cmd/swarm, swarm/api/http, swarm/bmt, swarm/fuse, swarm/network/stream, swarm/storage, swarm/storage/encryption, swarm/testutil: use pseudo-random instead of crypto-random for test files content generation (#18083)

- Replace "crypto/rand" to "math/rand" for files content generation
- Remove swarm/network_test.go.Shuffle and swarm/btm/btm_test.go.Shuffle - because go1.9 support dropped (see https://github.com/ethereum/go-ethereum/pull/17807 and comments to swarm/network_test.go.Shuffle)

18 files changed, 173 insertions, 283 deletions

diff --git a/swarm/api/client/client_test.go b/swarm/api/client/client_test.go
index c30d69911..76b349397 100644
--- a/swarm/api/client/client_test.go
+++ b/swarm/api/client/client_test.go
@@ -33,10 +33,9 @@ import (
 	swarmhttp "github.com/ethereum/go-ethereum/swarm/api/http"
 	"github.com/ethereum/go-ethereum/swarm/multihash"
 	"github.com/ethereum/go-ethereum/swarm/storage/feed"
-	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
-func serverFunc(api *api.API) testutil.TestServer {
+func serverFunc(api *api.API) swarmhttp.TestServer {
 	return swarmhttp.NewServer(api, "")
 }
 
@@ -49,7 +48,7 @@ func TestClientUploadDownloadRawEncrypted(t *testing.T) {
 }
 
 func testClientUploadDownloadRaw(toEncrypt bool, t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := swarmhttp.NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	client := NewClient(srv.URL)
@@ -90,7 +89,7 @@ func TestClientUploadDownloadFilesEncrypted(t *testing.T) {
 }
 
 func testClientUploadDownloadFiles(toEncrypt bool, t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := swarmhttp.NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	client := NewClient(srv.URL)
@@ -188,7 +187,7 @@ func newTestDirectory(t *testing.T) string {
 // TestClientUploadDownloadDirectory tests uploading and downloading a
 // directory of files to a swarm manifest
 func TestClientUploadDownloadDirectory(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := swarmhttp.NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	dir := newTestDirectory(t)
@@ -254,7 +253,7 @@ func TestClientFileListEncrypted(t *testing.T) {
 }
 
 func testClientFileList(toEncrypt bool, t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := swarmhttp.NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	dir := newTestDirectory(t)
@@ -312,7 +311,7 @@ func testClientFileList(toEncrypt bool, t *testing.T) {
 // TestClientMultipartUpload tests uploading files to swarm using a multipart
 // upload
 func TestClientMultipartUpload(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := swarmhttp.NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	// define an uploader which uploads testDirFiles with some data
@@ -378,7 +377,7 @@ func TestClientCreateFeedMultihash(t *testing.T) {
 
 	signer, _ := newTestSigner()
 
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := swarmhttp.NewTestSwarmServer(t, serverFunc, nil)
 	client := NewClient(srv.URL)
 	defer srv.Close()
 
@@ -440,7 +439,7 @@ func TestClientCreateUpdateFeed(t *testing.T) {
 
 	signer, _ := newTestSigner()
 
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := swarmhttp.NewTestSwarmServer(t, serverFunc, nil)
 	client := NewClient(srv.URL)
 	defer srv.Close()
 
diff --git a/swarm/api/http/response_test.go b/swarm/api/http/response_test.go
index 50a704be6..486c19ab0 100644
--- a/swarm/api/http/response_test.go
+++ b/swarm/api/http/response_test.go
@@ -24,12 +24,10 @@ import (
 	"testing"
 
 	"golang.org/x/net/html"
-
-	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 func TestError(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	var resp *http.Response
@@ -55,7 +53,7 @@ func TestError(t *testing.T) {
 }
 
 func Test404Page(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	var resp *http.Response
@@ -81,7 +79,7 @@ func Test404Page(t *testing.T) {
 }
 
 func Test500Page(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	var resp *http.Response
@@ -106,7 +104,7 @@ func Test500Page(t *testing.T) {
 	}
 }
 func Test500PageWith0xHashPrefix(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	var resp *http.Response
@@ -136,7 +134,7 @@ func Test500PageWith0xHashPrefix(t *testing.T) {
 }
 
 func TestJsonResponse(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	var resp *http.Response
diff --git a/swarm/api/http/server_test.go b/swarm/api/http/server_test.go
index 04d0e045a..1ef3deece 100644
--- a/swarm/api/http/server_test.go
+++ b/swarm/api/http/server_test.go
@@ -20,7 +20,6 @@ import (
 	"archive/tar"
 	"bytes"
 	"context"
-	"crypto/rand"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -58,7 +57,7 @@ func init() {
 	log.Root().SetHandler(log.CallerFileHandler(log.LvlFilterHandler(log.Lvl(*loglevel), log.StreamHandler(os.Stderr, log.TerminalFormat(true)))))
 }
 
-func serverFunc(api *api.API) testutil.TestServer {
+func serverFunc(api *api.API) TestServer {
 	return NewServer(api, "")
 }
 
@@ -79,7 +78,7 @@ func TestBzzFeedMultihash(t *testing.T) {
 
 	signer, _ := newTestSigner()
 
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	// add the data our multihash aliased manifest will point to
@@ -167,26 +166,19 @@ func TestBzzFeedMultihash(t *testing.T) {
 
 // Test Swarm feeds using the raw update methods
 func TestBzzFeed(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	signer, _ := newTestSigner()
 
 	defer srv.Close()
 
 	// data of update 1
-	update1Data := make([]byte, 666)
+	update1Data := testutil.RandomBytes(1, 666)
 	update1Timestamp := srv.CurrentTime
-	_, err := rand.Read(update1Data)
-	if err != nil {
-		t.Fatal(err)
-	}
 	//data for update 2
 	update2Data := []byte("foo")
 
 	topic, _ := feed.NewTopic("foo.eth", nil)
 	updateRequest := feed.NewFirstRequest(topic)
-	if err != nil {
-		t.Fatal(err)
-	}
 	updateRequest.SetData(update1Data)
 
 	if err := updateRequest.Sign(signer); err != nil {
@@ -450,7 +442,7 @@ func testBzzGetPath(encrypted bool, t *testing.T) {
 
 	addr := [3]storage.Address{}
 
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	for i, mf := range testmanifest {
@@ -688,7 +680,7 @@ func TestBzzTar(t *testing.T) {
 }
 
 func testBzzTar(encrypted bool, t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 	fileNames := []string{"tmp1.txt", "tmp2.lock", "tmp3.rtf"}
 	fileContents := []string{"tmp1textfilevalue", "tmp2lockfilelocked", "tmp3isjustaplaintextfile"}
@@ -823,7 +815,7 @@ func TestBzzRootRedirectEncrypted(t *testing.T) {
 }
 
 func testBzzRootRedirect(toEncrypt bool, t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	// create a manifest with some data at the root path
@@ -878,7 +870,7 @@ func testBzzRootRedirect(toEncrypt bool, t *testing.T) {
 }
 
 func TestMethodsNotAllowed(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 	databytes := "bar"
 	for _, c := range []struct {
@@ -937,7 +929,7 @@ func httpDo(httpMethod string, url string, reqBody io.Reader, headers map[string
 }
 
 func TestGet(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	for _, testCase := range []struct {
@@ -1020,7 +1012,7 @@ func TestGet(t *testing.T) {
 }
 
 func TestModify(t *testing.T) {
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	swarmClient := swarm.NewClient(srv.URL)
@@ -1121,7 +1113,7 @@ func TestMultiPartUpload(t *testing.T) {
 	// POST /bzz:/ Content-Type: multipart/form-data
 	verbose := false
 	// Setup Swarm
-	srv := testutil.NewTestSwarmServer(t, serverFunc, nil)
+	srv := NewTestSwarmServer(t, serverFunc, nil)
 	defer srv.Close()
 
 	url := fmt.Sprintf("%s/bzz:/", srv.URL)
@@ -1152,7 +1144,7 @@ func TestMultiPartUpload(t *testing.T) {
 // TestBzzGetFileWithResolver tests fetching a file using a mocked ENS resolver
 func TestBzzGetFileWithResolver(t *testing.T) {
 	resolver := newTestResolveValidator("")
-	srv := testutil.NewTestSwarmServer(t, serverFunc, resolver)
+	srv := NewTestSwarmServer(t, serverFunc, resolver)
 	defer srv.Close()
 	fileNames := []string{"dir1/tmp1.txt", "dir2/tmp2.lock", "dir3/tmp3.rtf"}
 	fileContents := []string{"tmp1textfilevalue", "tmp2lockfilelocked", "tmp3isjustaplaintextfile"}
diff --git a/swarm/testutil/http.go b/swarm/api/http/test_server.go
index cdf9239d0..9245c9c5b 100644
--- a/swarm/testutil/http.go
+++ b/swarm/api/http/test_server.go
@@ -14,7 +14,7 @@
 // You should have received a copy of the GNU Lesser General Public License
 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
 
