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Diffstat (limited to 'src/lib/pubkey/curve25519/donna128.h')
-rw-r--r-- | src/lib/pubkey/curve25519/donna128.h | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/src/lib/pubkey/curve25519/donna128.h b/src/lib/pubkey/curve25519/donna128.h new file mode 100644 index 000000000..f2b2d88ea --- /dev/null +++ b/src/lib/pubkey/curve25519/donna128.h @@ -0,0 +1,116 @@ +/* +* A minimal 128-bit integer type for curve25519-donna +* (C) 2014 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#ifndef BOTAN_CURVE25519_DONNA128_H__ +#define BOTAN_CURVE25519_DONNA128_H__ + +#include <botan/mul128.h> + +namespace Botan { + +class donna128 + { + public: + donna128(u64bit ll = 0, u64bit hh = 0) { l = ll; h = hh; } + + donna128(const donna128&) = default; + donna128& operator=(const donna128&) = default; + + friend donna128 operator>>(const donna128& x, size_t shift) + { + donna128 z = x; + const u64bit carry = z.h << (64 - shift); + z.h = (z.h >> shift); + z.l = (z.l >> shift) | carry; + return z; + } + + friend donna128 operator<<(const donna128& x, size_t shift) + { + donna128 z = x; + const u64bit carry = z.l >> (64 - shift); + z.l = (z.l << shift); + z.h = (z.h << shift) | carry; + return z; + } + + friend u64bit operator&(const donna128& x, u64bit mask) + { + return x.l & mask; + } + + u64bit operator&=(u64bit mask) + { + h = 0; + l &= mask; + return l; + } + + donna128& operator+=(const donna128& x) + { + l += x.l; + h += (l < x.l); + h += x.h; + return *this; + } + + donna128& operator+=(u64bit x) + { + l += x; + h += (l < x); + return *this; + } + + u64bit lo() const { return l; } + u64bit hi() const { return h; } + private: + u64bit h = 0, l = 0; + }; + +inline donna128 operator*(const donna128& x, u64bit y) + { + BOTAN_ASSERT(x.hi() == 0, "High 64 bits of donna128 set to zero during multiply"); + + u64bit lo = 0, hi = 0; + mul64x64_128(x.lo(), y, &lo, &hi); + return donna128(lo, hi); + } + +inline donna128 operator+(const donna128& x, const donna128& y) + { + donna128 z = x; + z += y; + return z; + } + +inline donna128 operator+(const donna128& x, u64bit y) + { + donna128 z = x; + z += y; + return z; + } + +inline donna128 operator|(const donna128& x, const donna128& y) + { + return donna128(x.lo() | y.lo(), x.hi() | y.hi()); + } + +inline u64bit carry_shift(const donna128& a, size_t shift) + { + return (a >> shift).lo(); + } + +inline u64bit combine_lower(const donna128 a, size_t s1, + const donna128 b, size_t s2) + { + donna128 z = (a >> s1) | (b << s2); + return z.lo(); + } + +} + +#endif |