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make the mppe salt unique

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This commit is contained in:
Andreas Steffen
2012-03-14 07:31:19 +01:00
parent 3cff2b598b
commit dae4ada4cd
1 changed files with 18 additions and 8 deletions
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src/libcharon/plugins/tnc_pdp/tnc_pdp.c
+18 -8
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@@ -187,7 +187,8 @@ static void send_message(private_tnc_pdp_t *this, radius_message_t *message,
* Encrypt a MS-MPPE-Send/Recv-Key
*/
static chunk_t encrypt_mppe_key(private_tnc_pdp_t *this, u_int8_t type,
chunk_t key, radius_message_t *request)
chunk_t key, u_int16_t *salt,
radius_message_t *request)
{
chunk_t a, r, seed, data;
u_char b[HASH_SIZE_MD5], *c;
@@ -213,17 +214,25 @@ static chunk_t encrypt_mppe_key(private_tnc_pdp_t *this, u_int8_t type,
memcpy(&mppe_key->key[1], key.ptr, key.len);
/* generate a 16 bit random salt value */
/**
* generate a 16 bit unique random salt value for the MPPE stream cipher
* the MSB of the salt MUST be set to 1
*/
a = chunk_create((u_char*)&(mppe_key->salt), sizeof(mppe_key->salt));
this->rng->get_bytes(this->rng, a.len, a.ptr);
do
{
this->rng->get_bytes(this->rng, a.len, a.ptr);
*a.ptr |= 0x80;
}
while (mppe_key->salt == *salt);
/* the MSB of the salt MUST be set to 1 */
*a.ptr |= 0x80;
/* update the salt value */
*salt = mppe_key->salt;
r = chunk_create(request->get_authenticator(request), HASH_SIZE_MD5);
seed = chunk_cata("cc", r, a);
c = mppe_key->key;
c = mppe_key->key;
while (c < data.ptr + data.len)
{
/* b(i) = MD5(S + c(i-1)) */
@@ -251,6 +260,7 @@ static void send_response(private_tnc_pdp_t *this, radius_message_t *request,
radius_message_t *response;
chunk_t data, recv, send;
u_int32_t tunnel_type;
u_int16_t salt = 0;
response = radius_message_create(code);
if (eap)
@@ -278,12 +288,12 @@ static void send_response(private_tnc_pdp_t *this, radius_message_t *request,
if (msk.len)
{
recv = chunk_create(msk.ptr, msk.len / 2);
data = encrypt_mppe_key(this, MS_MPPE_RECV_KEY, recv, request);
data = encrypt_mppe_key(this, MS_MPPE_RECV_KEY, recv, &salt, request);
response->add(response, RAT_VENDOR_SPECIFIC, data);
chunk_free(&data);
send = chunk_create(msk.ptr + recv.len, msk.len - recv.len);
data = encrypt_mppe_key(this, MS_MPPE_SEND_KEY, send, request);
data = encrypt_mppe_key(this, MS_MPPE_SEND_KEY, send, &salt, request);
response->add(response, RAT_VENDOR_SPECIFIC, data);
chunk_free(&data);
}