-package testutil
+package http
 
 import (
 	"io/ioutil"
diff --git a/swarm/bmt/bmt_test.go b/swarm/bmt/bmt_test.go
index 760aa11d8..683ba4f5b 100644
--- a/swarm/bmt/bmt_test.go
+++ b/swarm/bmt/bmt_test.go
@@ -18,10 +18,8 @@ package bmt
 
 import (
 	"bytes"
-	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
-	"io"
 	"math/rand"
 	"sync"
 	"sync/atomic"
@@ -29,6 +27,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 // the actual data length generated (could be longer than max datalength of the BMT)
@@ -116,14 +115,11 @@ func TestRefHasher(t *testing.T) {
 	})
 
 	// run the tests
-	for _, x := range tests {
+	for i, x := range tests {
 		for segmentCount := x.from; segmentCount <= x.to; segmentCount++ {
 			for length := 1; length <= segmentCount*32; length++ {
 				t.Run(fmt.Sprintf("%d_segments_%d_bytes", segmentCount, length), func(t *testing.T) {
-					data := make([]byte, length)
-					if _, err := io.ReadFull(crand.Reader, data); err != nil && err != io.EOF {
-						t.Fatal(err)
-					}
+					data := testutil.RandomBytes(i, length)
 					expected := x.expected(data)
 					actual := NewRefHasher(sha3.NewKeccak256, segmentCount).Hash(data)
 					if !bytes.Equal(actual, expected) {
@@ -156,7 +152,7 @@ func TestHasherEmptyData(t *testing.T) {
 
 // tests sequential write with entire max size written in one go
 func TestSyncHasherCorrectness(t *testing.T) {
-	data := newData(BufferSize)
+	data := testutil.RandomBytes(1, BufferSize)
 	hasher := sha3.NewKeccak256
 	size := hasher().Size()
 
@@ -182,7 +178,7 @@ func TestSyncHasherCorrectness(t *testing.T) {
 
 // tests order-neutral concurrent writes with entire max size written in one go
 func TestAsyncCorrectness(t *testing.T) {
-	data := newData(BufferSize)
+	data := testutil.RandomBytes(1, BufferSize)
 	hasher := sha3.NewKeccak256
 	size := hasher().Size()
 	whs := []whenHash{first, last, random}
@@ -236,7 +232,7 @@ func testHasherReuse(poolsize int, t *testing.T) {
 	bmt := New(pool)
 
 	for i := 0; i < 100; i++ {
-		data := newData(BufferSize)
+		data := testutil.RandomBytes(1, BufferSize)
 		n := rand.Intn(bmt.Size())
 		err := testHasherCorrectness(bmt, hasher, data, n, segmentCount)
 		if err != nil {
@@ -256,7 +252,7 @@ func TestBMTConcurrentUse(t *testing.T) {
 	for i := 0; i < cycles; i++ {
 		go func() {
 			bmt := New(pool)
-			data := newData(BufferSize)
+			data := testutil.RandomBytes(1, BufferSize)
 			n := rand.Intn(bmt.Size())
 			errc <- testHasherCorrectness(bmt, hasher, data, n, 128)
 		}()
@@ -290,7 +286,7 @@ func TestBMTWriterBuffers(t *testing.T) {
 			defer pool.Drain(0)
 			n := count * 32
 			bmt := New(pool)
-			data := newData(n)
+			data := testutil.RandomBytes(1, n)
 			rbmt := NewRefHasher(hasher, count)
 			refHash := rbmt.Hash(data)
 			expHash := syncHash(bmt, nil, data)
@@ -413,7 +409,7 @@ func BenchmarkPool(t *testing.B) {
 
 // benchmarks simple sha3 hash on chunks
 func benchmarkSHA3(t *testing.B, n int) {
-	data := newData(n)
+	data := testutil.RandomBytes(1, n)
 	hasher := sha3.NewKeccak256
 	h := hasher()
 
@@ -432,7 +428,7 @@ func benchmarkSHA3(t *testing.B, n int) {
 func benchmarkBMTBaseline(t *testing.B, n int) {
 	hasher := sha3.NewKeccak256
 	hashSize := hasher().Size()
-	data := newData(hashSize)
+	data := testutil.RandomBytes(1, hashSize)
 
 	t.ReportAllocs()
 	t.ResetTimer()
@@ -456,7 +452,7 @@ func benchmarkBMTBaseline(t *testing.B, n int) {
 
 // benchmarks BMT Hasher
 func benchmarkBMT(t *testing.B, n int) {
-	data := newData(n)
+	data := testutil.RandomBytes(1, n)
 	hasher := sha3.NewKeccak256
 	pool := NewTreePool(hasher, segmentCount, PoolSize)
 	bmt := New(pool)
@@ -470,12 +466,12 @@ func benchmarkBMT(t *testing.B, n int) {
 
 // benchmarks BMT hasher with asynchronous concurrent segment/section writes
 func benchmarkBMTAsync(t *testing.B, n int, wh whenHash, double bool) {
-	data := newData(n)
+	data := testutil.RandomBytes(1, n)
 	hasher := sha3.NewKeccak256
 	pool := NewTreePool(hasher, segmentCount, PoolSize)
 	bmt := New(pool).NewAsyncWriter(double)
 	idxs, segments := splitAndShuffle(bmt.SectionSize(), data)
-	shuffle(len(idxs), func(i int, j int) {
+	rand.Shuffle(len(idxs), func(i int, j int) {
 		idxs[i], idxs[j] = idxs[j], idxs[i]
 	})
 
@@ -488,7 +484,7 @@ func benchmarkBMTAsync(t *testing.B, n int, wh whenHash, double bool) {
 
 // benchmarks 100 concurrent bmt hashes with pool capacity
 func benchmarkPool(t *testing.B, poolsize, n int) {
-	data := newData(n)
+	data := testutil.RandomBytes(1, n)
 	hasher := sha3.NewKeccak256
 	pool := NewTreePool(hasher, segmentCount, poolsize)
 	cycles := 100
@@ -511,7 +507,7 @@ func benchmarkPool(t *testing.B, poolsize, n int) {
 
 // benchmarks the reference hasher
 func benchmarkRefHasher(t *testing.B, n int) {
-	data := newData(n)
+	data := testutil.RandomBytes(1, n)
 	hasher := sha3.NewKeccak256
 	rbmt := NewRefHasher(hasher, 128)
 
@@ -522,15 +518,6 @@ func benchmarkRefHasher(t *testing.B, n int) {
 	}
 }
 
-func newData(bufferSize int) []byte {
-	data := make([]byte, bufferSize)
-	_, err := io.ReadFull(crand.Reader, data)
-	if err != nil {
-		panic(err.Error())
-	}
-	return data
-}
-
 // Hash hashes the data and the span using the bmt hasher
 func syncHash(h *Hasher, span, data []byte) []byte {
 	h.ResetWithLength(span)
@@ -553,7 +540,7 @@ func splitAndShuffle(secsize int, data []byte) (idxs []int, segments [][]byte) {
 		section := data[i*secsize : end]
 		segments = append(segments, section)
 	}
-	shuffle(n, func(i int, j int) {
+	rand.Shuffle(n, func(i int, j int) {
 		idxs[i], idxs[j] = idxs[j], idxs[i]
 	})
 	return idxs, segments
@@ -594,29 +581,3 @@ func asyncHash(bmt SectionWriter, span []byte, l int, wh whenHash, idxs []int, s
 	}
 	return <-c
 }
-
-// this is also in swarm/network_test.go
-// shuffle pseudo-randomizes the order of elements.
-// n is the number of elements. Shuffle panics if n < 0.
-// swap swaps the elements with indexes i and j.
-func shuffle(n int, swap func(i, j int)) {
-	if n < 0 {
-		panic("invalid argument to Shuffle")
-	}
-
-	// Fisher-Yates shuffle: https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle
-	// Shuffle really ought not be called with n that doesn't fit in 32 bits.
-	// Not only will it take a very long time, but with 2³¹! possible permutations,
-	// there's no way that any PRNG can have a big enough internal state to
-	// generate even a minuscule percentage of the possible permutations.
-	// Nevertheless, the right API signature accepts an int n, so handle it as best we can.
-	i := n - 1
-	for ; i > 1<<31-1-1; i-- {
-		j := int(rand.Int63n(int64(i + 1)))
-		swap(i, j)
-	}
-	for ; i > 0; i-- {
-		j := int(rand.Int31n(int32(i + 1)))
-		swap(i, j)
-	}
-}
diff --git a/swarm/fuse/swarmfs_test.go b/swarm/fuse/swarmfs_test.go
index 87d918550..460e31c4e 100644
--- a/swarm/fuse/swarmfs_test.go
+++ b/swarm/fuse/swarmfs_test.go
@@ -20,20 +20,19 @@ package fuse
 
 import (
 	"bytes"
-	"crypto/rand"
 	"flag"
 	"fmt"
 	"io"
 	"io/ioutil"
+	"math/rand"
 	"os"
 	"path/filepath"
 	"testing"
 
