From 0cf535b26c8989a60df646f64dfcb14b59de1a86 Mon Sep 17 00:00:00 2001 From: drebs Date: Tue, 26 Dec 2017 08:48:18 -0200 Subject: [doc] improve documentation of ciphertext size estimation function --- src/leap/soledad/client/_crypto.py | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/src/leap/soledad/client/_crypto.py b/src/leap/soledad/client/_crypto.py index ce166c94..ab5fe881 100644 --- a/src/leap/soledad/client/_crypto.py +++ b/src/leap/soledad/client/_crypto.py @@ -541,9 +541,17 @@ def _ceiling(size): def get_unarmored_ciphertext_size(cleartext_size): - # used for blobs stream up (so we can tell the server how much data we are - # sending before starting to encrypt the stream) + """ + Get the (unarmored) ciphertext size from the cleartext size. + + In some cases (when streaming uploads, for example) we need to tell the + server how much data we are sending before starting to encrypt the stream. + This function returns the final size of what will be streamed from the + total size of the cleartext. + """ tag_size = 16 # AES-GCM 16-byte tag appended to ciphertext separator_size = 1 # space separating content from preamble size = tag_size + PREAMBLE_SIZE + separator_size + # without considering the preamble and tag, the ciphertext size is equal to + # the cleartext size. return cleartext_size + size -- cgit v1.2.3