# A Review of PCI Express Protocol-Based Systems in Response to 5G Application Demand
## 3 Technology Analysis Using PCI Express, CXL, USB, NVMe, and Security
### Security  
The Trust Platform Module (TPM) was released by the Trust Computing Group. The TCG defined the security system with security features in software and hardware. Figure 11, shows the TPM with data communication through secure features. The system reference TPM has security features for hardware, software, and application usage to enhance platform security [38]. Secure Hash Algorithms (SHA) function in SHA1 and SHA2 series, public-key cryptography, and PKCS, and are updated from sources including the Social Security Administration (SSA), etc. [38; 39]. These security-based algorithms are combined in different software-defined phases and states to enable these security features to secure software and firmware. The system security solutions used as platform designs for Windows-based and Linux-based systems in the market have been reviewed [40]. TPM 2.0 (SHA256, SHA384, and SM3-256 with RSA 2048 or larger) was the current common TCM from TPM 1.2 (RSA 2048 and SHA1) for hardware security key algorithms, combined with a platform that can let the firmware and OS enhance security for platform-specific designs based on the platform hardware security [38; 39]. Similar to Microsoft with BitLocker, usage methods are combined, using the SHA algorithm to enhance security [41]. Software TPM and hardware TPM are improved to construct TPM secure systems.  
Intel(tm) and AMD(tm) system chipsets still combine software and hardware security solutions in the system chipset, which can use hardware resources to define a combination of security solutions in the system (such as the SHA2 series with RSA with hardware public security keys and OEM security). There are some security-blocked resources that can protect specific resources for access resource requirements, such as AMD(tm) Secure Memory Encryption (SME), and Secure Encrypted Virtualization (SEV); Intel(tm) TDT in Intel(tm) Software Guard Extension, and Intel(tm) SGX [42; 43].  
IC-based security solutions are based on a traditional interface to secure data during transfers in the platform and connections. These make the original data into secure data during storage access. Some platforms and endpoint devices such as those in the IoT could use IC security to improve their security environments. Multiple software security solutions can be combined in the system. As well as the operating system and the firmware, the execution system should be assessed for security risks to reduce security concerns during execution [44]. To compare secure solutions, SHA-256 is the main option in the  
Figure 10: High-level architecture view for PD [37].  
current product line, but SHA-384 is scheduled to deliver solutions in 2020. More secure solutions may be combined for 5G and the cloud environment [4].  
The secure system references the TPM architecture, as shown in Figure 11 and enhances the security solutions that it contains. The interface across the TPM and the platform security algorithm reduces the security risks of a system. The TCG-defined methods rely on the root of trust. For a trusted platform, there are three items that need to be reviewed: Root of Trust Measurement (RTM), Root of Trust Storage (RTS), and Root of Trust for Reporting (PTR) [45].  
In Figure 11, the TPM covers secure solutions and shows the root of trust and the process in the system. The TPM 2.0 is listed in the OS vendor's support lists for Microsoft and Linux-based systems as a basic requirement for security [41]. When an operating system runs on open source and virtual machines in the PC industry, security solutions use hardware and software to enhance security capabilities.