public void encrypt(String plaintext){
		List<BigInteger> plaintext_list = String2BigInteger(plaintext);
		List<ElGamal_ciphertextblock> c = new ArrayList<ElGamal_ciphertextblock>();
		for(BigInteger plainblock: plaintext_list){
			// -------------------------
			// -- Hier programmieren ---
			// -------------------------
			BigInteger r = BigInteger.valueOf(rand.nextLong());
			BigInteger k = k_c.modPow(r, this.p);
			ElGamal_ciphertextblock c_tmp = new ElGamal_ciphertextblock(this.g.modPow(r, this.p), plainblock.multiply(k).mod(p));
			
			//Addition statt Multiplikation
			//ElGamal_ciphertextblock c_tmp = new ElGamal_ciphertextblock(this.g.modPow(r, this.p), plainblock.xor(k).mod(p));
			
			c.add(c_tmp);
			// -------------------------
			// -- bis hier -------------
			// -------------------------
		}

		ElGamal_Decrypter.getInstance().setCiphertext(c);
		if(c.size()>0){
			gui.append_Alice("Beginne Verschl\u00fcsselung von \n\""+plaintext+"\" in "+plaintext_list.size()+" Bl\u00f6cken:\n");
			for(BigInteger b: plaintext_list){
				gui.append_Alice("["+b+"], ");
			}
			gui.append_Alice("\n\nVerschl\u00fcsselt in Bl\u00f6cke:\n");
			for(ElGamal_ciphertextblock b: c){
				gui.append_Alice("[ "+visualiseCipher(b.c_1)+" | "+visualiseCipher(b.c_2)+" ]\n");
				gui.append_Bob("\n");
			}
			gui.append_Alice("\u00dcbertrage an Bob -->");
			gui.append_Bob("\n\n\n\n\n--> Empfange Schl\u00fcsseltext von Alice\n");
		} else gui.append_Alice("Bitte programmieren Sie zuerst die Methode encrypt() in der Klasse ElGamal_Encrypter.\n");
	}