Add dependencies/vendor (whatsapp)

vendor/go.mau.fi/libsignal/keys/session/DerivedSecrets.go

@@ -0,0 +1,29 @@
+package session
+
+// NewDerivedSecrets returns a new RootKey/ChainKey pair from 64 bytes of key material
+// generated by the key derivation function.
+func NewDerivedSecrets(keyMaterial []byte) *DerivedSecrets {
+	secrets := DerivedSecrets{
+		keyMaterial[:32],
+		keyMaterial[32:],
+	}
+
+	return &secrets
+}
+
+// DerivedSecrets is a structure for holding the derived secrets for the
+// Root and Chain keys for a session.
+type DerivedSecrets struct {
+	rootKey  []byte
+	chainKey []byte
+}
+
+// RootKey returns the RootKey bytes.
+func (d *DerivedSecrets) RootKey() []byte {
+	return d.rootKey
+}
+
+// ChainKey returns the ChainKey bytes.
+func (d *DerivedSecrets) ChainKey() []byte {
+	return d.chainKey
+}