From 45d5f5800afe6613f338a26f361cb5e03e861129 Mon Sep 17 00:00:00 2001 From: Werner Koch Date: Sun, 27 Aug 2017 16:42:52 +0200 Subject: [PATCH] scd: Convey the correct length for Le * scd/app-openpgp.c (determine_rsa_response): Round bits up. -- Co-authored-by: Arnaud Fontaine Arnaud wrote: Actually, when the incorrect expected response length (i.e. Le field) is transmitted to the card, the card's answer is missing a byte (i.e. ... 6101) so an additional command has to be sent to the card to retrieve the last byte. Using the correct length avoids to send the additional command to retrieve the missing byte, when the computed length is wrong. Note that an value of 65537 for E is pretty standard and thus we can avoid the 6101 return code inmost cases. Signed-off-by: Werner Koch --- scd/app-openpgp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/scd/app-openpgp.c b/scd/app-openpgp.c index 365f24649..f9d07ac46 100644 --- a/scd/app-openpgp.c +++ b/scd/app-openpgp.c @@ -943,8 +943,8 @@ determine_rsa_response (app_t app, int keyno) int size; size = 2 + 3 /* header */ - + 4 /* tag+len */ + app->app_local->keyattr[keyno].rsa.n_bits/8 - + 2 /* tag+len */ + app->app_local->keyattr[keyno].rsa.e_bits/8; + + 4 /* tag+len */ + (app->app_local->keyattr[keyno].rsa.n_bits+7)/8 + + 2 /* tag+len */ + (app->app_local->keyattr[keyno].rsa.e_bits+7)/8; return size; }