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author | Alexander Harkness <bearbin@gmail.com> | 2013-11-24 15:21:13 +0100 |
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committer | Alexander Harkness <bearbin@gmail.com> | 2013-11-24 15:21:13 +0100 |
commit | 3438e5d3ddf8444f0e31009ffbe8237ef3752c22 (patch) | |
tree | 7c2f76d5e9281c130e60fb932c4dda89a49863b6 /CryptoPP/gf2_32.cpp | |
parent | Moved source to src (diff) | |
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Diffstat (limited to 'CryptoPP/gf2_32.cpp')
-rw-r--r-- | CryptoPP/gf2_32.cpp | 99 |
1 files changed, 0 insertions, 99 deletions
diff --git a/CryptoPP/gf2_32.cpp b/CryptoPP/gf2_32.cpp deleted file mode 100644 index ae4874a40..000000000 --- a/CryptoPP/gf2_32.cpp +++ /dev/null @@ -1,99 +0,0 @@ -// gf2_32.cpp - written and placed in the public domain by Wei Dai - -#include "pch.h" -#include "misc.h" -#include "gf2_32.h" - -NAMESPACE_BEGIN(CryptoPP) - -GF2_32::Element GF2_32::Multiply(Element a, Element b) const -{ - word32 table[4]; - table[0] = 0; - table[1] = m_modulus; - if (a & 0x80000000) - { - table[2] = m_modulus ^ (a<<1); - table[3] = a<<1; - } - else - { - table[2] = a<<1; - table[3] = m_modulus ^ (a<<1); - } - -#if CRYPTOPP_FAST_ROTATE(32) - b = rotrFixed(b, 30U); - word32 result = table[b&2]; - - for (int i=29; i>=0; --i) - { - b = rotlFixed(b, 1U); - result = (result<<1) ^ table[(b&2) + (result>>31)]; - } - - return (b&1) ? result ^ a : result; -#else - word32 result = table[(b>>30) & 2]; - - for (int i=29; i>=0; --i) - result = (result<<1) ^ table[((b>>i)&2) + (result>>31)]; - - return (b&1) ? result ^ a : result; -#endif -} - -GF2_32::Element GF2_32::MultiplicativeInverse(Element a) const -{ - if (a <= 1) // 1 is a special case - return a; - - // warning - don't try to adapt this algorithm for another situation - word32 g0=m_modulus, g1=a, g2=a; - word32 v0=0, v1=1, v2=1; - - assert(g1); - - while (!(g2 & 0x80000000)) - { - g2 <<= 1; - v2 <<= 1; - } - - g2 <<= 1; - v2 <<= 1; - - g0 ^= g2; - v0 ^= v2; - - while (g0 != 1) - { - if (g1 < g0 || ((g0^g1) < g0 && (g0^g1) < g1)) - { - assert(BitPrecision(g1) <= BitPrecision(g0)); - g2 = g1; - v2 = v1; - } - else - { - assert(BitPrecision(g1) > BitPrecision(g0)); - g2 = g0; g0 = g1; g1 = g2; - v2 = v0; v0 = v1; v1 = v2; - } - - while ((g0^g2) >= g2) - { - assert(BitPrecision(g0) > BitPrecision(g2)); - g2 <<= 1; - v2 <<= 1; - } - - assert(BitPrecision(g0) == BitPrecision(g2)); - g0 ^= g2; - v0 ^= v2; - } - - return v0; -} - -NAMESPACE_END |