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95 Commits

Author SHA1 Message Date
Denys Vlasenko
446d136109 tls: tweak debug printout 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-11-27 12:03:43 +01:00
Denys Vlasenko
3b411ebbfc tls: replace "26-bit" P256 code with 32-bit one. 
function                                             old     new   delta
sp_256_ecc_mulmod_8                                    -    1171   +1171
sp_256_mod_mul_norm_8                                  -     834    +834
sp_256_proj_point_dbl_8                                -     374    +374
sp_256_mont_reduce_8                                   -     268    +268
sp_256_mont_mul_8                                      -     151    +151
sp_256_sub_8                                           -      76     +76
sp_256_add_8                                           -      76     +76
sp_256_cmp_8                                           -      38     +38
static.sp_256_mont_dbl_8                               -      31     +31
static.sp_256_mont_sub_8                               -      29     +29
sp_256_to_bin_8                                        -      28     +28
sp_256_point_from_bin2x32                             50      73     +23
sp_256_mont_sqr_8                                      -       7      +7
sp_256_mont_sqr_10                                     7       -      -7
p256_mod                                              40      32      -8
curve_P256_compute_pubkey_and_premaster              186     167     -19
sp_256_sub_10                                         22       -     -22
sp_256_add_10                                         22       -     -22
sp_256_cmp_10                                         24       -     -24
sp_256_norm_10                                        31       -     -31
static.sp_256_mont_sub_10                             49       -     -49
static.sp_256_mont_dbl_10                             52       -     -52
static.sp_256_mul_add_10                              82       -     -82
sp_256_from_bin_10                                   119       -    -119
sp_256_to_bin_10                                     120       -    -120
sp_256_mont_reduce_10                                178       -    -178
sp_256_mont_mul_10                                   214       -    -214
sp_256_proj_point_dbl_10                             451       -    -451
sp_256_ecc_mulmod_10                                1216       -   -1216
sp_256_mod_mul_norm_10                              1305       -   -1305
------------------------------------------------------------------------------
(add/remove: 12/15 grow/shrink: 1/2 up/down: 3106/-3919)     Total: -813 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-10-05 20:01:38 +02:00
Denys Vlasenko
55578f2fb7 tls: fix the case of sp_256_mont_tpl_10() leaving striay high bits 
It has no effect on correctness, but interferes with compating internal state
of different implementations.

function                                             old     new   delta
sp_256_proj_point_dbl_10                             443     451      +8
static.sp_256_mont_sub_10                             46      49      +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 11/0)               Total: 11 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-10-05 19:46:39 +02:00
Denys Vlasenko
934bb01d51 tls: "server cert is not RSA" is a fatal error 
function                                             old     new   delta
tls_handshake                                       2022    2019      -3

