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InvalidKeyException during getting privateKey from pem file java

public static RSAPrivateKey readPrivateKey(File file) throws Exception {
String key = new String(Files.readAllBytes(file.toPath()), Charset.defaultCharset());
String privateKeyPEM = key.replace("-----BEGIN PRIVATE KEY-----", "")
.replaceAll(System.lineSeparator(), "").replace("-----END PRIVATE KEY-----", "");
byte[] encoded = Base64.decodeBase64(privateKeyPEM);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encoded);
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
}
// to call above code
// private.key in PEM format
File file = new File("private.key");
PrivateKey key = readPrivateKey(file);
Above is my sample code, i am getting below error. I have a pem file and want to extract RsaKrivateKey from it in java.
java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : DerInputStream.getLength(): lengthTag=40, too big

How to fix "java.security.InvalidKeyException: Unsupported key algorithm: EC. Only RSA supported" while using Keystore in api 18

I need to store sensitive data in local storage with an API 18 , i choose to use the Keystore. I try several solution but none worked.
I try to make my RSAPrivateKey in PrivateKey without cast but it don't work.
I also try to use other crypting algorithm but i never success to make them work in API 18
public String decryptString(String alias, String encryptedText) {
KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);
String decryptedText = "";
try {
KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry)keyStore.getEntry(alias, null);
RSAPrivateKey privateKey = (RSAPrivateKey) privateKeyEntry.getPrivateKey();
Cipher output = Cipher.getInstance("RSA/ECB/PKCS1Padding");
output.init(Cipher.DECRYPT_MODE, privateKey);
CipherInputStream cipherInputStream = new CipherInputStream(
new ByteArrayInputStream(Base64.decode(encryptedText, Base64.DEFAULT)), output);
ArrayList<Byte> values = new ArrayList<>();
int nextByte;
while ((nextByte = cipherInputStream.read()) != -1) {
values.add((byte)nextByte);
}
byte[] bytes = new byte[values.size()];
for(int i = 0; i < bytes.length; i++) {
bytes[i] = values.get(i).byteValue();
}
decryptedText = new String(bytes, 0, bytes.length, "UTF-8");
} catch (Exception e) {
Log.e(TAG, Log.getStackTraceString(e));
}
return decryptedText;
}
public String encryptString(String alias, String initialText) {
KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);
String encryptedText = "";
try {
KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry)keyStore.getEntry(alias, null);
PublicKey publicKey = privateKeyEntry.getCertificate().getPublicKey();
// Encrypt the text
if(initialText.isEmpty()) {
Log.e(TAG, "initialText is Empty");
return "";
}
Cipher input = Cipher.getInstance("RSA/ECB/PKCS1Padding");
input.init(Cipher.ENCRYPT_MODE, publicKey);//Need RSA private or public key
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
CipherOutputStream cipherOutputStream = new CipherOutputStream(
outputStream, input);
cipherOutputStream.write(initialText.getBytes("UTF-8"));
cipherOutputStream.close();
byte [] vals = outputStream.toByteArray();
encryptedText = Base64.encodeToString(vals, Base64.DEFAULT);
} catch (Exception e) {
Log.e(TAG, Log.getStackTraceString(e));
}
return encryptedText;
}
Here is the erot i get. I would like to success to keep my data in a secure place
java.security.InvalidKeyException: Unsupported key algorithm: EC. Only RSA supported
at com.cryptor.Cryptor.encryptString(Cryptor.java:108)

I don't see where/when you generate your RSA key. On my side, I have done the following steps :
Create/retrieve the Keystore
Generate RSA keys with a KeyPairGenerator (be careful : different methods since Android M)
val generator = KeyPairGenerator.getInstance(ALGORITHM, CryptoConstants.ANDROID_KEY_STORE)
Here, ALGORITHM="RSA" and not "RSA/ECB/PKCS1Padding" and CryptoConstants.ANDROID_KEY_STORE = "AndroidKeyStore" (for example)
Save keys in the Keystore
Encrypt with the public key
Decrypt with the private key
With these steps, my encryption methods are
fun encrypt(publicKey: PublicKey, rawText: ByteArray): String {
try {
val cipher = CipherUtil.getStandardCipherInstance(TRANSFORMATION) // TRANSFORMATION = "RSA/ECB/PKCS1Padding"
cipher.init(Cipher.ENCRYPT_MODE, publicKey)
val bytes = cipher.doFinal(rawText)
return Base64.encodeToString(bytes, BASE64_SETTINGS) // BASE64_SETTINGS = Base64.NO_WRAP
} catch (e: GeneralSecurityException) {
throw SecurityException(e)
}
}
fun decrypt(privateKey: PrivateKey, base64CipherBytes: ByteArray): ByteArray {
try {
val cipher = CipherUtil.getStandardCipherInstance(TRANSFORMATION) // TRANSFORMATION = "RSA/ECB/PKCS1Padding"
cipher.init(Cipher.DECRYPT_MODE, privateKey)
val encryptedData = Base64.decode(base64CipherBytes, BASE64_SETTINGS) // BASE64_SETTINGS
return cipher.doFinal(encryptedData)
} catch (e: GeneralSecurityException) {
throw SecurityException(e)
}
}
Btw, you can bypass the Base64 encoding if you don't need it.

