Delphi DLL Requires Chilkat v11.0.0+

Duplicate openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

See more OpenSSL Examples

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

The in.dat file contains the original data that was signed, and can contain text or binary data of any type. The above OpenSSL command does the following:

1. Creates a SHA256 digest of the contents of the input file.
2. Verifies the SHA256 digest using the public key.

Delphi DLL

var
success: Boolean;
pubKey: HCkPublicKey;
bdFileData: HCkBinData;
bdSig: HCkBinData;
rsa: HCkRsa;

begin
success := False;

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

pubKey := CkPublicKey_Create();

//  Load the public key from an PEM file:
success := CkPublicKey_LoadFromFile(pubKey,'pubKey.pem');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

//  Load the data of the original file that was signed.
bdFileData := CkBinData_Create();
success := CkBinData_LoadFile(bdFileData,'in.dat');

//  Load the signature.
bdSig := CkBinData_Create();
success := CkBinData_LoadFile(bdSig,'signature.sig');

rsa := CkRsa_Create();

//  Import the public key into the RSA component:
success := CkRsa_UsePublicKey(rsa,pubKey);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

//  OpenSSL uses big-endian.
CkRsa_putLittleEndian(rsa,False);

success := CkRsa_VerifyBd(rsa,bdFileData,'sha256',bdSig);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Memo1.Lines.Add('The signature was invalid.');
    Exit;
  end;

Memo1.Lines.Add('The signature was verified.');

CkPublicKey_Dispose(pubKey);
CkBinData_Dispose(bdFileData);
CkBinData_Dispose(bdSig);
CkRsa_Dispose(rsa);