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-10-01 22:03:09 +02:00
Denys Vlasenko
1f5a44d20c tls: add scaffolding to selectively disable ciphers. no code changes 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-10-01 14:27:10 +02:00
Denys Vlasenko
6b69ab68b4 tls: make x25519 key generation code more similar to P256 
function                                             old     new   delta
curve_x25519_compute_pubkey_and_premaster              -      74     +74
tls_handshake                                       2146    2072     -74
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/1 up/down: 74/-74)              Total: 0 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-04-26 13:46:36 +02:00
Denys Vlasenko
f18a1fd6f3 tls: implement secp256r1 elliptic curve (aka P256) 
function                                             old     new   delta
sp_256_mod_mul_norm_10                                 -    1439   +1439
sp_256_ecc_mulmod_10                                   -    1363   +1363
sp_256_proj_point_dbl_10                               -     490    +490
p256_base                                              -     244    +244
static.sp_256_mont_sqr_10                              -     234    +234
static.sp_256_mont_mul_10                              -     214    +214
curve_P256_compute_pubkey_and_premaster                -     197    +197
static.sp_256_mont_reduce_10                           -     176    +176
static.sp_256_from_bin                                 -     149    +149
sp_256_to_bin                                          -     148    +148
tls_handshake                                       2046    2146    +100
static.sp_256_mul_add_10                               -      82     +82
.rodata                                           103275  103336     +61
static.sp_256_mont_sub_10                              -      52     +52
static.sp_256_mont_dbl_10                              -      52     +52
static.sp_256_cmp_10                                   -      43     +43
p256_mod                                               -      40     +40
static.sp_256_cond_sub_10                              -      32     +32
p256_mod_2                                             -      32     +32
sp_256_norm_10                                         -      31     +31
sp_256_cmp_equal_10                                    -      30     +30
sp_256_add_10                                          -      22     +22
addr_mask                                              -       8      +8
------------------------------------------------------------------------------
(add/remove: 22/0 grow/shrink: 2/0 up/down: 5239/0)          Total: 5239 bytes
   text	   data	    bss	    dec	    hex	filename
1018192	    559	   5020	1023771	  f9f1b	busybox_old
1023431	    559	   5020	1029010	  fb392	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-04-26 13:30:09 +02:00
Denys Vlasenko
6ca36077cc tls: "server did not provide EC key" is fatal 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-04-24 11:56:49 +02:00
Denys Vlasenko
972e29881a tls: make constant basepoint9[32] array 8-byte aligned 
Has no effect on binary size, but likely to be more efficient.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2021-04-22 10:25:04 +02:00
Denys Vlasenko
965b795b87 decrease paddign: gcc-9.3.1 slaps 32-byte alignment on arrays willy-nilly 
text	   data	    bss	    dec	    hex	filename
1021988	    559	   5052	1027599	  fae0f	busybox_old
1021236	    559	   5052	1026847	  fab1f	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2020-11-30 13:03:03 +01:00
Denys Vlasenko
9a2d899273 ntpd: fix refid reported in server mode, closes 13056 
function                                             old     new   delta
resolve_peer_hostname                                129     196     +67
recv_and_process_peer_pkt                           2475    2476      +1
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 68/0)               Total: 68 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2020-07-20 00:04:33 +02:00
James Byrne
6937487be7 libbb: reduce the overhead of single parameter bb_error_msg() calls 
Back in 2007, commit 0c97c9d437 ("'simple' error message functions by
Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower
overhead call to bb_perror_msg() when only a string was being printed
with no parameters. This saves space for some CPU architectures because
it avoids the overhead of a call to a variadic function. However there
has never been a simple version of bb_error_msg(), and since 2007 many
new calls to bb_perror_msg() have been added that only take a single
parameter and so could have been using bb_simple_perror_message().

This changeset introduces 'simple' versions of bb_info_msg(),
bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and
bb_herror_msg_and_die(), and replaces all calls that only take a
single parameter, or use something like ("%s", arg), with calls to the
corresponding 'simple' version.

Since it is likely that single parameter calls to the variadic functions
may be accidentally reintroduced in the future a new debugging config
option WARN_SIMPLE_MSG has been introduced. This uses some macro magic
which will cause any such calls to generate a warning, but this is
turned off by default to avoid use of the unpleasant macros in normal
circumstances.

This is a large changeset due to the number of calls that have been
replaced. The only files that contain changes other than simple
substitution of function calls are libbb.h, libbb/herror_msg.c,
libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c,
networking/udhcp/common.h and util-linux/mdev.c additonal macros have
been added for logging so that single parameter and multiple parameter
logging variants exist.

The amount of space saved varies considerably by architecture, and was
found to be as follows (for 'defconfig' using GCC 7.4):

Arm:     -92 bytes
MIPS:    -52 bytes
PPC:   -1836 bytes
x86_64: -938 bytes

Note that for the MIPS architecture only an exception had to be made
disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h)
because it made these files larger on MIPS.

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2019-07-02 11:35:03 +02:00
Denys Vlasenko
84fc645605 *: slap on a few ALIGN1/2s where appropriate 
The result of looking at "grep -F -B2 '*fill*' busybox_unstripped.map"