How to generate Private key from string using BouncyCastle

I have a String stored in a variable:
-----BEGIN RSA PUBLIC KEY-----
MIGHAoGBANAahj75ZIz9nXqW2H83nGcUao4wNyYZ9Z1kiNTUYQl7ob/RBmDzs5rY
mUahXAg0qyS7+a55eU/csShf5ATGzAXv+DDPcz8HrSTcHMEFpuyYooX6PrIZ07Ma
XtsJ2J4mhlySI5uOZVRDoaFY53MPQx5gud2quDz759IN/0gnDEEVAgED
-----END RSA PUBLIC KEY-----
I generate public key as:
public static PublicKey getFromString(String keystr) throws Exception
{
//String S1= asciiToHex(keystr);
byte[] keyBytes = new sun.misc.BASE64Decoder().decodeBuffer(keystr);
ASN1InputStream in = new ASN1InputStream(keyBytes);
DERObject obj = in.readObject();
RSAPublicKeyStructure pStruct = RSAPublicKeyStructure.getInstance(obj);
RSAPublicKeySpec spec = new RSAPublicKeySpec(pStrcut.getModulus(), pStruct.getPublicExponent());
KeyFactory kf = KeyFactory.getInstance("RSA");
return kf.generatePublic(spec);
}
How to generate the PrivateKey using bouncy castle in android
{Edit}
Without using bouncy castle i am generating private key like this:
public static PrivateKey getKey(String mKey){
try{
// Read in the key into a String
StringBuilder pkcs8Lines = new StringBuilder();
BufferedReader rdr = new BufferedReader(new StringReader(mKey));
String line;
while ((line = rdr.readLine()) != null) {
pkcs8Lines.append(line);
}
// Remove the "BEGIN" and "END" lines, as well as any whitespace
String pkcs8Pem = pkcs8Lines.toString();
pkcs8Pem = pkcs8Pem.replace("-----BEGIN RSA PRIVATE KEY-----", "");
pkcs8Pem = pkcs8Pem.replace("-----END RSA PRIVATE KEY-----", "");
pkcs8Pem = pkcs8Pem.replaceAll("\\s+","");
// Base64 decode the result
byte [] pkcs8EncodedBytes = Base64.decode(pkcs8Pem, Base64.DEFAULT);
// extract the private key
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pkcs8EncodedBytes);
KeyFactory kf = KeyFactory.getInstance("RSA");
PrivateKey privKey = kf.generatePrivate(keySpec);
System.out.println(privKey);
return privKey;
}catch (Exception ex){
ex.printStackTrace();
}
return null;
}
I want to achieve the same using Bouncy Castle

I'm a little confused on why you insist on using bouncycastle, but if you really want to use bouncycastle then the CMS/PKIX library has a nice helper class called PEMParser that will shorten the code needed, e.g:
public static PrivateKey getPemPrivateKey(String mKey) throws Exception {
PEMParser pemParser = new PEMParser(new StringReader(mKey));
final PEMKeyPair pemKeyPair = (PEMKeyPair) pemParser.readObject();
final byte[] encoded = pemKeyPair.getPrivateKeyInfo().getEncoded();
KeyFactory kf = KeyFactory.getInstance("RSA");
return kf.generatePrivate(new PKCS8EncodedKeySpec(encoded));
}

How to use SubjectPublicKeyInfo encrypt data?

