// OpenToEncode creates new Msg in encode mode.
func OpenToEncode(dest io.Writer, options EncodeOptions) (res *Msg, err error) {
var flags C.DWORD
res = new(Msg)
if len(options.Signers) == 0 {
err = fmt.Errorf("Signer certificates list is empty")
return
}
if options.HashAlg == nil {
options.HashAlg = GOST_R3411
}
if options.Detached {
flags = C.CMSG_DETACHED_FLAG
}
si := C.mkStreamInfo(unsafe.Pointer(res))
defer C.free(unsafe.Pointer(si))
signedInfo := C.mkSignedInfo(C.int(len(options.Signers)))
defer C.freeSignedInfo(signedInfo)
hashOID := C.CString(options.HashAlg.String())
defer C.free(unsafe.Pointer(hashOID))
for i, signerCert := range options.Signers {
var (
hCryptProv C.HCRYPTPROV
dwKeySpec C.DWORD
)
if 0 == C.CryptAcquireCertificatePrivateKey(signerCert.pCert, 0, nil, &hCryptProv, &dwKeySpec, nil) {
err = getErr("Error acquiring certificate private key")
return
}
C.setSignedInfo(signedInfo, C.int(i), hCryptProv, signerCert.pCert, dwKeySpec, (*C.CHAR)(hashOID))
}
res.hMsg = C.CryptMsgOpenToEncode(
C.MY_ENC_TYPE, // encoding type
flags, // flags
C.CMSG_SIGNED, // message type
unsafe.Pointer(signedInfo), // pointer to structure
nil, // inner content OID
si, // stream information
)
if res.hMsg == nil {
err = getErr("Error opening message for encoding")
return
}
res.dest = dest
res.updateCallback = res.onEncode
return
}
// OpenToDecode creates new Msg in decode mode. If detachedSig parameter is specified,
// it must contain detached P7S signature
func OpenToDecode(src io.Reader, detachedSig ...[]byte) (res *Msg, err error) {
var (
flags C.DWORD
si *C.CMSG_STREAM_INFO
)
res = new(Msg)
if len(detachedSig) > 0 {
flags = C.CMSG_DETACHED_FLAG
si = nil
} else {
si = C.mkStreamInfo(unsafe.Pointer(res))
defer C.free(unsafe.Pointer(si))
}
res.hMsg = C.CryptMsgOpenToDecode(
C.MY_ENC_TYPE, // encoding type
flags, // flags
0, // message type (get from message)
0, // default cryptographic provider
nil, // recipient information
si, // stream info
)
if res.hMsg == nil {
err = getErr("Error opening message for decoding")
return
}
res.src = src
res.updateCallback = res.onDecode
for i, p := range detachedSig {
if !res.update(p, len(p), i == len(detachedSig)-1) {
err = getErr("Error updating message header")
return
}
}
return
}