C_DigestInit

Initializes a message-digesting operation.

CK_DECLARE_FUNCTION( CK_RV, C_DigestInit )( CK_SESSION_HANDLE hSession,
                                            CK_MECHANISM_PTR pMechanism )
{
    P11Session_t * pxSession = prvSessionPointerFromHandle( hSession );
    CK_RV xResult = prvCheckValidSessionAndModule( pxSession );
    int32_t lMbedTLSResult = 0;
 
    if( pMechanism == NULL )
    {
        LogError( ( "Failed to initialize digest operation. Mechanism pointer "
                    "was NULL." ) );
        xResult = CKR_ARGUMENTS_BAD;
    }
 
    if( xResult == CKR_OK )
    {
        /* See explanation in prvCheckValidSessionAndModule for this exception. */
        /* coverity[misra_c_2012_rule_10_5_violation] */
        if( prvOperationActive( pxSession ) == ( CK_BBOOL ) CK_TRUE )
        {
            LogError( ( "Failed to initialize digest operation. An operation "
                        "was already active." ) );
            xResult = CKR_OPERATION_ACTIVE;
        }
    }
 
    if( xResult == CKR_OK )
    {
        if( pMechanism->mechanism != CKM_SHA256 )
        {
            LogError( ( "Failed to initialize digest operation. Currently only "
                        "the CKM_SHA256 mechanism is supported." ) );
            xResult = CKR_MECHANISM_INVALID;
        }
    }
 
    /*
     * Initialize the requested hash type
     */
    if( xResult == CKR_OK )
    {
        mbedtls_sha256_init( &pxSession->xSHA256Context );
        lMbedTLSResult = mbedtls_sha256_starts_ret( &pxSession->xSHA256Context, 0 );
 
        if( 0 != lMbedTLSResult )
        {
            LogError( ( "Failed to initialize digest operation. "
                        "mbedtls_sha256_starts_ret failed with: mbed TLS error = %s : %s.",
                        mbedtlsHighLevelCodeOrDefault( lMbedTLSResult ),
                        mbedtlsLowLevelCodeOrDefault( lMbedTLSResult ) ) );
            xResult = CKR_FUNCTION_FAILED;
        }
        else
        {
            pxSession->xOperationDigestMechanism = pMechanism->mechanism;
        }
    }
 
    return xResult;
}

See also

C_DigestUpdate(), C_DigestFinal()

Note

Digest parameters are shared by a session. Calling C_DigestInit(), C_DigestUpdate(), and C_DigestFinal() with the same session across different tasks may lead to unexpected results.

Parameters

[in]	hSession	Handle of a valid PKCS #11 session.
[in]	pMechanism	Digesting mechanism. This port only supports the mechanism CKM_SHA256.

Returns

CKR_OK if successful.