What is gRPC and How Does it Enhance API Security?

As the reliance on APIs grows, so do the challenges of ensuring they are both fast and secure. Enter gRPC—a high-performance, open-source framework that has revolutionised how systems communicate in real time. 

More than just a tool for building APIs, gRPC brings an added layer of efficiency and robust security features to the table. With its advanced protocol and streamlined architecture, gRPC is transforming the way developers tackle API vulnerabilities while maintaining lightning-fast performance. In this blog, we’ll explore what gRPC is, delve into its core features, and uncover how it raises the bar for API security in an era where cyber threats are at an all-time high. 

Let’s dive into the world of gRPC and discover why it’s becoming a go-to solution for developers and organisations prioritising secure, scalable, and efficient communication. 

Understanding gRPC 

Developed and open-sourced by Google in 2015, gRPC (Google Remote Procedure Call) is a high-performance framework for building distributed systems and APIs. As a language-agnostic evolution of the much older Remote Procedure Call (RPC), it facilitates communication between applications running not only on different platforms, as RPC does, but also in different programming languages.  

gRPC uses HTTP/2 as its transport protocol, offering improved performance compared to the HTTP/1.1 protocol used by traditional RPC. HTTP/2 offers features like multiplexing, header compression, and bidirectional streaming to streamline and accelerate communication. 

Another advantage of gRPC is its use of Protocol Buffers (Protobuf) as its interface definition language (IDL). Protobuf serialises structured data into a binary format, so it takes up less space and is easier to serialise and unserialise than text-based formats like JSON or XML.  

Moreover, Protobuf reduces development overhead, allows developers to add new fields to data structures without disrupting existing code, and promotes strong typing, thus ensuring data consistency and minimising the risk of error.  

How Does gRPC work? 

Here’s a high-level overview of how gRPC works:  

1. Defining the Service: Developers create a .proto file that contains service definitions and message types. This information serves as the blueprint for the API.  

1. Generating Code: The protoc compiler compresses the .proto file, generating client and server stubs in your desired programming language. These stubs serialize and deserialize data using Protobuf, manage HTTP/2 connects, and abstract request and response metrics. 

1. Implementing the Service: Developers write the logic for defined service methods on the server side. For example, GetUser could fetch user data from a database based on UserRequest.  

1. Making RPC Calls: The client uses the generated stub to handle remote procedure calls (RPCs). These calls are executed locally to handle Protobuf serialisation, transmit requests over HTTP/2, and deserialise responses. The four primary service methods gRPC uses for RPCs are:  

• Unary RPC: Simple request-response (e.g., GetUser). 

• Server-streaming RPC: A single request results in a stream of responses (e.g., real-time updates). 

• Client-streaming RPC: A stream of client requests results in a single server response (e.g., file uploads). 

• Bidirectional-streaming RPC: Both client and server exchange streams of data simultaneously (e.g., chat applications). 

1. Securing Communications: gRPC uses SSL/TLS by default to secure data in transit, protecting it from interception or tampering. Developers can also integrate advanced authentication mechanisms like JSON Web Tokens (JWT) or OAuth 2.0. 

How Does gRPC Enhance API Security? 

gRPC is a great communication protocol option for organisations with stringent security requirements, such as those operating in the financial services or healthcare sectors. But how, exactly, does gRPC enhance API security? 

Encryption and Data Protection 

The use of HTTP/2 as the transport protocol enables the use of Transport Layer Security (TLS) for encrypting data in transit, ensuring that sensitive information exchanged between clients and servers remains confidential and protected from interception. 

Authentication 

gRPC supports robust authentication methods to verify the identity of clients and servers: 

• JSON Web Tokens (JWT) provide a stateless, portable, and flexible way to authenticate clients. They can include custom claims for fine-tuned access control. 

• Mutual TLS (mTLS) ensures both the client and server authenticate each other, providing an additional layer of security. 

• gRPC offers integration with OAuth 2.0 for token-based authentication, particularly useful when connecting to Google services. 

Authorisation and Access Control 

gRPC implements strong authorization mechanisms to control access to resources. Through Role-Based Access Control (RBAC), administrators can assign permissions to roles rather than individual users, simplifying access management. In addition, gRPC allows for implementing detailed access policies, ensuring services only have the necessary permissions to perform their intended functions. These features enable the implementation of gRPC with a zero-trust approach, requiring strict verification for all users and systems. Finally, gRPC supports comprehensive logging and monitoring, which are crucial for detecting unauthorized access and analysing potential security threats. 

Besides the above security capabilities, it also essential to strengthen the secure gRPC implementation through: 

• Regular security audits and penetration testing. 

• Automated vulnerability scanning and testing in the CI/CD pipeline. 

• Tools that support dynamic application security testing (DAST) for gRPC services. 

Choosing Between REST and gRPC: Key Considerations 

That said, gRPC is not the best communication protocol for everyone. You must understand your application’s specific needs and how each protocol can meet them to decide between the two. Here’s an overview of each protocol’s benefits and use cases to help you decide:  

When to Use REST: 

• Internal systems with security requirements: REST is ideal for building secured internal systems where you need a clear standard for HTTP connections, as it operates on top of the HTTP protocol, which makes it compatible with firewalls, proxies, and standard web servers. 

• Controlled external exposure: If your system has limited interaction with the outside world, REST can handle this by using well-known patterns for interaction that are easy to control. 

• Rapid iteration and HTTP connection standardisation: REST’s simplicity and stateless nature make it suitable for quickly changing applications, as the HTTP methods (GET, POST, PUT, DELETE) standardise how requests and responses are handled. 

• Third-party integrations: Most third-party tools support REST, so if your system needs to integrate with external services or platforms, REST will simplify that process. 

• Cloud-based applications: REST’s statelessness (where each request is independent of others) makes it easy to scale and handle technical faults in cloud applications, as it allows for load balancing and fault tolerance. 

When to Use gRPC: 

• Internal systems: gRPC is often used for internal communications, particularly in microservices architectures. It’s a good choice when you need efficient, fast organisational communication. 

• Lightweight microservices: gRPC is designed for low-latency communication and quick data delivery, making it ideal for microservices that need to exchange data with minimal delay. 

• Real-time message delivery: gRPC’s support for HTTP/2.0 and two-way streaming makes it well-suited for applications requiring real-time, bidirectional communication (e.g., video or chat applications). 

• Multilingual applications: gRPC supports multiple programming languages, so it’s a great choice when building applications that need to support several languages or have a polyglot architecture. 

• Low power/bandwidth networks: Because gRPC uses Protocol Buffers (a lightweight and highly serialised message format), it’s ideal for constrained network resources, such as mobile applications or low-bandwidth environments. 

• Efficient mobile app development: gRPC doesn’t rely on a browser for communication, making it efficient for mobile applications where bandwidth and performance are crucial. 

TL/DR 

Ultimately, you want to use REST when building web services that need quick iteration, wide third-party integration, cloud compatibility, or secure internal systems with controlled external exposure. gRPC, however, is better for low-latency microservices, real-time applications, multilingual systems, and scenarios requiring lightweight, efficient communication, especially when dealing with mobile apps or low-bandwidth environments. 

Whatever communication protocol you choose, it is essential to secure your APIs and applications. Best-in-class API Security and WAAP (Web App and API Protection) solutions offer automated protection that works with any platform and any cloud, multi-cloud, cloud-native, hybrid, or on-premises environment.