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package stfe
import (
"fmt"
"crypto/x509"
"encoding/base64"
"github.com/google/certificate-transparency-go/tls"
"github.com/google/trillian"
)
// StFormat defines a particular StItem type that is versioned
type StFormat tls.Enum
const (
StFormatReserved StFormat = 0
StFormatSignedTreeHeadV1 StFormat = 1
StFormatSignedDebugInfoV1 StFormat = 2
StFormatConsistencyProofV1 StFormat = 3
StFormatInclusionProofV1 StFormat = 4
StFormatChecksumV1 = 5
)
// StItem references a versioned item based on a given format specifier.
type StItem struct {
Format StFormat `tls:"maxval:65535"`
SignedDebugInfoV1 *SignedDebugInfoV1 `tls:"selector:Format,val:2"`
InclusionProofV1 *InclusionProofV1 `tls:"selector:Format,val:4"`
ChecksumV1 *ChecksumV1 `tls:"selector:Format,val:5"`
// TODO: add more items
}
// ChecksumV1 associates a package name with an arbitrary checksum value
type ChecksumV1 struct {
Package []byte `tls:"minlen:0,maxlen:255"`
Checksum []byte `tls:"minlen:32,maxlen:255"`
}
// InclusionProofV1 is a Merkle tree inclusion proof, see RFC 6962/bis (§4.12)
type InclusionProofV1 struct {
LogID []byte `tls:"minlen:2,maxlen:127"`
TreeSize uint64
LeafIndex uint64
InclusionPath []NodeHash `tls:"minlen:1,maxlen:65535"`
}
// SignedDebugInfoV1 is a signed statement that we intend (but do not promise)
// to insert an entry into the log. Only Ed25519 signatures are supported.
// TODO: double-check that crypto/ed25519 encodes signature as in RFC 8032
// TODO: need to think about signature format, then update markdown/api.md
type SignedDebugInfoV1 struct {
LogId []byte `tls:"minlen:32,maxlen:127"`
Message []byte `tls:"minlen:0,maxlen:65535"`
Signature []byte `tls:"minlen:0,maxlen:65535"` // defined in RFC 8032
}
// NodeHash is a hashed Merkle tree node, see RFC 6962/bis (§4.9)
type NodeHash struct {
Data []byte `tls:"minlen:32,maxlen:255"`
}
func NewSignedDebugInfoV1(logId, message, signature []byte) StItem {
return StItem{
Format: StFormatSignedDebugInfoV1,
SignedDebugInfoV1: &SignedDebugInfoV1{
LogId: logId,
Message: message,
Signature: signature,
},
}
}
// NewChecksumV1 creates a new StItem of type checksum_v1
func NewChecksumV1(identifier []byte, checksum []byte) StItem {
return StItem{
Format: StFormatChecksumV1,
ChecksumV1: &ChecksumV1{
Package: identifier,
Checksum: checksum,
},
}
}
// NewInclusionProofV1 creates a new StItem of type inclusion_proof_v1
func NewInclusionProofV1(logID []byte, treeSize uint64, proof *trillian.Proof) StItem {
inclusionPath := make([]NodeHash, 0, len(proof.Hashes))
for _, hash := range proof.Hashes {
inclusionPath = append(inclusionPath, NodeHash{Data: hash})
}
return StItem{
Format: StFormatInclusionProofV1,
InclusionProofV1: &InclusionProofV1{
LogID: logID,
TreeSize: treeSize,
LeafIndex: uint64(proof.LeafIndex),
InclusionPath: inclusionPath,
},
}
}
func (f StFormat) String() string {
switch f {
case StFormatReserved:
return "reserved"
case StFormatSignedTreeHeadV1:
return "signed_tree_head_v1"
case StFormatSignedDebugInfoV1:
return "signed_debug_info_v1"
case StFormatConsistencyProofV1:
return "consistency_proof_v1"
case StFormatInclusionProofV1:
return "inclusion_proof_v1"
case StFormatChecksumV1:
return "checksum_v1"
default:
return fmt.Sprintf("Unknown StFormat: %d", f)
}
}
func (i StItem) String() string {
switch i.Format {
case StFormatChecksumV1:
return fmt.Sprintf("Format(%s): %s", i.Format, *i.ChecksumV1)
case StFormatInclusionProofV1:
return fmt.Sprintf("Format(%s): %s", i.Format, *i.InclusionProofV1)
case StFormatSignedDebugInfoV1:
return fmt.Sprintf("Format(%s): %s", i.Format, *i.SignedDebugInfoV1)
default:
return fmt.Sprintf("unknown StItem: %s", i.Format)
}
}
func (i SignedDebugInfoV1) String() string {
return fmt.Sprintf("LogId(%s) Message(%s) Signature(%s)", base64.StdEncoding.EncodeToString(i.LogId), string(i.Message), base64.StdEncoding.EncodeToString(i.Signature))
}
func (i ChecksumV1) String() string {
return fmt.Sprintf("Package(%v) Checksum(%v)", string(i.Package), base64.StdEncoding.EncodeToString(i.Checksum))
}
func (i InclusionProofV1) String() string {
path := make([]string, 0, len(i.InclusionPath))
for _, hash := range i.InclusionPath {
path = append(path, base64.StdEncoding.EncodeToString(hash.Data))
}
return fmt.Sprintf("LogID(%s) TreeSize(%d) LeafIndex(%d) AuditPath(%v)", base64.StdEncoding.EncodeToString(i.LogID), i.TreeSize, i.LeafIndex, path)
}
// StItemFromB64 creates an StItem from a serialized and base64-encoded string
func StItemFromB64(s string) (StItem, error) {
b, err := base64.StdEncoding.DecodeString(s)
if err != nil {
return StItem{}, fmt.Errorf("base64 decoding failed: %v", err)
}
var item StItem
extra, err := tls.Unmarshal(b, &item)
if err != nil {
return StItem{}, fmt.Errorf("tls unmarshal failed: %v", err)
} else if len(extra) > 0 {
return StItem{}, fmt.Errorf("tls unmarshal found extra data: %v", extra)
}
return item, nil
}
// Appendix is extra data that Trillian can store about a leaf
type Appendix struct {
Signature []byte `tls:"minlen:0,maxlen:16383"`
Chain []RawCertificate `tls:"minlen:0,maxlen:65535"`
}
// RawCertificate is a serialized X.509 certificate
type RawCertificate struct {
Data []byte `tls:"minlen:0,maxlen:65535"`
}
// NewAppendix creates a new leaf Appendix for an X.509 chain and signature
func NewAppendix(x509Chain []*x509.Certificate, signature []byte) Appendix {
chain := make([]RawCertificate, 0, 2) // TODO: base length on config param
for _, c := range x509Chain {
chain = append(chain, RawCertificate{c.Raw})
}
return Appendix{Signature: signature, Chain: chain}
}
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