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https://github.com/fumiama/go-x25519.git
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Refactor
This commit is contained in:
Riobard
109
x25519.go
109
x25519.go
@@ -13,59 +13,65 @@ import (
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// KeySize is the size of keys in bytes used in this package.
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const KeySize = 32
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type PublicKey [32]byte
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func (pk *PublicKey) String() string { return string(pk[:]) }
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// SecretKey is the type of Curve25519 secret keys
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// SecretKey is the type of Curve25519 secret keys.
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type SecretKey struct {
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sk [32]byte
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pk *PublicKey
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ur *[32]byte
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sk []byte
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pk PublicKey
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ur []byte // uniform representative of pk
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}
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func NewSecretKey(sk []byte) *SecretKey {
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k := new(SecretKey)
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copy(k.sk[:], sk)
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return k
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}
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func (k *SecretKey) Bytes() []byte { return k.sk[:] }
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func (k *SecretKey) String() string { return string(k.sk[:]) }
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// Bytes returns the secret key as a byte slice.
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func (k *SecretKey) Bytes() []byte { return k.sk }
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// Public returns the PublicKey corresponding to the secret key.
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func (k *SecretKey) Public() *PublicKey {
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func (k *SecretKey) Public() PublicKey {
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if k.pk == nil {
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k.pk = new(PublicKey)
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curve25519.ScalarBaseMult((*[32]byte)(k.pk), &k.sk)
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var pk, sk [32]byte
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copy(sk[:], k.sk)
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curve25519.ScalarBaseMult(&pk, &sk)
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k.pk = pk[:]
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}
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return k.pk
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}
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// Uniform returns the uniform representative of the public key corresponding to the secret key, or nil
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// PublicUniform returns the uniform representative of the public key corresponding to the secret key, or nil
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// if the public key does not have a uniform representative.
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func (k *SecretKey) Uniform() *[32]byte {
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func (k *SecretKey) PublicUniform() UniformRepresentative {
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if k.ur == nil {
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pk := new(PublicKey)
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ur := new([32]byte)
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if extra25519.ScalarBaseMult((*[32]byte)(pk), ur, &k.sk) {
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k.pk = pk
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k.ur = ur
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var sk, pk, ur [32]byte
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copy(sk[:], k.sk)
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if extra25519.ScalarBaseMult(&pk, &ur, &sk) {
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k.pk = pk[:]
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k.ur = ur[:]
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}
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}
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return k.ur
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}
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// Shared computes the shared secret between our secret key and their public key.
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func (k *SecretKey) Shared(shared *[32]byte, theirPublic *PublicKey) {
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curve25519.ScalarMult(shared, &k.sk, (*[32]byte)(theirPublic))
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// Shared computes the shared secret between our secret key and peer's public key.
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func (k *SecretKey) Shared(peer PublicKey) []byte {
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var shared, sk, pk [32]byte
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copy(sk[:], k.sk)
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copy(pk[:], peer)
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curve25519.ScalarMult(&shared, &sk, &pk)
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return shared[:]
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}
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// SharedUniform computes the shared secret between our secret key and their public key's uniform representative.
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func (k *SecretKey) SharedUniform(shared, theirRepresentative *[32]byte) {
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pk := new([32]byte)
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extra25519.RepresentativeToPublicKey(pk, theirRepresentative)
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curve25519.ScalarMult(shared, &k.sk, pk)
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// SharedUniform computes the shared secret between our secret key and peer public key's uniform representative.
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func (k *SecretKey) SharedUniform(peer UniformRepresentative) []byte {
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var shared, pk, sk, ur [32]byte
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copy(ur[:], peer)
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copy(sk[:], k.sk)
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extra25519.RepresentativeToPublicKey(&pk, &ur)
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curve25519.ScalarMult(&shared, &sk, &pk)
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return shared[:]
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}
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// NewSecretKey creates a SecretKey from byte slice sk and len(sk) must be 32.
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func NewSecretKey(sk []byte) *SecretKey {
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k := new(SecretKey)
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k.sk = sk
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return k
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}
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// GenerateKey generates a secret key using entropy from random, or crypto/rand.Reader
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@@ -74,9 +80,10 @@ func GenerateKey(random io.Reader) (*SecretKey, error) {
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if random == nil {
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random = rand.Reader
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}
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sk := new(SecretKey)
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_, err := io.ReadFull(random, sk.sk[:])
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return sk, err
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k := new(SecretKey)
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k.sk = make([]byte, 32)
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_, err := io.ReadFull(random, k.sk)
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return k, err
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}
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// GenerateKeyUniform generates a secret key whose corresponding public key has a uniform representative
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@@ -85,16 +92,30 @@ func GenerateKeyUniform(random io.Reader) (*SecretKey, error) {
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if random == nil {
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random = rand.Reader
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}
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sk := new(SecretKey)
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for ok := false; !ok; ok = extra25519.ScalarBaseMult((*[32]byte)(sk.pk), sk.ur, &sk.sk) {
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if _, err := io.ReadFull(random, sk.sk[:]); err != nil {
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var pk, sk, ur [32]byte
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for ok := false; !ok; ok = extra25519.ScalarBaseMult(&pk, &ur, &sk) {
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if _, err := io.ReadFull(random, sk[:]); err != nil {
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return nil, err
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}
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}
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return sk, nil
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k := new(SecretKey)
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k.sk = sk[:]
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k.pk = pk[:]
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k.ur = ur[:]
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return k, nil
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}
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// RepresentativeToPublicKey converts a uniform representative to a curve25519 public key.
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func RepresentativeToPublicKey(publicKey, representative *[32]byte) {
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extra25519.RepresentativeToPublicKey(publicKey, representative)
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// UniformRepresentative is the type of Curve25519 public key uniform representatives.
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// See https://www.imperialviolet.org/2013/12/25/elligator.html
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type UniformRepresentative []byte
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// Public returns the curve25519 public key corresponding to the uniform presentative.
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func (u UniformRepresentative) Public() PublicKey {
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var pk, ur [32]byte
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copy(ur[:], u)
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extra25519.RepresentativeToPublicKey(&pk, &ur)
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return pk[:]
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}
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// PublicKey is the type of Curve25519 public keys.
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type PublicKey []byte
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