B4X

PKCS7 Sign Text using RSA 2048, SHA256, Base64 Output

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Demonstrates how to sign text using 2048-bit RSA with SHA256, producing PKCS#7 output in Base64. The certificate w/ private key used for signing is loaded from a .p12/.pfx file. B4X

Dim success As Boolean = False

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

Dim cert As ChilkatCert
cert.Initialize("cert")

'  Load the cert and private key.  Whatever the private key happens to be,
'  such as RSA or ECC, then Chilkat will use it.  If the private key is 
'  a 2048-bit RSA key, then that's what will be used..
success = cert.LoadPfxFile("qa_data/pfx/myCertAndKey.p12", "password")
If success <> True Then
    Log(cert.LastErrorText)
    Return
End If


Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

success = crypt.SetSigningCert(cert)
If success <> True Then
    Log(crypt.LastErrorText)
    Return
End If


'  Use SHA-256
crypt.HashAlgorithm = "sha256"

'  Hash the utf-8 byte representation of the string
crypt.Charset = "utf-8"

'  Return the result in base64
crypt.EncodingMode = "base64"

'  Sign some text..
Dim textToSign As String = "This is the text to be hashed and signed."
Dim sigBase64 As String = crypt.OpaqueSignStringENC(textToSign)
If crypt.LastMethodSuccess <> True Then
    Log(crypt.LastErrorText)
    Return
End If


Log(sigBase64)

'  The result:
'  MIIS2wYJKoZIhvcNAQc ... zGeeY4Oxg==