114 lines
3.8 KiB
Go
114 lines
3.8 KiB
Go
package signed
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// The Sign function is a choke point for all code paths that do signing.
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// We use this fact to do key ID translation. There are 2 types of key ID:
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// - Scoped: the key ID based purely on the data that appears in the TUF
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// files. This may be wrapped by a certificate that scopes the
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// key to be used in a specific context.
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// - Canonical: the key ID based purely on the public key bytes. This is
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// used by keystores to easily identify keys that may be reused
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// in many scoped locations.
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// Currently these types only differ in the context of Root Keys in Notary
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// for which the root key is wrapped using an x509 certificate.
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import (
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"crypto/rand"
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"github.com/sirupsen/logrus"
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"github.com/theupdateframework/notary/trustmanager"
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"github.com/theupdateframework/notary/tuf/data"
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"github.com/theupdateframework/notary/tuf/utils"
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)
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// Sign takes a data.Signed and a cryptoservice containing private keys,
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// calculates and adds at least minSignature signatures using signingKeys the
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// data.Signed. It will also clean up any signatures that are not in produced
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// by either a signingKey or an otherWhitelistedKey.
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// Note that in most cases, otherWhitelistedKeys should probably be null. They
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// are for keys you don't want to sign with, but you also don't want to remove
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// existing signatures by those keys. For instance, if you want to call Sign
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// multiple times with different sets of signing keys without undoing removing
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// signatures produced by the previous call to Sign.
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func Sign(service CryptoService, s *data.Signed, signingKeys []data.PublicKey,
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minSignatures int, otherWhitelistedKeys []data.PublicKey) error {
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logrus.Debugf("sign called with %d/%d required keys", minSignatures, len(signingKeys))
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signatures := make([]data.Signature, 0, len(s.Signatures)+1)
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signingKeyIDs := make(map[string]struct{})
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tufIDs := make(map[string]data.PublicKey)
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privKeys := make(map[string]data.PrivateKey)
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// Get all the private key objects related to the public keys
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missingKeyIDs := []string{}
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for _, key := range signingKeys {
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canonicalID, err := utils.CanonicalKeyID(key)
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tufIDs[key.ID()] = key
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if err != nil {
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return err
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}
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k, _, err := service.GetPrivateKey(canonicalID)
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if err != nil {
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if _, ok := err.(trustmanager.ErrKeyNotFound); ok {
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missingKeyIDs = append(missingKeyIDs, canonicalID)
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continue
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}
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return err
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}
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privKeys[key.ID()] = k
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}
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// include the list of otherWhitelistedKeys
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for _, key := range otherWhitelistedKeys {
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if _, ok := tufIDs[key.ID()]; !ok {
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tufIDs[key.ID()] = key
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}
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}
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// Check to ensure we have enough signing keys
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if len(privKeys) < minSignatures {
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return ErrInsufficientSignatures{FoundKeys: len(privKeys),
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NeededKeys: minSignatures, MissingKeyIDs: missingKeyIDs}
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}
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emptyStruct := struct{}{}
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// Do signing and generate list of signatures
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for keyID, pk := range privKeys {
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sig, err := pk.Sign(rand.Reader, *s.Signed, nil)
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if err != nil {
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logrus.Debugf("Failed to sign with key: %s. Reason: %v", keyID, err)
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return err
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}
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signingKeyIDs[keyID] = emptyStruct
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signatures = append(signatures, data.Signature{
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KeyID: keyID,
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Method: pk.SignatureAlgorithm(),
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Signature: sig[:],
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})
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}
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for _, sig := range s.Signatures {
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if _, ok := signingKeyIDs[sig.KeyID]; ok {
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// key is in the set of key IDs for which a signature has been created
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continue
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}
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var (
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k data.PublicKey
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ok bool
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)
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if k, ok = tufIDs[sig.KeyID]; !ok {
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// key is no longer a valid signing key
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continue
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}
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if err := VerifySignature(*s.Signed, &sig, k); err != nil {
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// signature is no longer valid
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continue
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}
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// keep any signatures that still represent valid keys and are
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// themselves valid
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signatures = append(signatures, sig)
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}
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s.Signatures = signatures
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return nil
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}
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