87 lines
2.3 KiB
Go
87 lines
2.3 KiB
Go
package lafsession
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import (
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"crypto/ed25519"
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"crypto/rand"
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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)
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// Identity is a long-term Ed25519 key pair used for mutual authentication.
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type Identity struct {
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Private ed25519.PrivateKey
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Public ed25519.PublicKey
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}
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// GenerateIdentity creates a new random identity key pair.
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func GenerateIdentity() (*Identity, error) {
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pub, priv, err := ed25519.GenerateKey(rand.Reader)
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if err != nil {
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return nil, err
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}
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return &Identity{Private: priv, Public: pub}, nil
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}
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// IdentityFromSeed derives an identity from a 32-byte seed (deterministic).
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func IdentityFromSeed(seed []byte) (*Identity, error) {
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if len(seed) != ed25519.SeedSize {
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return nil, fmt.Errorf("lafsession: seed must be %d bytes", ed25519.SeedSize)
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}
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priv := ed25519.NewKeyFromSeed(seed)
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return &Identity{Private: priv, Public: priv.Public().(ed25519.PublicKey)}, nil
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}
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// PublicBytes returns the 32-byte public key.
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func (id *Identity) PublicBytes() []byte {
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return append([]byte(nil), id.Public...)
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}
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// Fingerprint returns a SHA-256 hex fingerprint of the public key (full 32 bytes hex).
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func (id *Identity) Fingerprint() string {
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sum := sha256.Sum256(id.Public)
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return hex.EncodeToString(sum[:])
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}
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// ShortFingerprint returns the first 20 bytes of SHA-256 as spaced hex groups (display).
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func (id *Identity) ShortFingerprint() string {
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sum := sha256.Sum256(id.Public)
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h := hex.EncodeToString(sum[:20])
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out := make([]byte, 0, 24+5)
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for i := 0; i < len(h); i += 4 {
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if i > 0 {
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out = append(out, ' ')
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}
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end := i + 4
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if end > len(h) {
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end = len(h)
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}
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out = append(out, h[i:end]...)
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}
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return string(out)
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}
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// Sign signs a transcript with the identity private key.
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func (id *Identity) Sign(msg []byte) []byte {
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return ed25519.Sign(id.Private, msg)
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}
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// Verify checks a signature under this identity public key.
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func (id *Identity) Verify(msg, sig []byte) bool {
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return ed25519.Verify(id.Public, msg, sig)
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}
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// VerifyPeer checks a signature under an arbitrary peer public key.
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func VerifyPeer(peerPub, msg, sig []byte) bool {
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if len(peerPub) != ed25519.PublicKeySize {
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return false
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}
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return ed25519.Verify(ed25519.PublicKey(peerPub), msg, sig)
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}
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// FingerprintOf returns SHA-256 hex of a raw public key.
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func FingerprintOf(pub []byte) string {
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sum := sha256.Sum256(pub)
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return hex.EncodeToString(sum[:])
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}
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