package org.freertr.cry;

import org.freertr.util.bits;

/**
 * secure hash algorithm 3-xof (fips202) hash
 *
 * @author matecsaba
 */
public class cryHashShake extends cryHashGeneric {

    /**
     * create instance
     */
    protected cryHashShake() {
    }

    /**
     * bit length
     */
    protected int bitLength;

    private static long[] KeccakRoundConstants = new long[]{
        0x0000000000000001L, 0x0000000000008082L, 0x800000000000808aL, 0x8000000080008000L,
        0x000000000000808bL, 0x0000000080000001L, 0x8000000080008081L, 0x8000000000008009L,
        0x000000000000008aL, 0x0000000000000088L, 0x0000000080008009L, 0x000000008000000aL,
        0x000000008000808bL, 0x800000000000008bL, 0x8000000000008089L, 0x8000000000008003L,
        0x8000000000008002L, 0x8000000000000080L, 0x000000000000800aL, 0x800000008000000aL,
        0x8000000080008081L, 0x8000000000008080L, 0x0000000080000001L, 0x8000000080008008L
    };

    private long[] state = new long[25];

    private byte[] dataQueue = new byte[192];

    private int rate;

    private int bitsInQueue;

    private int fixedOutputLength;

    private boolean squeezing;

    public String getName() {
        return "shake" + bitLength;
    }

    public byte[] getPkcs() {
        return null;
    }

    public int getHashSize() {
        return 1;
    }

    public int getBlockSize() {
        return fixedOutputLength / 4;
    }

    public byte[] finish() {
        if (!squeezing) {
            absorbBits(0x0F, 4);
        }
        byte[] buf = new byte[1];
        squeeze(buf, 0, 8);
        return buf;
    }

    public void update(byte[] buf, int ofs, int siz) {
        absorb(buf, ofs, siz);
    }

    public void init() {
        switch (bitLength) {
            case 128:
            case 224:
            case 256:
            case 288:
            case 384:
            case 512:
                rate = 1600 - (bitLength << 1);
                for (int i = 0; i < state.length; i++) {
                    state[i] = 0L;
                }
                bits.byteFill(dataQueue, 0, dataQueue.length, 0);
                bitsInQueue = 0;
                squeezing = false;
                fixedOutputLength = (1600 - rate) / 2;
                break;
        }
    }

    /**
     * fill up buffer with results
     *
     * @param buf buffer
     * @param ofs offset
     * @param max length
     */
    public void fillupBuffer(byte[] buf, int ofs, int max) {
        for (; ofs < max;) {
            byte[] res = finish();
            bits.byteCopy(res, 0, buf, ofs, res.length);
            ofs += res.length;
        }
    }

    private void absorb(byte[] data, int off, int len) {
        int bytesInQueue = bitsInQueue >>> 3;
        int rateBytes = rate >>> 3;
        int available = rateBytes - bytesInQueue;
        if (len < available) {
            bits.byteCopy(data, off, dataQueue, bytesInQueue, len);
            bitsInQueue += len << 3;
            return;
        }
        int count = 0;
        if (bytesInQueue > 0) {
            bits.byteCopy(data, off, dataQueue, bytesInQueue, available);
            count += available;
            KeccakAbsorb(dataQueue, 0);
        }
        int remaining;
        while ((remaining = (len - count)) >= rateBytes) {
            KeccakAbsorb(data, off + count);
            count += rateBytes;
        }
        bits.byteCopy(data, off + count, dataQueue, 0, remaining);
        bitsInQueue = remaining << 3;
    }

    private void absorbBits(int data, int bits) {
        int mask = (1 << bits) - 1;
        dataQueue[bitsInQueue >>> 3] = (byte) (data & mask);
        bitsInQueue += bits;
    }

    private void squeeze(byte[] output, int offset, long outputLength) {
        if (!squeezing) {
            dataQueue[bitsInQueue >>> 3] |= (byte) (1 << (bitsInQueue & 7));
            if (++bitsInQueue == rate) {
                KeccakAbsorb(dataQueue, 0);
            } else {
                int full = bitsInQueue >>> 6, partial = bitsInQueue & 63;
                int off = 0;
                for (int i = 0; i < full; i++) {
                    state[i] ^= bits.lsbGetQ(dataQueue, off);
                    off += 8;
                }

                if (partial > 0) {
                    long mask = (1L << partial) - 1L;
                    state[full] ^= bits.lsbGetQ(dataQueue, off) & mask;
                }
            }
            state[(rate - 1) >>> 6] ^= (1L << 63);
            bitsInQueue = 0;
            squeezing = true;
        }
        long i = 0;
        while (i < outputLength) {
            if (bitsInQueue == 0) {
                KeccakPermutation();
                int bsOff = 0;
                int nsLen = rate >>> 6;
                for (int o = 0; o < nsLen; o++) {
                    bits.lsbPutQ(dataQueue, bsOff, state[o]);
                    bsOff += 8;
                }
                bitsInQueue = rate;
            }
            int partialBlock = (int) Math.min((long) bitsInQueue, outputLength - i);
            bits.byteCopy(dataQueue, (rate - bitsInQueue) / 8, output, offset + (int) (i / 8), partialBlock / 8);
            bitsInQueue -= partialBlock;
            i += partialBlock;
        }
    }

    private void KeccakAbsorb(byte[] data, int off) {
        int count = rate >>> 6;
        for (int i = 0; i < count; i++) {
            state[i] ^= bits.lsbGetQ(data, off);
            off += 8;
        }
        KeccakPermutation();
    }

