ims-volte-vowifi
/
strongswan
9
0
Fork 0
Code Pull Requests Releases Activity

iv_gen: Mask sequential IVs with a random salt 

This makes it harder to attack a HA setup, even if the sequence numbers were
not fully in sync.
This commit is contained in:
Tobias Brunner 2013-08-05 16:24:40 +02:00
parent e8229ad558
commit 0c6f6c4e34
1 changed files with 24 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
src/libstrongswan/crypto/iv/iv_gen_seq.c
View File

@ -26,6 +26,11 @@ struct private_iv_gen_t {
* Public iv_gen_t interface. * Public iv_gen_t interface.
*/ */
iv_gen_t public; iv_gen_t public;
/**
* Salt to mask counter
*/
u_int8_t *salt;
}; };
METHOD(iv_gen_t, get_iv, bool, METHOD(iv_gen_t, get_iv, bool,
@ -34,12 +39,17 @@ METHOD(iv_gen_t, get_iv, bool,
u_int8_t iv[sizeof(u_int64_t)]; u_int8_t iv[sizeof(u_int64_t)];
size_t len = size; size_t len = size;
if (!this->salt)
{
return FALSE;
}
if (len > sizeof(u_int64_t)) if (len > sizeof(u_int64_t))
{ {
len = sizeof(u_int64_t); len = sizeof(u_int64_t);
memset(buffer, 0, size - len); memset(buffer, 0, size - len);
} }
htoun64(iv, seq); htoun64(iv, seq);
memxor(iv, this->salt, sizeof(u_int64_t));
memcpy(buffer + size - len, iv + sizeof(u_int64_t) - len, len); memcpy(buffer + size - len, iv + sizeof(u_int64_t) - len, len);
return TRUE; return TRUE;
} }
@ -59,12 +69,14 @@ METHOD(iv_gen_t, allocate_iv, bool,
METHOD(iv_gen_t, destroy, void, METHOD(iv_gen_t, destroy, void,
private_iv_gen_t *this) private_iv_gen_t *this)
{ {
free(this->salt);
free(this); free(this);
} }
iv_gen_t *iv_gen_seq_create() iv_gen_t *iv_gen_seq_create()
{ {
private_iv_gen_t *this; private_iv_gen_t *this;
rng_t *rng;
INIT(this, INIT(this,
.public = { .public = {
@ -74,5 +86,17 @@ iv_gen_t *iv_gen_seq_create()
}, },
); );
rng = lib->crypto->create_rng(lib->crypto, RNG_STRONG);
if (rng)
{
this->salt = malloc(sizeof(u_int64_t));
if (!rng->get_bytes(rng, sizeof(u_int64_t), this->salt))
{
free(this->salt);
this->salt = NULL;
}
rng->destroy(rng);
}
return &this->public; return &this->public;
} }