   text	   data	    bss	    dec	    hex	filename
 952537	    485	   7296	 960318	  ea73e	busybox_old
 952527	    485	   7296	 960308	  ea734	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2019-05-21 17:29:24 +02:00
Denys Vlasenko
959b04bc0e tls: add comment about dl.fedoraproject.org needing secp256r1 ECC curve 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2019-01-08 16:09:41 +01:00
Denys Vlasenko
3a4d5a73a8 tls: prepare for ECDH_anon ciphers 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-12-10 19:19:38 +01:00
Denys Vlasenko
c67ff8a1b0 tls: fix a potential (currently "disabled" by a macro) SHA1-related bug 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-12-10 18:49:29 +01:00
Denys Vlasenko
63bfe0e4c0 tls: if !ENABLE_FEATURE_TLS_SHA1, tls->MAC_size is always SHA256_OUTSIZE for AES-CBC 
function                                             old     new   delta
tls_xread_record                                     634     636      +2
xwrite_encrypted                                     579     580      +1
tls_handshake                                       2095    2085     -10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 3/-10)              Total: -7 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-12-10 16:43:53 +01:00
Denys Vlasenko
71fa5b0a4c tls: introduce FEATURE_TLS_SHA1 to make SHA1 code optional 
When disabled:

function                                             old     new   delta
xwrite_encrypted                                     580     579      -1
prf_hmac_sha256                                      222     217      -5
hmac_begin                                           158     149      -9
static.ciphers                                        32      20     -12
tls_handshake                                       2115    2095     -20
hmac                                                  87      61     -26
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/6 up/down: 0/-73)             Total: -73 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-12-10 16:14:58 +01:00
Denys Vlasenko
dffc8ff6a6 tls: add ECDHE_PSK and remove ARIA cipher ids 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-27 10:35:10 +01:00
Denys Vlasenko
8a46c74f8d tls: add _anon_ cipher definitions 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-26 17:33:17 +01:00
Denys Vlasenko
2eb04290f9 tls: enable TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 cipher 
function                                             old     new   delta
static.ciphers                                        30      32      +2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-26 16:39:35 +01:00
Denys Vlasenko
60f784027e tls: cipher 009D is not yet supported, don't test for it 
function                                             old     new   delta
tls_handshake                                       2116    2108      -8

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-26 16:30:22 +01:00
Denys Vlasenko
d9f6c3b091 tls: speed up prf_hmac_sha256() 
function                                             old     new   delta
hmac_sha_precomputed                                   -      58     +58
prf_hmac_sha256                                      181     222     +41
hmac_sha256                                           68       -     -68
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 1/0 up/down: 99/-68)             Total: 31 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-26 15:55:41 +01:00
Denys Vlasenko
d4681c7293 tls: simplify hmac_begin() 
function                                             old     new   delta
hmac_begin                                           196     158     -38

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-26 10:33:23 +01:00
Denys Vlasenko
ca7cdd4b03 tls: add support for 8 more cipher ids - all tested to work 
function                                             old     new   delta
tls_handshake                                       2059    2116     +57
static.ciphers                                         -      30     +30
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/0 up/down: 87/0)               Total: 87 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-26 00:17:10 +01:00
Denys Vlasenko
838b88c044 tls: fix comments 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-25 18:52:47 +01:00
Denys Vlasenko
330d7f53f7 tls: add a comment on expanding list of supported ciphers 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-25 17:27:48 +01:00
Denys Vlasenko
a6192f347f tls: do not leak RSA key 
function                                             old     new   delta
tls_handshake                                       1957    2059    +102

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-25 16:17:26 +01:00
Denys Vlasenko
eb53d01be5 tls: code shrink 
function                                             old     new   delta
xwrite_and_update_handshake_hash                      81      80      -1
tls_handshake                                       1987    1957     -30

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-25 14:45:55 +01:00
Denys Vlasenko
a33b008240 tls: code shrink 
function                                             old     new   delta
tls_handshake                                       1993    1987      -6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-25 14:28:32 +01:00
Denys Vlasenko
be5ca42e8d tls: code shrink 
function                                             old     new   delta
aesgcm_GHASH                                         223     196     -27

