[Bug 60486] New: crypt32: PFXExportCertStoreEx() and PFXImportCertStore() do not support ECDSA (CNG) keys

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=60486

            Bug ID: 60486
           Summary: crypt32: PFXExportCertStoreEx() and
                    PFXImportCertStore() do not support ECDSA (CNG) keys
           Product: Wine
           Version: 11.19
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: crypt32
          Assignee: [e-mail]
          Reporter: [e-mail]
  Target Milestone: ---
      Distribution: ---

Exporting or importing a PFX whose private key is an ECDSA key fails.

1. Export: X509Certificate2.Export(X509ContentType.Pfx) in .NET Framework 4.8
for a
   certificate with a CNG ECDSA P-256 key crashes. PFXExportCertStoreEx()
always asks NCrypt
   for BCRYPT_RSAFULLPRIVATE_BLOB, which ends in bcrypt's RSA export code with
an EC key
   (page fault inside the RSA key accessor).

2. Import: new X509Certificate2(pfxBytes, password, flags) with an EC key fails
with
   CRYPT_E_BAD_ENCODE (0x80092002). The unix side (open_cert_store) rejects
every key that is
   not GNUTLS_PK_RSA, and the PE side only knows how to import RSA keys into a
CAPI provider.

Steps (any .NET 4.8 program, 32- or 64-bit):
  var ec = ECDsa.Create(ECCurve.NamedCurves.nistP256);
  var req = new CertificateRequest("CN=test", ec, HashAlgorithmName.SHA256);
  var cert = req.CreateSelfSigned(DateTimeOffset.Now,
DateTimeOffset.Now.AddYears(1));
  var pfx = cert.Export(X509ContentType.Pfx, "pw");                  // crash
  var back = new X509Certificate2(pfx, "pw", X509KeyStorageFlags.Exportable);
// 0x80092002
(CreateSelfSigned itself needs the ncrypt changes from bug 60443.)

A suggested patch is attached (tested on Wine 11.19, applies to master too):
- PFXExportCertStoreEx(): read NCRYPT_ALGORITHM_GROUP_PROPERTY and export
  BCRYPT_ECCPRIVATE_BLOB for ECDSA/ECDH; unix export_cert_store builds the key
with
  gnutls_x509_privkey_import_ecc_raw(GNUTLS_ECC_CURVE_SECP256R1).
- open_cert_store accepts GNUTLS_PK_ECDSA; import returns a
BCRYPT_ECCPRIVATE_BLOB built with
  gnutls_x509_privkey_export_ecc_raw().
- PFXImportCertStore(): ECC blobs are imported with
NCryptOpenStorageProvider(MS_KEY_STORAGE_PROVIDER)
  + NCryptImportKey() and attached with CERT_NCRYPT_KEY_HANDLE_PROP_ID plus a
CNG
  CERT_KEY_PROV_INFO, so HasPrivateKey is true and
CryptAcquireCertificatePrivateKey() returns
  the NCrypt handle. RSA keeps the existing CAPI path.

With it, export/import round trip and signing with the imported key work (32-
and 64-bit);
crypt32 conformance tests are unchanged.

Limitations, why this is a suggestion rather than a finished patch: P-256 only;
the
CERT_KEY_PROV_INFO names a container that does not exist (Wine has no persisted
NCrypt keys);
PKCS12_ALWAYS_CNG_KSP is still ignored; no new tests yet. Possibly related: bug
59038.

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