Windows CryptAcquireContext API failing with error code 127 - windows

Question

Error 127 is 'ERROR_PROC_NOT_FOUND' ('The specified procedure could not be found').
I'm running on a Windows Server 2016 running Citrix XenApp with Remote Desktop Services. The CryptAcquireContext API is in advapi32.dll. I ran Microsoft's Depends32.exe on it, and the function CryptAcquireContextA and CryptAcquireContextW are definitely in the DLL file. Same error seems to happen with all the crypto api functions. I tested CryptDestroyHash and it also returns an error of 127 (ERROR_PROC_NOT_FOUND).
Here is my C++ code:
HCRYPTPROV hProv = 0;
BOOL bCryptAcquireContext = CryptAcquireContext(&hProv, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, 0);
dwError = GetLastError();
This C++ does work in an EXE, but if the same code is put into a DLL that is called from VB6, it does not work. It's almost like any vb6 app is blocked from those APIs?
Here is the VB6 code:
Private Declare Function CryptAcquireContext Lib "advapi32.dll" Alias "CryptAcquireContextA" (ByRef phProv As Long, ByVal pszContainer As String, ByVal pszProvider As String, ByVal dwProvType As Long, ByVal dwFlags As Long) As Long
Private Sub Form_Load()
Dim sProvider As String
Dim rv as Long
Dim sContainer As String
Dim m_lProvider As Long
Const PROV_RSA_FULL = 1
Const CRYPT_VERIFYCONTEXT As Long = &HF0000000
Const MS_DEF_PROV As String = "Microsoft Base Cryptographic Provider v1.0"
sProvider = MS_DEF_PROV & vbNullChar
sContainer = vbNullChar
rv = CryptAcquireContext(m_lProvider, 0, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)
dwError = Err.LastDllError
If rv = 0 and dwError <> 127 Then
rv = CryptAcquireContext(m_lProvider, 0&, ByVal sProvider, PROV_RSA_FULL, CRYPT_NEWKEYSET)
End If
End Sub

Answer 1

You're passing a Long to a parameter (pszContainer) you defined to be a string:
Private Declare Function CryptAcquireContext Lib "advapi32.dll" _
Alias "CryptAcquireContextA" _
(ByRef phProv As Long, ByVal pszContainer As String, _
ByVal pszProvider As String, ByVal dwProvType As Long, _
ByVal dwFlags As Long) As Long
rv = CryptAcquireContext(m_lProvider, 0, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)
Try this instead (also for the 2nd call of CryptAcquireContext):
rv = CryptAcquireContext(m_lProvider, vbNullString, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)

Answer 2

I can say that I observed similar issue at a customer machine (error code 127 - ERROR_PROC_NOT_FOUND - set by CryptAcquireContextA Windows API function). Googling led me to the http://tracker.firebirdsql.org/browse/CORE-6154 page where the same issue was discussed. The page said that the issue "was solved Updating Windows Server 2016 with Windows Update". The customer I worked with reported that the issue disappeared after Windows updates were installed.