+	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/swarm/api"
 	"github.com/ethereum/go-ethereum/swarm/storage"
-
-	"github.com/ethereum/go-ethereum/log"
-
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 	colorable "github.com/mattn/go-colorable"
 )
 
@@ -229,12 +228,6 @@ func checkFile(t *testing.T, testMountDir, fname string, contents []byte) {
 	}
 }
 
-func getRandomBytes(size int) []byte {
-	contents := make([]byte, size)
-	rand.Read(contents)
-	return contents
-}
-
 func isDirEmpty(name string) bool {
 	f, err := os.Open(name)
 	if err != nil {
@@ -328,22 +321,22 @@ func (ta *testAPI) mountListAndUnmount(t *testing.T, toEncrypt bool) {
 	dat.testMountDir = filepath.Join(dat.testDir, "testMountDir")
 	dat.files = make(map[string]fileInfo)
 
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["2.txt"] = fileInfo{0711, 333, 444, getRandomBytes(10)}
-	dat.files["3.txt"] = fileInfo{0622, 333, 444, getRandomBytes(100)}
-	dat.files["4.txt"] = fileInfo{0533, 333, 444, getRandomBytes(1024)}
-	dat.files["5.txt"] = fileInfo{0544, 333, 444, getRandomBytes(10)}
-	dat.files["6.txt"] = fileInfo{0555, 333, 444, getRandomBytes(10)}
-	dat.files["7.txt"] = fileInfo{0666, 333, 444, getRandomBytes(10)}
-	dat.files["8.txt"] = fileInfo{0777, 333, 333, getRandomBytes(10)}
-	dat.files["11.txt"] = fileInfo{0777, 333, 444, getRandomBytes(10)}
-	dat.files["111.txt"] = fileInfo{0777, 333, 444, getRandomBytes(10)}
-	dat.files["two/2.txt"] = fileInfo{0777, 333, 444, getRandomBytes(10)}
-	dat.files["two/2/2.txt"] = fileInfo{0777, 333, 444, getRandomBytes(10)}
-	dat.files["two/2./2.txt"] = fileInfo{0777, 444, 444, getRandomBytes(10)}
-	dat.files["twice/2.txt"] = fileInfo{0777, 444, 333, getRandomBytes(200)}
-	dat.files["one/two/three/four/five/six/seven/eight/nine/10.txt"] = fileInfo{0777, 333, 444, getRandomBytes(10240)}
-	dat.files["one/two/three/four/five/six/six"] = fileInfo{0777, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["2.txt"] = fileInfo{0711, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["3.txt"] = fileInfo{0622, 333, 444, testutil.RandomBytes(3, 100)}
+	dat.files["4.txt"] = fileInfo{0533, 333, 444, testutil.RandomBytes(4, 1024)}
+	dat.files["5.txt"] = fileInfo{0544, 333, 444, testutil.RandomBytes(5, 10)}
+	dat.files["6.txt"] = fileInfo{0555, 333, 444, testutil.RandomBytes(6, 10)}
+	dat.files["7.txt"] = fileInfo{0666, 333, 444, testutil.RandomBytes(7, 10)}
+	dat.files["8.txt"] = fileInfo{0777, 333, 333, testutil.RandomBytes(8, 10)}
+	dat.files["11.txt"] = fileInfo{0777, 333, 444, testutil.RandomBytes(9, 10)}
+	dat.files["111.txt"] = fileInfo{0777, 333, 444, testutil.RandomBytes(10, 10)}
+	dat.files["two/2.txt"] = fileInfo{0777, 333, 444, testutil.RandomBytes(11, 10)}
+	dat.files["two/2/2.txt"] = fileInfo{0777, 333, 444, testutil.RandomBytes(12, 10)}
+	dat.files["two/2./2.txt"] = fileInfo{0777, 444, 444, testutil.RandomBytes(13, 10)}
+	dat.files["twice/2.txt"] = fileInfo{0777, 444, 333, testutil.RandomBytes(14, 200)}
+	dat.files["one/two/three/four/five/six/seven/eight/nine/10.txt"] = fileInfo{0777, 333, 444, testutil.RandomBytes(15, 10240)}
+	dat.files["one/two/three/four/five/six/six"] = fileInfo{0777, 333, 444, testutil.RandomBytes(16, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -386,7 +379,7 @@ func (ta *testAPI) runMaxMounts(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "max-upload1")
 	dat.testMountDir = filepath.Join(dat.testDir, "max-mount1")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -396,7 +389,7 @@ func (ta *testAPI) runMaxMounts(t *testing.T, toEncrypt bool) {
 
 	dat.testUploadDir = filepath.Join(dat.testDir, "max-upload2")
 	dat.testMountDir = filepath.Join(dat.testDir, "max-mount2")
-	dat.files["2.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["2.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -405,7 +398,7 @@ func (ta *testAPI) runMaxMounts(t *testing.T, toEncrypt bool) {
 
 	dat.testUploadDir = filepath.Join(dat.testDir, "max-upload3")
 	dat.testMountDir = filepath.Join(dat.testDir, "max-mount3")
-	dat.files["3.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["3.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -414,7 +407,7 @@ func (ta *testAPI) runMaxMounts(t *testing.T, toEncrypt bool) {
 
 	dat.testUploadDir = filepath.Join(dat.testDir, "max-upload4")
 	dat.testMountDir = filepath.Join(dat.testDir, "max-mount4")
-	dat.files["4.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["4.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -423,7 +416,7 @@ func (ta *testAPI) runMaxMounts(t *testing.T, toEncrypt bool) {
 
 	dat.testUploadDir = filepath.Join(dat.testDir, "max-upload5")
 	dat.testMountDir = filepath.Join(dat.testDir, "max-mount5")
-	dat.files["5.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["5.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -436,7 +429,7 @@ func (ta *testAPI) runMaxMounts(t *testing.T, toEncrypt bool) {
 	if err != nil {
 		t.Fatalf("Couldn't create upload dir 6: %v", err)
 	}
-	dat.files["6.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["6.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 	testMountDir6 := filepath.Join(dat.testDir, "max-mount6")
 	err = os.MkdirAll(testMountDir6, 0777)
 	if err != nil {
@@ -475,7 +468,7 @@ func (ta *testAPI) remount(t *testing.T, toEncrypt bool) {
 	dat.testMountDir = filepath.Join(dat.testDir, "remount-mount1")
 	dat.files = make(map[string]fileInfo)
 
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -494,7 +487,7 @@ func (ta *testAPI) remount(t *testing.T, toEncrypt bool) {
 	}
 
