1 files changed, 73 insertions, 0 deletions
diff --git a/types/types.go b/types/types.go
new file mode 100644
index 0000000..483dac0
--- /dev/null
+++ b/types/types.go
@@ -0,0 +1,73 @@
+package types
+
+import (
+	"crypto/ed25519"
+	"crypto/sha256"
+)
+
+const (
+	HashSize      = sha256.Size
+	SignatureSize = ed25519.SignatureSize
+)
+
+// Leaf is the log's Merkle tree leaf.
+//
+// Ref: https://github.com/system-transparency/stfe/blob/design/doc/api.md#merkle-tree-leaf
+type Leaf struct {
+	Message
+	SigIdent
+}
+
+// Message is composed of a shard hint and a checksum.  The submitter selects
+// these values to fit the log's shard interval and the opaque data in question.
+type Message struct {
+	ShardHint uint64
+	Checksum  [HashSize]byte
+}
+
+// SigIdent is composed of a signature-signer pair.  The signature is computed
+// over the Trunnel-serialized leaf message.  KeyHash identifies the signer.
+type SigIdent struct {
+	Signature [SignatureSize]byte
+	KeyHash   [HashSize]byte
+}
+
+// SignedTreeHead is composed of a tree head and a list of signature-signer
+// pairs.  Each signature is computed over the Trunnel-serialized tree head.
+//
+// Ref: https://github.com/system-transparency/stfe/blob/design/doc/api.md#get-tree-head-cosigned
+// Ref: https://github.com/system-transparency/stfe/blob/design/doc/api.md#get-tree-head-to-sign
+// Ref: https://github.com/system-transparency/stfe/blob/design/doc/api.md#get-tree-head-latest
+type SignedTreeHead struct {
+	TreeHead
+	SigIdent []SigIdent
+}
+
+// TreeHead is the log's tree head.
+//
+// Ref: https://github.com/system-transparency/stfe/blob/design/doc/api.md#merkle-tree-head
+type TreeHead struct {
+	Timestamp uint64
+	TreeSize  uint64
+	RootHash  [HashSize]byte
+}
+
+// ConsistencyProof is a consistency proof that proves the log's append-only
+// property.
+//
+// Ref: https://github.com/system-transparency/stfe/blob/design/doc/api.md#get-consistency-proof
+type ConsistencyProof struct {
+	NewSize uint64
+	OldSize uint64
+	Path    [][HashSize]byte
+}
+
+// InclusionProof is an inclusion proof that proves a leaf is included in the
+// log.
+//
+// Ref: https://github.com/system-transparency/stfe/blob/design/doc/api.md#get-proof-by-hash
+type InclusionProof struct {
+	TreeSize  uint64
+	LeafIndex uint64
+	Path      [][HashSize]byte
+}