use more official blake2b checksum

admin/sync/exercice_hints.go

@@ -2,6 +2,7 @@ package sync
 
 import (
 	"bufio"
+	"crypto"
 	"encoding/hex"
 	"fmt"
 	"io"
@@ -11,7 +12,7 @@ import (
 
 	"srs.epita.fr/fic-server/libfic"
 
-	"github.com/dchest/blake2b"
+	_ "golang.org/x/crypto/blake2b"
 )
 
 func SyncExerciceHints(i Importer, exercice fic.Exercice) (errs []string) {
@@ -52,7 +53,7 @@ func SyncExerciceHints(i Importer, exercice fic.Exercice) (errs []string) {
 				// Handle big files as downloadable content
 				if res, err := i.importFile(path.Join(exercice.Path, "hints", hfile), func(filePath string, origin string) (interface{}, error) {
 					// Calculate hash
-					hash512 := blake2b.New512()
+					hash512 := crypto.BLAKE2b_512.New()
 					if fd, err := os.Open(filePath); err != nil {
 						return nil, err
 					} else {