 	// mount a different hash in already mounted point
-	dat.files["2.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["2.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 	testUploadDir2, err3 := addDir(dat.testDir, "remount-upload2")
 	if err3 != nil {
 		t.Fatalf("Error creating second upload dir: %v", err3)
@@ -543,7 +536,7 @@ func (ta *testAPI) unmount(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "ex-upload1")
 	dat.testMountDir = filepath.Join(dat.testDir, "ex-mount1")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -591,7 +584,7 @@ func (ta *testAPI) unmountWhenResourceBusy(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "ex-upload1")
 	dat.testMountDir = filepath.Join(dat.testDir, "ex-mount1")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -609,7 +602,7 @@ func (ta *testAPI) unmountWhenResourceBusy(t *testing.T, toEncrypt bool) {
 	//we need to manually close the file before mount for this test
 	//but let's defer too in case of errors
 	defer d.Close()
-	_, err = d.Write(getRandomBytes(10))
+	_, err = d.Write(testutil.RandomBytes(1, 10))
 	if err != nil {
 		t.Fatalf("Couldn't write to file: %v", err)
 	}
@@ -667,7 +660,7 @@ func (ta *testAPI) seekInMultiChunkFile(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "seek-upload1")
 	dat.testMountDir = filepath.Join(dat.testDir, "seek-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10240)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10240)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -733,9 +726,9 @@ func (ta *testAPI) createNewFile(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "create-upload1")
 	dat.testMountDir = filepath.Join(dat.testDir, "create-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["five.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["six.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["five.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["six.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -751,11 +744,7 @@ func (ta *testAPI) createNewFile(t *testing.T, toEncrypt bool) {
 	}
 	defer d.Close()
 	log.Debug("Opened file")
-	contents := make([]byte, 11)
-	_, err = rand.Read(contents)
-	if err != nil {
-		t.Fatalf("Could not rand read contents %v", err)
-	}
+	contents := testutil.RandomBytes(1, 11)
 	log.Debug("content read")
 	_, err = d.Write(contents)
 	if err != nil {
@@ -815,7 +804,7 @@ func (ta *testAPI) createNewFileInsideDirectory(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "createinsidedir-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "createinsidedir-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["one/1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["one/1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -832,11 +821,7 @@ func (ta *testAPI) createNewFileInsideDirectory(t *testing.T, toEncrypt bool) {
 	}
 	defer d.Close()
 	log.Debug("File opened")
-	contents := make([]byte, 11)
-	_, err = rand.Read(contents)
-	if err != nil {
-		t.Fatalf("Error filling random bytes into byte array %v", err)
-	}
+	contents := testutil.RandomBytes(1, 11)
 	log.Debug("Content read")
 	_, err = d.Write(contents)
 	if err != nil {
@@ -896,7 +881,7 @@ func (ta *testAPI) createNewFileInsideNewDirectory(t *testing.T, toEncrypt bool)
 	dat.testUploadDir = filepath.Join(dat.testDir, "createinsidenewdir-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "createinsidenewdir-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -916,11 +901,7 @@ func (ta *testAPI) createNewFileInsideNewDirectory(t *testing.T, toEncrypt bool)
 	}
 	defer d.Close()
 	log.Debug("File opened")
-	contents := make([]byte, 11)
-	_, err = rand.Read(contents)
-	if err != nil {
-		t.Fatalf("Error writing random bytes to byte array: %v", err)
-	}
+	contents := testutil.RandomBytes(1, 11)
 	log.Debug("content read")
 	_, err = d.Write(contents)
 	if err != nil {
@@ -976,9 +957,9 @@ func (ta *testAPI) removeExistingFile(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "remove-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "remove-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["five.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["six.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["five.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["six.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -1036,9 +1017,9 @@ func (ta *testAPI) removeExistingFileInsideDir(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "remove-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "remove-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["one/five.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["one/six.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["one/five.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["one/six.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -1104,9 +1085,9 @@ func (ta *testAPI) removeNewlyAddedFile(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "removenew-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "removenew-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["five.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["six.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["five.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["six.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -1127,11 +1108,7 @@ func (ta *testAPI) removeNewlyAddedFile(t *testing.T, toEncrypt bool) {
 	}
 	defer d.Close()
 	log.Debug("file opened")
-	contents := make([]byte, 11)
-	_, err = rand.Read(contents)
-	if err != nil {
-		t.Fatalf("Error writing random bytes to byte array: %v", err)
-	}
+	contents := testutil.RandomBytes(1, 11)
 	log.Debug("content read")
 	_, err = d.Write(contents)
 	if err != nil {
@@ -1201,9 +1178,9 @@ func (ta *testAPI) addNewFileAndModifyContents(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "modifyfile-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "modifyfile-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["five.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["six.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["five.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["six.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -1357,9 +1334,9 @@ func (ta *testAPI) removeEmptyDir(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "rmdir-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "rmdir-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["five.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["six.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["five.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["six.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -1406,9 +1383,9 @@ func (ta *testAPI) removeDirWhichHasFiles(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "rmdir-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "rmdir-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["one/1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["two/five.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["two/six.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["one/1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["two/five.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["two/six.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -1480,12 +1457,12 @@ func (ta *testAPI) removeDirWhichHasSubDirs(t *testing.T, toEncrypt bool) {
 	dat.testUploadDir = filepath.Join(dat.testDir, "rmsubdir-upload")
 	dat.testMountDir = filepath.Join(dat.testDir, "rmsubdir-mount")
 	dat.files = make(map[string]fileInfo)
-	dat.files["one/1.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["two/three/2.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["two/three/3.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["two/four/5.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["two/four/6.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
-	dat.files["two/four/six/7.txt"] = fileInfo{0700, 333, 444, getRandomBytes(10)}
+	dat.files["one/1.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(1, 10)}
+	dat.files["two/three/2.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(2, 10)}
+	dat.files["two/three/3.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(3, 10)}
+	dat.files["two/four/5.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(4, 10)}
+	dat.files["two/four/6.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(5, 10)}
+	dat.files["two/four/six/7.txt"] = fileInfo{0700, 333, 444, testutil.RandomBytes(6, 10)}
 
 	dat, err = ta.uploadAndMount(dat, t)
 	if err != nil {
@@ -1567,11 +1544,7 @@ func (ta *testAPI) appendFileContentsToEnd(t *testing.T, toEncrypt bool) {
 	dat.testMountDir = filepath.Join(dat.testDir, "appendlargefile-mount")
 	dat.files = make(map[string]fileInfo)
 
-	line1 := make([]byte, 10)
-	_, err = rand.Read(line1)
-	if err != nil {
-		t.Fatalf("Error writing random bytes to byte array: %v", err)
-	}
+	line1 := testutil.RandomBytes(1, 10)
 
 	dat.files["1.txt"] = fileInfo{0700, 333, 444, line1}
 
@@ -1588,11 +1561,7 @@ func (ta *testAPI) appendFileContentsToEnd(t *testing.T, toEncrypt bool) {
 	}
 	defer fd.Close()
 	log.Debug("file opened")
-	line2 := make([]byte, 5)
-	_, err = rand.Read(line2)
-	if err != nil {
-		t.Fatalf("Error writing random bytes to byte array: %v", err)
-	}
+	line2 := testutil.RandomBytes(1, 5)
 	log.Debug("line read")
 	_, err = fd.Seek(int64(len(line1)), 0)
 	if err != nil {
diff --git a/swarm/network/stream/common_test.go b/swarm/network/stream/common_test.go
index 72fdb2bd9..721b873b7 100644
--- a/swarm/network/stream/common_test.go
+++ b/swarm/network/stream/common_test.go
@@ -18,7 +18,6 @@ package stream
 
 import (
 	"context"
-	crand "crypto/rand"
 	"errors"
 	"flag"
 	"fmt"
@@ -40,6 +39,7 @@ import (
 	"github.com/ethereum/go-ethereum/swarm/state"
 	"github.com/ethereum/go-ethereum/swarm/storage"
 	mockdb "github.com/ethereum/go-ethereum/swarm/storage/mock/db"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 	colorable "github.com/mattn/go-colorable"
 )
 
@@ -230,12 +230,7 @@ func generateRandomFile() (string, error) {
 	//generate a random file size between minFileSize and maxFileSize
 	fileSize := rand.Intn(maxFileSize-minFileSize) + minFileSize
 	log.Debug(fmt.Sprintf("Generated file with filesize %d kB", fileSize))
-	b := make([]byte, fileSize*1024)
-	_, err := crand.Read(b)
-	if err != nil {
-		log.Error("Error generating random file.", "err", err)
-		return "", err
-	}
+	b := testutil.RandomBytes(1, fileSize*1024)
 	return string(b), nil
 }
 
