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PPP, MPPE, fixed SHA1 padding

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SHA1 padding is 40 byte, not 256 byte. Rekeying is done for each
packet in stateless mode, ensure speedness using static table for padding.
This commit is contained in:
Sylvain Rochet 2015-04-11 23:57:47 +02:00
parent dcdb360a19
commit 4d6d65ee33
1 changed files with 15 additions and 17 deletions
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32
src/netif/ppp/mppe.c
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@ -87,6 +87,19 @@ struct ppp_mppe_state {
#define MPPE_OVHD 2 /* MPPE overhead/packet */
#define SANITY_MAX 1600 /* Max bogon factor we will tolerate */
static const u8_t sha1_pad1[SHA1_PAD_SIZE] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
static const u8_t sha1_pad2[SHA1_PAD_SIZE] = {
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2
};
/*
* Key Derivation, from RFC 3078, RFC 3079.
* Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
@ -94,27 +107,12 @@ struct ppp_mppe_state {
static void get_new_key_from_sha(struct ppp_mppe_state * state)
{
sha1_context sha1;
/* sha1 is faster when using 64 byte chunks */
u8_t pad[64];
u8_t i;
sha1_starts(&sha1);
sha1_update(&sha1, state->master_key, state->keylen);
/* first padding, 256 bytes of 0x00 */
memset(pad, 0x00, sizeof(pad));
for (i = 0; i < 4; i++) {
sha1_update(&sha1, pad, sizeof(pad));
}
sha1_update(&sha1, (unsigned char *)sha1_pad1, SHA1_PAD_SIZE);
sha1_update(&sha1, state->session_key, state->keylen);
/* second padding, 256 bytes of 0xf2 */
memset(pad, 0xf2, sizeof(pad));
for (i = 0; i < 4; i++) {
sha1_update(&sha1, pad, sizeof(pad));
}
sha1_update(&sha1, (unsigned char *)sha1_pad2, SHA1_PAD_SIZE);
sha1_finish(&sha1, state->sha1_digest);
}