Android Java Freelance Programmer

        If you are going to use RSA encryption in Android client devices, then the easiest way is to use a ready-made set of JAVA classes for key generation, encryption, decryption, key storage, key recovery, code transformations and obfuscation.
        This is convenient because you can get a ready-made open source Java code (Java classes) with comments, examples and manuals. And with technical consulting - this is freelance programming.
        
        JAVA Class
        
        I provide a set of Java classes for using asymmetric strong RSA encryption in Android projects of Android Studio.
        Java classes contain 100% open source which you can control and upgrade.
        Java classes can be used to encrypt data before writing it to a database, to transfer it to a web server or a corporate server with a database (for example, clients or cargo shipments), or to run a messenger or mail.
        Java classes contain methods for converting encrypted data into different formats, for example, for writing to an Excel spreadsheet.
        
        For Example
        
        // ============================================================
        // Generate key pair for 1024 or 2048 -bit RSA encryption and decryption
        // ============================================================
        RSACode rsagente = new RSACode(); // Class instance RSACode
        Key[] KeyPMass = new Key[2]; //An array of two keys to return values from a method
        KeyPMass = rsagente.RSAKeyGen(); //GENERATE Key Pair
        publicKey = KeyPMass[0];
        privateKey = KeyPMass[1];
        // ============================================================
        
        JAVA Class Method
        
        //==========================================================
        // Encrypt Text
        //==========================================================
        public byte[] RSATextEncode(Key publicKey, Key privateKey, String PlainText) {
        byte[] encodedBytes = null; //RSA
        try {
        Cipher c = Cipher.getInstance("RSA");
        c.init(Cipher.ENCRYPT_MODE, privateKey);
        encodedBytes = c.doFinal(PlainText.getBytes());
        } catch (Exception e) {
        Log.e("Crypto", "RSA encryption error");
        }
        return encodedBytes; //Return coded Text (bytes array)
        
        }
        //==========================================================
        
        For encryption, the cryptographic provider of the Android operating system is used.
        This Java class provides a very strong commercial level of encryption. It can be significantly increased if additional obfuscation of data and encryption keys is used. You can reach military levels of cryptography.