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-25 14:03:59 +01:00
Denys Vlasenko
ab3c5e4c44 tls: actually fill in CIPHER_ID3 value in hello message 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-25 00:53:19 +01:00
Denys Vlasenko
d2923b3d23 tls: fix is.gd again, fix AES-CBC using decrypt key instead of encrypt 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-24 21:26:20 +01:00
Denys Vlasenko
03569bc50f tls: speed up xor'ing of aligned 16-byte buffers 
function                                             old     new   delta
xorbuf_aligned_AES_BLOCK_SIZE                          -      23     +23
xwrite_encrypted                                     585     580      -5
aesgcm_GHASH                                         233     228      -5
GMULT                                                192     187      -5
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/3 up/down: 23/-15)              Total: 8 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-24 14:08:29 +01:00
Denys Vlasenko
941440cf16 tls: in AES-GCM decoding, avoid memmove 
function                                             old     new   delta
xorbuf3                                                -      36     +36
xorbuf                                                24      12     -12
tls_xread_record                                     656     634     -22
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/2 up/down: 36/-34)              Total: 2 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-24 13:51:46 +01:00
Denys Vlasenko
624066f0cc tls: make tls_get_random() FAST_FUNC 
function                                             old     new   delta
tls_handshake                                       1977    1985      +8
tls_get_random                                        32      28      -4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 8/-4)                Total: 4 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-23 19:24:57 +01:00
Denys Vlasenko
219c9d4b5d tls: code shrink 
function                                             old     new   delta
xwrite_encrypted                                     599     585     -14

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-23 18:48:20 +01:00
Denys Vlasenko
ecc9090cfc tls: simplify aesgcm_GHASH() 
function                                             old     new   delta
xwrite_encrypted                                     604     599      -5
FlattenSzInBits                                       52       -     -52
aesgcm_GHASH                                         395     262    -133
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 0/2 up/down: 0/-190)           Total: -190 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-23 18:31:26 +01:00
Denys Vlasenko
5e4236d226 tls: in AES-CBC code, do not set key for every record - do it once 
function                                             old     new   delta
aes_setkey                                            16     212    +196
tls_handshake                                       1941    1977     +36
aes_encrypt_1                                        382     396     +14
xwrite_encrypted                                     605     604      -1
tls_xread_record                                     659     656      -3
aes_encrypt_one_block                                 65      59      -6
aes_cbc_encrypt                                      172     121     -51
aesgcm_setkey                                         58       -     -58
aes_cbc_decrypt                                      958     881     -77
KeyExpansion                                         188       -    -188
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 3/5 up/down: 246/-384)         Total: -138 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-23 18:02:44 +01:00
Denys Vlasenko
83e5c627e1 tls: add support for TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher 
function                                             old     new   delta
xwrite_encrypted                                     209     605    +396
GHASH                                                  -     395    +395
aes_encrypt_1                                          -     382    +382
GMULT                                                  -     192    +192
tls_xread_record                                     489     659    +170
aes_encrypt_one_block                                  -      65     +65
aesgcm_setkey                                          -      58     +58
FlattenSzInBits                                        -      52     +52
tls_handshake                                       1890    1941     +51
xwrite_and_update_handshake_hash                      46      81     +35
xorbuf                                                 -      24     +24
aes_setkey                                             -      16     +16
psRsaEncryptPub                                      413     421      +8
stty_main                                           1221    1227      +6
ssl_client_main                                      138     143      +5
next_token                                           841     845      +4
spawn_ssl_client                                     218     219      +1
volume_id_probe_hfs_hfsplus                          564     563      -1
read_package_field                                   232     230      -2
i2cdetect_main                                       674     672      -2
fail_hunk                                            139     136      -3
parse_expr                                           891     883      -8
curve25519                                           802     793      -9
aes_cbc_decrypt                                      971     958     -13
xwrite_handshake_record                               43       -     -43
aes_cbc_encrypt                                      644     172    -472
------------------------------------------------------------------------------
(add/remove: 9/1 grow/shrink: 9/8 up/down: 1860/-553)        Total: 1307 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-23 17:48:07 +01:00
Denys Vlasenko
4e46b98a45 tls: add comment, no code changes 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-18 19:50:24 +01:00
Denys Vlasenko
d5a0405a6f tls: code shrink 
function                                             old     new   delta
tls_get_zeroed_outbuf                                  -      28     +28
static.empty_client_cert                               7       -      -7
tls_handshake                                       1930    1890     -40
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 0/1 up/down: 28/-47)            Total: -19 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-13 11:58:53 +01:00
Denys Vlasenko
de7b5bb59a tls: tidy up recently added ECDSA code 
function                                             old     new   delta
tls_handshake                                       1935    1930      -5
static.OID_ECDSA_KEY_ALG                              21      11     -10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-15)             Total: -15 bytes
   text	   data	    bss	    dec	    hex	filename
 950036	    477	   7296	 957809	  e9d71	busybox_old
 950048	    477	   7296	 957821	  e9d7d	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-13 11:44:32 +01:00
Denys Vlasenko
bddb6545a9 tls: add support for ECDHE-ECDSA-AES-128-CBC-SHA and x25519 curve 
function                                             old     new   delta
curve25519                                             -     835    +835
tls_handshake                                       1619    1935    +316
xc_diffadd                                             -     230    +230
fe_mul__distinct                                       -     149    +149
lm_sub                                                 -     103    +103
lm_add                                                 -      82     +82
fe_mul_c                                               -      74     +74
fe_select                                              -      45     +45
static.f25519_one                                      -      32     +32
static.basepoint9                                      -      32     +32
static.OID_ECDSA_KEY_ALG                               -      21     +21
static.OID_RSA_KEY_ALG                                 -      13     +13
static.supported_groups                                -       8      +8
static.empty_client_cert                               -       7      +7
der_binary_to_pstm                                    40      42      +2
static.expected                                       13       -     -13
------------------------------------------------------------------------------
(add/remove: 14/1 grow/shrink: 2/0 up/down: 1949/-13)        Total: 1936 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-13 02:17:54 +01:00
Denys Vlasenko
084bac472b tls: code shrink 
function                                             old     new   delta
tls_handshake                                       1643    1619     -24