I'm newer to RSA and used BC get SubjectPublicKeyInfo from a public key.
String key = "-----BEGIN RSA PUBLIC KEY-----\n" +
"........\n" +// Multiple lines here
"-----END RSA PUBLIC KEY-----\n";
Security.addProvider(new BouncyCastleProvider());
PEMParser reader = new PEMParser(new StringReader(key));
SubjectPublicKeyInfo subjectPublicKeyInfo = (SubjectPublicKeyInfo) reader.readObject();
And then I want encrypt datas. I found some one use RSAEngine to do it:
AsymmetricKeyParameter aKey = (RSAKeyParameters) PublicKeyFactory.createKey(subjectPublicKeyInfo);
AsymmetricBlockCipher engine = new RSAEngine();
engine.init(false, aKey);
byte[] dataEncrypted = engine.processBlock(data, 0, data.length);
After I run those code, I found the result isn't equal to the expection. So I want to know is there any mistake in my code?

Finally I found my way out.
If anyone is familiar with BouncyCastle, he can point me the low-level mistakes.
Firstly, to encrypt data should init Engine with true at first arg in init function.
Secondly, my public key is start with '-----BEGIN RSA PUBLIC KEY-----'. It's PKCS#1 format RSA public key and should use BouncyCastle to read in, but encrypt data should have padding. So, I shouldn't use RSAEngine directly, use PKCS1Encoding instead.
At last , post my encrypt code and decrypt code:
Encryption:
Security.addProvider(new BouncyCastleProvider());
PEMParser reader = new PEMParser(new StringReader(key));
SubjectPublicKeyInfo subjectPublicKeyInfo = (SubjectPublicKeyInfo) reader.readObject();
RSAKeyParameters rsaKeyParameters = (RSAKeyParameters)
PublicKeyFactory.createKey(subjectPublicKeyInfo);
PKCS1Encoding engine = new PKCS1Encoding(new RSAEngine());
engine.init(true, rsaKeyParameters);
return engine.processBlock(data, 0, data.length);
Decryption:
public static byte[] decryptByPublicKey(String data, String key) throws Exception {
byte[] rawData = Base64.decode(data);
Security.addProvider(new BouncyCastleProvider());
PEMParser reader = new PEMParser(new StringReader(key));
PEMKeyPair pemKeyPair = (PEMKeyPair) reader.readObject();
SubjectPublicKeyInfo publicKeyInfo = pemKeyPair.getPublicKeyInfo();
PrivateKeyInfo privateKeyInfo = pemKeyPair.getPrivateKeyInfo();
RSAKeyParameters rsaKeyParameters = (RSAKeyParameters)
PrivateKeyFactory.createKey(privateKeyInfo);
PKCS1Encoding engine = new PKCS1Encoding(new RSAEngine());
engine.init(false, rsaKeyParameters);
return engine.processBlock(rawData, 0, rawData.length);
}
For encryption , you can use modulus and public exponent to create a key that support by JDK:
Security.addProvider(new BouncyCastleProvider());
PEMParser reader = new PEMParser(new StringReader(key));
PemObject obj = reader.readPemObject();
org.bouncycastle.asn1.pkcs.RSAPublicKey rsaPublicKey = org.bouncycastle.asn1.pkcs.RSAPublicKey.getInstance(obj.getContent());
BigInteger modulus = rsaPublicKey.getModulus();
BigInteger publicExponent = rsaPublicKey.getPublicExponent();
KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(modulus, publicExponent);
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC");//This line should use right padding.For PKCS#1 format RSA key , it should be this.
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
return cipher.doFinal(data);
See Also:Basic RSA example.

