CD4J-34 Update readme files with info about extra JVM arguments

README.md

@@ -25,6 +25,12 @@ This project started with the help of European Regional Development Fund.
 ## How to use it
 Take a look at the [examples](https://github.com/open-eid/cdoc4j/wiki/Examples-of-how-to-use-it)
 
+## Decrypting a file using a smart card with Java version 17 or higher
+Using a smart card to decrypt a file while using Java 17 or a later version, an extra JVM argument is required:
+```bash
+--add-exports jdk.crypto.cryptoki/sun.security.pkcs11=ALL-UNNAMED
+```
+
 ## Maven Central
 You can use the library as a dependency from [Maven Central](http://mvnrepository.com/artifact/org.open-eid.cdoc4j/cdoc4j)
 

util/README.md

@@ -35,6 +35,11 @@ java -jar cdoc4j-util-1.5-SNAPSHOT.jar encrypt -f path/to/file path/to/another/f
 java -jar cdoc4j-util-1.5-SNAPSHOT.jar pkcs11-decrypt -f /path/to/cdoc -d /path/to/pkcs11/driver -p [pin number] -s [slot] -o /path/to/output/directory/of/decrypted/file
 ```
 
+* **NB**: when decrypting a file using PKCS#11 with Java 17 or higher, an extra Java argument `--add-exports jdk.crypto.cryptoki/sun.security.pkcs11=ALL-UNNAMED` is required:
+```bash
+java --add-exports jdk.crypto.cryptoki/sun.security.pkcs11=ALL-UNNAMED -jar cdoc4j-util-1.5-SNAPSHOT.jar pkcs11-decrypt -f /path/to/cdoc -d /path/to/pkcs11/driver -p [pin number] -s [slot] -o /path/to/output/directory/of/decrypted/file
+```
+
 * Example of decrypting a file with PKCS#12
 ```bash
 java -jar cdoc4j-util-1.5-SNAPSHOT.jar pkcs12-decrypt -f path/to/cdoc -k /path/to/p12/keystore -p [keystore password] -o /path/to/output/directory/of/decrypted/file