Duplicate openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

Demonstrates how to duplicate the creation of an RSA signature produced by this OpenSSL command:

openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

Download: Chilkat .NET Assemblies

Chilkat.PrivateKey pkey = new Chilkat.PrivateKey();

//  Load the private key from an RSA PEM file:
pkey.LoadPemFile("myKey.pem");

bool success;

string pkeyXml;

//  Get the private key in XML format:
pkeyXml = pkey.GetXml();

Chilkat.Rsa rsa = new Chilkat.Rsa();

//  Any string argument automatically begins the 30-day trial.

success = rsa.UnlockComponent("30-day trial");
if (success != true) {
    textBox1.Text += rsa.LastErrorText + "\r\n";
    return;
}

//  Import the private key into the RSA component:
success = rsa.ImportPrivateKey(pkeyXml);
if (success != true) {
    textBox1.Text += rsa.LastErrorText + "\r\n";
    return;
}

//  OpenSSL uses BigEndian byte ordering:
rsa.LittleEndian = false;

//  The resulting signature will be a Base64 string:
rsa.EncodingMode = "base64";

//  For simplicity, we're not loading
//  the data to be signed from a file.  We are instead simply
//  using a literal string value.
string strData;
strData = "This is the text to be signed.";

//  Hash the input using MD5, and then sign the hash:
//  Other valid hash algorithm choices are "md2" and "sha-1".
string base64Sig;
base64Sig = rsa.SignStringENC(strData,"md5");

textBox1.Text += base64Sig + "\r\n";

MessageBox.Show("Success!");