diff --git a/swarm/network/stream/delivery_test.go b/swarm/network/stream/delivery_test.go
index c77682e0e..c9a530115 100644
--- a/swarm/network/stream/delivery_test.go
+++ b/swarm/network/stream/delivery_test.go
@@ -19,9 +19,7 @@ package stream
 import (
 	"bytes"
 	"context"
-	crand "crypto/rand"
 	"fmt"
-	"io"
 	"os"
 	"sync"
 	"testing"
@@ -39,6 +37,7 @@ import (
 	"github.com/ethereum/go-ethereum/swarm/network/simulation"
 	"github.com/ethereum/go-ethereum/swarm/state"
 	"github.com/ethereum/go-ethereum/swarm/storage"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 //Tests initializing a retrieve request
@@ -530,7 +529,7 @@ func testDeliveryFromNodes(t *testing.T, nodes, conns, chunkCount int, skipCheck
 		//now we can actually upload a (random) file to the round-robin store
 		size := chunkCount * chunkSize
 		log.Debug("Storing data to file store")
-		fileHash, wait, err := roundRobinFileStore.Store(ctx, io.LimitReader(crand.Reader, int64(size)), int64(size), false)
+		fileHash, wait, err := roundRobinFileStore.Store(ctx, testutil.RandomReader(1, size), int64(size), false)
 		// wait until all chunks stored
 		if err != nil {
 			return err
@@ -719,7 +718,7 @@ func benchmarkDeliveryFromNodes(b *testing.B, nodes, conns, chunkCount int, skip
 			for i := 0; i < chunkCount; i++ {
 				// create actual size real chunks
 				ctx := context.TODO()
-				hash, wait, err := remoteFileStore.Store(ctx, io.LimitReader(crand.Reader, int64(chunkSize)), int64(chunkSize), false)
+				hash, wait, err := remoteFileStore.Store(ctx, testutil.RandomReader(i, chunkSize), int64(chunkSize), false)
 				if err != nil {
 					b.Fatalf("expected no error. got %v", err)
 				}
diff --git a/swarm/network/stream/intervals_test.go b/swarm/network/stream/intervals_test.go
index 0c95fabb7..037984f22 100644
--- a/swarm/network/stream/intervals_test.go
+++ b/swarm/network/stream/intervals_test.go
@@ -18,10 +18,8 @@ package stream
 
 import (
 	"context"
-	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
-	"io"
 	"os"
 	"sync"
 	"testing"
@@ -36,6 +34,7 @@ import (
 	"github.com/ethereum/go-ethereum/swarm/network/simulation"
 	"github.com/ethereum/go-ethereum/swarm/state"
 	"github.com/ethereum/go-ethereum/swarm/storage"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 func TestIntervalsLive(t *testing.T) {
@@ -130,7 +129,8 @@ func testIntervals(t *testing.T, live bool, history *Range, skipCheck bool) {
 		fileStore := item.(*storage.FileStore)
 
 		size := chunkCount * chunkSize
-		_, wait, err := fileStore.Store(ctx, io.LimitReader(crand.Reader, int64(size)), int64(size), false)
+
+		_, wait, err := fileStore.Store(ctx, testutil.RandomReader(1, size), int64(size), false)
 		if err != nil {
 			log.Error("Store error: %v", "err", err)
 			t.Fatal(err)
diff --git a/swarm/network/stream/snapshot_sync_test.go b/swarm/network/stream/snapshot_sync_test.go
index 2ddbed936..4bd7f38f5 100644
--- a/swarm/network/stream/snapshot_sync_test.go
+++ b/swarm/network/stream/snapshot_sync_test.go
@@ -17,9 +17,7 @@ package stream
 
 import (
 	"context"
-	crand "crypto/rand"
 	"fmt"
-	"io"
 	"os"
 	"runtime"
 	"sync"
@@ -39,6 +37,7 @@ import (
 	"github.com/ethereum/go-ethereum/swarm/state"
 	"github.com/ethereum/go-ethereum/swarm/storage"
 	mockdb "github.com/ethereum/go-ethereum/swarm/storage/mock/db"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 const MaxTimeout = 600
@@ -603,7 +602,7 @@ func uploadFileToSingleNodeStore(id enode.ID, chunkCount int, lstore *storage.Lo
 	size := chunkSize
 	var rootAddrs []storage.Address
 	for i := 0; i < chunkCount; i++ {
-		rk, wait, err := fileStore.Store(context.TODO(), io.LimitReader(crand.Reader, int64(size)), int64(size), false)
+		rk, wait, err := fileStore.Store(context.TODO(), testutil.RandomReader(i, size), int64(size), false)
 		if err != nil {
 			return nil, err
 		}
diff --git a/swarm/network/stream/syncer_test.go b/swarm/network/stream/syncer_test.go
index b0e35b0db..a543cae05 100644
--- a/swarm/network/stream/syncer_test.go
+++ b/swarm/network/stream/syncer_test.go
@@ -18,9 +18,7 @@ package stream
 
 import (
 	"context"
-	crand "crypto/rand"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"math"
 	"os"
@@ -39,6 +37,7 @@ import (
 	"github.com/ethereum/go-ethereum/swarm/state"
 	"github.com/ethereum/go-ethereum/swarm/storage"
 	mockdb "github.com/ethereum/go-ethereum/swarm/storage/mock/db"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 const dataChunkCount = 200
@@ -183,7 +182,7 @@ func testSyncBetweenNodes(t *testing.T, nodes, conns, chunkCount int, skipCheck
 				}
 				fileStore := item.(*storage.FileStore)
 				size := chunkCount * chunkSize
-				_, wait, err := fileStore.Store(ctx, io.LimitReader(crand.Reader, int64(size)), int64(size), false)
+				_, wait, err := fileStore.Store(ctx, testutil.RandomReader(j, size), int64(size), false)
 				if err != nil {
 					t.Fatal(err.Error())
 				}
diff --git a/swarm/network_test.go b/swarm/network_test.go
index aab1c0509..d84f28147 100644
--- a/swarm/network_test.go
+++ b/swarm/network_test.go
@@ -335,7 +335,7 @@ func testSwarmNetwork(t *testing.T, o *testSwarmNetworkOptions, steps ...testSwa
 
 		result := sim.Run(ctx, func(ctx context.Context, sim *simulation.Simulation) error {
 			nodeIDs := sim.UpNodeIDs()
-			shuffle(len(nodeIDs), func(i, j int) {
+			rand.Shuffle(len(nodeIDs), func(i, j int) {
 				nodeIDs[i], nodeIDs[j] = nodeIDs[j], nodeIDs[i]
 			})
 			for _, id := range nodeIDs {
@@ -404,7 +404,7 @@ func retrieve(
 	nodeStatusM *sync.Map,
 	totalFoundCount *uint64,
 ) (missing uint64) {
-	shuffle(len(files), func(i, j int) {
+	rand.Shuffle(len(files), func(i, j int) {
 		files[i], files[j] = files[j], files[i]
 	})
 
@@ -499,32 +499,3 @@ func retrieve(
 
 	return uint64(totalCheckCount) - atomic.LoadUint64(totalFoundCount)
 }
-
-// Backported from stdlib https://golang.org/src/math/rand/rand.go?s=11175:11215#L333
-//
-// Replace with rand.Shuffle from go 1.10 when go 1.9 support is dropped.
-//
-// shuffle pseudo-randomizes the order of elements.
-// n is the number of elements. Shuffle panics if n < 0.
-// swap swaps the elements with indexes i and j.
-func shuffle(n int, swap func(i, j int)) {
-	if n < 0 {
-		panic("invalid argument to Shuffle")
-	}
-
-	// Fisher-Yates shuffle: https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle
-	// Shuffle really ought not be called with n that doesn't fit in 32 bits.
-	// Not only will it take a very long time, but with 2³¹! possible permutations,
-	// there's no way that any PRNG can have a big enough internal state to
-	// generate even a minuscule percentage of the possible permutations.
-	// Nevertheless, the right API signature accepts an int n, so handle it as best we can.
-	i := n - 1
-	for ; i > 1<<31-1-1; i-- {
-		j := int(rand.Int63n(int64(i + 1)))
-		swap(i, j)
-	}
-	for ; i > 0; i-- {
-		j := int(rand.Int31n(int32(i + 1)))
-		swap(i, j)
-	}
-}
diff --git a/swarm/storage/chunker_test.go b/swarm/storage/chunker_test.go
index 6172d8a09..1f847edcb 100644
--- a/swarm/storage/chunker_test.go
+++ b/swarm/storage/chunker_test.go
@@ -19,13 +19,13 @@ package storage
 import (
 	"bytes"
 	"context"
-	"crypto/rand"
 	"encoding/binary"
 	"fmt"
 	"io"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 /*
@@ -47,7 +47,7 @@ func newTestHasherStore(store ChunkStore, hash string) *hasherStore {
 }
 
 func testRandomBrokenData(n int, tester *chunkerTester) {
-	data := io.LimitReader(rand.Reader, int64(n))
+	data := testutil.RandomReader(1, n)
 	brokendata := brokenLimitReader(data, n, n/2)
 
 	buf := make([]byte, n)
@@ -56,7 +56,7 @@ func testRandomBrokenData(n int, tester *chunkerTester) {
 		tester.t.Fatalf("Broken reader is not broken, hence broken. Returns: %v", err)
 	}
 
