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)
Related
I had generate public key using Java Spring Security, but I can not use that public key to encrypt the data using Nodejs crypto library. I think it is because of its format(X509).
My Nodejs code
module.exports.encryptRsa = (toEncrypt, pemPath) => {
let absolutePath = path.resolve(pemPath);
let publicKey = fs.readFileSync(absolutePath, "utf8");
let buffer = Buffer.from(toEncrypt);
let encrypted = crypto.publicEncrypt(publicKey, buffer);
return encrypted.toString("base64");
};
My Java code
KeyPairGenerator keyGen = KeyPairGenerator.getInstance(keyAlgorithm);
keyGen.initialize(2048);
KeyPair keyPair = keyGen.genKeyPair();
PrivateKey privateKey = keyPair.getPrivate();
PublicKey publicKey = keyPair.getPublic();
byte[] privateKeyBytes = privateKey.getEncoded();
byte[] publicKeyBytes = publicKey.getEncoded();
String formatPrivate = privateKey.getFormat(); // PKCS#8
String formatPublic = publicKey.getFormat(); // X.509
FileWriter fos = new FileWriter("publicKey.pem");
fos.write("-----BEGIN RSA PUBLIC KEY-----\n");
fos.write(enc.encodeToString(publicKeyBytes));
fos.write("\n-----END RSA PUBLIC KEY-----\n");
fos.close();
Java's getEncoded() method returns the public key in format called 'spki' by Node crypto. Java's name for that format is "X.509", an unfortunate choice because it causes confusion with certificates of that name.
The proper PEM header for spki keys is simply -----BEGIN PUBLIC KEY-----. Just get rid of RSA in the header and footer.
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.
So I am creating a basic socket program where I want to send an encrypted string in C to a Java program. My C program encrypts the string with a public PEM key. I have converted the matching private PEM key to a DER key and now want to decrypt the string that was sent to my Java program. How do I do this?
At the moment I am getting an IllegalBlockSizeException stating that "Data must not be longer than 256 bytes" when trying to run the code as it stands.
This is what I have at the moment:
C client program...
//Get our public key from the publickey file created by server
FILE *publicKeyFile = fopen("publicKey.pem", "rb");
RSA *rsa = RSA_new();
rsa = PEM_read_RSA_PUBKEY(publicKeyFile, &rsa, NULL, NULL);
if(rsa == NULL) {
printf("Error with public key...\n");
}
else {
//if the public key is correct we will encrypt the message
RSA_public_encrypt(2048, sigMessage, sigMessage, rsa, RSA_PKCS1_PADDING);
}
Java decryption...
public static String decrypt(byte[] encryptedMessage) {
try {
Cipher rsa;
rsa = Cipher.getInstance("RSA");
PrivateKey ourKey = getKey("resources/privateKey.der");
rsa.init(Cipher.DECRYPT_MODE, ourKey);
byte[] utf8 = rsa.doFinal(encryptedMessage);
return new String(utf8, "UTF8");
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public static PrivateKey getKey(String filePath) throws IOException, NoSuchAlgorithmException, InvalidKeySpecException {
File f = new File(filePath);
FileInputStream fis = new FileInputStream(f);
DataInputStream dis = new DataInputStream(fis);
byte[] keyBytes = new byte[(int) f.length()];
dis.readFully(keyBytes);
dis.close();
PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory kf = KeyFactory.getInstance("RSA");
return kf.generatePrivate(spec);
}
You can't encrypt 2,048 bytes with RSA unless you have an RSA key of over 16K. You probably have a 2048 bit RSA key, which limits you to under 256 bytes. Check out the openssl man page for RSA_public_encrypt:
flen must be less than RSA_size(rsa) - 11 for the PKCS #1 v1.5 based
padding modes, less than RSA_size(rsa) - 41 for RSA_PKCS1_OAEP_PADDING
and exactly RSA_size(rsa) for RSA_NO_PADDING. The random number
generator must be seeded prior to calling RSA_public_encrypt().
