RSA

    private int e;
    private BigInteger n;
    private BigInteger d;
    private BigInteger p;
    private BigInteger q;
    private BigInteger dmp1;
    private BigInteger dmq1;
    private BigInteger coeff;

    private RSA(final BigInteger n, final int e, final BigInteger d, final BigInteger p, final BigInteger q, final BigInteger dmp1, final BigInteger dmq1, final BigInteger coeff){
        this.n = n;
        this.e = e;
        this.d = d;
        this.p = p;
        this.q = q;
        this.dmp1 = dmp1;
        this.dmq1 = dmq1;
        this.coeff = coeff;
    }

    private int GetBlockSize() {
        return ((this.n.bitCount() + 7) / 8);
    }

    private byte[] pkcs1unpad(final BigInteger _arg1, final int _arg2) {
        byte[] bytes = _arg1.toByteArray();
        int i = 0;

        while (i < bytes.length && bytes[i] == 0) ++i;
        if (bytes.length - i != (_arg2 - 1) || bytes[i] != 0x2)
        {
            return null;
        }
        i++;
        while(bytes[i] != 0) {
            ++i;
            if(i >= bytes.length) {
                return null;
            }
        }
        byte[] result = new byte[bytes.length - i + 1];

        int p = 0;
        while(++i < bytes.length) {
            result[p++] = bytes[i];
        }

        return result;
    }

    public BigInteger doPrivate2(final BigInteger k) {
        return k.modPow(this.d, this.n);
    }

    public byte[] Decript(String Key) {
        BigInteger m = new BigInteger(Key, 16);
        BigInteger c = this.doPrivate2(m);

        if (c.bitLength() == 0)
        {
            return null;
        }

        byte[] bytes = this.pkcs1unpad(c, this.GetBlockSize());

        if (bytes.length == 0)
        {
            return null;
        }

        return bytes;
    }