API CryptImportKey & CryptExportKey

[David Roberts]

Has anyone messed around with these APIs and, in particular, importing a PLAINTEXTKEYBLOB?

[David Roberts]

I don't believe this.

Function PBMain
Dim OurKeyBlob As KeyBlob
Dim HMACInfo As HMAC_Info

caused an error 87 ("The parameter is incorrect") when the UDT HMACInfo was used in a parameter list.

This

Function PBMain
Dim HMACInfo As HMAC_Info
Dim OurKeyBlob As KeyBlob

solved the problem.

All I've done is change the Dims order.

Alignment? Nope - tried Dword - the obvious candidate.

Why did I change the order? After two days there wasn't much left I could do.

Now, is anyone going to put me out of my misery or do I have a PB bug on my hands?

[José Roca]

And what is KeyBlob? A DWORD, a LONG a pointer? If it is dimmed in the first position maybe it becomes a register variable.

[David Roberts]

They are both UDTs

Type PublicKeyStruc
  bType As Byte
  bVersion As Byte
  Reserved As Word
  ALG_ID As Dword
End Type

Type KeyBlob
  BlobHeader As PublicKeyStruc
  cbData As Dword
  pbData( 1 To 1024 ) As Byte
End Type

Type HMAC_Info
  HashAlgid As Dword
  dummy As String * 10
End Type

> If it is dimmed in the first position maybe it becomes a register variable.

I must remember that one, José.

[José Roca]

In other of your posts, I see that you have defined HMAC_Info as follows:

Type HMAC_Info
  HashAlgid As Dword
  dummy As String * 10
End Type

This is wrong. It should be:

TYPE HMAC_INFO
   HashAlgid     AS DWORD      ' ALG_ID  HashAlgid
   pbInnerString AS BYTE PTR   ' BYTE   *pbInnerString
   cbInnerString AS DWORD      ' DWORD   cbInnerString
   pbOuterString AS BYTE PTR   ' BYTE   *pbOuterString
   cbOuterString AS DWORD      ' DWORD   cbOuterString
END TYPE

This is the original C++ declaration:

typedef struct _HMAC_Info {
  ALG_ID HashAlgid;
  BYTE * pbInnerString;
  DWORD  cbInnerString;
  BYTE * pbOuterString;
  DWORD  cbOuterString;
}HMAC_INFO, *PHMAC_INFO;

pbInnerString and pbOuterString aren't bytes, but byte pointers.

[David Roberts]

Wow, I'm lucky to get away with it.

I'll now use:

Type HMAC_Info
  HashAlgid As Dword
  dummy As String * 16
End Type

From SDK:

HashAlgid
Specifies the hash algorithm to be used.
pbInnerString
Pointer to the inner string to be used in the HMAC calculation. The default inner string is defined as the byte 0x36 repeated 64 times.
cbInnerString
The count of bytes in pbInnerString. The CSP uses the default inner string if cbInnerString is equal to zero.
pbOuterString
Pointer to the outer string to be used in the HMAC calculation. The default outer string is defined as the byte 0x5C repeated 64 times.
cbOuterString
The count of bytes in pbOuterString. The CSP uses the default outer string if cbOuterString is equal to zero.

The 0x36 and 0x5C are from the standard HMAC protocol utilizing the best Hamming distance so I left them alone.

I read that rather quickly and missed the pointer reference.

Thanks, José - an incorrect structure size could do untold damage.

PS The very first code snippet no longer gives an error. Magic!