package types import ( "crypto" "crypto/ed25519" "encoding/binary" "fmt" "io" "git.sigsum.org/sigsum-go/pkg/ascii" ) type Statement struct { ShardHint uint64 `ascii:"shard_hint"` Checksum Hash `ascii:"checksum"` } type Leaf struct { Statement Signature Signature `ascii:"signature"` KeyHash Hash `ascii:"key_hash"` } type Leaves []Leaf func (s *Statement) ToBinary() []byte { namespace := fmt.Sprintf("tree_leaf:v0:%d@sigsum.org", s.ShardHint) b := make([]byte, 6+4+len(namespace)+4+0+4+6+4+HashSize) copy(b[0:6], "SSHSIG") i := 6 i += putSSHString(b[i:], namespace) i += putSSHString(b[i:], "") i += putSSHString(b[i:], "sha256") i += putSSHString(b[i:], string(s.Checksum[:])) return b } func (s *Statement) Sign(signer crypto.Signer) (*Signature, error) { sig, err := signer.Sign(nil, s.ToBinary(), crypto.Hash(0)) if err != nil { return nil, fmt.Errorf("types: failed signing statement") } var signature Signature copy(signature[:], sig) return &signature, nil } func (s *Statement) Verify(key *PublicKey, sig *Signature) bool { return ed25519.Verify(ed25519.PublicKey(key[:]), s.ToBinary(), sig[:]) } func (l *Leaf) ToBinary() []byte { b := make([]byte, 136) binary.BigEndian.PutUint64(b[0:8], l.ShardHint) copy(b[8:40], l.Checksum[:]) copy(b[40:104], l.Signature[:]) copy(b[104:136], l.KeyHash[:]) return b } func (l *Leaf) FromBinary(b []byte) error { if len(b) != 136 { return fmt.Errorf("types: invalid leaf size: %d", len(b)) } l.ShardHint = binary.BigEndian.Uint64(b[0:8]) copy(l.Checksum[:], b[8:40]) copy(l.Signature[:], b[40:104]) copy(l.KeyHash[:], b[104:136]) return nil } func (l *Leaf) ToASCII(w io.Writer) error { return ascii.StdEncoding.Serialize(w, l) } func (l *Leaf) FromASCII(r io.Reader) error { return ascii.StdEncoding.Deserialize(r, l) } func (l *Leaves) FromASCII(r io.Reader) error { leaves := &struct { ShardHint []uint64 `ascii:"shard_hint"` Checksum []Hash `ascii:"checksum"` Signature []Signature `ascii:"signature"` KeyHash []Hash `ascii:"key_hash"` }{} if err := ascii.StdEncoding.Deserialize(r, leaves); err != nil { return err } n := len(leaves.ShardHint) if n != len(leaves.Checksum) { return fmt.Errorf("types: mismatched leaf field counts") } if n != len(leaves.Signature) { return fmt.Errorf("types: mismatched leaf field counts") } if n != len(leaves.KeyHash) { return fmt.Errorf("types: mismatched leaf field counts") } *l = make([]Leaf, 0, n) for i := 0; i < n; i++ { *l = append(*l, Leaf{ Statement: Statement{ ShardHint: leaves.ShardHint[i], Checksum: leaves.Checksum[i], }, Signature: leaves.Signature[i], KeyHash: leaves.KeyHash[i], }) } return nil }