You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Survey of QoS routing protocols in Wireless Multimedia Sensor Networks 
Chapter Title:  Secure Routing. 
1. Abstract of Cited Paper (BIB001):  The emerging use of Wireless Multimedia Sensor Networks (WMSNs) and communication facilities have increased the need for network security measures to protect different types of multimedia data either real time or non-real time during the transmission period. A lot of researchers are becoming more interested on secure WMSNs due to the broad application necessities which can be range over smart environment, security surveillance and smart health-care; so requirements on secure aggregation of multimedia data, Quality of Service (QoS) and privacy should be satisfied. Current technologies vs. proposed security techniques in WMSNs and its pros and cons from a security point of view are explored in details. In addition to promising future trends of this research area by giving more attention for new challenging problems including secure routing protocol, fault tolerant, robustness and recovery process. We believe that this paper will add significantly a valuable discussion among the researchers and promote them to fetch new research ideas to design approximately best model by combining the most important security issues in order to reach secure WMSNs. 
2. Abstract of Cited Paper (BIB002):  Multimedia applications are gradually becoming an essential--and flourishing--part of our daily lives. The area of wireless sensor networks is not an exception to this trend, as multimedia data have attracted the attention of researchers. Their importance is due to the shift of focus from traditional scalar sensors to sensors equipped with multimedia devices, as well as to the next-generation wireless multimedia sensor networks (WMSNs). The highly sensitive nature of multimedia traffic makes data routing with security even more important in WMSNs. This paper discusses the challenges of secure routing in WMSNs, where most of the proposed works in the literature deal with routing and security as individual issues. A critical and comprehensive review of state-of-the-art routing and security approaches for WMSNs is presented, followed by the discussion of their limitations and features. It is hoped that this extensive review and discussion ultimately identifies the future research directions and the open challenges of secure routing approaches in WMSNs.

Literature Review:
WMSNs are usually deployed at unattended or in hostile environments. Therefore, they are vulnerable to various security attacks, such as wormhole, sinkhole, sybil, spoofed, altered, and selective forwarding attacks BIB003 . Due to the unreliable wireless channels and unsupervised feature of WMSNs, a malicious adversary may readily launch attacks to compromise the security of the sensor node or network. The constrained capabilities of sensor nodes make it very difficult to implement strong security protocols. A strong security protocol requires more resources that can shorten the lifetime of the sensor node. However, simple security protocol can be easily compromised by an adversary. Due to limited resources available with the sensor nodes, standard security protocols may not be suitable for WMSNs. Security can be provided with the help of five different services, namely, confidentiality, authentication, integrity, nonrepudiation, and availability. Work done to support extremely simple security features has been reported. Due to limited resources, symmetric cryptography is an ideal choice for scalar-based sensor nodes to implement security. However, in general, symmetric cryptography is not able to support nonrepudiation, authentication, and digital signatures in an effective manner. Additionally, because of the use of simple symmetric keys, nodes can be easily compromised by attack that can disrupt the entire network. For further improvement of secure routing, asymmetric cryptography can be incorporated among a few high-processing multimedia sensor nodes. Therefore, incorporating symmetric and asymmetric encryption techniques and designing mechanisms to prevent different types of attacks and key distribution techniques in resource constraint environment are few promising areas of research in secure routing. QoS guarantee and network security management are two critical aspects that will determine the success of future WMSNs BIB001 BIB003  BIB002 .