Java Verschlüsselung

[dehlen]

Hey Leute habe eine kurze Frage
wir müssen ein Java Programm schreiben, dass Strings verschlüsselt
Cäsar und Vigenere Verschlüsselung habe ich auch super hinbekommen, allerdings will ich was anspruchsvolleres machen um ne gute Note zu bekommen, daher meine Frage welche Verschlüsselungen ihr noch kennt bzw welche man in Java implementiert also RSA hab ich mir schonmal angeschaut aber noch nicht wirklich getraut mich dadran zu wagen *g*
also danke erstmal für eure Antworten

 

[Final_Striker]

Klassische Kryptologie
Symmetrisches Verschlüsselungsverfahren
Asymmetrisches Verschlüsselungsverfahren

Such dir welche aus. ;-)

 

[dehlen]

Ok danke schonmal ;-)

 

[kay73]

Es gibt noch die RC4-Verschlüsselung, die sehr sehr einfach und schnell in Java zu implementieren ist.

also RSA hab ich mir schonmal angeschaut aber noch nicht wirklich getraut mich dadran zu wagen *g*

Wenn Du unbedingt willst: Du kannst grundsätzlich den RSA-Pseudocode aus Wikipedia sogar "1:1" in Java abtippen, denn die Klasse BigInteger hat all die "aufwendigen" Operationen fertig implementiert.

Ich habe das in diesem Thread mal gemacht, allerdings um eine Art digitale Signatur zu bauen: http://www.java-forum.org/allgemeine-java-themen/108274-seriennummer.html?highlight=seriennummer.
Du müsstest

• den private gegen den public Key austauschen
• die Strings kleinschnippeln, damit sie in die Blöcke passen.

 

[dehlen]

ok super werde mal schauen ;-)

 

[Guybrush Threepwood]

Das sollte Deine Wünsche erfüllen (verschlüsselt unter anderem Strings und entschlüsselt sie auch wieder; siehe auch die angegebene URL):

/**
 * A Base64 encoder/decoder.
 * 
 * <p>
 * This class is used to encode and decode data in Base64 format as described in
 * RFC 1521.
 * 
 * <p>
 * Project home page: <a
 * href="http://www.source-code.biz/base64coder/java/">www.
 * source-code.biz/base64coder/java</a><br>
 * Author: Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland<br>
 * Multi-licensed: EPL / LGPL / GPL / AL / BSD.
 */
public class Base64Coder {

	// The line separator string of the operating system.
	private static final String systemLineSeparator = System
			.getProperty("line.separator");

	// Mapping table from 6-bit nibbles to Base64 characters.
	private static char[] map1 = new char[64];
	static {
		int i = 0;
		for (char c = 'A'; c <= 'Z'; c++)
			map1[i++] = c;
		for (char c = 'a'; c <= 'z'; c++)
			map1[i++] = c;
		for (char c = '0'; c <= '9'; c++)
			map1[i++] = c;
		map1[i++] = '+';
		map1[i++] = '/';
	}

	// Mapping table from Base64 characters to 6-bit nibbles.
	private static byte[] map2 = new byte[128];
	static {
		for (int i = 0; i < map2.length; i++)
			map2[i] = -1;
		for (int i = 0; i < 64; i++)
			map2[map1[i]] = (byte) i;
	}

	/**
	 * Encodes a string into Base64 format. No blanks or line breaks are
	 * inserted.
	 * 
	 * @param s
	 *            A String to be encoded.
	 * @return A String containing the Base64 encoded data.
	 */
	public static String encodeString(String s) {
		return new String(encode(s.getBytes()));
	}

	/**
	 * Encodes a byte array into Base 64 format and breaks the output into lines
	 * of 76 characters. This method is compatible with
	 * <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @return A String containing the Base64 encoded data, broken into lines.
	 */
	public static String encodeLines(byte[] in) {
		return encodeLines(in, 0, in.length, 76, systemLineSeparator);
	}

	/**
	 * Encodes a byte array into Base 64 format and breaks the output into
	 * lines.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @param iOff
	 *            Offset of the first byte in <code>in</code> to be processed.
	 * @param iLen
	 *            Number of bytes to be processed in <code>in</code>, starting
	 *            at <code>iOff</code>.
	 * @param lineLen
	 *            Line length for the output data. Should be a multiple of 4.
	 * @param lineSeparator
	 *            The line separator to be used to separate the output lines.
	 * @return A String containing the Base64 encoded data, broken into lines.
	 */
	public static String encodeLines(byte[] in, int iOff, int iLen,
			int lineLen, String lineSeparator) {
		int blockLen = (lineLen * 3) / 4;
		if (blockLen <= 0)
			throw new IllegalArgumentException();
		int lines = (iLen + blockLen - 1) / blockLen;
		int bufLen = ((iLen + 2) / 3) * 4 + lines * lineSeparator.length();
		StringBuilder buf = new StringBuilder(bufLen);
		int ip = 0;
		while (ip < iLen) {
			int l = Math.min(iLen - ip, blockLen);
			buf.append(encode(in, iOff + ip, l));
			buf.append(lineSeparator);
			ip += l;
		}
		return buf.toString();
	}

	/**
	 * Encodes a byte array into Base64 format. No blanks or line breaks are
	 * inserted in the output.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @return A character array containing the Base64 encoded data.
	 */
	public static char[] encode(byte[] in) {
		return encode(in, 0, in.length);
	}

	/**
	 * Encodes a byte array into Base64 format. No blanks or line breaks are
	 * inserted in the output.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @param iLen
	 *            Number of bytes to process in <code>in</code>.
	 * @return A character array containing the Base64 encoded data.
	 */
	public static char[] encode(byte[] in, int iLen) {
		return encode(in, 0, iLen);
	}

