   gnu-crypto   RSA    ,   
  . :         
     JCE.    JCE,   
 gnu-crypto.  ?  - .
,   ,       
 FileUtils ( Temp ):
1) PrivateKey privateKey = GnuRSAPrivateKey.valueOf( Utils.hexStringToBytes( rsaPrvKey ) );

2) BigInteger decryptedLic = RSA.decrypt( privateKey, new BigInteger( Utils.hexStringToBytes( value ) ) );
           Java
Cryptography Extension, ,      
  .