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| author | Samuel Dobson <dobsonsa68@gmail.com> | 2021-11-23 15:52:33 +1300 |
|---|---|---|
| committer | Samuel Dobson <dobsonsa68@gmail.com> | 2021-12-01 11:01:20 +1300 |
| commit | 405c96fc9fd909ccc461f10d55dfdd822b76f5bf (patch) | |
| tree | 839c476f0b9e9ccefee8c63b1e604caa3afa08d6 /src/bech32.cpp | |
| parent | 28d9c2857f1c430069bffe0547d12800c84ed9ec (diff) | |
Use bounds-checked array lookups in Bech32 error detection code
Diffstat (limited to 'src/bech32.cpp')
| -rw-r--r-- | src/bech32.cpp | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/src/bech32.cpp b/src/bech32.cpp index 740c331989..484586cfa5 100644 --- a/src/bech32.cpp +++ b/src/bech32.cpp @@ -457,9 +457,9 @@ std::string LocateErrors(const std::string& str, std::vector<int>& error_locatio int s2 = syn >> 20; // Get the discrete logs of these values in GF1024 for more efficient computation - int l_s0 = GF1024_LOG[s0]; - int l_s1 = GF1024_LOG[s1]; - int l_s2 = GF1024_LOG[s2]; + int l_s0 = GF1024_LOG.at(s0); + int l_s1 = GF1024_LOG.at(s1); + int l_s2 = GF1024_LOG.at(s2); // First, suppose there is only a single error. Then E(x) = e1*x^p1 for some position p1 // Then s0 = E((e)^997) = e1*(e)^(997*p1) and s1 = E((e)^998) = e1*(e)^(998*p1) @@ -494,15 +494,15 @@ std::string LocateErrors(const std::string& str, std::vector<int>& error_locatio // (Because we are working in characteristic 2.) // = e2*(e)^(998*p2) ((e)^p2 + (e)^p1) // - int s2_s1p1 = s2 ^ (s1 == 0 ? 0 : GF1024_EXP[(l_s1 + p1) % 1023]); + int s2_s1p1 = s2 ^ (s1 == 0 ? 0 : GF1024_EXP.at((l_s1 + p1) % 1023)); if (s2_s1p1 == 0) continue; - int l_s2_s1p1 = GF1024_LOG[s2_s1p1]; + int l_s2_s1p1 = GF1024_LOG.at(s2_s1p1); // Similarly, s1 + s0*(e)^p1 // = e2*(e)^(997*p2) ((e)^p2 + (e)^p1) - int s1_s0p1 = s1 ^ (s0 == 0 ? 0 : GF1024_EXP[(l_s0 + p1) % 1023]); + int s1_s0p1 = s1 ^ (s0 == 0 ? 0 : GF1024_EXP.at((l_s0 + p1) % 1023)); if (s1_s0p1 == 0) continue; - int l_s1_s0p1 = GF1024_LOG[s1_s0p1]; + int l_s1_s0p1 = GF1024_LOG.at(s1_s0p1); // So, putting these together, we can compute the second error position as // (e)^p2 = (s2 + s1^p1)/(s1 + s0^p1) @@ -515,12 +515,12 @@ std::string LocateErrors(const std::string& str, std::vector<int>& error_locatio // Now we want to compute the error values e1 and e2. // Similar to above, we compute s1 + s0*(e)^p2 // = e1*(e)^(997*p1) ((e)^p1 + (e)^p2) - int s1_s0p2 = s1 ^ (s0 == 0 ? 0 : GF1024_EXP[(l_s0 + p2) % 1023]); + int s1_s0p2 = s1 ^ (s0 == 0 ? 0 : GF1024_EXP.at((l_s0 + p2) % 1023)); if (s1_s0p2 == 0) continue; - int l_s1_s0p2 = GF1024_LOG[s1_s0p2]; + int l_s1_s0p2 = GF1024_LOG.at(s1_s0p2); // And compute (the log of) 1/((e)^p1 + (e)^p2)) - int inv_p1_p2 = 1023 - GF1024_LOG[GF1024_EXP[p1] ^ GF1024_EXP[p2]]; + int inv_p1_p2 = 1023 - GF1024_LOG.at(GF1024_EXP.at(p1) ^ GF1024_EXP.at(p2)); // Then (s1 + s0*(e)^p1) * (1/((e)^p1 + (e)^p2))) // = e2*(e)^(997*p2) |