Visual Basic 6.0 Requires Chilkat v11.0.0+

Duplicate openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -sign private.pem -out sha256.sig in.dat

The in.dat file can contain text or binary data of any type. The OpenSSL command does the following:

1. Creates a SHA256 digest of the contents of the input file
2. Signs the SHA256 digest using the private key.

Visual Basic 6.0

Dim success As Long
success = 0

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim pkey As New PrivateKey

'  Load the private key from an PEM file:
success = pkey.LoadPemFile("private.pem")
If (success = 0) Then
    Debug.Print pkey.LastErrorText
    Exit Sub
End If

'  Load the file to be signed.
Dim fac As New CkFileAccess
Dim inData() As Byte
inData = fac.ReadEntireFile("in.dat")

Dim rsa As New ChilkatRsa

'  Import the private key into the RSA component:
success = rsa.UsePrivateKey(pkey)
If (success = 0) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

'  OpenSSL uses big-endian.
rsa.LittleEndian = 0

Dim sigBytes() As Byte
sigBytes = rsa.SignBytes(inData,"sha256")
If (rsa.LastMethodSuccess = 0) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

'  Save the binary signature to a file.
success = fac.WriteEntireFile("signature.sig",sigBytes)
If (success = 0) Then
    Debug.Print fac.LastErrorText
    Exit Sub
End If

Debug.Print "Success."