Niko Marmeladkov
9d66003689
- server: relay storing signed objects (PUT/GET), per-IP rate limiting, per-subject quota (1000), one-response-per-request, pagination, /v1/healthz /v1/readyz /v1/metrics - verify: signature-verifying trust evaluator; every object is checked via env.Verify(), approvals via VerifyApprovalResponse, revocations via VerifyRevocationOf; k-of-n approval quorum - docs: TRUST-MODEL.md and API.md describing issuer-anchored signatures and the endpoint/status-code contract - tests: server, verify, and ratelimit packages
94 lines
2.4 KiB
Go
94 lines
2.4 KiB
Go
package tce
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import (
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"crypto/sha256"
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"crypto/subtle"
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"encoding/hex"
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"errors"
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)
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// ID is the content address of a TCE object: SHA-256 over its canonical
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// bytes.
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//
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// ID is a distinct type rather than a []byte so that a hash cannot be passed
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// where a message is expected. Nothing in the tree signs or verifies an ID:
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// the signature covers the TCE bytes, and the ID exists only to name and
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// reference the object (see docs/IMPLEMENTATION_NOTES.md property 1).
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type ID [HashSize]byte
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// ErrBadID is returned when a hex string is not a valid object ID.
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var ErrBadID = errors.New("tce: malformed object id")
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// ComputeID returns the content address of the given canonical bytes.
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func ComputeID(tceBytes []byte) ID {
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return ID(sha256.Sum256(tceBytes))
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}
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// ParseID decodes a lowercase hex object ID.
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func ParseID(s string) (ID, error) {
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var id ID
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if len(s) != HashSize*2 {
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return id, ErrBadID
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}
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// Reject uppercase so that one ID has one textual form.
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for i := 0; i < len(s); i++ {
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c := s[i]
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if !(c >= '0' && c <= '9' || c >= 'a' && c <= 'f') {
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return id, ErrBadID
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}
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}
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b, err := hex.DecodeString(s)
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if err != nil {
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return id, ErrBadID
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}
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copy(id[:], b)
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return id, nil
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}
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// IDFromBytes builds an ID from exactly 32 bytes.
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func IDFromBytes(b []byte) (ID, error) {
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var id ID
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if len(b) != HashSize {
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return id, ErrBadID
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}
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copy(id[:], b)
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return id, nil
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}
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// String renders the ID as lowercase hex.
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func (id ID) String() string { return hex.EncodeToString(id[:]) }
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// Bytes returns a copy of the raw hash.
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func (id ID) Bytes() []byte {
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out := make([]byte, HashSize)
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copy(out, id[:])
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return out
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}
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// Equal compares two IDs in constant time.
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//
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// The comparison is not obviously timing-sensitive, but the analysis needed to
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// prove any individual case safe is not worth repeating, and the cost is
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// negligible.
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func (id ID) Equal(other ID) bool {
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return subtle.ConstantTimeCompare(id[:], other[:]) == 1
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}
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// IsZero reports whether the ID is unset.
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func (id ID) IsZero() bool {
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var zero ID
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return subtle.ConstantTimeCompare(id[:], zero[:]) == 1
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}
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// MarshalText implements encoding.TextMarshaler.
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func (id ID) MarshalText() ([]byte, error) { return []byte(id.String()), nil }
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// UnmarshalText implements encoding.TextUnmarshaler.
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func (id *ID) UnmarshalText(b []byte) error {
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parsed, err := ParseID(string(b))
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if err != nil {
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return err
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}
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*id = parsed
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return nil
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}
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