(C#) 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

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

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

Chilkat.PrivateKey pkey = new 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.
bool success = pkey.LoadAnyFormatFile("qa_data/rsa/rsaPrivKey_secret.pem","secret");
if (success != true) {
    Debug.WriteLine(pkey.LastErrorText);
    return;
}

// Assuming this is an RSA private key..
Chilkat.Rsa rsa = new Chilkat.Rsa();

// Import the private key into the RSA object:
success = rsa.ImportPrivateKeyObj(pkey);
if (success != true) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// OpenSSL uses big-endian.
rsa.LittleEndian = false;

// SHA1 hash and sign, and return base64.
rsa.EncodingMode = "base64";
string b64sig = rsa.SignStringENC("2018-05-18,2018-05-18T11:22:19;FAC 001/18;53.00;","sha1");
Debug.WriteLine(b64sig);

// 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.