Hi,
Thanks . I would do what you have suggested if I cannot find a way out.
But your suggestion doesnt actually solve my problem.
I want to use the SSL_CTX_set_tmp_rsa/dh_cb(.....,cb) so that i can decide on
what length key to use depending
on the cipher used.
So firstly i pre-generate 2 pairs of keys for RSA and DH, one of 512 bits and
the other 1024 bits.
I then store these in the SSL_CTX using SSL_CTX_set_app_data(....).
In my callback I retrieve them from the SSL_CTX in the following way
RSA * CSetupCallbacks::SSLCallbackTmpRSA(SSL *pSSL, int isExport, int
nKeyLen)
{
RSA *pRsa;
pRsa = NULL;
CCallbackData * pCbData = reinterpret_cast<CCallbackData
*>(SSL_CTX_get_app_data(pSSL->ctx));
if (!isExport) {
if (nKeyLen == 512)
pRsa = pCbData->m_p512BitRSAKey;
else
pRsa = pCbData->m_p1024BitRSAKey;
}
else {
pRsa = pCbData->m_p512BitRSAKey;
}
return pRsa;
}
/*
* Handle out the already generated DH parameters...
*/
DH * CSetupCallbacks::SSLCallbackTmpDH(SSL *pSSL, int isExport, int nKeyLen)
{
DH *pDh;
pDh = NULL;
CCallbackData * pCbData = reinterpret_cast<CCallbackData
*>(SSL_CTX_get_app_data(pSSL->ctx));
if (!isExport) {
if(nKeyLen == 512)
pDh = pCbData->m_p512BitDHKey;
else
pDh = pCbData->m_p1024BitDHKey;
}
else {
pDh = pCbData->m_p512BitDHKey;
}
return pDh;
}
Now these keys are returned so send_server_key_exchange to be used in the key
exchange.
Assuming all is well when i cleanup SSL_CTX structure I do the following
if (m_pSSLCTX)
{
delete reinterpret_cast<CCallbackData *>(SSL_CTX_get_app_data(m_pSSLCTX)) ;
SSL_CTX_free(m_pSSLCTX);
m_pSSLCTX = NULL;
}
........................
......................
CCallbackData : : ~CCallbackData()
{
if(m_pCRLStore != NULL)
X509_STORE_free(m_pCRLStore);
if(m_p512BitRSAKey != NULL)
RSA_free(m_p512BitRSAKey);
if(m_p1024BitRSAKey != NULL)
RSA_free(m_p1024BitRSAKey);
if(m_p512BitDHKey != NULL)
DH_free(m_p512BitDHKey);
if(m_p1024BitDHKey != NULL)
DH_free(m_p1024BitDHKey);
}
then my application terminates with some DH key leaks though i seem to have
cleaned it up all
(The cipher causes a DH key exchange in my test case).
This is my problem and even after looking into the SSL code i'm more confused
than ever
Is there a clean way out?
One more thing!! How does SSL_OP_SINGLE_DH_USE work with all this??
Thanks,
Amit.
Bodo Moeller wrote:
> On Tue, Apr 11, 2000 at 05:10:12PM +0530, Amit Chopra wrote:
>
> > I found that when my application terminates the temporary keys
> > generated leak.
>
> Directly after SSL_[CTX_]_set_tmp_{rsa,dh}, you may call {RSA,DH}_free
> for the key given in the parameter. This is because the reference
> account is increased for RSA keys, and DH parameters are copied.
>
> > So to clean it up I am storing some information like the temp DH key
> > generated during the handshake in the SSL ex_data structure [...]
>
> Doing this is unnecessarily complicated, see above.
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