use fips-compliant hash for K8sNameHash func (#35)

* add unit-test for K8sNameHash

On-behalf-of: SAP <simon.bein@sap.com>
Signed-off-by: Simon Bein <simontheleg@gmail.com>

* use fips-compliant sha256 hash

On-behalf-of: SAP <simon.bein@sap.com>
Signed-off-by: Simon Bein <simontheleg@gmail.com>

---------

Signed-off-by: Simon Bein <simontheleg@gmail.com>

Author: SimonTheLeg

pkg/controller/utils.go

@@ -1,7 +1,7 @@
 package controller
 
 import (
-	"crypto/sha1"
+	"crypto/sha256"
 	"encoding/base32"
 	"reflect"
 	"strings"
@@ -10,15 +10,16 @@ import (
 )
 
 const (
-	maxLength                int = 63
-	Base32EncodeStdLowerCase     = "abcdefghijklmnopqrstuvwxyz234567"
+	Base32EncodeStdLowerCase = "abcdefghijklmnopqrstuvwxyz234567"
 )
 
-// K8sNameHash takes any number of string arguments and computes a hash out of it, which is then base32-encoded to be a valid k8s resource name.
+// K8sNameHash takes any number of string arguments and computes a hash out of it, which is then base32-encoded to be a valid DNS1123Subdomain k8s resource name
 // The arguments are joined with '/' before being hashed.
 func K8sNameHash(ids ...string) string {
 	name := strings.Join(ids, "/")
-	h := sha1.New()
+	// since we are not worried about length-extension attacks (in fact we are not even using hashing for
+	// any security purposes), use sha2 for better performance compared to sha3
+	h := sha256.New()
 	_, _ = h.Write([]byte(name))
 	// we need base32 encoding as some base64 (even url safe base64) characters are not supported by k8s
 	// see https://kubernetes.io/docs/concepts/overview/working-with-objects/names/

pkg/controller/utils_test.go

@@ -0,0 +1,50 @@
+package controller
+
+import (
+	"fmt"
+	"testing"
+
+	"k8s.io/apimachinery/pkg/util/validation"
+)
+
+func TestK8sNameHash(t *testing.T) {
+	tt := []struct {
+		input   []string
+		expHash string
+	}{
+		{
+			[]string{"test1"},
+			"dnhq5gcrs4mzrzzsa6cujsllg3b5ahhn67fkgmrvtvxr3a2woaka",
+		},
+		{
+			// check that the same string produces the same hash
+			[]string{"test1"},
+			"dnhq5gcrs4mzrzzsa6cujsllg3b5ahhn67fkgmrvtvxr3a2woaka",
+		},
+		{
+			[]string{"bla"},
+			"jxz4h5upzsb3e7u5ileqimnhesm7c6dvzanftg2wnsmitoljm4bq",
+		},
+		{
+			[]string{"some other test", "this is a very, very long string"},
+			"rjphpfjbmwn6qqydv6xhtmj3kxrlzepn2tpwy4okw2ypoc3nlffq",
+		},
+	}
+
+	for _, tc := range tt {
+		t.Run(fmt.Sprint(tc.input), func(t *testing.T) {
+			res := K8sNameHash(tc.input...)
+
+			if res != tc.expHash {
+				t.Errorf("exp hash %q, got %q", tc.expHash, res)
+			}
+
+			// ensure the result is a valid DNS1123Subdomain
+			if errs := validation.IsDNS1123Subdomain(res); errs != nil {
+				t.Errorf("value %q is invalid: %v", res, errs)
+			}
+
+		})
+	}
+
+}