Senior Software Engineer, Security

Senior Software Engineer, Security

at Square

San Francisco, CA

Company Description

We believe everyone should be able to participate and thrive in the economy. So we’re building tools that make commerce easier and more accessible to all. We started with a little white credit card reader but haven’t stopped there. Our new reader helps our sellers accept chip cards and NFC payments, and our Cash app lets people pay each other back instantly. We’re empowering the independent electrician to send invoices, setting up the favorite food truck with a delivery option, helping the ice cream shop pay its employees, and giving the burgeoning coffee chain capital for a second, third, and fourth location. Let’s shorten the distance between having an idea and making a living from it. We’re here to help sellers of all sizes start, run, and grow their business—and helping them grow their business is good business for everyone.

Job Description

The Square Security team works to ensure the security of every transaction from swipe to receipt and beyond. We embed ourselves in other teams at Square to build world-class products for both customers and employees. Our ultimate goal is to ensure that every single experience with Square is simple, secure, and safe.

Square’s security engineers design, build, and maintain some of the company’s most critical, high-SLA systems. Our software protects our customers’ most sensitive data. Our purpose is to identify Square engineers’ security needs, and to meet those needs in a central and scalable way.

We’re active contributors to open-source! Some of the projects we maintain are:

  • Keywhiz
  • Ghostunnel
  • Go-Jose
  • Certigo
  • Certstrap
  • Sharkey

You will:

  • Design, implement, and build security-oriented software to make it easier for non-security engineers to build secure products
  • Build automation to provide security insights to other Square engineers (e.g. static analysis, dependency tracking)
  • Own Square’s internal PKI and secrets management infrastructure
  • Act as an internal security subject matter expert, advocating for better security practices throughout Square


You have:

  • A passion for building secure systems
  • Experience in software architecture and engineering
  • Experience in designing, deploying, and monitoring critical production systems

Even better:

  • Strong background in applied cryptography
  • Experience with PCI security standards (including DSS and PTS)
  • Experience with Hardware Security Modules (HSMs)
  • Experience with distributed systems
  • Experience with securing cloud platforms

Some of the technologies we use and teach:

  • Java
  • C
  • Go
  • Ruby
  • MySQL
  • HSMs