66 lines
1.5 KiB
C++
66 lines
1.5 KiB
C++
#include <cmath>
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#include <cassert>
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#include <stdexcept>
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#include <tuple>
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#include "generator.h"
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using namespace std;
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struct G_state{
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long k;
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unsigned __int128 ctr;
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};
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G_state *initialize_generator(){
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auto G = new G_state;
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G->k = 0;
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G->ctr = 0;
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return G;
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};
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string do_crypto(long k, unsigned __int128 ctr){
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/* this function calls the block cipher
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* returns a string of k*(16 bytes);
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do whatever atm */
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k = 0;
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ctr = 0;
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return "";
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}
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/* lacking objects, we have to return both the state and the string */
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tuple<string, G_state> generate_blocks(G_state G, int k_blocks){
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assert (G.ctr!=0);
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string r = "";
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for (int i = 0; i < k_blocks; ++i) {
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r += do_crypto(G.k, G.ctr);
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G.ctr += 1;
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}
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return {r, G};
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}
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/* n is number of random bytes to generate */
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tuple<string, G_state> generate_random_data(G_state G, uint n){
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string r = "";
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if (n < 0){
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/* this should not be possible */
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printf("[*] error: n cannot be < 0\n");
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throw invalid_argument("n cannot be < 0");
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} else if (n > pow(2,20)){
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printf("[*] error: n cannot be > 2^20\n");
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throw invalid_argument("n cannot be > 2^20");
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}
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/* do magic to compute r
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* r ← first-n-bytes(GenerateBlocks(G, ceil(n/16) )) */
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string rr = std::get<0>(generate_blocks(G,ceil(n/16)));
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r = rr.substr(0,n);
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/* re-key */
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// TODO: check conversions
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G.k = stoul(std::get<0>(generate_blocks(G, 2)));
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// returning just r throws away our state, this should be reworked
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// using OOP
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// return r;
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return {r, G};
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};
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