1 files changed, 100 insertions, 0 deletions
diff --git a/Master/Kryptografie/prakt3/prakt3WS/p3/src/otp/LinReg.java b/Master/Kryptografie/prakt3/prakt3WS/p3/src/otp/LinReg.java
new file mode 100644
index 0000000..1e82b0e
--- /dev/null
+++ b/Master/Kryptografie/prakt3/prakt3WS/p3/src/otp/LinReg.java
@@ -0,0 +1,100 @@
+package otp;
+
+public class LinReg {
+	private int config;
+	private int status;
+	
+	public static final int bitMask = 0xff;
+	public static final int bitLength = 8;
+	
+	public LinReg (int config, int init)
+	{
+		this.config = 0;
+		this.status = 0;
+		this.config = config & bitMask;
+		this.status = init & bitMask;
+		//printOut();
+	}
+	
+	public int getNextKeyBit()
+	{
+		return this.getNextBit();
+	}
+	
+	public int getNextKey()
+	{
+		int ret=0;
+		int newBit;
+		for (int i=7;i>=0;i--)
+		{
+			newBit = getNextBit();
+			//System.out.println(i+". key bit is: "+Integer.toBinaryString(newBit));
+			ret += ( newBit << i);
+			//System.out.println("act key is: "+LinReg.to8BitString(ret));
+		}
+		//System.out.println("New key is: "+LinReg.to8BitString(ret));
+		return ret & bitMask;
+	}
+	
+	private int getNextBit()
+	{
+		//printOut();
+		int ret=0;
+		//boolean tmp=false;
+		int cnt=0;
+		// left shift status to get next bit at bitLength + 1;
+		this.status = this.status << 1;
+		//System.out.println("Left shifted status: "+Integer.toBinaryString(this.status));
+		// get bit at bitLength + 1;
+		ret = this.status & (~bitMask);
+		//System.out.println("key bit unshifted is: "+Integer.toBinaryString(ret));
+		ret >>= bitLength;
+		//System.out.println("New key bit is: "+Integer.toBinaryString(ret));
+		// calculate next bit from status and config
+		for (int i = 7; i >= 0; i--)
+		{
+			// test if actual status and config bit are
+			// set at position i
+			//if ( (this.status & i) && (this.config & i) )
+			int statusBit = ((this.status & (1<<i) ) >> i);
+			int configBit = ((this.config & (1<<i) ) >> i);
+			
+			//System.out.println("Bit in Status: "+Integer.toBinaryString(statusBit));
+			//System.out.println("Bit in Config: "+Integer.toBinaryString(configBit));
+			
+			if ( (statusBit & configBit) == 1 )
+			{
+				//System.out.println("Bit "+i+" is set in C and S");
+				//tmp=!tmp;
+				cnt++;
+			}
+		}
+		if ( (cnt%2) == 1 )
+		{
+			this.status |= 1;
+			//System.out.println("Appending 1 to status");
+		}
+		else
+		{
+			//System.out.println("Appending 0 to status");
+		}
+		this.status &= bitMask;
+		//printOut();
+		return ret;
+	}
+	public void printOut()
+	{
+		System.out.println("Config is: "+to8BitString(this.config));
+		System.out.println("Status is: "+to8BitString(this.status));
+	}
+	
+	public static final String to8BitString(int input)
+	{
+		String res = Integer.toBinaryString(input);
+		for (int i = res.length();i<bitLength;i++)
+		{
+			res="0"+res;
+		}
+		return res;
+	}
+}