diff --git a/backend/app/rest/proxy/image.go b/backend/app/rest/proxy/image.go
index 16abf9d0..8284bda9 100644
--- a/backend/app/rest/proxy/image.go
+++ b/backend/app/rest/proxy/image.go
@@ -3,13 +3,10 @@ package proxy
 import (
 	"bytes"
 	"context"
-	"crypto/sha1" //nolint:gosec // not used for cryptography
 	"encoding/base64"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
-	"net/url"
 	"strings"
 	"time"
 
@@ -92,7 +89,7 @@ func (p Image) Handler(w http.ResponseWriter, r *http.Request) {
 
 	imgURL := string(src)
 	var img []byte
-	imgID, err := cachedImgID(imgURL)
+	imgID, err := image.CachedImgID(imgURL)
 	if err != nil {
 		rest.SendErrorJSON(w, r, http.StatusBadRequest, err, "can't parse image url "+imgURL, rest.ErrAssetNotFound)
 		return
@@ -174,20 +171,3 @@ func (p Image) downloadImage(ctx context.Context, imgURL string) ([]byte, error)
 	}
 	return imgData, nil
 }
-
-func sha1Str(s string) string {
-	return fmt.Sprintf("%x", sha1.Sum([]byte(s))) //nolint:gosec // not used for cryptography
-}
-
-// generates ID for a cached image.
-// ID would look like: "cached_images/<sha1-of-image-url-hostname>-<sha1-of-image-entire-url>"
-// <sha1-of-image-url-hostname> - would allow us to identify all images from particular site if ever needed
-// <sha1-of-image-entire-url> - would allow us to avoid storing duplicates of the same image
-//                              (as accurate as deduplication based on potentially mutable url can be)
-func cachedImgID(imgURL string) (string, error) {
-	parsedURL, err := url.Parse(imgURL)
-	if err != nil {
-		return "", errors.Wrapf(err, "can parse url %s", imgURL)
-	}
-	return fmt.Sprintf("cached_images/%s-%s", sha1Str(parsedURL.Hostname()), sha1Str(imgURL)), nil
-}
diff --git a/backend/app/rest/proxy/image_test.go b/backend/app/rest/proxy/image_test.go
index 6eb84f06..398b38f8 100644
--- a/backend/app/rest/proxy/image_test.go
+++ b/backend/app/rest/proxy/image_test.go
@@ -186,7 +186,7 @@ func TestImage_RoutesCachingImage(t *testing.T) {
 	assert.Equal(t, "image/png", resp.Header["Content-Type"][0])
 
 	imageStore.AssertCalled(t, "Load", mock.Anything)
-	imageStore.AssertCalled(t, "Save", "cached_images/4b84b15bff6ee5796152495a230e45e3d7e947d9-"+sha1Str(imgURL), gopherPNGBytes())
+	imageStore.AssertCalled(t, "Save", "cached_images/4b84b15bff6ee5796152495a230e45e3d7e947d9-"+image.Sha1Str(imgURL), gopherPNGBytes())
 	imageStore.AssertCalled(t, "Commit", mock.Anything)
 }
 
diff --git a/backend/app/store/image/image.go b/backend/app/store/image/image.go
index 2f5cc7b9..7289b506 100644
--- a/backend/app/store/image/image.go
+++ b/backend/app/store/image/image.go
@@ -8,6 +8,8 @@ package image
 import (
 	"bytes"
 	"context"
+	"crypto/sha1" //nolint:gosec // not used for cryptography
+	"fmt"
 	"image"
 	// support gif and jpeg images decoding
 	_ "image/gif"
@@ -16,6 +18,7 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"net/url"
 	"path"
 	"strings"
 	"sync"
@@ -323,3 +326,21 @@ func readAndValidateImage(r io.Reader, maxSize int) ([]byte, error) {
 func guid() string {
 	return xid.New().String()
 }
+
+// Sha1Str converts provided string to sha1
+func Sha1Str(s string) string {
+	return fmt.Sprintf("%x", sha1.Sum([]byte(s))) //nolint:gosec // not used for cryptography
+}
+
+// CachedImgID generates ID for a cached image.
+// ID would look like: "cached_images/<sha1-of-image-url-hostname>-<sha1-of-image-entire-url>"
+// <sha1-of-image-url-hostname> - would allow us to identify all images from particular site if ever needed
+// <sha1-of-image-entire-url> - would allow us to avoid storing duplicates of the same image
+//                              (as accurate as deduplication based on potentially mutable url can be)
+func CachedImgID(imgURL string) (string, error) {
+	parsedURL, err := url.Parse(imgURL)
+	if err != nil {
+		return "", errors.Wrapf(err, "can parse url %s", imgURL)
+	}
+	return fmt.Sprintf("cached_images/%s-%s", Sha1Str(parsedURL.Hostname()), Sha1Str(imgURL)), nil
+}
diff --git a/backend/app/store/image/image_test.go b/backend/app/store/image/image_test.go
index cd77995f..259cc8c8 100644
--- a/backend/app/store/image/image_test.go
+++ b/backend/app/store/image/image_test.go
@@ -217,3 +217,13 @@ func TestGetProportionalSizes(t *testing.T) {
 		})
 	}
 }
+
+func TestCachedImgID(t *testing.T) {
+	img, err := CachedImgID(" http://foo.com")
+	assert.Error(t, err)
+	assert.Empty(t, img)
+	imgURL := "http://example.org/img/1.png"
+	img, err = CachedImgID(imgURL)
+	assert.NoError(t, err)
+	assert.Equal(t, "cached_images/"+Sha1Str("example.org")+"-"+Sha1Str(imgURL), img)
+}