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gpg: Use 128 MiB as default AEAD chunk size.

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* g10/gpg.c (oDebugAllowLargeChunks): New.
(opts): New option --debug-allow-large-chunks.
(main): Implement that option.
--

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2018-07-24 09:50:02 +02:00
parent 1c9584dabb
commit 9aa1b368ef
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
2 changed files with 20 additions and 7 deletions
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14
doc/gpg.texi
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@ -2258,9 +2258,8 @@ The AEAD encryption mode encrypts the data in chunks so that a
receiving side can check for transmission errors or tampering at the
end of each chunk and does not need to delay this until all data has
been received. The used chunk size is 2^@var{n} byte. The lowest
allowed value for @var{n} is 6 (64 byte) and the largest is 62 (4
EiB). The default value for @var{n} is 30 which creates chunks not
larger than 1 GiB.
allowed value for @var{n} is 6 (64 byte) and the largest is the
default of 27 which creates chunks not larger than 128 MiB.
@item --input-size-hint @var{n}
@opindex input-size-hint
@ -2621,7 +2620,7 @@ to declare that a not yet standardized feature is used.
@opindex disable-mdc
These options are obsolete and have no effect since GnuPG 2.2.8. The
MDC is always used unless the keys indicate that an AEAD algorithm can
be used in which case AEAD is used. But note: If the creation or of a
be used in which case AEAD is used. But note: If the creation of a
legacy non-MDC message is exceptionally required, the option
@option{--rfc2440} allows for this.
@ -2862,6 +2861,13 @@ Change the buffer size of the IOBUFs to @var{n} kilobyte. Using 0
prints the current size. Note well: This is a maintainer only option
and may thus be changed or removed at any time without notice.
@item --debug-allow-large-chunks
@opindex debug-allow-large-chunks
To facilitate in-memory decryption on the receiving site, the largest
recommended chunk size is 128 MiB (@code{--chunk-size 27}). This
option allows to specify a limit of up to 4 EiB (@code{--chunk-size
62}) for experiments.
@item --faked-system-time @var{epoch}
@opindex faked-system-time
This option is only useful for testing; it sets the system time back or

13
g10/gpg.c
View File

@ -225,6 +225,7 @@ enum cmd_and_opt_values
oDebugAll,
oDebugIOLBF,
oDebugSetIobufSize,
oDebugAllowLargeChunks,
oStatusFD,
oStatusFile,
oAttributeFD,
@ -634,6 +635,7 @@ static ARGPARSE_OPTS opts[] = {
ARGPARSE_s_n (oDebugAll, "debug-all", "@"),
ARGPARSE_s_n (oDebugIOLBF, "debug-iolbf", "@"),
ARGPARSE_s_u (oDebugSetIobufSize, "debug-set-iobuf-size", "@"),
ARGPARSE_s_u (oDebugAllowLargeChunks, "debug-allow-large-chunks", "@"),
ARGPARSE_s_i (oStatusFD, "status-fd", "@"),
ARGPARSE_s_s (oStatusFile, "status-file", "@"),
ARGPARSE_s_i (oAttributeFD, "attribute-fd", "@"),
@ -2347,6 +2349,7 @@ main (int argc, char **argv)
static int print_dane_records;
static int print_pka_records;
static int allow_large_chunks;
#ifdef __riscos__
@ -2761,6 +2764,10 @@ main (int argc, char **argv)
opt_set_iobuf_size_used = 1;
break;
case oDebugAllowLargeChunks:
allow_large_chunks = 1;
break;
case oStatusFD:
set_status_fd ( translate_sys2libc_fd_int (pargs.r.ret_int, 1) );
break;
@ -3884,15 +3891,15 @@ main (int argc, char **argv)
/* Check chunk size. Please fix also the man page if you chnage
* the default. The limits are given by the specs. */
if (!opt.chunk_size)
opt.chunk_size = 30; /* Default to 1 GiB chunks. */
opt.chunk_size = 27; /* Default to the suggested max of 128 MiB. */
else if (opt.chunk_size < 6)
{
opt.chunk_size = 6;
log_info (_("chunk size invalid - using %d\n"), opt.chunk_size);
}
else if (opt.chunk_size > 62)
else if (opt.chunk_size > (allow_large_chunks? 62 : 27))
{
opt.chunk_size = 62;
opt.chunk_size = (allow_large_chunks? 62 : 27);
log_info (_("chunk size invalid - using %d\n"), opt.chunk_size);
}