52 lines
1.4 KiB
Go
52 lines
1.4 KiB
Go
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package gf127
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import (
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"encoding/binary"
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"encoding/hex"
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"unsafe"
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)
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// GF127x2 represents a pair of elements of GF(2^127) stored together.
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type GF127x2 [4]uint64
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// Split returns 2 components of pair without additional allocations.
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func Split(a *GF127x2) (*GF127, *GF127) {
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return (*GF127)(unsafe.Pointer(a)), (*GF127)(unsafe.Pointer(&(*a)[2]))
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}
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// CombineTo 2 elements of GF(2^127) to the respective components of pair.
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func CombineTo(a *GF127, b *GF127, c *GF127x2) {
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c[0] = a[0]
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c[1] = a[1]
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c[2] = b[0]
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c[3] = b[1]
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}
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// Equal checks if both elements of GF(2^127) pair are equal.
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func (a *GF127x2) Equal(b *GF127x2) bool {
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return a[0] == b[0] && a[1] == b[1] && a[2] == b[2] && a[3] == b[3]
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}
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// String returns hex-encoded representation, starting with MSB.
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// Elements of pair are separated by comma.
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func (a *GF127x2) String() string {
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b := a.ByteArray()
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return hex.EncodeToString(b[:16]) + " , " + hex.EncodeToString(b[16:])
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}
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// ByteArray represents element of GF(2^127) as byte array of length 32.
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func (a *GF127x2) ByteArray() (buf []byte) {
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buf = make([]byte, 32)
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binary.BigEndian.PutUint64(buf, a[1])
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binary.BigEndian.PutUint64(buf[8:], a[0])
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binary.BigEndian.PutUint64(buf[16:], a[3])
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binary.BigEndian.PutUint64(buf[24:], a[2])
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return
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}
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// Mul10x2 sets (b1, b2) to (a1*x, a2*x)
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func Mul10x2(a, b *GF127x2)
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// Mul10x2 sets (b1, b2) to (a1*(x+1), a2*(x+1))
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func Mul11x2(a, b *GF127x2)
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