And RSA_size:
RSA_size() returns the RSA modulus size in bytes. It can be used to
determine how much memory must be allocated for an RSA encrypted
value.
You should not encrypt a full 256 bytes with a 2048 bit key, though. You want to always use random padding with RSA encryption, and choose OAEP over v1.5.
I need to decrypt file in C++. What I have is byte array and pair of keys generated in Java using KeyPairGenerator from java.security;
Java Code:
public void generateKeys() {
try {
final KeyPairGenerator pairGenerator = KeyPairGenerator.getInstance(algorithmName);
pairGenerator.initialize(1024); //1024 - keysize
final KeyPair keyPair = pairGenerator.generateKeyPair();
savePublicKeyIntoFile(keyPair);
savePrivateKeyIntoFile(keyPair);
} catch (Exception e) {
System.err.println("Class EncryptionTool.generateKeys() ");
e.printStackTrace();
}
}
public static String encrypt() throws Exception {
// Encrypt the string using the public key
ObjectInputStream inputStream = null;
inputStream = new ObjectInputStream(new FileInputStream(publicKeyFilepath));
final PublicKey publicKey = (PublicKey) inputStream.readObject();
// get an RSA cipher object and print the provider
final Cipher cipher = Cipher.getInstance(algorithmName);
// encrypt the plain text using the public key
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] cipherText = null;
**cipherText = cipher.doFinal( loadPassword() );**
return changeByteArrayToString(cipherText);
}
I have generated keys saved in files and this cipherText array in C++.
What should I use to decrypt this ?
Background:
I have created an applet to extract public key of a certificate extracted from a smart card.
This public key is then stored in database.
The private key of certificate is used to sign data and the public key is then used to verify the signature.
Code for extracting public key from certificate:
private byte[] getPublicKey(KeyStore paramKeyStore)
throws GeneralSecurityException {
Enumeration localEnumeration = paramKeyStore.aliases();
if (localEnumeration.hasMoreElements()) {
String element = (String) localEnumeration.nextElement();
Certificate[] arrayOfCertificate =
paramKeyStore.getCertificateChain(element);
byte[] publicKeyByteArray =
arrayOfCertificate[0].getPublicKey().getEncoded();
return publicKeyByteArray;
}
throw new KeyStoreException("The keystore is empty!");
}
This publicKeyByteArray is then storeed in database as BLOB after converting to string using bytes2String method:
private static String bytes2String(byte[] bytes) {
StringBuilder string = new StringBuilder();
for (byte b : bytes) {
String hexString = Integer.toHexString(0x00FF & b);
string.append(hexString.length() == 1 ? "0" + hexString : hexString);
}
return string.toString();
}
The content of the BLOB(key) saved in database is:
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
After reading the stored public key byte[] from database, I try to convert it back to Public Key using following code:
Cipher rsa;
rsa = Cipher.getInstance("RSA");
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(pkey.getBytes());
PublicKey pk = keyFactory.generatePublic(publicKeySpec);
rsa.init(Cipher.DECRYPT_MODE, pk);
byte[] cipherDecrypt = rsa.doFinal(encryptedText.getBytes());
but it gives following error:
Caused by: java.security.InvalidKeyException: invalid key format
at sun.security.x509.X509Key.decode(X509Key.java:387)
at sun.security.x509.X509Key.decode(X509Key.java:403)
at sun.security.rsa.RSAPublicKeyImpl.<init>(RSAPublicKeyImpl.java:83)
at sun.security.rsa.RSAKeyFactory.generatePublic(RSAKeyFactory.java:298)
at sun.security.rsa.RSAKeyFactory.engineGeneratePublic(RSAKeyFactory.java:201)
Please suggest the reason and resolution for this issue.
You must have an error in the way you read the key back from the database. The following code works just fine for me:
String key = "3082012230..."; // full key omitted for brevity
byte[] derPublicKey = DatatypeConverter.parseHexBinary(key);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(derPublicKey);
keyFactory.generatePublic(publicKeySpec);
I would guess, based on the use of pkey.getBytes(), that you've simply tried to get the bytes from the string rather than hex-decoding it.