Java Utililty Methods Key Public

List of utility methods to do Key Public

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Description

The list of methods to do Key Public are organized into topic(s).

Method

PublicKeygetPublicKey(KeyStore ks, String alias, char[] password)
Get the Public Key from the keystore 
PublicKey publicKey = null;
Key key = ks.getKey(alias, password);
if (key instanceof PrivateKey) {
    Certificate cert = ks.getCertificate(alias);
    publicKey = cert.getPublicKey();
if (publicKey == null) {
    Certificate cert = ks.getCertificate(alias);
...
PublicKeygetPublicKey(String algo)
get Public Key 
if (algo.equalsIgnoreCase("DSA")) {
    return getPublicKey("DSA", 1024);
} else if (algo.equalsIgnoreCase("RSA")) {
    return getPublicKey("RSA", 512);
} else {
    throw new RuntimeException("Unsupported key algorithm " + algo);
PublicKeygetPublicKey(String alias)
get Public Key 
return ks.getCertificate(alias).getPublicKey();
PublicKeygetPublicKey(String certificatePath)
get Public Key 
Certificate certificate = getCertificate(certificatePath);
PublicKey key = certificate.getPublicKey();
return key;
PublicKeygetPublicKey(String certPath)
get Public Key 
Certificate cert = getCert(certPath);
return cert.getPublicKey();
PublicKeygetPublicKey(String filename)
get Public Key 
byte[] keyBytes = Files.readAllBytes(Paths.get(filename));
X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
KeyFactory kf = KeyFactory.getInstance(KEY_TYPE_RSA);
return kf.generatePublic(spec);
PublicKeygetPublicKey(String filename)
get Public Key 
try {
    final byte[] keyBytes = Files.readAllBytes(Paths.get(filename));
    final X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
    return factory().generatePublic(spec);
} catch (IOException ex) {
    throw new RuntimeException("Error loading public key '" + filename + "'.", ex);
} catch (final InvalidKeySpecException ex) {
    throw new RuntimeException("Error reading public key '" + filename + "'.", ex);
...
PublicKeygetPublicKey(String filename)
get Public Key 
try {
    byte[] keyBytes = Files.readAllBytes(new File(filename).toPath());
    EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
    KeyFactory kf = KeyFactory.getInstance("RSA");
    return kf.generatePublic(spec);
} catch (Exception e) {
    e.printStackTrace();
return null;
PublicKeygetPublicKey(String key)
get Public Key 
byte[] keyBytes;
keyBytes = (new BASE64Decoder()).decodeBuffer(key);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return keyFactory.generatePublic(keySpec);
PublicKeygetPublicKey(String modulus, String exponent)
get Public Key 
try {
    BigInteger b1 = new BigInteger(modulus);
    BigInteger b2 = new BigInteger(exponent);
    KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
    RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
    return keyFactory.generatePublic(keySpec);
} catch (Exception e) {
    throw new RuntimeException("getPublicKey error", e);
...