diff --git a/pkg/rekor/rekor.go b/pkg/rekor/rekor.go index d6bcdaa3..17bc903c 100644 --- a/pkg/rekor/rekor.go +++ b/pkg/rekor/rekor.go @@ -25,7 +25,6 @@ import ( "encoding/pem" "errors" "fmt" - "strings" "github.com/go-openapi/runtime" "github.com/go-openapi/strfmt" @@ -110,12 +109,16 @@ func (c *Client) WriteMessage(ctx context.Context, message, signature []byte, ce } func (c *Client) get(ctx context.Context, data []byte, cert *x509.Certificate) (*models.LogEntryAnon, error) { + h := sha256.New() + h.Write(data) + hash := hex.EncodeToString(h.Sum(nil)) + pem, err := cryptoutils.MarshalCertificateToPEM(cert) if err != nil { return nil, err } - uuids, err := c.findTLogEntriesByPayloadAndPK(ctx, data, pem) + uuids, err := c.findTLogEntriesByPK(ctx, pem) if err != nil { return nil, err } @@ -132,13 +135,20 @@ func (c *Client) get(ctx context.Context, data []byte, cert *x509.Certificate) ( return nil, err } - // Verify that the cert used in the tlog matches the cert - // used to sign the data. - tlogCerts, err := extractCerts(e) + // Extract the hash of payload the entry is for + // and its certificates + entryHash, tlogCerts, err := extractData(e) if err != nil { fmt.Println("could not extract cert", err) continue } + if entryHash != hash { + fmt.Println("hashes don't match") + continue + } + + // Verify that the cert used in the tlog matches the cert + // used to sign the data. for _, c := range tlogCerts { if cert.Equal(c) { return e, nil @@ -149,16 +159,14 @@ func (c *Client) get(ctx context.Context, data []byte, cert *x509.Certificate) ( return nil, errors.New("could not find matching tlog entry") } -// findTLogEntriesByPayloadAndPK is roughly equivalent to cosign.FindTLogEntriesByPayload, -// but also filters by the public key used. -func (c *Client) findTLogEntriesByPayloadAndPK(ctx context.Context, payload, pubKey []byte) (uuids []string, err error) { +// findTLogEntriesByPK is roughly equivalent to cosign.FindTLogEntriesByPayload, +// but only filters by the public key used. Earlier, this filtered on both the +// payload and the public key, but returned uuids of entries that matched +// either. +func (c *Client) findTLogEntriesByPK(ctx context.Context, pubKey []byte) (uuids []string, err error) { params := index.NewSearchIndexParamsWithContext(ctx) params.Query = &models.SearchIndex{} - h := sha256.New() - h.Write(payload) - params.Query.Hash = fmt.Sprintf("sha256:%s", strings.ToLower(hex.EncodeToString(h.Sum(nil)))) - params.Query.PublicKey = &models.SearchIndexPublicKey{ Content: strfmt.Base64(pubKey), Format: swag.String(models.SearchIndexPublicKeyFormatX509), @@ -188,55 +196,60 @@ func (c *Client) Verify(ctx context.Context, commitSHA string, cert *x509.Certif return e, cosign.VerifyTLogEntryOffline(ctx, e, c.publicKeys) } -// extractCerts is taken from cosign's cmd/cosign/cli/verify/verify_blob.go. +// extractData extracts the data hash and certs from a given LogEntryAnon. // TODO: Refactor this into a shared lib. -func extractCerts(e *models.LogEntryAnon) ([]*x509.Certificate, error) { +func extractData(e *models.LogEntryAnon) (string, []*x509.Certificate, error) { b, err := base64.StdEncoding.DecodeString(e.Body.(string)) if err != nil { - return nil, err + return "", nil, err } pe, err := models.UnmarshalProposedEntry(bytes.NewReader(b), runtime.JSONConsumer()) if err != nil { - return nil, err + return "", nil, err } eimpl, err := types.CreateVersionedEntry(pe) if err != nil { - return nil, err + return "", nil, err } - var publicKeyB64 []byte + var ( + publicKeyB64 []byte + entryHash string + ) switch e := eimpl.(type) { case *rekord_v001.V001Entry: + entryHash = *e.RekordObj.Data.Hash.Value publicKeyB64, err = e.RekordObj.Signature.PublicKey.Content.MarshalText() if err != nil { - return nil, err + return "", nil, err } case *hashedrekord_v001.V001Entry: + entryHash = *e.HashedRekordObj.Data.Hash.Value publicKeyB64, err = e.HashedRekordObj.Signature.PublicKey.Content.MarshalText() if err != nil { - return nil, err + return "", nil, err } default: - return nil, errors.New("unexpected tlog entry type") + return "", nil, errors.New("unexpected tlog entry type") } publicKey, err := base64.StdEncoding.DecodeString(string(publicKeyB64)) if err != nil { - return nil, err + return "", nil, err } certs, err := cryptoutils.UnmarshalCertificatesFromPEM(publicKey) if err != nil { - return nil, err + return "", nil, err } if len(certs) == 0 { - return nil, errors.New("no certs found in pem tlog") + return "", nil, errors.New("no certs found in pem tlog") } - return certs, err + return entryHash, certs, err } func (c *Client) PublicKeys() *cosign.TrustedTransparencyLogPubKeys {