(C#) 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

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

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:
bool success = pkey.LoadPemFile("private.pem");
if (success != true) {
    Debug.WriteLine(pkey.LastErrorText);
    return;
}

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

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

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

// Load the file to be signed.
Chilkat.BinData bdFileData = new Chilkat.BinData();
success = bdFileData.LoadFile("in.dat");

Chilkat.BinData bdSig = new Chilkat.BinData();
success = rsa.SignBd(bdFileData,"sha256",bdSig);
if (success != true) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// Save the binary signature to a file.
success = bdSig.WriteFile("signature.sig");
if (success != true) {
    Debug.WriteLine("Failed to write signature.sig.");
    return;
}

Debug.WriteLine("Success.");