diff --git a/taiga/projects/attachments/migrations/0005_attachment_sha1.py b/taiga/projects/attachments/migrations/0005_attachment_sha1.py
new file mode 100644
index 00000000..c67043e1
--- /dev/null
+++ b/taiga/projects/attachments/migrations/0005_attachment_sha1.py
@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('attachments', '0004_auto_20150508_1141'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='attachment',
+            name='sha1',
+            field=models.CharField(default='', verbose_name='sha1', max_length=40, blank=True),
+            preserve_default=True,
+        ),
+    ]
\ No newline at end of file
diff --git a/taiga/projects/attachments/models.py b/taiga/projects/attachments/models.py
index 61c590e4..30fa5c22 100644
--- a/taiga/projects/attachments/models.py
+++ b/taiga/projects/attachments/models.py
@@ -68,6 +68,7 @@ class Attachment(models.Model):
                                      upload_to=get_attachment_file_path,
                                      verbose_name=_("attached file"))
 
+    sha1 = models.CharField(default="", max_length=40, verbose_name=_("sha1"), blank=True)
 
     is_deprecated = models.BooleanField(default=False, verbose_name=_("is deprecated"))
     description = models.TextField(null=False, blank=True, verbose_name=_("description"))
@@ -83,11 +84,30 @@ class Attachment(models.Model):
             ("view_attachment", "Can view attachment"),
         )
 
+    def __init__(self, *args, **kwargs):
+        super(Attachment, self).__init__(*args, **kwargs)
+        self._orig_attached_file = self.attached_file
+
+    def _generate_sha1(self, blocksize=65536):
+        hasher = hashlib.sha1()
+        while True:
+            buff = self.attached_file.file.read(blocksize)
+            if not buff:
+                break
+            hasher.update(buff)
+        self.sha1 = hasher.hexdigest()
+
     def save(self, *args, **kwargs):
         if not self._importing or not self.modified_date:
             self.modified_date = timezone.now()
-
-        return super().save(*args, **kwargs)
+        if self.attached_file:
+            if not self.sha1 or self.attached_file != self._orig_attached_file:
+                self._generate_sha1()
+        save = super().save(*args, **kwargs)
+        self._orig_attached_file = self.attached_file
+        if self.attached_file:
+            self.attached_file.file.close()
+        return save
 
     def __str__(self):
         return "Attachment: {}".format(self.id)
diff --git a/taiga/projects/attachments/serializers.py b/taiga/projects/attachments/serializers.py
index 878b0e3c..f255fa8e 100644
--- a/taiga/projects/attachments/serializers.py
+++ b/taiga/projects/attachments/serializers.py
@@ -34,8 +34,8 @@ class AttachmentSerializer(serializers.ModelSerializer):
         model = models.Attachment
         fields = ("id", "project", "owner", "name", "attached_file", "size", "url",
                   "description", "is_deprecated", "created_date", "modified_date",
-                  "object_id", "order")
-        read_only_fields = ("owner", "created_date", "modified_date")
+                  "object_id", "order", "sha1")
+        read_only_fields = ("owner", "created_date", "modified_date", "sha1")
 
     def get_url(self, obj):
-        return obj.attached_file.url
+        return obj.attached_file.url
\ No newline at end of file