Examples of IGF2

com.securityinnovation.jNeo.inputstream.IGF2
This class implements the IGF2 Index Generation Function defined in the X9.92 specification for NtruEncrypt..
An Index Generation Function produces a sequence of numbers in the range [0..N-1] for some N.
The IGF2 algorithm is defined in terms of the following inputs:
- An underlying bitstream generator
- The max returnable value N
- An integer 'bitsPerIndex'
- A cutoff value, that is the largest multiple of N that is smaller than 2^bitsPerIndex.
The algorithm generates an index by reading 'bitsPerIndex' bits off of the input stream. If the result is larger than or equal to the cutoff the value is discarded and a new value is read. Once a value less than the cutoff is found the igf returns (value % N).
In addition to the IGF2 parameters, the default constructor also takes in the parameters needed to initialize an MGF1 byte stream. This is used as the underlying bitstream generator. A secondary constructor is also provided to make testing easier.

Examples of com.securityinnovation.jNeo.inputstream.IGF2

        InputStream  prng)
        throws ParamSetNotSupportedException
    {
        KeyParams keyParams = KeyParams.getKeyParams(oid);


        IGF2 igf = new IGF2(keyParams.N, keyParams.c, prng);


        // Generate trinomial g that is invertible
        FullPolynomial g = null;
        boolean gIsInvertible = false;
        while (!gIsInvertible)

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Examples of com.securityinnovation.jNeo.inputstream.IGF2

            
            // Form sData = OID | m | b | hTrunc
            byte sData[] = form_sData(message, 0, message.length, M, 0);
            
            // Form r from sData.
            IGF2 igf = new IGF2(
                keyParams.N, keyParams.c, keyParams.igfHash, keyParams.minCallsR, 
                sData, 0, sData.length);
            FullPolynomial r = BPGM3.genTrinomial(
                keyParams.N, keyParams.dr, keyParams.dr, igf);
            igf.close();
            
            // Calculate R = r * h mod q
            R = FullPolynomial.convolution(r, h, keyParams.q);
            
            // calculate R4 = R mod 4, form octet string

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Examples of com.securityinnovation.jNeo.inputstream.IGF2

        // Form sData from OID, m, b, hTrunc
        // Note: b is the leading bytes of cM.
        byte sData[] = form_sData(cM, mOffset, mLen, cM, 0);


        // Calc cr from sData
        IGF2 igf = new IGF2(
            keyParams.N, keyParams.c, keyParams.igfHash, keyParams.minCallsR, 
            sData, 0, sData.length);
        FullPolynomial cr = BPGM3.genTrinomial(
            keyParams.N, keyParams.dr, keyParams.dr, igf);
        igf.close();


        // Calculate cR' = h * cr mod q
        FullPolynomial cRPrime = FullPolynomial.convolution(cr, h, keyParams.q);
        // If cR != cR', fail
        if (!cR.equals(cRPrime))

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Examples of com.securityinnovation.jNeo.inputstream.IGF2

    @Test public void test_oddeven()
    {
        byte igfSequence[] = {0,0,  0,2,  0,4,  0,6,  0,8,
                              0,1,  0,3,  0,5,  0,7,  0,9};
        ByteArrayInputStream is = new ByteArrayInputStream(igfSequence);
        IGF2 igf = new IGF2(0x7fff, 16, is);
        
        short polyCoeffs[] = {1, -1, 1, -1, 1, -1, 1, -1, 1, -1};
        FullPolynomial expected = new FullPolynomial(polyCoeffs);


        FullPolynomial out = BPGM3.genTrinomial(10, 5, 5, igf);

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Examples of com.securityinnovation.jNeo.inputstream.IGF2

        byte igfSequence[] = {0,0,  0,2,  0,4,  0,6,  
                              0,0,  0,2,  0,4,  0,6,  0,8,
                              0,0,  0,2,  0,4,  0,6,  0,8,
                              0,1,  0,3,  0,5,  0,7,  0,9};
        ByteArrayInputStream is = new ByteArrayInputStream(igfSequence);
        IGF2 igf = new IGF2(0x7fff, 16, is);
        
        short polyCoeffs[] = {1, -1, 1, -1, 1, -1, 1, -1, 1, -1};
        FullPolynomial expected = new FullPolynomial(polyCoeffs);


        FullPolynomial out = BPGM3.genTrinomial(10, 5, 5, igf);

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Examples of com.securityinnovation.jNeo.inputstream.IGF2

        NtruEncryptTestVector tests[] = NtruEncryptTestVector.getTestVectors();
        for (int t=0; t<tests.length; t++)
        {
            KeyParams keyParams = KeyParams.getKeyParams(tests[t].oid);
            FullPolynomial expected = new FullPolynomial(tests[t].r);
            IGF2 igf = new IGF2(
                keyParams.N, keyParams.c, keyParams.igfHash, 1,
                tests[t].sData, 0, tests[t].sData.length);
            FullPolynomial out = BPGM3.genTrinomial(
                keyParams.N, keyParams.dr, keyParams.dr, igf);

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