-	data = io.LimitReader(rand.Reader, int64(n))
+	data = testutil.RandomReader(2, n)
 	brokendata = brokenLimitReader(data, n, n/2)
 
 	putGetter := newTestHasherStore(NewMapChunkStore(), SHA3Hash)
@@ -77,7 +77,8 @@ func testRandomData(usePyramid bool, hash string, n int, tester *chunkerTester)
 	input, found := tester.inputs[uint64(n)]
 	var data io.Reader
 	if !found {
-		data, input = GenerateRandomData(n)
+		input = testutil.RandomBytes(1, n)
+		data = bytes.NewReader(input)
 		tester.inputs[uint64(n)] = input
 	} else {
 		data = io.LimitReader(bytes.NewReader(input), int64(n))
@@ -118,14 +119,13 @@ func testRandomData(usePyramid bool, hash string, n int, tester *chunkerTester)
 	// testing partial read
 	for i := 1; i < n; i += 10000 {
 		readableLength := n - i
-		output := make([]byte, readableLength)
 		r, err := reader.ReadAt(output, int64(i))
 		if r != readableLength || err != io.EOF {
 			tester.t.Fatalf("readAt error with offset %v read: %v  n = %v  err = %v\n", i, r, readableLength, err)
 		}
 		if input != nil {
-			if !bytes.Equal(output, input[i:]) {
-				tester.t.Fatalf("input and output mismatch\n IN: %v\nOUT: %v\n", input[i:], output)
+			if !bytes.Equal(output[:readableLength], input[i:]) {
+				tester.t.Fatalf("input and output mismatch\n IN: %v\nOUT: %v\n", input[i:], output[:readableLength])
 			}
 		}
 	}
@@ -177,7 +177,8 @@ func TestDataAppend(t *testing.T) {
 		input, found := tester.inputs[uint64(n)]
 		var data io.Reader
 		if !found {
-			data, input = GenerateRandomData(n)
+			input = testutil.RandomBytes(i, n)
+			data = bytes.NewReader(input)
 			tester.inputs[uint64(n)] = input
 		} else {
 			data = io.LimitReader(bytes.NewReader(input), int64(n))
@@ -199,7 +200,8 @@ func TestDataAppend(t *testing.T) {
 		appendInput, found := tester.inputs[uint64(m)]
 		var appendData io.Reader
 		if !found {
-			appendData, appendInput = GenerateRandomData(m)
+			appendInput = testutil.RandomBytes(i, m)
+			appendData = bytes.NewReader(appendInput)
 			tester.inputs[uint64(m)] = appendInput
 		} else {
 			appendData = io.LimitReader(bytes.NewReader(appendInput), int64(m))
@@ -272,7 +274,7 @@ func benchReadAll(reader LazySectionReader) {
 func benchmarkSplitJoin(n int, t *testing.B) {
 	t.ReportAllocs()
 	for i := 0; i < t.N; i++ {
-		data := testDataReader(n)
+		data := testutil.RandomReader(i, n)
 
 		putGetter := newTestHasherStore(NewMapChunkStore(), SHA3Hash)
 		ctx := context.TODO()
@@ -292,7 +294,7 @@ func benchmarkSplitJoin(n int, t *testing.B) {
 func benchmarkSplitTreeSHA3(n int, t *testing.B) {
 	t.ReportAllocs()
 	for i := 0; i < t.N; i++ {
-		data := testDataReader(n)
+		data := testutil.RandomReader(i, n)
 		putGetter := newTestHasherStore(&FakeChunkStore{}, SHA3Hash)
 
 		ctx := context.Background()
@@ -311,7 +313,7 @@ func benchmarkSplitTreeSHA3(n int, t *testing.B) {
 func benchmarkSplitTreeBMT(n int, t *testing.B) {
 	t.ReportAllocs()
 	for i := 0; i < t.N; i++ {
-		data := testDataReader(n)
+		data := testutil.RandomReader(i, n)
 		putGetter := newTestHasherStore(&FakeChunkStore{}, BMTHash)
 
 		ctx := context.Background()
@@ -329,7 +331,7 @@ func benchmarkSplitTreeBMT(n int, t *testing.B) {
 func benchmarkSplitPyramidBMT(n int, t *testing.B) {
 	t.ReportAllocs()
 	for i := 0; i < t.N; i++ {
-		data := testDataReader(n)
+		data := testutil.RandomReader(i, n)
 		putGetter := newTestHasherStore(&FakeChunkStore{}, BMTHash)
 
 		ctx := context.Background()
@@ -347,7 +349,7 @@ func benchmarkSplitPyramidBMT(n int, t *testing.B) {
 func benchmarkSplitPyramidSHA3(n int, t *testing.B) {
 	t.ReportAllocs()
 	for i := 0; i < t.N; i++ {
-		data := testDataReader(n)
+		data := testutil.RandomReader(i, n)
 		putGetter := newTestHasherStore(&FakeChunkStore{}, SHA3Hash)
 
 		ctx := context.Background()
@@ -365,8 +367,8 @@ func benchmarkSplitPyramidSHA3(n int, t *testing.B) {
 func benchmarkSplitAppendPyramid(n, m int, t *testing.B) {
 	t.ReportAllocs()
 	for i := 0; i < t.N; i++ {
-		data := testDataReader(n)
-		data1 := testDataReader(m)
+		data := testutil.RandomReader(i, n)
+		data1 := testutil.RandomReader(t.N+i, m)
 
 		store := NewMapChunkStore()
 		putGetter := newTestHasherStore(store, SHA3Hash)
diff --git a/swarm/storage/common_test.go b/swarm/storage/common_test.go
index 600be164a..af104a5ae 100644
--- a/swarm/storage/common_test.go
+++ b/swarm/storage/common_test.go
@@ -19,7 +19,6 @@ package storage
 import (
 	"bytes"
 	"context"
-	"crypto/rand"
 	"flag"
 	"fmt"
 	"io"
@@ -31,7 +30,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/log"
 	ch "github.com/ethereum/go-ethereum/swarm/chunk"
-	colorable "github.com/mattn/go-colorable"
+	"github.com/mattn/go-colorable"
 )
 
 var (
@@ -151,10 +150,6 @@ func mget(store ChunkStore, hs []Address, f func(h Address, chunk Chunk) error)
 	return err
 }
 
-func testDataReader(l int) (r io.Reader) {
-	return io.LimitReader(rand.Reader, int64(l))
-}
-
 func (r *brokenLimitedReader) Read(buf []byte) (int, error) {
 	if r.off+len(buf) > r.errAt {
 		return 0, fmt.Errorf("Broken reader")
diff --git a/swarm/storage/encryption/encryption_test.go b/swarm/storage/encryption/encryption_test.go
index c3abefdce..0c0d0508c 100644
--- a/swarm/storage/encryption/encryption_test.go
+++ b/swarm/storage/encryption/encryption_test.go
@@ -18,12 +18,12 @@ package encryption
 
