wanderer/ fortuna
1
0
Fork 0
forked from ak-fortuna/fortuna
Code Issues Pull Requests Releases Activity

Merge branch 'fixing-generator' into add-random-sources 

* fixing-generator:
  generator: use a proper uin64_t literal
  chore(generator): erase -> clear
  generator: memcpy -> memmove
  fix(generator): incorrect copying, no protections
This commit is contained in:
surtur 2021-12-11 02:35:06 +01:00
parent a6719d4947 25cbddf41f
commit 0ccd60ce1b
Signed by: wanderer
GPG Key ID: 19CE1EC1D9E0486D
1 changed files with 51 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
generator.cpp
View File

@ -53,18 +53,21 @@ auto Generator::get_state() -> G_state {
}
auto Generator::reseed(const std::string& s) -> void {
// TODO(me): proper concat - WIP below
// ref: https://www.cryptopp.com/wiki/SecBlock
std::string da_key(reinterpret_cast<const char*>(&G.k[0]), G.k.size());
std::string da_key(reinterpret_cast<const char*>(&G.k[0]),
G.k.SizeInBytes() * 8); // we need the size in bits
std::string to_be_hashed{da_key+s};
// fmt::print("s -> {}\n", s); // debugging
// fmt::print("da_key -> {}\n", da_key); // debugging
// fmt::print("concat \"da_key + s\" -> {}\n", to_be_hashed); // debugging
// TODO(me): wrap do_sha in a try-catch
std::string a{do_sha(to_be_hashed)};
std::memcpy(&a[0], &G.k[0], a.size());
++G.ctr;
try {
std::string a{do_sha(to_be_hashed)};
std::memmove(&G.k[0], &a[0], G.k.SizeInBytes());
++G.ctr;
} catch(std::exception& e) {
fmt::print("{}", e.what());
}
}
auto Generator::do_sha(const std::string& k_n_s) -> std::string {
@ -78,7 +81,7 @@ auto Generator::do_sha(const std::string& k_n_s) -> std::string {
// no reason not to go for Keccak
CryptoPP::SHA3_256 sha3_256;
digest.erase();
digest.clear();
// FIXME: commented to test reseeds
// const std::string to_compare{
// "8eccfbbbc9df48b4272e6237ce45aad8fbe59629b4963c4dcda5716e61bb34e1"
@ -125,7 +128,7 @@ auto Generator::do_crypto() -> std::string {
// 16 bytes --> 128bit
static constexpr const std::size_t ctr_length{16};
CryptoPP::FixedSizeSecBlock<CryptoPP::byte, ctr_length> ctr;
std::memcpy(&G.ctr, &ctr, sizeof(G.ctr));
std::memmove(&ctr, &G.ctr, ctr_length);
try {
// fmt::print("plain text: {}\n", plain);
@ -168,6 +171,15 @@ auto Generator::generate_blocks(unsigned int k_blocks) -> std::string {
r += do_crypto();
++G.ctr;
}
try {
std::string da_key{""};
da_key.resize(G.k.size());
std::memmove(&da_key[0], &G.k[0], G.k_length);
// TODO(me): assert reseed_time > 100ms
reseed(do_sha(da_key));
} catch(std::exception& e) {
fmt::print("{}", e.what());
}
// fmt::print("r from generate_blocks -> {}\n", r); // debugging
return r;
}
@ -183,30 +195,41 @@ auto Generator::generate_random_data(uint n) -> std::string {
throw std::invalid_argument("n cannot be > 2^20");
}
/* do magic to compute r
* r ← first-n-bytes(GenerateBlocks(G, ceil(n/16) )) */
// n is number of bytes, i.e. pass n*8 to get number of bits
unsigned int how_many = (int)ceil((n*8)/16);
// fmt::print("how_many: {}\n", how_many); // debugging
std::string rr{generate_blocks(how_many)};
fmt::print("rr (output from generate_blocks): {}\n", rr);
// since we're truncating hex, we need to get twice more characters
std::string r{rr.substr(0,n*2)};
rr.erase();
std::string r;
try {
/* do magic to compute r
* r ← first-n-bytes(GenerateBlocks(G, ceil(n/16) )) */
// n is number of bytes, i.e. pass n*8 to get number of bits
unsigned int how_many(static_cast<unsigned int>(ceil((n*8)/16)));
// fmt::print("how_many: {}\n", how_many); // debugging
std::string rr{generate_blocks(how_many)};
fmt::print("rr (output from generate_blocks): {}\n", rr);
// since we're truncating hex, we need to get twice more characters
r = rr.substr(0,n*0x02ul);
rr.clear();
} catch(std::exception& e) {
fmt::print("{}", e.what());
}
/* re-key */
std::string nu_G_k{generate_blocks(2)};
// fmt::print("nu_G_k: {}\n", nu_G_k); // debugging
std::string dst;
CryptoPP::StringSource str_s(
nu_G_k,true,new CryptoPP::HexDecoder(new CryptoPP::StringSink(dst))
);
try {
std::string nu_G_k{generate_blocks(2)};
// fmt::print("nu_G_k: {}\n", nu_G_k); // debugging
std::string dst;
CryptoPP::StringSource str_s(
nu_G_k,true,new CryptoPP::HexDecoder(new CryptoPP::StringSink(dst))
);
nu_G_k.erase();
nu_G_k.clear();
/* clear out the old key and set a new one */
std::memset(G.k, 0x00, G.k.size());
std::memcpy(&dst[0], &G.k[0], dst.size());
/* clear out the old key and set a new one */
std::memset(G.k, 0x00, G.k.size());
std::memmove(&G.k[0], &dst[0], dst.size());
} catch(std::exception& e) {
fmt::print("{}", e.what());
}
return r;
};