Category Archives: Linux

Linux mixed reality

Alice, Bob and Asymmetric Cryptography

I suppose a lot of people know about Alice and Bob, the characters of many cryptographic tales. Previously I posted article “Encrypt and Decrypt Data on Linux Devices using OpenSSL” which explains how encrypt and decrypt files in symmetric way, currently I want to do the same using asymmetric cryptography, exactly how Alice and Bob… Read More »

Experimenting with ECB and CBC Ciphers of AES

The openssl help shows 2 groups ciphers with ECB (Electronic Code book) and CBC (Cipher Block Chaining) suffixes. For example aes-128-ecb and aes-128-cbc or aes-256-ecb and aes-256-cbc for AES (Advanced Encryption Standard) ciphers. In ECB mode input data is divided in blocks of the same length. Then every block will be encrypted with the same… Read More »

Changing Certificate Verification Flags in openssl

Recently I was needed to modify some flags for verification of X.509 public key certificates. These flags defined in x509_vfy.h include files. Particularly it was necessary to set X509_V_FLAG_X509_STRICT flag, which enables additional security checks and turns off workarounds for broken certificate chain. In other words this flag makes the certificate verification more strictly. This… Read More »

About dladdr function.

dladdr function from Unix-like OS looks similar as GetProcAddress Win32 API function. However dladdr obtains more information related to requested function than function entry point address as GetProcAddress does. Besides GetProcAddress requires the handle of the DLL module that contains the requested function, dladdr needs only the function name. Definitely in both cases DLL or… Read More »

Apache on CentOS and HTTP -> HTTPS redirection

Apache HTTP server is a free, open source and popular web Server. It is cross platform server that may run on Linux, Windows and other operating systems. This post is about Apache installation and configuration on CentOS 8. I wrote it for myself as a reminder for future own references. Apache is available in CentOS… Read More »

Installing swift on CentOS 8

Previously I worked with swift occasionally and using xCode only. There is my previous post with XML parser written in swift language. Here is my experience in swift installation on Linux platform with initial command line programming example. The first step – swift installation: It takes several minutes. Check swift version: # swift –version Swift… Read More »

Signing Windows PE file on Linux

The first question is: what for? There are a lot of reason for example someone download Windows application from Linux Apache server. The downloaded application is signed in runtime with different certificate according to selected license. Later during execution Windows application checks certificate type, revocation status and blocks or grants some features. Also application may… Read More »

Installing Powershell and Invoke-Obfuscation on CentOS 8

This article shows how to obfuscate PowerShell command or script for free using Invoke-Obfuscation. We will obfuscate powershell command on Linux CentOS machine and execute obfuscated command on Windows PC. Invoke-Obfuscation runs under powershell and because Microsoft powershell is cross-platform tool and available for many not Windows platforms this obfuscator could be also used anywhere.… Read More »

PID File and Process Name

PID file is small file that contains process identification number usually for daemon processes. Typically pid file location is /var/run directory or sub-directories of /var/run. In new Linux versions /var/run is symbolic link to /run directory. The PID file is created when daemon service is started and deleted when the service stops. If daemon process… Read More »