 import (
 	"bytes"
-	"crypto/rand"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 var expectedTransformedHex = "352187af3a843decc63ceca6cb01ea39dbcf77caf0a8f705f5c30d557044ceec9392b94a79376f1e5c10cd0c0f2a98e5353bf22b3ea4fdac6677ee553dec192e3db64e179d0474e96088fb4abd2babd67de123fb398bdf84d818f7bda2c1ab60b3ea0e0569ae54aa969658eb4844e6960d2ff44d7c087ee3aaffa1c0ee5df7e50b615f7ad90190f022934ad5300c7d1809bfe71a11cc04cece5274eb97a5f20350630522c1dbb7cebaf4f97f84e03f5cfd88f2b48880b25d12f4d5e75c150f704ef6b46c72e07db2b705ac3644569dccd22fd8f964f6ef787fda63c46759af334e6f665f70eac775a7017acea49f3c7696151cb1b9434fa4ac27fb803921ffb5ec58dafa168098d7d5b97e384be3384cf5bc235c3d887fef89fe76c0065f9b8d6ad837b442340d9e797b46ef5709ea3358bc415df11e4830de986ef0f1c418ffdcc80e9a3cda9bea0ab5676c0d4240465c43ba527e3b4ea50b4f6255b510e5d25774a75449b0bd71e56c537ade4fcf0f4d63c99ae1dbb5a844971e2c19941b8facfcfc8ee3056e7cb3c7114c5357e845b52f7103cb6e00d2308c37b12baa5b769e1cc7b00fc06f2d16e70cc27a82cb9c1a4e40cb0d43907f73df2c9db44f1b51a6b0bc6d09f77ac3be14041fae3f9df2da42df43ae110904f9ecee278030185254d7c6e918a5512024d047f77a992088cb3190a6587aa54d0c7231c1cd2e455e0d4c07f74bece68e29cd8ba0190c0bcfb26d24634af5d91a81ef5d4dd3d614836ce942ddbf7bb1399317f4c03faa675f325f18324bf9433844bfe5c4cc04130c8d5c329562b7cd66e72f7355de8f5375a72202971613c32bd7f3fcdcd51080758cd1d0a46dbe8f0374381dbc359f5864250c63dde8131cbd7c98ae2b0147d6ea4bf65d1443d511b18e6d608bbb46ac036353b4c51df306a10a6f6939c38629a5c18aaf89cac04bd3ad5156e6b92011c88341cb08551bab0a89e6a46538f5af33b86121dba17e3a434c273f385cd2e8cb90bdd32747d8425d929ccbd9b0815c73325988855549a8489dfd047daf777aaa3099e54cf997175a5d9e1edfe363e3b68c70e02f6bf4fcde6a0f3f7d0e7e98bde1a72ae8b6cd27b32990680cc4a04fc467f41c5adcaddabfc71928a3f6872c360c1d765260690dd28b269864c8e380d9c92ef6b89b0094c8f9bb22608b4156381b19b920e9583c9616ce5693b4d2a6c689f02e6a91584a8e501e107403d2689dd0045269dd9946c0e969fb656a3b39d84a798831f5f9290f163eb2f97d3ae25071324e95e2256d9c1e56eb83c26397855323edc202d56ad05894333b7f0ed3c1e4734782eb8bd5477242fd80d7a89b12866f85cfae476322f032465d6b1253993033fccd4723530630ab97a1566460af9c90c9da843c229406e65f3fa578bd6bf04dee9b6153807ddadb8ceefc5c601a8ab26023c67b1ab1e8e0f29ce94c78c308005a781853e7a2e0e51738939a657c987b5e611f32f47b5ff461c52e63e0ea390515a8e1f5393dae54ea526934b5f310b76e3fa050e40718cb4c8a20e58946d6ee1879f08c52764422fe542b3240e75eccb7aa75b1f8a651e37a3bc56b0932cdae0e985948468db1f98eb4b77b82081ea25d8a762db00f7898864984bd80e2f3f35f236bf57291dec28f550769943bcfb6f884b7687589b673642ef7fe5d7d5a87d3eca5017f83ccb9a3310520474479464cb3f433440e7e2f1e28c0aef700a45848573409e7ab66e0cfd4fe5d2147ace81bc65fd8891f6245cd69246bbf5c27830e5ab882dd1d02aba34ff6ca9af88df00fd602892f02fedbdc65dedec203faf3f8ff4a97314e0ddb58b9ab756a61a562597f4088b445fcc3b28a708ca7b1485dcd791b779fbf2b3ef1ec5c6205f595fbe45a02105034147e5a146089c200a49dae33ae051a08ea5f974a21540aaeffa7f9d9e3d35478016fb27b871036eb27217a5b834b461f535752fb5f1c8dded3ae14ce3a2ef6639e2fe41939e3509e46e347a95d50b2080f1ba42c804b290ddc912c952d1cec3f2661369f738feacc0dbf1ea27429c644e45f9e26f30c341acd34c7519b2a1663e334621691e810767e9918c2c547b2e23cce915f97d26aac8d0d2fcd3edb7986ad4e2b8a852edebad534cb6c0e9f0797d3563e5409d7e068e48356c67ce519246cd9c560e881453df97cbba562018811e6cf8c327f399d1d1253ab47a19f4a0ccc7c6d86a9603e0551da310ea595d71305c4aad96819120a92cdbaf1f77ec8df9cc7c838c0d4de1e8692dd81da38268d1d71324bcffdafbe5122e4b81828e021e936d83ae8021eac592aa52cd296b5ce392c7173d622f8e07d18f59bb1b08ba15211af6703463b09b593af3c37735296816d9f2e7a369354a5374ea3955e14ca8ac56d5bfe4aef7a21bd825d6ae85530bee5d2aaaa4914981b3dfdb2e92ec2a27c83d74b59e84ff5c056f7d8945745f2efc3dcf28f288c6cd8383700fb2312f7001f24dd40015e436ae23e052fe9070ea9535b9c989898a9bda3d5382cf10e432fae6ccf0c825b3e6436edd3a9f8846e5606f8563931b5f29ba407c5236e5730225dda211a8504ec1817bc935e1fd9a532b648c502df302ed2063aed008fd5676131ac9e95998e9447b02bd29d77e38fcfd2959f2de929b31970335eb2a74348cc6918bc35b9bf749eab0fe304c946cd9e1ca284e6853c42646e60b6b39e0d3fb3c260abfc5c1b4ca3c3770f344118ca7c7f5c1ad1f123f8f369cd60afc3cdb3e9e81968c5c9fa7c8b014ffe0508dd4f0a2a976d5d1ca8fc9ad7a237d92cfe7b41413d934d6e142824b252699397e48e4bac4e91ebc10602720684bd0863773c548f9a2f9724245e47b129ecf65afd7252aac48c8a8d6fd3d888af592a01fb02dc71ed7538a700d3d16243e4621e0fcf9f8ed2b4e11c9fa9a95338bb1dac74a7d9bc4eb8cbf900b634a2a56469c00f5994e4f0934bdb947640e6d67e47d0b621aacd632bfd3c800bd7d93bd329f494a90e06ed51535831bd6e07ac1b4b11434ef3918fa9511813a002913f33f836454798b8d1787fea9a4c4743ba091ed192ed92f4d33e43a226bf9503e1a83a16dd340b3cbbf38af6db0d99201da8de529b4225f3d2fa2aad6621afc6c79ef3537720591edfc681ae6d00ede53ed724fc71b23b90d2e9b7158aaee98d626a4fe029107df2cb5f90147e07ebe423b1519d848af18af365c71bfd0665db46be493bbe99b79a188de0cf3594aef2299f0324075bdce9eb0b87bc29d62401ba4fd6ae48b1ba33261b5b845279becf38ee03e3dc5c45303321c5fac96fd02a3ad8c9e3b02127b320501333c9e6360440d1ad5e64a6239501502dde1a49c9abe33b66098458eee3d611bb06ffcd234a1b9aef4af5021cd61f0de6789f822ee116b5078aae8c129e8391d8987500d322b58edd1595dc570b57341f2df221b94a96ab7fbcf32a8ca9684196455694024623d7ed49f7d66e8dd453c0bae50e0d8b34377b22d0ece059e2c385dfc70b9089fcd27577c51f4d870b5738ee2b68c361a67809c105c7848b68860a829f29930857a9f9d40b14fd2384ac43bafdf43c0661103794c4bd07d1cfdd4681b6aeaefad53d4c1473359bcc5a83b09189352e5bb9a7498dd0effb89c35aad26954551f8b0621374b449bf515630bd3974dca982279733470fdd059aa9c3df403d8f22b38c4709c82d8f12b888e22990350490e16179caf406293cc9e65f116bafcbe96af132f679877061107a2f690a82a8cb46eea57a90abd23798c5937c6fe6b17be3f9bfa01ce117d2c268181b9095bf49f395fea07ca03838de0588c5e2db633e836d64488c1421e653ea52d810d096048c092d0da6e02fa6613890219f51a76148c8588c2487b171a28f17b7a299204874af0131725d793481333be5f08e86ca837a226850b0c1060891603bfecf9e55cddd22c0dbb28d495342d9cc3de8409f72e52a0115141cffe755c74f061c1a770428ccb0ae59536ee6fc074fbfc6cacb51a549d327527e20f8407477e60355863f1153f9ce95641198663c968874e7fdb29407bd771d94fdda8180cbb0358f5874738db705924b8cbe0cd5e1484aeb64542fe8f38667b7c34baf818c63b1e18440e9fba575254d063fd49f24ef26432f4eb323f3836972dca87473e3e9bb26dc3be236c3aae6bc8a6da567442309da0e8450e242fc9db836e2964f2c76a3b80a2c677979882dda7d7ebf62c93664018bcf4ec431fe6b403d49b3b36618b9c07c2d0d4569cb8d52223903debc72ec113955b206c34f1ae5300990ccfc0180f47d91afdb542b6312d12aeff7e19c645dc0b9fe6e3288e9539f6d5870f99882df187bfa6d24d179dfd1dac22212c8b5339f7171a3efc15b760fed8f68538bc5cbd845c2d1ab41f3a6c692820653eaef7930c02fbe6061d93805d73decdbb945572a7c44ed0241982a6e4d2d730898f82b3d9877cb7bca41cc6dcee67aa0c3d6db76f0b0a708ace0031113e48429de5d886c10e9200f68f32263a2fbf44a5992c2459fda7b8796ba796e3a0804fc25992ed2c9a5fe0580a6b809200ecde6caa0364b58be11564dcb9a616766dd7906db5636ee708b0204f38d309466d8d4a162965dd727e29f5a6c133e9b4ed5bafe803e479f9b2a7640c942c4a40b14ac7dc9828546052761a070f6404008f1ec3605836339c3da95a00b4fd81b2cabf88b51d2087d5b83e8c5b69bf96d8c72cbd278dad3bbb42b404b436f84ad688a22948adf60a81090f1e904291503c16e9f54b05fc76c881a5f95f0e732949e95d3f1bae2d3652a14fe0dda2d68879604657171856ef72637def2a96ac47d7b3fe86eb3198f5e0e626f06be86232305f2ae79ffcd2725e48208f9d8d63523f81915acc957563ab627cd6bc68c2a37d59fb0ed77a90aa9d085d6914a8ebada22a2c2d471b5163aeddd799d90fbb10ed6851ace2c4af504b7d572686700a59d6db46d5e42bb83f8e0c0ffe1dfa6582cc0b34c921ff6e85e83188d24906d5c08bb90069639e713051b3102b53e6f703e8210017878add5df68e6f2b108de279c5490e9eef5590185c4a1c744d4e00d244e1245a8805bd30407b1bc488db44870ccfd75a8af104df78efa2fb7ba31f048a263efdb3b63271fff4922bece9a71187108f65744a24f4947dc556b7440cb4fa45d296bb7f724588d1f245125b21ea063500029bd49650237f53899daf1312809552c81c5827341263cc807a29fe84746170cdfa1ff3838399a5645319bcaff674bb70efccdd88b3d3bb2f2d98111413585dc5d5bd5168f43b3f55e58972a5b2b9b3733febf02f931bd436648cb617c3794841aab961fe41277ab07812e1d3bc4ff6f4350a3e615bfba08c3b9480ef57904d3a16f7e916345202e3f93d11f7a7305170cb8c4eb9ac88ace8bbd1f377bdd5855d3162d6723d4435e84ce529b8f276a8927915ac759a0d04e5ca4a9d3da6291f0333b475df527e99fe38f7a4082662e8125936640c26dd1d17cf284ce6e2b17777a05aa0574f7793a6a062cc6f7263f7ab126b4528a17becfdec49ac0f7d8705aa1704af97fb861faa8a466161b2b5c08a5bacc79fe8500b913d65c8d3c52d1fd52d2ab2c9f52196e712455619c1cd3e0f391b274487944240e2ed8858dd0823c801094310024ae3fe4dd1cf5a2b6487b42cc5937bbafb193ee331d87e378258963d49b9da90899bbb4b88e79f78e866b0213f4719f67da7bcc2fce073c01e87c62ea3cdbcd589cfc41281f2f4c757c742d6d1e"
@@ -125,8 +125,7 @@ func testEncryptDecryptIsIdentity(t *testing.T, padding int, initCtr uint32, dat
 	key := GenerateRandomKey(keyLength)
 	enc := New(key, padding, initCtr, hashFunc)
 