RSA Encryption Javascript and Decrypt Java

Spent almost 2 days with different combinations.I am generating a asymmetric key pair (public and private) in java using RSA algorithm and trying to use the public key in javascript to encrypt some text and decrypt back in java on server side. I am getting "javax.crypto.IllegalBlockSizeException: Data must not be longer than 128 bytes" exception while trying to decrypt back the string encrypted in javascript. Would appreciate some help...
Using thi Javascript library to encrypt.
https://github.com/wwwtyro/cryptico
var publicKeyString = ""// base64encoded public key string generated in java
Here is my javascript code
var EncryptionResult = cryptico.encrypt("somestring", publicKeyString);
console.log("Encrypted status-"+EncryptionResult.status);
console.log("Encrypted String-"+EncryptionResult.cipher);
It is successfully encrypting the string.
Java Key Generation and Decryption
Cipher cipher = Cipher.getInstance("RSA");
KeyFactory fact = KeyFactory.getInstance("RSA");
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
keyPairGenerator.initialize(1024); // 1024 used for normal
KeyPair keyPair = keyPairGenerator.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();
FileOutputStream fos = null;
ObjectOutputStream oos = null;
Code to store the private key in file which is used to decrypt in decrypt method.
RSAPrivateKeySpec rsaPrivKeySpec = fact.getKeySpec(privateKey,
RSAPrivateKeySpec.class);
System.out.println("Writing private key...");
fos = new FileOutputStream(PRIVATE_KEY_FILE);
oos = new ObjectOutputStream(new BufferedOutputStream(fos));
oos = new ObjectOutputStream(new BufferedOutputStream(fos));
oos.writeObject(rsaPrivKeySpec.getModulus());
oos.writeObject(rsaPrivKeySpec.getPrivateExponent());
oos.close();
Decrypt method
public String decrypt(String ciphertext)
throws IllegalBlockSizeException, BadPaddingException, InvalidKeyException
{
if (ciphertext.length() == 0) return null;
byte[] dec = org.apache.commons.codec.binary.Base64.decodeBase64(ciphertext);
try {
System.out.println("Private Key file name----"+PRIVATE_KEY_FILE);
privateKey = readPrivateKeyFromFile(PRIVATE_KEY_FILE);
} catch (IOException e) {
e.printStackTrace();
}
cipher.init(Cipher.DECRYPT_MODE, privateKey);
byte[] decrypted = cipher.doFinal(dec);
return new String(decrypted, PLAIN_TEXT_ENCODING);
}
//reading private key from file
public PrivateKey readPrivateKeyFromFile(String fileName)
throws IOException {
FileInputStream fis = null;
ObjectInputStream ois = null;
try {
fis = new FileInputStream(new File(fileName));
ois = new ObjectInputStream(fis);
System.out.println("Private Key file-"+fileName);
BigInteger modulus = (BigInteger) ois.readObject();
BigInteger exponent = (BigInteger) ois.readObject();
// Get Private Key
RSAPrivateKeySpec rsaPrivateKeySpec = new RSAPrivateKeySpec(modulus, exponent);
KeyFactory fact = KeyFactory.getInstance("RSA");
PrivateKey privateKey = fact.generatePrivate(rsaPrivateKeySpec);
return privateKey;
} catch (Exception e) {
e.printStackTrace();
} finally {
if (ois != null) {
ois.close();
if (fis != null) {
fis.close();
}
}
}
return null;
}

From the Cryptico documentation it seems that it is not a simple RSA encryption, but a complex operation that generates AES key, encrypts it with RSA, encrypts the data with AES and outputs a concatenation of encrypted AES key and encrypted data. If you want to decrypt that in Java you will have to check the Cryptico source code and reimplement the same in Java.
As for your current attempt and javax.crypto.IllegalBlockSizeException: Data must not be longer than 128 bytes error:
When you do not specify the full transformation the default JCE transformation for RSA is RSA/ECB/PKCS1Padding.
In this mode the RSA encrypts or decrypts a single block of data which the length is not greater than the size of the key (more specifically, if the input sequence of bytes is interpreted as a big integer, its value should be less that the modulus used by the RSA). You can find additional information in this and this questions.
With the key size of 1024 bits the maximum data size is 128 bytes, and that is exactly what the exception says because the output of Cryptico is obviously not a single RSA block and its length is greater that expected by "plain" RSA. Trying to use some other cipher mode or padding mode in Java will not help in that situation either.

Thanks Oleg for the detailed information. I will definitely take a look into it.
For now I switched to jsencrypt and it seems to work fine.
https://github.com/travist/jsencrypt
EDIT
How you get the encoded public key for the js encrypt?