	/**
	 * Encodes a byte array into Base64 format. No blanks or line breaks are
	 * inserted in the output.
	 * 
	 * @param in
	 *            An array containing the data bytes to be encoded.
	 * @param iOff
	 *            Offset of the first byte in <code>in</code> to be processed.
	 * @param iLen
	 *            Number of bytes to process in <code>in</code>, starting at
	 *            <code>iOff</code>.
	 * @return A character array containing the Base64 encoded data.
	 */
	public static char[] encode(byte[] in, int iOff, int iLen) {
		int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
		int oLen = ((iLen + 2) / 3) * 4; // output length including padding
		char[] out = new char[oLen];
		int ip = iOff;
		int iEnd = iOff + iLen;
		int op = 0;
		while (ip < iEnd) {
			int i0 = in[ip++] & 0xff;
			int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
			int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
			int o0 = i0 >>> 2;
			int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
			int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
			int o3 = i2 & 0x3F;
			out[op++] = map1[o0];
			out[op++] = map1[o1];
			out[op] = op < oDataLen ? map1[o2] : '=';
			op++;
			out[op] = op < oDataLen ? map1[o3] : '=';
			op++;
		}
		return out;
	}

	/**
	 * Decodes a string from Base64 format. No blanks or line breaks are allowed
	 * within the Base64 encoded input data.
	 * 
	 * @param s
	 *            A Base64 String to be decoded.
	 * @return A String containing the decoded data.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static String decodeString(String s) {
		return new String(decode(s));
	}

	/**
	 * Decodes a byte array from Base64 format and ignores line separators, tabs
	 * and blanks. CR, LF, Tab and Space characters are ignored in the input
	 * data. This method is compatible with
	 * <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>.
	 * 
	 * @param s
	 *            A Base64 String to be decoded.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decodeLines(String s) {
		char[] buf = new char[s.length()];
		int p = 0;
		for (int ip = 0; ip < s.length(); ip++) {
			char c = s.charAt(ip);
			if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
				buf[p++] = c;
		}
		return decode(buf, 0, p);
	}

	/**
	 * Decodes a byte array from Base64 format. No blanks or line breaks are
	 * allowed within the Base64 encoded input data.
	 * 
	 * @param s
	 *            A Base64 String to be decoded.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decode(String s) {
		return decode(s.toCharArray());
	}

	/**
	 * Decodes a byte array from Base64 format. No blanks or line breaks are
	 * allowed within the Base64 encoded input data.
	 * 
	 * @param in
	 *            A character array containing the Base64 encoded data.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decode(char[] in) {
		return decode(in, 0, in.length);
	}

	/**
	 * Decodes a byte array from Base64 format. No blanks or line breaks are
	 * allowed within the Base64 encoded input data.
	 * 
	 * @param in
	 *            A character array containing the Base64 encoded data.
	 * @param iOff
	 *            Offset of the first character in <code>in</code> to be
	 *            processed.
	 * @param iLen
	 *            Number of characters to process in <code>in</code>, starting
	 *            at <code>iOff</code>.
	 * @return An array containing the decoded data bytes.
	 * @throws IllegalArgumentException
	 *             If the input is not valid Base64 encoded data.
	 */
	public static byte[] decode(char[] in, int iOff, int iLen) {
		if (iLen % 4 != 0)
			throw new IllegalArgumentException(
					"Length of Base64 encoded input string is not a multiple of 4.");
		while (iLen > 0 && in[iOff + iLen - 1] == '=')
			iLen--;
		int oLen = (iLen * 3) / 4;
		byte[] out = new byte[oLen];
		int ip = iOff;
		int iEnd = iOff + iLen;
		int op = 0;
		while (ip < iEnd) {
			int i0 = in[ip++];
			int i1 = in[ip++];
			int i2 = ip < iEnd ? in[ip++] : 'A';
			int i3 = ip < iEnd ? in[ip++] : 'A';
			if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
				throw new IllegalArgumentException(
						"Illegal character in Base64 encoded data.");
			int b0 = map2[i0];
			int b1 = map2[i1];
			int b2 = map2[i2];
			int b3 = map2[i3];
			if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
				throw new IllegalArgumentException(
						"Illegal character in Base64 encoded data.");
			int o0 = (b0 << 2) | (b1 >>> 4);
			int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
			int o2 = ((b2 & 3) << 6) | b3;
			out[op++] = (byte) o0;
			if (op < oLen)
				out[op++] = (byte) o1;
			if (op < oLen)
				out[op++] = (byte) o2;
		}
		return out;
	}

	// Dummy constructor.
	private Base64Coder() {
	}

} // end class Base64Coder

 

[dehlen]

wow danke
schätze ich werd es mir mal anschauen und versuchen zu verstehen aber auf jeden Fall vielen vielen Dank für deine Mühen
schätze habe jetzt einige Ideen von euch bekommen was ich machen könnte also ich betrachte das hier jetzt mal erledigt ;-)
Danke für die super Links ;-)

 

[kay73]

Ich vermute mal, base64 ist nicht ganz das, was sich der Lehrer so vorstellt. Eher was mit "geheimem Schlüssel" usw...

 

[dehlen]

ja genau
ist mir auch aufgefallen gerade als ich mal ins Programm geschaut habe, mein lehrer will halt eher sowas wie vigenere,cäsar,enigma usw
aber wie oben geschrieben cäsar oder vigenere macht irgendwie jeder und ich wollte halt was echt cooles machen aber naja mal sehen wofür ich mich nun entscheide