From 9116fd1e9a2da9c83f94acfe41fb6e5c6f03e8d1 Mon Sep 17 00:00:00 2001 From: Jussi Kivilinna Date: Tue, 8 Feb 2022 18:31:54 +0200 Subject: [PATCH] g10: Avoid extra hash contexts when decrypting MDC input * g10/mainproc.c (mainproc_context): New member 'seen_pkt_encrypted_mdc'. (release_list): Clear 'seen_pkt_encrypted_mdc'. (proc_encrypted): Set 'seen_pkt_encrypted_mdc'. (have_seen_pkt_encrypted_aead): Rename to... (have_seen_pkt_encrypted_aead_or_mdc): ...this and add check for 'seen_pkt_encrypted_mdc'. (proc_plaintext): Do not enable extra hash contexts when decrypting MDC input. -- Avoiding extra hash contexts speeds up CFB/MDC decryption quite a lot. For example, decrypting symmetric-key AES-256 encrypted 4 GiB file from RAM to /dev/null sees ~3.4x speed increase on AMD Ryzen 5800X: AES256.CFB encryption: 783 MB/s AES256.CFB decryption: 386 MB/s (before) AES256.CFB encryption: 1.3 GB/s (after patch) Note, AEAD is still significantly faster: AES256.OCB encryption: 2.2 GB/s AES256.OCB decryption: 3.0 GB/s GnuPG-bug-id: T5820 Signed-off-by: Jussi Kivilinna (cherry picked from commit ab177eed514f7f3432d78e7e6521ad24cc0f4762) Even 2.2 with the older Libgcrypt 1.8 gets a threefold speedup; see https://dev.gnupg.org/T5820#155447 (AES-128 vs. AES-256 does not make a substanial difference) Signed-off-by: Werner Koch --- g10/mainproc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/g10/mainproc.c b/g10/mainproc.c index b032afb8b..871403ad7 100644 --- a/g10/mainproc.c +++ b/g10/mainproc.c @@ -98,6 +98,7 @@ struct mainproc_context ulong symkeys; /* Number of symmetrically encrypted session keys. */ struct kidlist_item *pkenc_list; /* List of encryption packets. */ int seen_pkt_encrypted_aead; /* PKT_ENCRYPTED_AEAD packet seen. */ + int seen_pkt_encrypted_mdc; /* PKT_ENCRYPTED_MDC packet seen. */ struct { unsigned int sig_seen:1; /* Set to true if a signature packet has been seen. */ @@ -147,6 +148,7 @@ release_list( CTX c ) c->any.uncompress_failed = 0; c->last_was_session_key = 0; c->seen_pkt_encrypted_aead = 0; + c->seen_pkt_encrypted_mdc = 0; xfree (c->dek); c->dek = NULL; } @@ -639,6 +641,8 @@ proc_encrypted (CTX c, PACKET *pkt) if (pkt->pkttype == PKT_ENCRYPTED_AEAD) c->seen_pkt_encrypted_aead = 1; + if (pkt->pkttype == PKT_ENCRYPTED_MDC) + c->seen_pkt_encrypted_mdc = 1; if (early_plaintext) { @@ -864,7 +868,7 @@ proc_encrypted (CTX c, PACKET *pkt) static int -have_seen_pkt_encrypted_aead( CTX c ) +have_seen_pkt_encrypted_aead_or_mdc( CTX c ) { CTX cc; @@ -872,6 +876,8 @@ have_seen_pkt_encrypted_aead( CTX c ) { if (cc->seen_pkt_encrypted_aead) return 1; + if (cc->seen_pkt_encrypted_mdc) + return 1; } return 0; @@ -953,7 +959,7 @@ proc_plaintext( CTX c, PACKET *pkt ) } } - if (!any && !opt.skip_verify && !have_seen_pkt_encrypted_aead(c)) + if (!any && !opt.skip_verify && !have_seen_pkt_encrypted_aead_or_mdc(c)) { /* This is for the old GPG LITERAL+SIG case. It's not legal according to 2440, so hopefully it won't come up that often.