128 lines
3.4 KiB
Go
128 lines
3.4 KiB
Go
package sharedsecret
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import (
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"bytes"
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"crypto/ecdsa"
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"database/sql"
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"errors"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/ecies"
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"go.uber.org/zap"
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)
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const sskLen = 16
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type Secret struct {
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Identity *ecdsa.PublicKey
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Key []byte
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}
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// SharedSecret generates and manages negotiated secrets.
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// Identities (public keys) stored by SharedSecret
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// are compressed.
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// TODO: make it a part of sqlitePersistence instead of SharedSecret.
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type SharedSecret struct {
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persistence *sqlitePersistence
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logger *zap.Logger
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}
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func New(db *sql.DB, logger *zap.Logger) *SharedSecret {
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if logger == nil {
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logger = zap.NewNop()
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}
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return &SharedSecret{
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persistence: newSQLitePersistence(db),
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logger: logger.With(zap.Namespace("SharedSecret")),
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}
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}
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func (s *SharedSecret) generate(myPrivateKey *ecdsa.PrivateKey, theirPublicKey *ecdsa.PublicKey, installationID string) (*Secret, error) {
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sharedKey, err := ecies.ImportECDSA(myPrivateKey).GenerateShared(
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ecies.ImportECDSAPublic(theirPublicKey),
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sskLen,
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sskLen,
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)
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if err != nil {
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return nil, err
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}
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logger := s.logger.With(zap.String("site", "generate"))
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logger.Debug(
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"saving a shared key",
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zap.Binary("their-public-key", crypto.FromECDSAPub(theirPublicKey)),
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zap.String("installation-id", installationID),
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)
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theirIdentity := crypto.CompressPubkey(theirPublicKey)
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if err = s.persistence.Add(theirIdentity, sharedKey, installationID); err != nil {
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return nil, err
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}
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return &Secret{Key: sharedKey, Identity: theirPublicKey}, err
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}
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// Generate will generate a shared secret for a given identity, and return it.
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func (s *SharedSecret) Generate(myPrivateKey *ecdsa.PrivateKey, theirPublicKey *ecdsa.PublicKey, installationID string) (*Secret, error) {
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return s.generate(myPrivateKey, theirPublicKey, installationID)
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}
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// Agreed returns true if a secret has been acknowledged by all the installationIDs.
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func (s *SharedSecret) Agreed(myPrivateKey *ecdsa.PrivateKey, myInstallationID string, theirPublicKey *ecdsa.PublicKey, theirInstallationIDs []string) (*Secret, bool, error) {
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logger := s.logger.With(zap.String("site", "Agreed"))
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logger.Debug(
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"checking if shared secret is acknowledged",
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zap.Binary("their-public-key", crypto.FromECDSAPub(theirPublicKey)),
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zap.Strings("their-installation-ids", theirInstallationIDs),
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)
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secret, err := s.generate(myPrivateKey, theirPublicKey, myInstallationID)
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if err != nil {
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return nil, false, err
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}
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if len(theirInstallationIDs) == 0 {
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return secret, false, nil
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}
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theirIdentity := crypto.CompressPubkey(theirPublicKey)
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response, err := s.persistence.Get(theirIdentity, theirInstallationIDs)
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if err != nil {
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return nil, false, err
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}
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for _, installationID := range theirInstallationIDs {
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if !response.installationIDs[installationID] {
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logger.Debug("no shared secret for installation", zap.String("installation-id", installationID))
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return secret, false, nil
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}
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}
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if !bytes.Equal(secret.Key, response.secret) {
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return nil, false, errors.New("computed and saved secrets are different for a given identity")
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}
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return secret, true, nil
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}
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func (s *SharedSecret) All() ([]*Secret, error) {
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var secrets []*Secret
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tuples, err := s.persistence.All()
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if err != nil {
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return nil, err
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}
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for _, tuple := range tuples {
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key, err := crypto.DecompressPubkey(tuple[0])
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if err != nil {
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return nil, err
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}
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secrets = append(secrets, &Secret{Identity: key, Key: tuple[1]})
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}
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return secrets, nil
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}
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