DES_CheckKey

Checks for weak or invalid-length DES or TDEA keys.

VBA/VB6 Syntax

nRet = DES_CheckKey(abKey(0), nKeyBytes)

C/C++ Syntax

Parameters

lpKey

[in] array containing the key.

nKeyLen

[in] containing the length of the key in bytes.

Returns (VBA/C)

If successful, the return value is 0; otherwise it returns a non-zero error code.

.NET Equivalent

Des.CheckKey Method (Byte[])
Tdea.CheckKey Method (Byte[])

Remarks

DES_CheckKey verifies that the key size is valid for a single, double or triple DES key - i.e. is 8, 16 or 24 bytes long - and that no part of the key is a weak or semi-weak DES key.

Example

    Dim abKey() As Byte
    Dim nKeyBytes As Long
    Dim nRet As Long
    
    nKeyBytes = 8
    ReDim abKey(nKeyBytes - 1)
    ' Generate a random DES key
    nRet = RNG_KeyBytes(abKey(0), nKeyBytes, "", 0)
    Debug.Print cnvHexStrFromBytes(abKey)
    ' Check if it's OK
    nRet = DES_CheckKey(abKey(0), nKeyBytes)
    Debug.Print "DES_CheckKey returns " & nRet & " (" & apiErrorLookup(nRet) & ")"
    If nRet <> 0 Then
        ' Error...
    End If

This should produce output similar to:

5305A0FA4CC94A82
DES_CheckKey returns 0 (OK, success, no error)

unless the key generated is weak (a 1 in 4500 billion chance!).

See Also

DES_CheckKeyHex

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