I'm looking for a Java sample how to do RSA Encryption with a given public key (I have it in base64 format, seems it is 1024 bit length).
Below is my code, but I have InvalidKeySpec exception.
String publicKey = "AJOnAeTfeU4K+do5QdBM2BQUhfrRI2rYf/Gk4a3jZJB2ewekgq2VgLNislBdql/glA39w0NjXZyTg0mW917JdUlHqKoQ9765pJc4aTjvX+3IxdFhteyO2jE3vKX1GgA3i3n6+sMBAJiT3ax57i68mbT+KAeP1AX9199aj2W4JZeP";
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
byte[] res = new Base64Encoder().decode(publicKey.getBytes());
X509EncodedKeySpec KeySpec = new X509EncodedKeySpec(res);
RSAPublicKey pubKey = (RSAPublicKey)keyFactory.generatePublic(KeySpec);
// here the exception occurs..
Cipher cipher = Cipher.getInstance("RSA/None/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
byte[] cipherData = cipher.doFinal(input.getBytes());
return cipherData;
Please give me the sample,
Here's how I manage to encrypt a string with only a RSA public key.
First save the public key in PEM-format to the filename pubkey.pem
-----BEGIN PUBLIC KEY-----
AJOnAeTfeU4K+do5QdBM2BQUhfrRI2rYf/Gk4...
-----END PUBLIC KEY-----
Find the public RSA key modulus
$ openssl rsa -pubin -in pubkey.pem -modulus -noout
Modulus=F56D...
Find the public RSA key Exponent
$ openssl rsa -pubin -in pubkey.pem -text -noout
...
Exponent: 65537 (0x10001)
Then insert them into the following code.
BigInteger modulus = new BigInteger("F56D...", 16);
BigInteger pubExp = new BigInteger("010001", 16);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(modulus, pubExp);
RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(pubKeySpec);
Cipher cipher = Cipher.getInstance("RSA/ECB/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] cipherData = cipher.doFinal(text.getBytes());