Implement handling of COSE_KeySet and TTL payload #42
There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -18,6 +18,9 @@ import ( | |
| "time" | ||
|
|
||
| "github.com/Microsoft/cosesign1go/pkg/cosesign1" | ||
| "github.com/fxamacker/cbor/v2" | ||
| "github.com/pkg/errors" | ||
| "github.com/veraison/go-cose" | ||
| ) | ||
|
|
||
| // jwk is a minimal JSON Web Key representation used to parse CCF transparency | ||
|
|
@@ -103,14 +106,19 @@ func validateIssuerForJWKSFetch(issuer string, allowedDomains []string) (string, | |
| // error aborts the connection. | ||
| type CertVerifier func(issuer string, cert *x509.Certificate) error | ||
|
|
||
| type kidWithParsedKey struct { | ||
| Kid string | ||
| Key crypto.PublicKey | ||
| } | ||
|
|
||
| // fetchIssuerJWKS GETs https://<issuer>/jwks and returns the keys keyed by | ||
| // their `kid` as either a map or a list. If verifyCert is not nil, the leaf | ||
| // certificate presented by the server is passed to verifyCert. The issuer host | ||
| // is validated against allowedDomains before any network request is made. | ||
| func fetchIssuerJWKS(issuer string, allowedDomains []string, verifyCert CertVerifier) (outMap map[string]crypto.PublicKey, outList []kidWithParsedKey, err error) { | ||
|
There was a problem hiding this comment. Recent versions of scitt-ccf-ledger implement .well-known/scitt-key, as well as /jwks. It would be good to check if that's rolled out already or when it is, to switch to it, because:
Member
Author
There was a problem hiding this comment.
|
||
| host, err := validateIssuerForJWKSFetch(issuer, allowedDomains) | ||
| if err != nil { | ||
| return nil, nil, err | ||
| } | ||
| reqURL := (&url.URL{Scheme: "https", Host: host, Path: "/jwks"}).String() | ||
| tlsConfig := &tls.Config{InsecureSkipVerify: true} //nolint:gosec // CCF uses self-signed certs that are supposed to be validated via attestation, and so will never pass the normal verification. | ||
|
|
@@ -135,51 +143,81 @@ func fetchIssuerJWKS(issuer string, allowedDomains []string, verifyCert CertVeri | |
| } | ||
| resp, err := client.Get(reqURL) | ||
| if err != nil { | ||
| return nil, nil, fmt.Errorf("GET %s: %w", reqURL, err) | ||
| } | ||
| defer resp.Body.Close() | ||
| if resp.StatusCode != http.StatusOK { | ||
| return nil, nil, fmt.Errorf("GET %s: status %d", reqURL, resp.StatusCode) | ||
| } | ||
| // Limit the response body to a sane size to avoid excessive memory usage | ||
| // from a hostile or misconfigured server. | ||
| const maxJWKSBytes = 1 << 20 // 1 MiB | ||
| body, err := io.ReadAll(io.LimitReader(resp.Body, maxJWKSBytes+1)) | ||
| if err != nil { | ||
| return nil, nil, fmt.Errorf("reading %s: %w", reqURL, err) | ||
| } | ||
| if int64(len(body)) > maxJWKSBytes { | ||
| return nil, nil, fmt.Errorf("reading %s: response exceeds %d bytes", reqURL, maxJWKSBytes) | ||
| } | ||
| var set jwkSet | ||
| if err := json.Unmarshal(body, &set); err != nil { | ||
| return nil, nil, fmt.Errorf("parsing %s: %w", reqURL, err) | ||
| } | ||
| outMap = make(map[string]crypto.PublicKey, len(set.Keys)) | ||
| outList = make([]kidWithParsedKey, 0, len(set.Keys)) | ||
| for i, k := range set.Keys { | ||
| pub, err := jwkToPublicKey(k) | ||
| if err != nil { | ||
| return nil, nil, fmt.Errorf("key %d (kid=%s): %w", i, k.Kid, err) | ||
| } | ||
| if existingKey, exists := outMap[k.Kid]; exists { | ||
| // Equal is implemented for all crypto.PublicKey types in std | ||
| eq, ok := existingKey.(interface{ Equal(crypto.PublicKey) bool }) | ||
| if !ok || !eq.Equal(pub) { | ||
| return nil, nil, fmt.Errorf("conflicting kid %s seen in JWKS from %s", k.Kid, reqURL) | ||
| } | ||
| continue | ||
| } | ||
| outMap[k.Kid] = pub | ||
| outList = append(outList, kidWithParsedKey{Kid: k.Kid, Key: pub}) | ||
| } | ||
| return outMap, outList, nil | ||
| } | ||
|
|
||
| // Encodes a list of fetched keys into a COSE_KeySet. | ||
| func encodeKeySet(keys []kidWithParsedKey) ([]byte, error) { | ||
| if len(keys) == 0 { | ||
| return nil, errors.New("empty keys list") | ||
| } | ||
| rawKeys := make([]cbor.RawMessage, 0, len(keys)) | ||
| for _, kidWithKey := range keys { | ||
| kid := kidWithKey.Kid | ||
| pk := kidWithKey.Key | ||
| k, err := cose.NewKeyFromPublic(pk) | ||
| if err != nil { | ||
| return nil, errors.Wrapf(err, "construct cose.Key for key ID %q", kid) | ||
| } | ||
| k.ID = []byte(kid) | ||
| raw, err := k.MarshalCBOR() | ||
| if err != nil { | ||
| return nil, errors.Wrapf(err, "MarshalCBOR for key ID %q", kid) | ||
| } | ||
| rawKeys = append(rawKeys, raw) | ||
| } | ||
| data, err := cbor.Marshal(rawKeys) | ||
| if err != nil { | ||
| return nil, errors.Wrap(err, "Failed to encode the COSE_KeySet") | ||
| } | ||
| return data, nil | ||
| } | ||
|
|
||
| // fetchCCFReceiptKeys returns a kid->PublicKey map by fetching the JWKS for | ||
| // each unique receipt issuer. allowedDomains is the list of domains that | ||
| // receipt issuers must match (equal or subdomain) before any network request | ||
| // is made. If a receipt's issuer is present in preloaded, the supplied keys are | ||
| // used for that issuer instead of fetching its JWKS over the network. If not | ||
| // nil, verifyCert is invoked with the leaf certificate presented by each issuer. | ||
| func fetchCCFReceiptKeys(receipts []cosesign1.ParsedCOSEReceipt, allowedDomains []string, preloaded map[string]map[string]crypto.PublicKey, verifyCert CertVerifier) (map[string]crypto.PublicKey, error) { | ||
| seen := map[string]bool{} | ||
| keys := map[string]crypto.PublicKey{} | ||
| for _, r := range receipts { | ||
|
|
@@ -190,9 +228,15 @@ func fetchCCFReceiptKeys(receipts []cosesign1.ParsedCOSEReceipt, allowedDomains | |
| continue | ||
| } | ||
| seen[r.Issuer] = true | ||
| var issuerKeys map[string]crypto.PublicKey | ||
| if preloadedKeys, ok := preloaded[r.Issuer]; ok { | ||
| issuerKeys = preloadedKeys | ||
| } else { | ||
| var err error | ||
| issuerKeys, _, err = fetchIssuerJWKS(r.Issuer, allowedDomains, verifyCert) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| } | ||
| for kid, k := range issuerKeys { | ||
| if _, exists := keys[kid]; exists { | ||
|
|
||
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
It's unfortunate there is not a go version of EverCBOR, I wonder if it's worth bringing up with Tahina?