I found the solution for the interoperability problem between Java and C:
no padding does not work, but PKCS1PADDING does.
In the Java code below, change the line:
Cipher c = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
And in the C code the change at decryption is to use RSA_PKCS1_PADDING
instead of RSA_NO_PADDING:
Regards,
Paul
I wrote earlier:
> 22.08.2008 17:09
>
> Hi,
>
> we have a server using OpenSLL crypto library functions around RSA.
> I want to write a Java client that sends an encrypted message to the
> server, which can be decrypted there.
>
> To test this I use the following Java code below:
>
> The encoded public key is created with OpenSSL.
> RSA* rsa_private= RSA_generate_key (keylength, RSA_F4, NULL, NULL);
> len = i2d_RSA_PUBKEY(rsa_private, NULL);
> pBuffer=(char *)OPENSSL_malloc(len);
> upBuffer = (unsigned char*)pBuffer;
> len = i2d_RSA_PUBKEY(rsa_private, &upBuffer);
>
> The server decrypts the password with the same private key used to
> generate the public key:
> retval = RSA_private_decrypt(RSA_size(rsa_private),
> encryptedPasswordCharArrayfromJavaClient, cleartext-output,
> rsa_private, RSA_NO_PADDING);
>
> I tested my code so that encryption / decryption works in the C
> code using OpenSSL.
> I tested my Java code so that encryption / decryption works in the
> Java code using standard Java packages with a Sun provider for RSA.
> I have trouble to get the two together. If I use RSA_private_decrypt
> with a byte sequence created from the Java client the output is
> wrong - no error occurs.
>
> One thing that might point to a reason for the incompatibility:
> I observe that the Java client always creates the same encrypted
> byte sequence from a given input string and a public key.
> The OpenSSL C client produces different encrypted byte sequences for
> each separate run with a given input string and a public key.
> Decryption works with all of them.
> If I let the C client encrypt the same given input string twice in
> the same run, it creates the same encrypted sequence.
>
> The java client code:
>
> import java.security.KeyFactory;
> import java.security.PublicKey;
> import java.security.spec.X509EncodedKeySpec;
> import java.util.Date;
>
> import javax.crypto.Cipher;
>
> public class ClientX509Encryption {
>
> static final byte[] encodedPublicKey = {
> 48, -127, -97, 48, 13, 6, 9, 42, -122, 72, -122, -9, 13, 1, 1, 1,
> 5, 0, 3, -127, -115, 0, 48, -127, -119, 2, -127, -127, 0, -77, 119,
-61,
> 76, -66, -58, -102, -98, 84, 20, 83, 117, -9, 69, 109, -105, 51,
-58, 12,
> 31, -113, 110, -118, 20, 115, 107, -86, -97, 14, -39, 62, 8, 50,
-22, 65,
> 121, -124, -52, 27, 17, -104, -123, -78, -56, 92, 18, -31, 116,
> 69, 105, -96,
> -87, 44, 60, -115, -110, 8, -124, 59, -68, 54, 33, 63, 108, 24,114,
-11,
> -103, -31, 48, -89, 10, 98, 106, -80, 123, -94, -100, -24, -59,
> 18, 112, 74,
> 112, 58, -94, -23, 70, -41, 35, 92, 92, 26, -27, -51, 127,
> -125, -109, 15,
> -30, -18, -12, 27, 101, 92, 4, 77, 11, -22, 123, 47, -18, 88, -96,
95,
> 32, -118, -128, 82, 22, -55, -39, 9, -34, 4, 90, 88, -17, 2, 3, 1,
> 0, 1,
> };
>
> public static void main(String[] args) {
>
> byte[] encryptedpassword = null;
>
> try {
> Cipher c = Cipher.getInstance("RSA/ECB/NoPadding");
>
> X509EncodedKeySpec publicKeySpec = new
X509EncodedKeySpec(encodedPublicKey
> );
>
> KeyFactory keyFactory = KeyFactory.getInstance("RSA");
> PublicKey publicKey = keyFactory.generatePublic(publicKeySpec);
>
> c.init(Cipher.ENCRYPT_MODE, publicKey);
>
> byte[] arg0Bytes = args[0].getBytes();
>
> // encrypt input parameter
> encryptedpassword = c.doFinal(arg0Bytes);
>
> System.out.print("static signed char
> encryptedPasswordStringfromJavaClient[] = {");
> for (int i = 0; i < encryptedpassword.length; i++) {
> if (i % 16 == 0) {
> System.out.println("");
> System.out.print(" ");
> }
> System.out.print(encryptedpassword[i] + ", ");
> }
> System.out.println("\n};");
>
> } catch (Exception e) {
> e.printStackTrace();
> }
>
> }
> }