Here is the solution for data Encryption from JS and Decrypt on Java(server side). I have used Cryptico js library for encryption(http://wwwtyro.github.io/cryptico/).
First of all we have to generate the java Keystore file from your local system. Don't use other Keystore files such as online Keystore. For creating the java Keystore(JKS) you can use KeyStore Explorer tool.
Below is the config I have used, using KeyStore Explorer tool
Keystore type - JKS
RSA algorithm - Keysize 1024
Version - version 3
Signature algorithm - SHA256 with RSA
Validity period - 99 years(based on your requirement)
Name filed - Fill all the mandatory fields - remember the "alias" and "password" what you entered here.
Finally, save the file as .jks on your local system.
Step-1
we have to use this Keystore file on the java side and we send the public key to the frontend.
I have created the service class which is responsible to load Keystore from the keystore file path(string), Keypair and Decrypt. You have to provide the alias, password, keystore type.
public KeyPair getExistingKeyStoreKeyPair(String keystorePath){
KeyPair generateKeyPair = null
try {
File file = new File(keystorePath)
KeyStore keyStore = loadKeyStore(file, "password", "JKS")
generateKeyPair = getKeyPair(keyStore, "fin360", "password")
} catch (Exception ex){
println(ex)
}
return generateKeyPair
}
public KeyStore loadKeyStore(final File keystoreFile, final String password, final String keyStoreType) throws KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
if (null == keystoreFile) {
throw new IllegalArgumentException("Keystore url may not be null")
}
final URI keystoreUri = keystoreFile.toURI()
final URL keystoreUrl = keystoreUri.toURL()
final KeyStore keystore = KeyStore.getInstance(keyStoreType)
InputStream is = null
try {
is = keystoreUrl.openStream();
keystore.load(is, null == password ? null : password.toCharArray())
} finally {
if (null != is) {
is.close()
}
}
return keystore;
}
public KeyPair getKeyPair(final KeyStore keystore, final String alias, final String password) {
PublicKey publicKey
PrivateKey privateKey
Key key
KeyPair keyPair
try {
key = (PrivateKey) keystore.getKey(alias, password.toCharArray())
final Certificate cert = keystore.getCertificate(alias)
publicKey = cert.getPublicKey()
privateKey = key
keyPair = new KeyPair(publicKey, privateKey)
} catch (Exception ex){
println(ex)
}
return keyPair;
}
public decryptData(String data, String keystorePath) throws IllegalBlockSizeException, BadPaddingException, InvalidKeyException{
try {
byte[] dectyptedText = new byte[1]
byte[] byteArray = new byte[256]
BigInteger passwordInt = new BigInteger(data, 16)
if (passwordInt.toByteArray().length > 256) {
for (int i=1; i<257; i++) {
byteArray[i-1] = passwordInt.toByteArray()[i]
}
} else {
byteArray = passwordInt.toByteArray();
}
KeyPair generateKeyPair = getExistingKeyStoreKeyPair(keystorePath)
PrivateKey privateKey = generateKeyPair.getPrivate()
Cipher cipher = Cipher.getInstance("RSA")
cipher.init(Cipher.DECRYPT_MODE, privateKey)
dectyptedText = cipher.doFinal(byteArray)
String txt2 = new String(dectyptedText)
return txt2
}
catch (Exception ex){
println(ex)
return null
}
}
decryptData() method will playing the main role here. When you send the value data.getBytes() directly to the dycrypt method cipher.doFinal(byteArray) you get the exception - IllegalBlockSizeException size should not more than 128 bytes. So we have get rid of the issue I get the workaroud here - [Getting 1 byte extra in the modulus RSA Key and sometimes for exponents also
Basically it adds the zero when we converting data from BigInteger to byteArray. So I removed the zero from the array.
Let's start use the service class to get the key values.
String publicKey= null
String keystorePath = your file path
KeyPair generateKeyPair = encryptDecryptService.getExistingKeyStoreKeyPair(keystorePath)
PublicKey publicKey1 = generateKeyPair.getPublic()
KeyFactory keyFactory;
RSAPublicKeySpec rsaPublicKeySpec = new RSAPublicKeySpec(BigInteger.ZERO, BigInteger.ZERO)
try {
keyFactory = KeyFactory.getInstance("RSA")
rsaPublicKeySpec = keyFactory.getKeySpec(publicKey1, RSAPublicKeySpec.class)
} catch(NoSuchAlgorithmException e1) {
println(e1)
} catch(InvalidKeySpecException e) {
println(e)
}
String testPublicKey = rsaPublicKeySpec.getModulus().toString(16)
publicKey = testPublicKey
Send you publicKey to JS.
In your HTML or servlet import all the required js and jar files(you will get it from the cryptico js library).
try{
var rsa = new RSAKey();
rsa.setPublic(pub, "10001");
password = rsa.encrypt(password);
formdata = "password="+password+"&dataEncrypt=true";
}
catch (error){
console.log(error);
}
above I have directly used new RSA() instance(in cryptico library it will be different. Internaly library is using the same) and set the publickey to the instance. We have to use hex string value is '10001'. Form the query string with encrypted data which we send to server. Form data holds the encrypted data well as well as 'dataEncrypt' key value. I used to check whether data is encrypted or not.
Finally on the server side you will get the request params and below is the code for decrypt.
Boolean isDataEncrypted = false
String decryptedPassword = null
isDataEncrypted = params.containsKey("dataEncrypt")
if(params.containsKey("password")){
if(isDataEncrypted) {
String keystorePath = helperService.fetchKeystoreFilePath()
decryptedPassword = encryptDecryptService.decryptData(params.password, keystorePath)
// update decrypted data into request params
params.password = decryptedPassword
}
}
println("Data decrypted => " + decryptedPassword)