Problem - Kevin Tafuro

if (!CryptAcquireContext(&hProvider, 0, MS_ENHANCED_PROV, PROV_RSA_FULL, 0)) {
if (GetLastError( ) != NTE_BAD_KEYSET) return 0;
if (!CryptAcquireContext(&hProvider, 0, MS_ENHANCED_PROV, PROV_RSA_FULL,
CRYPT_NEWKEYSET)) return 0;
}
return hProvider;
}
SpcGetExportableContext( ) will obtain a handle to the Microsoft Enhanced Cryptographic
Service Provider that allows for the use of private keys. Public key pairs are
stored in containers by the underlying CSP. This function will use the default container,
creating it if it doesn’t already exist.
Every public key container can have a special public key pair known as an exchange
key, which is the key that we’ll use to encrypt the exported key data. The function
CryptGetUserKey( ) is used to obtain the exchange key. If it doesn’t exist,
SpcImportKeyData( ), listed later in this section, will create a 1,024-bit exchange key,
which will be stored as the exchange key in the public key container so future
attempts to get the key will succeed. The special algorithm identifier AT_KEYEXCHANGE
is used to reference the exchange key.
Symmetric keys are always imported via CryptImportKey( ) in “simple blob” format,
specified by the SIMPLEBLOB constant passed to CryptImportKey( ). A simple blob is
composed of a BLOBHEADER structure, followed by an ALG_ID for the algorithm used to
encrypt the key data. The raw key data follows the BLOBHEADER and ALG_ID header
information. To import the raw key data into a CryptoAPI key, a simple blob structure
must be constructed and passed to CryptImportKey( ).
Finally, the raw key data must be encrypted using CryptEncrypt( ) and the exchange
key. (The CryptEncrypt( ) function is described in more detail in Recipe 5.25.) The
return from SpcImportKeyData( ) will be a handle to a CryptoAPI key object if the
operation was performed successfully; otherwise, it will be 0. The CryptoAPI makes
a copy of the key data internally in the key object it creates, so the key data passed
into the function may be safely freed. The spc_memset( ) function from Recipe 13.2 is
used here to destroy the unencrypted key data before returning.
HCRYPTKEY SpcImportKeyData(HCRYPTPROV hProvider, ALG_ID Algid, BYTE *pbKeyData,
DWORD cbKeyData) {
BOOL bResult = FALSE;
BYTE *pbData = 0;
DWORD cbData, cbHeaderLen, cbKeyLen, dwDataLen;
ALG_ID *pAlgid;
HCRYPTKEY hImpKey = 0, hKey;
BLOBHEADER *pBlob;
if (!CryptGetUserKey(hProvider, AT_KEYEXCHANGE, &hImpKey)) {
if (GetLastError( ) != NTE_NO_KEY) goto done;
if (!CryptGenKey(hProvider, AT_KEYEXCHANGE, (1024