Re: Converting Diffie-Hellman Session keys to CALG_AES_128

On Thu, 14 Sep 2006 14:09:13 -0700, Medical-Fix wrote:

How can I convert a Diffie-Hellman Session keys to CALG_AES_128??
The following code snip shows how I created my Diffie-Hellman Session
Keys, now I need to convert this session key to AES...

Thansk for the help!


1) CryptAcquireContext(&hProv, NULL, MS_ENH_DSS_DH_PROV, PROV_DSS_DH,
CRYPT_VERIFYCONTEXT);

2)CryptGenKey(hProv, CALG_DH_EPHEM, (DHKEYSIZE << 16) |CRYPT_EXPORTABLE
| CRYPT_PREGEN, &hPrivateKey1);

3)CryptSetKeyParam(hPrivateKey1, KP_P, (PBYTE)&P, 0);

4)CryptSetKeyParam(hPrivateKey1, KP_G, (PBYTE)&G, 0);

5)CryptSetKeyParam( hPrivateKey1, KP_X, NULL, 0);

6)CryptExportKey(hPrivateKey1, NULL, PUBLICKEYBLOB, 0, NULL,
&dwDataLen2);

7)CryptImportKey(hProv, pbKeyBlobParty2, dwDataLen2, hPrivateKey1, 0,
&hSessionKey);

-------- snip --------

Alg = CALG_AES_128;

CryptSetKeyParam(hSessionKey, KP_ALGID,(BYTE *) &Alg, (128 << 16) |
CRYPT_EXPORTABLE);

// defaults to IV vector 0x00 x 16 (16 bytes of null)

--------unsnip -------------------

hth,
tlviewer
.

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