NewGamePhysics.Physics.SimpleEntropyCollector Class Reference

Collects entropy from submitted floating point values of physical processes (measurements or simulations fed by physical processes). Uses the bitcount of the difference of submitted floating point values and a von Neumann unbiaser. The submissions of the values will yield usable entropy if: if the value changes sufficiently much between submissions the submissions are independent from the value generation either the value source or the submission trigger is based on a real physical random process (i.e. uncorrelated user trigger). More...

List of all members.

Public Member Functions
	SimpleEntropyCollector ()
	Default constructor.
void	Reset ()
	Reset collector to initial state.
void	AddValue (double value)
	Adds a float value to the collector.
override string	ToString ()
	Return the current entropy collector bit-pool as string of 0 and 1 characters.
Properties
int	BitsInPool [get]
	Gets the current number of valid entropy bits in a the pool.

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Detailed Description

Collects entropy from submitted floating point values of physical processes (measurements or simulations fed by physical processes). Uses the bitcount of the difference of submitted floating point values and a von Neumann unbiaser. The submissions of the values will yield usable entropy if: if the value changes sufficiently much between submissions the submissions are independent from the value generation either the value source or the submission trigger is based on a real physical random process (i.e. uncorrelated user trigger).

Definition at line 24 of file SimpleEntropyCollector.cs.

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Constructor & Destructor Documentation

NewGamePhysics.Physics.SimpleEntropyCollector.SimpleEntropyCollector

(

)

Default constructor.

Definition at line 71 of file SimpleEntropyCollector.cs.

        {
            // Initialize bitcount helper
            bitCount = new BitCount();

            // Initialize collector state
            this.Reset();
        }

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Member Function Documentation

void NewGamePhysics.Physics.SimpleEntropyCollector.AddValue

(

double

value

)

Adds a float value to the collector.

Parameters:

value

Value to add.

Definition at line 105 of file SimpleEntropyCollector.cs.

        {
            if (numValues == 1)
            {
                // Different between values
                double delta = this.lastValue - value;

                // Translate the double into a 64 bit long.
                long deltaBits = BitConverter.DoubleToInt64Bits(delta);

                // Get bitcount
                int totalBits = this.bitCount.FastBitcount(deltaBits);

                // Generate this bit
                bool newBit = (bool)((totalBits & 1) == 1);

                // von Neumann corrector to unbias bitstream
                if (numBits == 1)
                {
                    // Check for 10: add a 1
                    if ((!newBit) && (this.lastBit))
                    {
                        // Use LSB of bitcount
                        if (this.bitsInPool < 1024)
                        {
                            this.bitPool[this.bitsInPool] = true;
                            this.bitsInPool++;
                        }
                    }
                    // Check for 01: add a 0
                    else if ((newBit) && (!this.lastBit))
                    {
                        // Use LSB of bitcount
                        if (this.bitsInPool < 1024)
                        {
                            this.bitPool[this.bitsInPool] = false;
                            this.bitsInPool++;
                        }
                    }
                    else
                    {
                        // Discard 00 and 11 patterns
                    }
                    // Reset corrector counter
                    this.numBits = 0;
                }
                else
                {
                    // Store bit
                    this.lastBit = newBit;
                    this.numBits++;
                }

                // Reset value count to we cache the next submission
                this.numValues = 0;
            }
            else
            {
                // Just cache value for next call
                this.lastValue = value;

                // Set value count so we process the next submission
                this.numValues = 1;
            }
        }

void NewGamePhysics.Physics.SimpleEntropyCollector.Reset

(

)

Reset collector to initial state.

Definition at line 91 of file SimpleEntropyCollector.cs.

        {
            // Reset pool and value trackers
            this.poolSize = 1024;
            this.bitsInPool = 0;
            this.bitPool = new bool[poolSize];
            this.numValues = 0;
            this.numBits = 0;
        }

override string NewGamePhysics.Physics.SimpleEntropyCollector.ToString

(

)

Return the current entropy collector bit-pool as string of 0 and 1 characters.

Returns:

The current bit pool as string.

Definition at line 176 of file SimpleEntropyCollector.cs.

        {
            StringBuilder sb = new StringBuilder();

            if (this.bitsInPool > 0)
            {
                for (int i = bitsInPool - 1; i >= 0; i--)
                {
                    if (bitPool[i])
                    {
                        sb.Append("1");
                    }
                    else
                    {
                        sb.Append("0");
                    }
                }
            }

            return sb.ToString();
        }

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Property Documentation

int NewGamePhysics.Physics.SimpleEntropyCollector.BitsInPool [get]

Gets the current number of valid entropy bits in a the pool.

Definition at line 84 of file SimpleEntropyCollector.cs.

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The documentation for this class was generated from the following file:

• C:/Users/Andreas Schiffler/Desktop/SVN/NewGamePhysics/NewGamePhysics/Physics/SimpleEntropyCollector.cs