mirror of
https://github.com/luxfi/lattice.git
synced 2026-09-24 00:25:44 +00:00
zeekay
eaf864890e
- Update module path to github.com/luxfi/lattice/v7 - Add GPU acceleration with Metal (macOS) and CUDA backends - Enhance threshold FHE operations - Revert to vanilla Apache 2.0 license (remove tfhe) - Update Go version to 1.25.5 - Merge upstream lattigo improvements
53 lines
2.0 KiB
Go
53 lines
2.0 KiB
Go
package ckks
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import (
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"fmt"
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"github.com/luxfi/lattice/v7/core/rlwe"
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"github.com/luxfi/lattice/v7/ring"
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"github.com/luxfi/lattice/v7/utils"
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)
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// TraceNew maps X -> sum((-1)^i * X^{i*n+1}) for 0 <= i < N and returns the result on a new ciphertext.
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// For log(n) = logSlots.
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func (eval Evaluator) TraceNew(ctIn *rlwe.Ciphertext, logSlots int) (opOut *rlwe.Ciphertext, err error) {
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opOut = NewCiphertext(*eval.GetParameters(), 1, ctIn.Level())
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return opOut, eval.Trace(ctIn, logSlots, opOut)
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}
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// Average returns the average of vectors of batchSize elements.
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// The operation assumes that ctIn encrypts SlotCount/batchSize sub-vectors of size batchSize.
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// It then replaces all values of those sub-vectors by the component-wise average between all the sub-vectors.
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// Example for batchSize=4 and slots=8: [{a, b, c, d}, {e, f, g, h}] -> [0.5*{a+e, b+f, c+g, d+h}, 0.5*{a+e, b+f, c+g, d+h}]
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// Operation requires log2(SlotCout/batchSize) rotations.
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// Required rotation keys can be generated with RotationsForInnerSumLog(batchSize, SlotCount/batchSize).
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func (eval Evaluator) Average(ctIn *rlwe.Ciphertext, logBatchSize int, opOut *rlwe.Ciphertext) (err error) {
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if ctIn.Degree() != 1 || opOut.Degree() != 1 {
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return fmt.Errorf("cannot Average: ctIn.Degree() != 1 or opOut.Degree() != 1")
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}
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if logBatchSize > ctIn.LogDimensions.Cols {
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return fmt.Errorf("cannot Average: batchSize must be smaller or equal to the number of slots")
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}
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ringQ := eval.GetParameters().RingQ()
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level := utils.Min(ctIn.Level(), opOut.Level())
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n := 1 << (ctIn.LogDimensions.Cols - logBatchSize)
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// pre-multiplication by n^-1
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for i, s := range ringQ.SubRings[:level+1] {
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/* #nosec G115 -- n cannot be negative */
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invN := ring.ModExp(uint64(n), s.Modulus-2, s.Modulus)
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invN = ring.MForm(invN, s.Modulus, s.BRedConstant)
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s.MulScalarMontgomery(ctIn.Value[0].Coeffs[i], invN, opOut.Value[0].Coeffs[i])
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s.MulScalarMontgomery(ctIn.Value[1].Coeffs[i], invN, opOut.Value[1].Coeffs[i])
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}
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return eval.InnerSum(opOut, 1<<logBatchSize, n, opOut)
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}
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