diff --git a/lib/go/blobref/Makefile b/lib/go/blobref/Makefile
index 2ac95f5bc..71fc93b5d 100644
--- a/lib/go/blobref/Makefile
+++ b/lib/go/blobref/Makefile
@@ -2,6 +2,7 @@ include $(GOROOT)/src/Make.inc
 
 TARG=camli/blobref
 GOFILES=\
-	blobref.go
+	blobref.go\
+	fetcher.go\
 
 include $(GOROOT)/src/Make.pkg
diff --git a/lib/go/blobref/blobref.go b/lib/go/blobref/blobref.go
index 26ce0e5ff..269ce360d 100644
--- a/lib/go/blobref/blobref.go
+++ b/lib/go/blobref/blobref.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"hash"
 	"io"
-	"os"
 	"regexp"
 )
 
@@ -28,10 +27,6 @@ type ReadSeekCloser interface {
 	io.Closer
 }
 
-type Fetcher interface {
-	Fetch(*BlobRef) (file ReadSeekCloser, size int64, err os.Error)
-}
-
 func (b *BlobRef) HashName() string {
 	return b.hashName
 }
diff --git a/lib/go/blobref/fetcher.go b/lib/go/blobref/fetcher.go
new file mode 100644
index 000000000..7d9963a5a
--- /dev/null
+++ b/lib/go/blobref/fetcher.go
@@ -0,0 +1,35 @@
+package blobref
+
+import (
+	"fmt"
+	"os"
+)
+
+type Fetcher interface {
+	Fetch(*BlobRef) (file ReadSeekCloser, size int64, err os.Error)
+}
+
+func NewSimpleDirectoryFetcher(dir string) Fetcher {
+	return &dirFetcher{dir, "camli"}
+}
+
+type dirFetcher struct {
+	directory, extension string
+}
+
+func (df *dirFetcher) Fetch(b *BlobRef) (file ReadSeekCloser, size int64, err os.Error) {
+	fileName := fmt.Sprintf("%s/%s.%s", df.directory, b.String(), df.extension)
+	var stat *os.FileInfo
+	stat, err = os.Stat(fileName)
+	if err != nil {
+		return
+	}
+	file, err = os.Open(fileName, os.O_RDONLY, 0)
+	if err != nil {
+		return
+	}
+	size = stat.Size
+	return
+}
+
+
diff --git a/server/go/sigserver/camsigd.go b/server/go/sigserver/camsigd.go
index a584f26c9..fb92aa417 100644
--- a/server/go/sigserver/camsigd.go
+++ b/server/go/sigserver/camsigd.go
@@ -16,27 +16,11 @@ var accessPassword string
 var flagPubKeyDir *string = flag.String("pubkey-dir", "test/pubkey-blobs",
 	"Temporary development hack; directory to dig-xxxx.camli public keys.")
 
-type pubkeyDirFetcher struct{}
-func (_ *pubkeyDirFetcher) Fetch(b *blobref.BlobRef) (file blobref.ReadSeekCloser, size int64, err os.Error) {
-	fileName := fmt.Sprintf("%s/%s.camli", *flagPubKeyDir, b.String())
-	var stat *os.FileInfo
-	stat, err = os.Stat(fileName)
-	if err != nil {
-		return
-	}
-	file, err = os.Open(fileName, os.O_RDONLY, 0)
-	if err != nil {
-		return
-	}
-	size = stat.Size
-	return
-}
-
 // TODO: for now, the only implementation of the blobref.Fetcher
 // interface for fetching public keys is the "local, from disk"
 // implementation used for testing.  In reality we'd want to be able
 // to fetch these from blobservers.
-var pubKeyFetcher = &pubkeyDirFetcher{}
+var pubKeyFetcher = blobref.NewSimpleDirectoryFetcher(*flagPubKeyDir)
 
 func handleRoot(conn http.ResponseWriter, req *http.Request) {
 	fmt.Fprintf(conn, "camsigd")