Encrypt/Decrypt String with RSA and X509Certificate

[b.croissant]

Hi,
I've 2 files : CA.cert (X509 certificate) and CA.key (contains private
key)
I want to encrypt a string "secret message" with the public key of the
certificate and decrypt this string with the private key.
I think encryption is ok, but I can't import the private key from the
file.
Here is my code:
--------------------------------------------------------------------
[...]

InputStream inStream = new FileInputStream("./CA.crt"); //The X509
certificate
CertificateFactory cf = CertificateFactory.getInstance("X.509");
X509Certificate cert =
(X509Certificate)cf.generateCertificate(inStream);
inStream.close();

RSAPublicKey rsaPublicKey = (RSAPublicKey)cert.getPublicKey();
BouncyCastleProvider bcp = new BouncyCastleProvider();
Security.addProvider(bcp);
Cipher encryptCipher = Cipher.getInstance("RSA", bcp);
encryptCipher.init(Cipher.ENCRYPT_MODE, rsaPublicKey);

String message = "secret message";
byte[] messageACrypter = message.getBytes();
byte[] messageCrypte = encryptCipher.doFinal(messageACrypter);

System.out.println("\nSource : "+message);
System.out.println("Source crypted: "+new String(messageCrypte)+"\n");

File keyFile = new File("./CA.key");
DataInputStream in = new DataInputStream(new FileInputStream(keyFile));
byte [] fileBytes = new byte[(int) keyFile.length()];
in.readFully(fileBytes);
in.close();
KeyFactory kf = KeyFactory.getInstance("RSA");
KeySpec ks = new X509EncodedKeySpec(fileBytes);
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey)kf.generatePrivate(ks);

Cipher decryptCipher = Cipher.getInstance("RSA", bcp);
decryptCipher.init(Cipher.DECRYPT_MODE,rsaPrivateKey);

byte[] messageDecrypte = decryptCipher.doFinal(messageCrypte);
System.out.println("Source decrypted: "+new
String(messageDecrypte)+"\n");
[...]
-------------------------------------------------------------
I've an error :

java.security.spec.InvalidKeySpecException: Key spec not RSA.

How to correct this?
Thanks a lot.

 

[iksrazal]

(e-mail address removed) escreveu:

Hi,
I've 2 files : CA.cert (X509 certificate) and CA.key (contains private
key)
I want to encrypt a string "secret message" with the public key of the
certificate and decrypt this string with the private key.
I think encryption is ok, but I can't import the private key from the
file.

OK. I store my Certs in LDAP and the private key as a serialized object
in LDAP. When I create my certs/private key and store them in LDAP - I
use the keystore file created by the java tool keygen. So this may not
help you - but the general idea is:

pk = (PrivateKey)ks.getKey(privateKeyAlias,
privateKeyPass.toCharArray());

I can show you the rest if you decide you want to go that route.

HTH,
iksrazal
http://www.braziloutsource.com/

Here is my code:
--------------------------------------------------------------------
[...]

InputStream inStream = new FileInputStream("./CA.crt"); //The X509
certificate
CertificateFactory cf = CertificateFactory.getInstance("X.509");
X509Certificate cert =
(X509Certificate)cf.generateCertificate(inStream);
inStream.close();

RSAPublicKey rsaPublicKey = (RSAPublicKey)cert.getPublicKey();
BouncyCastleProvider bcp = new BouncyCastleProvider();
Security.addProvider(bcp);
Cipher encryptCipher = Cipher.getInstance("RSA", bcp);
encryptCipher.init(Cipher.ENCRYPT_MODE, rsaPublicKey);

String message = "secret message";
byte[] messageACrypter = message.getBytes();
byte[] messageCrypte = encryptCipher.doFinal(messageACrypter);

System.out.println("\nSource : "+message);
System.out.println("Source crypted: "+new String(messageCrypte)+"\n");

File keyFile = new File("./CA.key");
DataInputStream in = new DataInputStream(new FileInputStream(keyFile));
byte [] fileBytes = new byte[(int) keyFile.length()];
in.readFully(fileBytes);
in.close();
KeyFactory kf = KeyFactory.getInstance("RSA");
KeySpec ks = new X509EncodedKeySpec(fileBytes);
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey)kf.generatePrivate(ks);

Cipher decryptCipher = Cipher.getInstance("RSA", bcp);
decryptCipher.init(Cipher.DECRYPT_MODE,rsaPrivateKey);

byte[] messageDecrypte = decryptCipher.doFinal(messageCrypte);
System.out.println("Source decrypted: "+new
String(messageDecrypte)+"\n");
[...]
-------------------------------------------------------------
I've an error :

java.security.spec.InvalidKeySpecException: Key spec not RSA.

How to correct this?
Thanks a lot.

 

[=?iso-8859-1?B?QmVub+50?=]

Thanks.
I use keystore generated with keytool.
Your solution with LDAP is interresting but a little complex in my
case.
I keep your email if I'me interrested later

Bye