diff --git a/session/service.go b/session/service.go
index ecbd6f5..6e293d3 100644
--- a/session/service.go
+++ b/session/service.go
@@ -1,20 +1,5 @@
 package session
 
-import (
-	"context"
-	"crypto/ecdsa"
-
-	"github.com/nspcc-dev/neofs-api-go/refs"
-)
-
-type (
-	// KeyStore is an interface that describes storage,
-	// that allows to fetch public keys by OwnerID.
-	KeyStore interface {
-		Get(ctx context.Context, id refs.OwnerID) ([]*ecdsa.PublicKey, error)
-	}
-)
-
 // NewInitRequest returns new initialization CreateRequest from passed Token.
 func NewInitRequest(t *Token) *CreateRequest {
 	return &CreateRequest{Message: &CreateRequest_Init{Init: t}}
diff --git a/session/types.go b/session/types.go
index bacc770..435616a 100644
--- a/session/types.go
+++ b/session/types.go
@@ -1,6 +1,9 @@
 package session
 
 import (
+	"context"
+	"crypto/ecdsa"
+
 	"github.com/nspcc-dev/neofs-api-go/internal"
 	"github.com/nspcc-dev/neofs-api-go/refs"
 	"github.com/nspcc-dev/neofs-api-go/service"
@@ -51,6 +54,14 @@ type PrivateTokenStore interface {
 	Store(TokenID, PrivateToken) error
 }
 
+// KeyStore is an interface of the storage of public keys addressable by OwnerID,
+type KeyStore interface {
+	// Get must return the storage record corresponding to the passed key.
+	//
+	// Resulting error must be ErrKeyNotFound if there is no corresponding record.
+	Get(context.Context, OwnerID) ([]*ecdsa.PublicKey, error)
+}
+
 const ErrPrivateTokenNotFound = internal.Error("private token not found")
 
 const (