    private void KeccakPermutation() {
        long[] A = state;
        long a00 = A[0], a01 = A[1], a02 = A[2], a03 = A[3], a04 = A[4];
        long a05 = A[5], a06 = A[6], a07 = A[7], a08 = A[8], a09 = A[9];
        long a10 = A[10], a11 = A[11], a12 = A[12], a13 = A[13], a14 = A[14];
        long a15 = A[15], a16 = A[16], a17 = A[17], a18 = A[18], a19 = A[19];
        long a20 = A[20], a21 = A[21], a22 = A[22], a23 = A[23], a24 = A[24];
        for (int i = 0; i < 24; i++) {
            long c0 = a00 ^ a05 ^ a10 ^ a15 ^ a20;
            long c1 = a01 ^ a06 ^ a11 ^ a16 ^ a21;
            long c2 = a02 ^ a07 ^ a12 ^ a17 ^ a22;
            long c3 = a03 ^ a08 ^ a13 ^ a18 ^ a23;
            long c4 = a04 ^ a09 ^ a14 ^ a19 ^ a24;
            long d1 = (c1 << 1 | c1 >>> -1) ^ c4;
            long d2 = (c2 << 1 | c2 >>> -1) ^ c0;
            long d3 = (c3 << 1 | c3 >>> -1) ^ c1;
            long d4 = (c4 << 1 | c4 >>> -1) ^ c2;
            long d0 = (c0 << 1 | c0 >>> -1) ^ c3;
            a00 ^= d1;
            a05 ^= d1;
            a10 ^= d1;
            a15 ^= d1;
            a20 ^= d1;
            a01 ^= d2;
            a06 ^= d2;
            a11 ^= d2;
            a16 ^= d2;
            a21 ^= d2;
            a02 ^= d3;
            a07 ^= d3;
            a12 ^= d3;
            a17 ^= d3;
            a22 ^= d3;
            a03 ^= d4;
            a08 ^= d4;
            a13 ^= d4;
            a18 ^= d4;
            a23 ^= d4;
            a04 ^= d0;
            a09 ^= d0;
            a14 ^= d0;
            a19 ^= d0;
            a24 ^= d0;
            c1 = a01 << 1 | a01 >>> 63;
            a01 = a06 << 44 | a06 >>> 20;
            a06 = a09 << 20 | a09 >>> 44;
            a09 = a22 << 61 | a22 >>> 3;
            a22 = a14 << 39 | a14 >>> 25;
            a14 = a20 << 18 | a20 >>> 46;
            a20 = a02 << 62 | a02 >>> 2;
            a02 = a12 << 43 | a12 >>> 21;
            a12 = a13 << 25 | a13 >>> 39;
            a13 = a19 << 8 | a19 >>> 56;
            a19 = a23 << 56 | a23 >>> 8;
            a23 = a15 << 41 | a15 >>> 23;
            a15 = a04 << 27 | a04 >>> 37;
            a04 = a24 << 14 | a24 >>> 50;
            a24 = a21 << 2 | a21 >>> 62;
            a21 = a08 << 55 | a08 >>> 9;
            a08 = a16 << 45 | a16 >>> 19;
            a16 = a05 << 36 | a05 >>> 28;
            a05 = a03 << 28 | a03 >>> 36;
            a03 = a18 << 21 | a18 >>> 43;
            a18 = a17 << 15 | a17 >>> 49;
            a17 = a11 << 10 | a11 >>> 54;
            a11 = a07 << 6 | a07 >>> 58;
            a07 = a10 << 3 | a10 >>> 61;
            a10 = c1;
            c0 = a00 ^ (~a01 & a02);
            c1 = a01 ^ (~a02 & a03);
            a02 ^= ~a03 & a04;
            a03 ^= ~a04 & a00;
            a04 ^= ~a00 & a01;
            a00 = c0;
            a01 = c1;
            c0 = a05 ^ (~a06 & a07);
            c1 = a06 ^ (~a07 & a08);
            a07 ^= ~a08 & a09;
            a08 ^= ~a09 & a05;
            a09 ^= ~a05 & a06;
            a05 = c0;
            a06 = c1;
            c0 = a10 ^ (~a11 & a12);
            c1 = a11 ^ (~a12 & a13);
            a12 ^= ~a13 & a14;
            a13 ^= ~a14 & a10;
            a14 ^= ~a10 & a11;
            a10 = c0;
            a11 = c1;
            c0 = a15 ^ (~a16 & a17);
            c1 = a16 ^ (~a17 & a18);
            a17 ^= ~a18 & a19;
            a18 ^= ~a19 & a15;
            a19 ^= ~a15 & a16;
            a15 = c0;
            a16 = c1;
            c0 = a20 ^ (~a21 & a22);
            c1 = a21 ^ (~a22 & a23);
            a22 ^= ~a23 & a24;
            a23 ^= ~a24 & a20;
            a24 ^= ~a20 & a21;
            a20 = c0;
            a21 = c1;
            a00 ^= KeccakRoundConstants[i];
        }
        A[0] = a00;
        A[1] = a01;
        A[2] = a02;
        A[3] = a03;
        A[4] = a04;
        A[5] = a05;
        A[6] = a06;
        A[7] = a07;
        A[8] = a08;
        A[9] = a09;
        A[10] = a10;
        A[11] = a11;
        A[12] = a12;
        A[13] = a13;
        A[14] = a14;
        A[15] = a15;
        A[16] = a16;
        A[17] = a17;
        A[18] = a18;
        A[19] = a19;
        A[20] = a20;
        A[21] = a21;
        A[22] = a22;
        A[23] = a23;
        A[24] = a24;
    }

}
