    /**
+     * Loads an EC public key from the given hexadecimal x and y coordinates alongside the curve name.
+     * <p>
+     * This method converts the hexadecimal string representations of the EC point coordinates into {@link BigInteger}
+     * instances, then constructs an {@link ECPoint} and retrieves the corresponding {@link ECParameterSpec} for the
+     * named curve. Subsequently, it utilises the {@link KeyFactory} to generate an {@link ECPublicKey}.
+     * <p>
+     * Only curves listed in {@link #SUPPORTED_CURVES} are supported. Should the specified curve name be unsupported,
+     * or if key construction fails due to invalid parameters or unsupported algorithms, a {@link KeyLoadingException}
+     * will be thrown.
+     *
+     * @param xHex      the hexadecimal string representing the x-coordinate of the EC point
+     * @param yHex      the hexadecimal string representing the y-coordinate of the EC point
+     * @param curveName the name of the elliptic curve
+     * @return the {@link ECPublicKey} generated from the specified coordinates and curve
+     * @throws KeyLoadingException if the curve is unsupported or key generation fails
+     */
+    @Override
+    public ECPublicKey loadPublicKey(String xHex, String yHex, String curveName) {
+        if (!SUPPORTED_CURVES.contains(curveName)) {
+            throw new KeyLoadingException("Given curve is not supported yet.");
+        }
+
+        try {
+            // Convert hex string coordinates to BigInteger
+            var x = new BigInteger(xHex, 16);
+            var y = new BigInteger(yHex, 16);
+
+            // Create ECPoint with (x, y)
+            var ecPoint = new ECPoint(x, y);
+
+            // Get EC parameter spec for the named curve
+            var parameters = AlgorithmParameters.getInstance("EC");
+            parameters.init(new ECGenParameterSpec(curveName));
+            var ecParameterSpec = parameters.getParameterSpec(ECParameterSpec.class);
+
+            // Create ECPublicKeySpec with point and curve params
+            var pubSpec = new ECPublicKeySpec(ecPoint, ecParameterSpec);
+
+            // Generate public key using KeyFactory
+            var publicKey = keyFactory.generatePublic(pubSpec);
+
+            if (publicKey instanceof ECPublicKey ecPublicKey) {
+                return ecPublicKey;
+            } else {
+                throw new KeyLoadingException("Cannot load EC public key with given x, y and curve name.");
+            }
+        } catch (NoSuchAlgorithmException | InvalidParameterSpecException | InvalidKeySpecException e) {
+            throw new KeyLoadingException("Cannot load EC public key with given x, y and curve name.", e);
+        }
+    }
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/algorithm/rsa/RSAPrivateKeyLoader.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto.algorithm.rsa;
+
+import com.onixbyte.crypto.PrivateKeyLoader;
+import com.onixbyte.crypto.exception.KeyLoadingException;
+import com.onixbyte.crypto.util.CryptoUtil;
+
+import java.math.BigInteger;
+import java.security.KeyFactory;
+import java.security.NoSuchAlgorithmException;
+import java.security.interfaces.RSAPrivateKey;
+import java.security.interfaces.RSAPublicKey;
+import java.security.spec.*;
+import java.util.Base64;
+
+/**
+ * A class responsible for loading RSA keys from PEM formatted text.
+ * <p>
+ * This class implements the {@link PrivateKeyLoader} interface and provides methods to load both private
+ * and public RSA keys. The keys are expected to be in the standard PEM format, which includes
+ * Base64-encoded key content surrounded by header and footer lines. The class handles the decoding
+ * of Base64 content and the generation of keys using the RSA key factory.
+ * <p>
+ * Any exceptions encountered during the loading process are encapsulated in a
+ * {@link KeyLoadingException}, allowing for flexible error handling.
+ *
+ * @author siujamo
+ * @see PrivateKeyLoader
+ * @see KeyLoadingException
+ */
+public class RSAPrivateKeyLoader implements PrivateKeyLoader {
+
+    private final Base64.Decoder decoder;
+
+    private final KeyFactory keyFactory;
+
+    /**
+     * Constructs an instance of {@code RsaKeyLoader}.
+     * <p>
+     * This constructor initialises the Base64 decoder and the RSA {@link KeyFactory}. It may throw
+     * a {@link KeyLoadingException} if the RSA algorithm is not available.
+     */
+    public RSAPrivateKeyLoader() {
+        try {
+            this.decoder = Base64.getDecoder();
+            this.keyFactory = KeyFactory.getInstance("RSA");
+        } catch (NoSuchAlgorithmException e) {
+            throw new KeyLoadingException(e);
+        }
+    }
+
+    /**
+     * Loads an RSA private key from a given PEM formatted key text.
+     * <p>
+     * This method extracts the raw key content from the provided PEM text, decodes the
+     * Base64-encoded content, and generates an instance of {@link RSAPrivateKey}. If the key cannot
+     * be loaded due to invalid specifications or types, a {@link KeyLoadingException} is thrown.
+     *
+     * @param pemKeyText the PEM formatted private key text
+     * @return an instance of {@link RSAPrivateKey}
+     * @throws KeyLoadingException if the key loading process encounters an error
+     */
+    @Override
+    public RSAPrivateKey loadPrivateKey(String pemKeyText) {
+        // Extract the raw key content
+        var rawKeyContent = CryptoUtil.getRawContent(pemKeyText);
+
+        // Decode the Base64-encoded content
+        var keyBytes = decoder.decode(rawKeyContent);
+
+        // Create a PKCS8EncodedKeySpec from the decoded bytes
+        var keySpec = new PKCS8EncodedKeySpec(keyBytes);
+
+        try {
+            // Get an RSA KeyFactory and generate the private key
+            var _key = keyFactory.generatePrivate(keySpec);
+            if (_key instanceof RSAPrivateKey key) {
+                return key;
+            } else {
+                throw new KeyLoadingException("Unable to load private key from pem-formatted key text.");
+            }
+        } catch (InvalidKeySpecException e) {
+            throw new KeyLoadingException("Key spec is invalid.", e);
+        }
+    }
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/algorithm/rsa/RSAPublicKeyLoader.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto.algorithm.rsa;
+
+import com.onixbyte.crypto.PublicKeyLoader;
+import com.onixbyte.crypto.exception.KeyLoadingException;
+import com.onixbyte.crypto.util.CryptoUtil;
+
