56 lines
1.6 KiB
Go
56 lines
1.6 KiB
Go
package common
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import (
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"fmt"
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"io"
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"github.com/crate-crypto/go-ipa/bandersnatch/fr"
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"github.com/crate-crypto/go-ipa/banderwagon"
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)
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// VectorLength is the number of elements in the vector. This value is fixed.
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// Note that this means that the degree of the polynomial is one less than this value.
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const VectorLength = 256
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// Returns powers of x from 0 to degree-1
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// <1, x, x^2, x^3, x^4,...,x^(degree-1)>
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// TODO This method is used in two places; one is to evaluate a polynomial (test), and the other is to
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// TODO compute powers of challenges.
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// TODO the first one we can use the bls package for
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// TODO The second we _could_ just multiply on each iteration, (depends on how readable it is)
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func PowersOf(x fr.Element, degree int) []fr.Element {
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result := make([]fr.Element, degree)
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result[0] = fr.One()
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for i := 1; i < degree; i++ {
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result[i].Mul(&result[i-1], &x)
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}
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return result
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}
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func ReadPoint(r io.Reader) (*banderwagon.Element, error) {
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var x = make([]byte, 32)
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if _, err := io.ReadAtLeast(r, x, 32); err != nil {
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return nil, fmt.Errorf("reading x coordinate: %w", err)
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}
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var p = &banderwagon.Element{}
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if err := p.SetBytes(x); err != nil {
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return nil, fmt.Errorf("deserializing point: %w", err)
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}
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return p, nil
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}
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func ReadScalar(r io.Reader) (*fr.Element, error) {
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var x = make([]byte, 32)
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if _, err := io.ReadAtLeast(r, x, 32); err != nil {
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return nil, fmt.Errorf("reading scalar: %w", err)
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}
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var scalar = &fr.Element{}
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if _, err := scalar.SetBytesLECanonical(x); err != nil {
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return nil, fmt.Errorf("deserializing scalar: %s", err)
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}
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return scalar, nil
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}
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