From b0b73ac7dae5fd4fa9c738c89d9a46fda42c8ff0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philipp=20H=C3=B6rist?= Date: Fri, 17 Jan 2020 22:49:19 +0100 Subject: [PATCH] [preview] Add back 12 byte IV read support --- url_image_preview/utils.py | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/url_image_preview/utils.py b/url_image_preview/utils.py index 830bb6e..4148769 100644 --- a/url_image_preview/utils.py +++ b/url_image_preview/utils.py @@ -271,10 +271,19 @@ def parse_fragment(fragment): raise ValueError('Invalid fragment') fragment = binascii.unhexlify(fragment) - key = fragment[16:] - iv = fragment[:16] - if len(key) != 32 or len(iv) != 16: - raise ValueError('Invalid fragment') + size = len(fragment) + # Clients started out with using a 16 byte IV but long term + # want to swtich to the more performant 12 byte IV + # We have to support both + if size == 48: + key = fragment[16:] + iv = fragment[:16] + elif size == 44: + key = fragment[12:] + iv = fragment[:12] + else: + raise ValueError('Invalid fragment size: %s' % size) + return key, iv