+import java.math.BigInteger;
+import java.security.KeyFactory;
+import java.security.NoSuchAlgorithmException;
+import java.security.interfaces.RSAPublicKey;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.KeySpec;
+import java.security.spec.RSAPublicKeySpec;
+import java.security.spec.X509EncodedKeySpec;
+import java.util.Base64;
+
+public class RSAPublicKeyLoader implements PublicKeyLoader {
+
+    private final Base64.Decoder decoder;
+
+    private final Base64.Decoder urlDecoder;
+
+    private final KeyFactory keyFactory;
+
+    /**
+     * Constructs an instance of {@code RsaKeyLoader}.
+     * <p>
+     * This constructor initialises the Base64 decoder and the RSA {@link KeyFactory}. It may throw
+     * a {@link KeyLoadingException} if the RSA algorithm is not available.
+     */
+    public RSAPublicKeyLoader() {
+        try {
+            this.decoder = Base64.getDecoder();
+            this.urlDecoder = Base64.getUrlDecoder();
+            this.keyFactory = KeyFactory.getInstance("RSA");
+        } catch (NoSuchAlgorithmException e) {
+            throw new KeyLoadingException(e);
+        }
+    }
+
+    /**
+     * Loads an RSA public key from a given PEM formatted key text.
+     * <p>
+     * This method extracts the raw key content from the provided PEM text, decodes the
+     * Base64-encoded content, and generates an instance of {@link RSAPublicKey}. If the key cannot
+     * be loaded due to invalid specifications or types, a {@link KeyLoadingException} is thrown.
+     *
+     * @param pemKeyText the PEM formatted public key text
+     * @return an instance of {@link RSAPublicKey}
+     * @throws KeyLoadingException if the key loading process encounters an error
+     */
+    @Override
+    public RSAPublicKey loadPublicKey(String pemKeyText) {
+        // Extract the raw key content
+        var rawKeyContent = CryptoUtil.getRawContent(pemKeyText);
+
+        // Decode the Base64-encoded content
+        var keyBytes = decoder.decode(rawKeyContent);
+
+        // Create an X509EncodedKeySpec from the decoded bytes
+        var keySpec = new X509EncodedKeySpec(keyBytes);
+
+        // Get an RSA KeyFactory and generate the public key
+        try {
+            var _key = keyFactory.generatePublic(keySpec);
+            if (_key instanceof RSAPublicKey key) {
+                return key;
+            } else {
+                throw new KeyLoadingException("Unable to load public key from pem-formatted key text.");
+            }
+        } catch (InvalidKeySpecException e) {
+            throw new KeyLoadingException("Key spec is invalid.", e);
+        }
+    }
+
+    /**
+     * Get the public key with given modulus and public exponent.
+     *
+     * @param modulus  the modulus
+     * @param exponent the public exponent
+     * @return generated public key object from the provided key specification
+     * @see KeyFactory#getInstance(String)
+     * @see KeyFactory#generatePublic(KeySpec)
+     */
+    @Override
+    public RSAPublicKey loadPublicKey(String modulus, String exponent) {
+        try {
+            var _modulus = new BigInteger(1, urlDecoder.decode(modulus));
+            var _exponent = new BigInteger(1, urlDecoder.decode(exponent));
+
+            var keySpec = new RSAPublicKeySpec(_modulus, _exponent);
+            var kf = KeyFactory.getInstance("RSA");
+            if (kf.generatePublic(keySpec) instanceof RSAPublicKey rsaPublicKey) {
+                return rsaPublicKey;
+            } else {
+                throw new KeyLoadingException("Cannot generate RSA public key with given modulus and exponent.");
+            }
+        } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
+            throw new KeyLoadingException("Cannot generate RSA public key with given modulus and exponent.", e);
+        }
+    }
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/exception/KeyLoadingException.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto.exception;
+
+/**
+ * The {@code KeyLoadingException} class represents an exception that is thrown when there is an
+ * error loading cryptographic keys. This exception can be used to indicate various issues such as
+ * invalid key specifications, unsupported key algorithms, or other key loading errors.
+ * <p>
+ * This class extends {@link RuntimeException}, allowing it to be thrown without being declared in
+ * a method's {@code throws} clause.
+ * </p>
+ * 
+ * <p><b>Example usage:</b></p>
+ * <pre>{@code
+ * try {
+ *     PrivateKeyLoader keyLoader = new ECPrivateKeyLoader();
+ *     ECPrivateKey privateKey = keyLoader.loadPrivateKey(pemPrivateKey);
+ * } catch (KeyLoadingException e) {
+ *     // Handle the exception
+ *     e.printStackTrace();
+ * }
+ * }</pre>
+ *
+ * @author zihluwang
+ * @version 3.0.0
+ * @since 1.6.0
+ */
+public class KeyLoadingException extends RuntimeException {
+
+    /**
+     * Creates a new instance of {@code KeyLoadingException} without a specific message or cause.
+     */
+    public KeyLoadingException() {
+    }
+
+    /**
+     * Creates a new instance of {@code KeyLoadingException} with the specified detail message.
+     *
+     * @param message the detail message
+     */
+    public KeyLoadingException(String message) {
+        super(message);
+    }
+
+    /**
+     * Creates a new instance of {@code KeyLoadingException} with the specified detail message
+     * and cause.
+     *
+     * @param message the detail message
+     * @param cause   the cause of this exception
+     */
+    public KeyLoadingException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    /**
+     * Creates a new instance of {@code KeyLoadingException} with the specified cause.
+     *
+     * @param cause the cause of this exception
+     */
+    public KeyLoadingException(Throwable cause) {
+        super(cause);
+    }
+
+    /**
+     * Constructs a new exception with the specified detail message, cause, suppression enabled
+     * or disabled, and writable stack trace enabled or disabled.
+     *
+     * @param message the detail message
+     * @param cause the cause of this exception
+     * @param enableSuppression whether suppression is enabled or disabled
+     * @param writableStackTrace whether the stack trace should be writable
+     */
+    public KeyLoadingException(String message,
+                               Throwable cause,
+                               boolean enableSuppression,
+                               boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+}

