diff --git a/deb/contents.go b/deb/contents.go
new file mode 100644
index 00000000..99cf169d
--- /dev/null
+++ b/deb/contents.go
@@ -0,0 +1,71 @@
+package deb
+
+import (
+	"fmt"
+	"github.com/smira/aptly/aptly"
+	"io"
+	"sort"
+	"strings"
+)
+
+// ContentsIndex calculates mapping from files to packages, with sorting and aggregation
+type ContentsIndex struct {
+	index map[string][]*Package
+}
+
+// NewContentsIndex creates empty ContentsIndex
+func NewContentsIndex() *ContentsIndex {
+	return &ContentsIndex{
+		index: make(map[string][]*Package),
+	}
+}
+
+// Push adds package to contents index, calculating package contents as required
+func (index *ContentsIndex) Push(p *Package, packagePool aptly.PackagePool) {
+	contents := p.Contents(packagePool)
+
+	for _, path := range contents {
+		index.index[path] = append(index.index[path], p)
+	}
+}
+
+// Empty checks whether index contains no packages
+func (index *ContentsIndex) Empty() bool {
+	return len(index.index) == 0
+}
+
+// WriteTo dumps sorted mapping of files to qualified package names
+func (index *ContentsIndex) WriteTo(w io.Writer) (int64, error) {
+	var n int64
+
+	paths := make([]string, len(index.index))
+
+	i := 0
+	for path := range index.index {
+		paths[i] = path
+		i++
+	}
+
+	sort.Strings(paths)
+
+	nn, err := fmt.Fprintf(w, "%s %s\n", "FILE", "LOCATION")
+	n += int64(nn)
+	if err != nil {
+		return n, err
+	}
+
+	for _, path := range paths {
+		packages := index.index[path]
+		parts := make([]string, len(packages))
+		for i := range packages {
+			parts[i] = packages[i].QualifiedName()
+		}
+		nn, err = fmt.Fprintf(w, "%s %s\n", path, strings.Join(parts, ","))
+		n += int64(nn)
+		if err != nil {
+			return n, err
+		}
+	}
+
+	return n, nil
+}