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iv-gen: Ensure external sequential IVs are actually sequential 

We allow gaps in IVs, but ensure that an IV is never used more than once.
This commit is contained in:
Martin Willi 2015-04-17 14:08:14 +02:00 committed by Andreas Steffen
parent 823a8a9b46
commit d0ed107910
2 changed files with 23 additions and 0 deletions
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20
src/libstrongswan/crypto/iv/iv_gen_seq.c
View File

@ -15,6 +15,11 @@
#include "iv_gen_seq.h"
/**
* Magic value for the initial IV state
*/
#define SEQ_IV_INIT_STATE (~(u_int64_t)0)
typedef struct private_iv_gen_t private_iv_gen_t;
/**
@ -27,6 +32,11 @@ struct private_iv_gen_t {
*/
iv_gen_t public;
/**
* Previously passed sequence number to enforce uniqueness
*/
u_int64_t prev;
/**
* Salt to mask counter
*/
@ -43,6 +53,15 @@ METHOD(iv_gen_t, get_iv, bool,
{
return FALSE;
}
if (this->prev != SEQ_IV_INIT_STATE && seq <= this->prev)
{
return FALSE;
}
if (seq == SEQ_IV_INIT_STATE)
{
return FALSE;
}
this->prev = seq;
if (len > sizeof(u_int64_t))
{
len = sizeof(u_int64_t);
@ -84,6 +103,7 @@ iv_gen_t *iv_gen_seq_create()
.allocate_iv = _allocate_iv,
.destroy = _destroy,
},
.prev = SEQ_IV_INIT_STATE,
);
rng = lib->crypto->create_rng(lib->crypto, RNG_STRONG);

3
src/libstrongswan/crypto/iv/iv_gen_seq.h
View File

@ -25,6 +25,9 @@
/**
* Create an IV generator that generates sequential IVs (counter).
*
* The passed external IV must be larger than the one passed to any previous
* call.
*
* @return IV generator
*/
iv_gen_t *iv_gen_seq_create();