crypto-toolbox/src/main/java/com/onixbyte/crypto/util/CryptoUtil.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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.
+ */
+
+package com.onixbyte.crypto.util;
+
+public final class CryptoUtil {
+
+    private CryptoUtil() {
+    }
+
+    /**
+     * Retrieves the raw content of a PEM formatted key by removing unnecessary headers, footers,
+     * and new line characters.
+     *
+     * <p>
+     * This method processes the provided PEM key text to return a cleaned string that contains
+     * only the key content. The method strips away the
+     * {@code "-----BEGIN (EC )?(PRIVATE|PUBLIC) KEY-----"} and
+     * {@code "-----END (EC )?(PRIVATE|PUBLIC) KEY-----"} lines, as well as any new line characters,
+     * resulting in a continuous string representation of the key, which can be used for further
+     * cryptographic operations.
+     *
+     * @param pemKeyText the PEM formatted key as a string, which may include headers, footers and
+     *                   line breaks
+     * @return a string containing the raw key content devoid of  any unnecessary formatting
+     * or whitespace
+     */
+    public static String getRawContent(String pemKeyText) {
+        // remove all unnecessary parts of the pem key text
+        return pemKeyText
+            .replaceAll("-----BEGIN ((EC )|(RSA ))?(PRIVATE|PUBLIC) KEY-----", "")
+            .replaceAll("-----END ((EC )|(RSA ))?(PRIVATE|PUBLIC) KEY-----", "")
+            .replaceAll("\n", "");
+    }
+}