-	data := make([]byte, dataLength)
-	rand.Read(data)
+	data := testutil.RandomBytes(1, dataLength)
 
 	encrypted, err := enc.Encrypt(data)
 	if err != nil {
diff --git a/swarm/storage/filestore_test.go b/swarm/storage/filestore_test.go
index 9fe58f60c..fb0f761a4 100644
--- a/swarm/storage/filestore_test.go
+++ b/swarm/storage/filestore_test.go
@@ -23,6 +23,8 @@ import (
 	"io/ioutil"
 	"os"
 	"testing"
+
+	"github.com/ethereum/go-ethereum/swarm/testutil"
 )
 
 const testDataSize = 0x0001000
@@ -49,9 +51,9 @@ func testFileStoreRandom(toEncrypt bool, t *testing.T) {
 	fileStore := NewFileStore(localStore, NewFileStoreParams())
 	defer os.RemoveAll("/tmp/bzz")
 
-	reader, slice := GenerateRandomData(testDataSize)
+	slice := testutil.RandomBytes(1, testDataSize)
 	ctx := context.TODO()
-	key, wait, err := fileStore.Store(ctx, reader, testDataSize, toEncrypt)
+	key, wait, err := fileStore.Store(ctx, bytes.NewReader(slice), testDataSize, toEncrypt)
 	if err != nil {
 		t.Fatalf("Store error: %v", err)
 	}
@@ -63,13 +65,13 @@ func testFileStoreRandom(toEncrypt bool, t *testing.T) {
 	if isEncrypted != toEncrypt {
 		t.Fatalf("isEncrypted expected %v got %v", toEncrypt, isEncrypted)
 	}
-	resultSlice := make([]byte, len(slice))
+	resultSlice := make([]byte, testDataSize)
 	n, err := resultReader.ReadAt(resultSlice, 0)
 	if err != io.EOF {
 		t.Fatalf("Retrieve error: %v", err)
 	}
-	if n != len(slice) {
-		t.Fatalf("Slice size error got %d, expected %d.", n, len(slice))
+	if n != testDataSize {
+		t.Fatalf("Slice size error got %d, expected %d.", n, testDataSize)
 	}
 	if !bytes.Equal(slice, resultSlice) {
 		t.Fatalf("Comparison error.")
@@ -114,9 +116,9 @@ func testFileStoreCapacity(toEncrypt bool, t *testing.T) {
 		DbStore:  db,
 	}
 	fileStore := NewFileStore(localStore, NewFileStoreParams())
-	reader, slice := GenerateRandomData(testDataSize)
+	slice := testutil.RandomBytes(1, testDataSize)
 	ctx := context.TODO()
-	key, wait, err := fileStore.Store(ctx, reader, testDataSize, toEncrypt)
+	key, wait, err := fileStore.Store(ctx, bytes.NewReader(slice), testDataSize, toEncrypt)
 	if err != nil {
 		t.Errorf("Store error: %v", err)
 	}
diff --git a/swarm/storage/types.go b/swarm/storage/types.go
index 092843db0..42557766e 100644
--- a/swarm/storage/types.go
+++ b/swarm/storage/types.go
@@ -25,7 +25,6 @@ import (
 	"fmt"
 	"hash"
 	"io"
-	"io/ioutil"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
@@ -251,16 +250,6 @@ func GenerateRandomChunks(dataSize int64, count int) (chunks []Chunk) {
 	return chunks
 }
 
-func GenerateRandomData(l int) (r io.Reader, slice []byte) {
-	slice, err := ioutil.ReadAll(io.LimitReader(rand.Reader, int64(l)))
-	if err != nil {
-		panic("rand error")
-	}
-	// log.Warn("generate random data", "len", len(slice), "data", common.Bytes2Hex(slice))
-	r = io.LimitReader(bytes.NewReader(slice), int64(l))
-	return r, slice
-}
-
 // Size, Seek, Read, ReadAt
 type LazySectionReader interface {
 	Context() context.Context
diff --git a/swarm/testutil/file.go b/swarm/testutil/file.go
index ecb0d971e..70732aa92 100644
--- a/swarm/testutil/file.go
+++ b/swarm/testutil/file.go
@@ -17,8 +17,10 @@
 package testutil
 
 import (
+	"bytes"
 	"io"
 	"io/ioutil"
+	"math/rand"
 	"os"
 	"strings"
 	"testing"
@@ -42,3 +44,22 @@ func TempFileWithContent(t *testing.T, content string) string {
 	}
 	return tempFile.Name()
 }
+
+// RandomBytes returns pseudo-random deterministic result
+// because test fails must be reproducible
+func RandomBytes(seed, length int) []byte {
+	b := make([]byte, length)
+	reader := rand.New(rand.NewSource(int64(seed)))
+	for n := 0; n < length; {
+		read, err := reader.Read(b[n:])
+		if err != nil {
+			panic(err)
+		}
+		n += read
+	}
+	return b
+}
+
+func RandomReader(seed, length int) *bytes.Reader {
+	return bytes.NewReader(RandomBytes(seed, length))
+}