(Visual FoxPro) Create a Hash Signature for Value Added Tax Audit SOAP Message for Angola

Demonstrates how to create a hash signature that is required in Value Added Tax Audit Files in Angola, Africa.

It is the following two instructions that should be used to create a hash value to be put into a <hash></hash> field in SOAP XML file containing the tax data for the VAT authorities:

openssl dgst -shal -sign private.pem -outRegisto1.shal Registo1.txt

then

openssl enc -base64 - in Registo1.shal -out Registo1.b64 -A

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loPkey
LOCAL loRsa
LOCAL lcB64sig

lnSuccess = 0

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

loPkey = CreateObject('Chilkat.PrivateKey')

* Load the private key from an PEM file.
* Provide the password in the 2nd argument.
* If no password is needed, just pass an empty string.
lnSuccess = loPkey.LoadAnyFormatFile("qa_data/rsa/rsaPrivKey_secret.pem","secret")
IF (lnSuccess = 0) THEN
    ? loPkey.LastErrorText
    RELEASE loPkey
    CANCEL
ENDIF

* Assuming this is an RSA private key..
loRsa = CreateObject('Chilkat.Rsa')

* Import the private key into the RSA object:
lnSuccess = loRsa.UsePrivateKey(loPkey)
IF (lnSuccess = 0) THEN
    ? loRsa.LastErrorText
    RELEASE loPkey
    RELEASE loRsa
    CANCEL
ENDIF

* OpenSSL uses big-endian.
loRsa.LittleEndian = 0

* SHA1 hash and sign, and return base64.
loRsa.EncodingMode = "base64"
lcB64sig = loRsa.SignStringENC("2018-05-18,2018-05-18T11:22:19;FAC 001/18;53.00;","sha1")
? lcB64sig

* The signature is equal in size to your private key.  For example, if you have a 1024-bit RSA key,
* then 1024 bits = 128 bytes.   When 128 bytes is base64 encoded, the result is a string approximately
* 4/3rds the size of the original.  128 * 4 / 3 = (approximately) 172 bytes.

* If your RSA key is 2048-bits, then your signature will be twice as long.

RELEASE loPkey
RELEASE loRsa