crypto-toolbox/src/main/resources/logback.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright (C) 2024-2024 OnixByte.
+  ~
+  ~ 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
+  ~
+  ~     http://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.
+  -->
+
+<configuration>
+    <property name="COLOURFUL_OUTPUT" value="%black(%date{'dd MMM, yyyy HH:mm:ss', Asia/Hong_Kong, en-UK}) %highlight(%-5level) %black(---) %black([%10.10t]) %cyan(%-20.20logger{20}) %black(:) %msg%n"/>
+    <property name="STANDARD_OUTPUT" value="%date{'dd MMM, yyyy HH:mm:ss', Asia/Hong_Kong, en-UK} %-5level %black(---) [%10.10t] %-20.20logger{20} : %msg%n"/>
+
+    <statusListener class="ch.qos.logback.core.status.NopStatusListener" />
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
+            <pattern>${COLOURFUL_OUTPUT}</pattern>
+        </encoder>
+    </appender>
+    <root level="INFO">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>

crypto-toolbox/src/test/resources/ec_private_key.pem

@@ -0,0 +1,5 @@
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgs79JlARgXEf6EDV7
++PHQCTHEMtqIoHOy1GZ1+ynQJ6yhRANCAARkA7GRY2i4gg8qx0XViAXUP9cPw9pn
+Jg1wfrQ41FaMyqVBejNYxvaLtamErF/ySimnjafMJ+VZCh34lBj6Ez8R
+-----END PRIVATE KEY-----

crypto-toolbox/src/test/resources/ec_public_key.pem

@@ -0,0 +1,4 @@
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEZAOxkWNouIIPKsdF1YgF1D/XD8Pa
+ZyYNcH60ONRWjMqlQXozWMb2i7WphKxf8kopp42nzCflWQod+JQY+hM/EQ==
+-----END PUBLIC KEY-----

crypto-toolbox/src/test/resources/rsa_private_key.pem

@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----

crypto-toolbox/src/test/resources/rsa_public_key.pem

@@ -0,0 +1,9 @@
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA+FSBWCRTALNeYyd1dyIn
+B3e7CNkyBak2TBONM5TpVQJTyi2Zk0L2RSzYGlAALLz4uYtQ0dssMCugJQX58FZ8
+75g1wuZihzs+KMTkFQOjZadslWkDM4nZn2DUpDLXL/+B0T7GrXOyvzOZeqQj9tA1
+UY5IpAXSMvHvcPsegayBaeUPD2XP19gRjQFDDGAAnXmB+UfwNAsapDQ9d3rHOIJM
+pzDq72a2Rhws+dbrH0gqsg1lsLDfhhui2FomuBpDZUtHq0Jz/IEvd3X45XvegSH8
+t8+yL/pFK3+YpDVtj/IzMSwL+izvnXFALvZOO+8CABeyKuSjLh/6LbAzrvoftql5
+gQIDAQAB
+-----END PUBLIC KEY-----