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libradius: refactor generic RADIUS en-/decryption function to a message method

This commit is contained in:
Martin Willi 2013-07-22 13:45:31 +02:00
parent 9aeb6cea4c
commit 15483a6223
3 changed files with 85 additions and 44 deletions
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62
src/libradius/radius_message.c
View File

@ -366,6 +366,67 @@ METHOD(radius_message_t, add, void,
this->msg->length = htons(ntohs(this->msg->length) + attribute->length);
}
METHOD(radius_message_t, crypt, bool,
private_radius_message_t *this, chunk_t salt, chunk_t in, chunk_t out,
chunk_t secret, hasher_t *hasher)
{
char b[HASH_SIZE_MD5];
/**
* From RFC2548 (encryption):
* b(1) = MD5(S + R + A) c(1) = p(1) xor b(1) C = c(1)
* b(2) = MD5(S + c(1)) c(2) = p(2) xor b(2) C = C + c(2)
* . . .
* b(i) = MD5(S + c(i-1)) c(i) = p(i) xor b(i) C = C + c(i)
*
* P/C = Plain/Crypted => in/out
* S = secret
* R = authenticator
* A = salt
*/
if (in.len != out.len)
{
return FALSE;
}
if (in.len % HASH_SIZE_MD5 || in.len < HASH_SIZE_MD5)
{
return FALSE;
}
if (out.ptr != in.ptr)
{
memcpy(out.ptr, in.ptr, in.len);
}
/* Preparse seed for first round:
* b(1) = MD5(S + R + A) */
if (!hasher->get_hash(hasher, secret, NULL) ||
!hasher->get_hash(hasher,
chunk_from_thing(this->msg->authenticator), NULL) ||
!hasher->get_hash(hasher, salt, b))
{
return FALSE;
}
while (in.len)
{
/* p(i) = b(i) xor c(1) */
memxor(out.ptr, b, HASH_SIZE_MD5);
out = chunk_skip(out, HASH_SIZE_MD5);
if (out.len)
{
/* Prepare seed for next round::
* b(i) = MD5(S + c(i-1)) */
if (!hasher->get_hash(hasher, secret, NULL) ||
!hasher->get_hash(hasher,
chunk_create(in.ptr, HASH_SIZE_MD5), b))
{
return FALSE;
}
}
in = chunk_skip(in, HASH_SIZE_MD5);
}
return TRUE;
}
METHOD(radius_message_t, sign, bool,
private_radius_message_t *this, u_int8_t *req_auth, chunk_t secret,
hasher_t *hasher, signer_t *signer, rng_t *rng, bool msg_auth)
@ -563,6 +624,7 @@ static private_radius_message_t *radius_message_create_empty()
.get_encoding = _get_encoding,
.sign = _sign,
.verify = _verify,
.crypt = _crypt,
.destroy = _destroy,
},
);

16
src/libradius/radius_message.h
View File

@ -284,6 +284,22 @@ struct radius_message_t {
bool (*verify)(radius_message_t *this, u_int8_t *req_auth, chunk_t secret,
hasher_t *hasher, signer_t *signer);
/**
* Perform RADIUS attribute en-/decryption.
*
* Performs en-/decryption by XOring the hash-extended secret into data,
* as specified in RFC 2865 5.2 and used by RFC 2548.
*
* @param salt salt to append to message authenticator, if any
* @param in data to en-/decrypt, multiple of HASH_SIZE_MD5
* @param out en-/decrypted data, length equal to in
* @param secret RADIUS secret
* @param hasher MD5 hasher
* @return TRUE if en-/decryption successful
*/
bool (*crypt)(radius_message_t *this, chunk_t salt, chunk_t in, chunk_t out,
chunk_t secret, hasher_t *hasher);
/**
* Destroy the message.
*/

51
src/libradius/radius_socket.c
View File

@ -233,54 +233,17 @@ METHOD(radius_socket_t, request, radius_message_t*,
static chunk_t decrypt_mppe_key(private_radius_socket_t *this, u_int16_t salt,
chunk_t C, radius_message_t *request)
{
chunk_t A, R, P, seed;
u_char *c, *p;
chunk_t decrypted;
/**
* From RFC2548 (encryption):
* b(1) = MD5(S + R + A) c(1) = p(1) xor b(1) C = c(1)
* b(2) = MD5(S + c(1)) c(2) = p(2) xor b(2) C = C + c(2)
* . . .
* b(i) = MD5(S + c(i-1)) c(i) = p(i) xor b(i) C = C + c(i)
*/
if (C.len % HASH_SIZE_MD5 || C.len < HASH_SIZE_MD5)
{
return chunk_empty;
}
A = chunk_create((u_char*)&salt, sizeof(salt));
R = chunk_create(request->get_authenticator(request), HASH_SIZE_MD5);
P = chunk_alloca(C.len);
p = P.ptr;
c = C.ptr;
seed = chunk_cata("cc", R, A);
while (c < C.ptr + C.len)
{
/* b(i) = MD5(S + c(i-1)) */
if (!this->hasher->get_hash(this->hasher, this->secret, NULL) ||
!this->hasher->get_hash(this->hasher, seed, p))
{
return chunk_empty;
}
/* p(i) = b(i) xor c(1) */
memxor(p, c, HASH_SIZE_MD5);
/* prepare next round */
seed = chunk_create(c, HASH_SIZE_MD5);
c += HASH_SIZE_MD5;
p += HASH_SIZE_MD5;
}
/* remove truncation, first byte is key length */
if (*P.ptr >= P.len)
decrypted = chunk_alloca(C.len);
if (!request->crypt(request, chunk_from_thing(salt), C, decrypted,
this->secret, this->hasher) ||
decrypted.ptr[0] >= decrypted.len)
{ /* decryption failed? */
return chunk_empty;
}
return chunk_clone(chunk_create(P.ptr + 1, *P.ptr));
/* remove truncation, first byte is key length */
return chunk_clone(chunk_create(decrypted.ptr + 1, decrypted.ptr[0]));
}
METHOD(radius_socket_t, decrypt_msk, chunk_t,