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-05 00:19:15 +01:00
Denys Vlasenko
5df3b12241 tls: reorder a few more cipher ids 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-04 21:25:41 +01:00
Denys Vlasenko
b29d045581 tls: move TLS_AES_128_GCM_SHA256 definition up 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-04 21:18:29 +01:00
Denys Vlasenko
9b0ce4d608 tls: add more cipher ids, no code changes 
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-11-04 20:53:54 +01:00
Ivan Abrea
5cb4f9081f tls: fix to handle X.509 v1 certificates correctly 
The syntax of public key certificates can be found in RFC 5280 section
4.1. The relevant part of the syntax is the following:

  TBSCertificate  ::=  SEQUENCE  {
    version         [0]  EXPLICIT Version DEFAULT v1,
    serialNumber         CertificateSerialNumber,
    ... remaining fields omitted ...
  }

The version field has a default value of v1. RFC 5280 section 4.1.2.1
says the following:

  If only basic fields are present, the version SHOULD be 1 (the value
  is omitted from the certificate as the default value); however, the
  version MAY be 2 or 3.

To help detect if the version field is present or not, the type of the
version field has an explicit tag of [0]. Due to this tag, if the
version field is present, its encoding will have an identifier octet
that is distinct from that of the serialNumber field.

ITU-T X.690 specifies how a value of such a type should be encoded with
DER. There is a PDF of X.690 freely available from ITU-T. X.690 section
8.1.2 specifies the format of identifier octets which is the first
component of every encoded value. Identifier octets encode the tag of a
type. Bits 8 and 7 encode the tag class. Bit 6 will be 0 if the encoding
is primitive and 1 if the encoding is constructed. Bits 5 to 1 encode
the tag number.

X.690 section 8.14 specifies what the identifier octet should be for
explicitly tagged types. Section 8.14.3 says if implicit tagging is not
used, then the encoding shall be constructed. The version field uses
explicit tagging and not implicit tagging, so its encoding will be
constructed. This means bit 6 of the identifier octet should be 1.

X.690 section 8.14 and Annex A provide examples. Note from their
examples that the notation for tags could look like [APPLICATION 2]
where both the tag class and tag number are given. For this example, the
tag class is 1 (application) and the tag number is 2. For notation like
[0] where the tag class is omitted and only the tag number is given, the
tag class will be context-specific.

Putting this all together, the identifier octet for the DER encoding of
the version field should have a tag class of 2 (context-specific), bit 6
as 1 (constructed), and a tag number of 0.

Signed-off-by: Ivan Abrea <ivan@algosolutions.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-06-24 20:05:24 +02:00
Denys Vlasenko
a48eadbc22 tls: remove redundant floor prevention 
function                                             old     new   delta
tls_xread_record                                     499     489     -10

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
 2018-02-14 17:37:41 +01:00