From 8ede3ae29a39641a2f98ad9a4cf61ea99085a892 Mon Sep 17 00:00:00 2001 From: Daniel Kahn Gillmor Date: Thu, 28 Sep 2017 08:32:26 -0400 Subject: gpg: default-preference-list: prefer SHA512. * g10/keygen.c (keygen_set_std_prefs): when producing default internal personal-digest-preferences, keep the same order. When publishing external preferences, state preference for SHA512 first. -- SHA-512 has a wider security margin than SHA-256. It is also slightly faster on most of the architectures on which GnuPG runs today. New keys should publish defaults that indicate we prefer the stronger, more performant digest. Specifically, this changes --default-preference-list from: SHA256 SHA384 SHA512 SHA224 to: SHA512 SHA384 SHA256 SHA224 This patch deliberately avoids touching --personal-digest-preferences (which itself would affect the default of --digest-algo and --cert-digest-algo), so that public-facing cleartext signatures and identity certifications will continue to be made with SHA256 by default. Signed-off-by: Daniel Kahn Gillmor --- g10/keygen.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/g10/keygen.c b/g10/keygen.c index 38686b213..7ef3cac1d 100644 --- a/g10/keygen.c +++ b/g10/keygen.c @@ -384,19 +384,36 @@ keygen_set_std_prefs (const char *string,int personal) strcat(dummy_string,"S7 "); strcat(dummy_string,"S2 "); /* 3DES */ - /* The default hash algo order is: - SHA-256, SHA-384, SHA-512, SHA-224, SHA-1. - */ - if (!openpgp_md_test_algo (DIGEST_ALGO_SHA256)) - strcat (dummy_string, "H8 "); + if (personal) + { + /* The default internal hash algo order is: + * SHA-256, SHA-384, SHA-512, SHA-224, SHA-1. + */ + if (!openpgp_md_test_algo (DIGEST_ALGO_SHA256)) + strcat (dummy_string, "H8 "); + + if (!openpgp_md_test_algo (DIGEST_ALGO_SHA384)) + strcat (dummy_string, "H9 "); + + if (!openpgp_md_test_algo (DIGEST_ALGO_SHA512)) + strcat (dummy_string, "H10 "); + } + else + { + /* The default advertised hash algo order is: + * SHA-512, SHA-384, SHA-256, SHA-224, SHA-1. + */ + if (!openpgp_md_test_algo (DIGEST_ALGO_SHA512)) + strcat (dummy_string, "H10 "); - if (!openpgp_md_test_algo (DIGEST_ALGO_SHA384)) - strcat (dummy_string, "H9 "); + if (!openpgp_md_test_algo (DIGEST_ALGO_SHA384)) + strcat (dummy_string, "H9 "); - if (!openpgp_md_test_algo (DIGEST_ALGO_SHA512)) - strcat (dummy_string, "H10 "); + if (!openpgp_md_test_algo (DIGEST_ALGO_SHA256)) + strcat (dummy_string, "H8 "); + } - if (!openpgp_md_test_algo (DIGEST_ALGO_SHA224)) + if (!openpgp_md_test_algo (DIGEST_ALGO_SHA224)) strcat (dummy_string, "H11 "); strcat (dummy_string, "H2 "); /* SHA-1 */ -- cgit v1.2.3