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// Package ensemble provides a collection of addition chain algorithms intended
// for target integers of cryptographic interest.
package ensemble
import (
"github.com/mmcloughlin/addchain/alg"
"github.com/mmcloughlin/addchain/alg/contfrac"
"github.com/mmcloughlin/addchain/alg/dict"
"github.com/mmcloughlin/addchain/alg/heuristic"
"github.com/mmcloughlin/addchain/alg/opt"
)
// Ensemble is a convenience for building an ensemble of chain algorithms intended for large integers.
func Ensemble() []alg.ChainAlgorithm {
// Choose sequence algorithms.
seqalgs := []alg.SequenceAlgorithm{
heuristic.NewAlgorithm(heuristic.UseFirst(
heuristic.Halving{},
heuristic.DeltaLargest{},
)),
heuristic.NewAlgorithm(heuristic.UseFirst(
heuristic.Halving{},
heuristic.Approximation{},
)),
}
for _, strategy := range contfrac.Strategies {
if strategy.Singleton() {
seqalgs = append(seqalgs, contfrac.NewAlgorithm(strategy))
}
}
// Build decomposers.
decomposers := []dict.Decomposer{}
for k := uint(4); k <= 128; k *= 2 {
decomposers = append(decomposers, dict.SlidingWindow{K: k})
}
decomposers = append(decomposers, dict.RunLength{T: 0})
for t := uint(16); t <= 128; t *= 2 {
decomposers = append(decomposers, dict.RunLength{T: t})
}
for k := uint(2); k <= 8; k++ {
decomposers = append(decomposers, dict.Hybrid{K: k, T: 0})
for t := uint(16); t <= 64; t *= 2 {
decomposers = append(decomposers, dict.Hybrid{K: k, T: t})
}
}
// Build dictionary algorithms for every combination.
as := []alg.ChainAlgorithm{}
for _, decomp := range decomposers {
for _, seqalg := range seqalgs {
a := dict.NewAlgorithm(decomp, seqalg)
as = append(as, a)
}
}
// Add the runs algorithms.
for _, seqalg := range seqalgs {
as = append(as, dict.NewRunsAlgorithm(seqalg))
}
// Wrap in an optimization layer.
for i, a := range as {
as[i] = opt.Algorithm{Algorithm: a}
}
return as
}
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