Senior Software Security Engineer, Infrastructure

  • San Francisco, CA
  • Full-time

Company Description

Square builds common business tools in unconventional ways so more people can start, run, and grow their businesses. When Square started, it was difficult and expensive (or just plain impossible) for some businesses to take credit cards. Square made credit card payments possible for all by turning a mobile phone into a credit card reader. Since then Square has been building an entire business toolkit of both hardware and software products including Square Capital, Square Terminal, Square Payroll, and more. We’re working to find new and better ways to help businesses succeed on their own terms—and we’re looking for people like you to help shape tomorrow at Square.

Job Description

The Square Security team works with other teams at Square to build world-class products for both customers and employees. Our ultimate goal is to ensure that every experience with Square is simple, secure, and safe.

Square's Security Infrastructure engineering team is responsible for some of the company's most essential, high-SLA systems. Our software protects our customers' most sensitive data. Our purpose is to identify our ecosystem's security needs, and to meet those needs in a central and scalable way.


You will:

  • Design, implement, and maintain security-oriented software that makes it easier for non-security engineers to build secure products.
  • Own the delivery and success of critical payments security, secure storage, service identity, and PKI services.
  • Collaborate with many teams and functions across Square to make technical, design, strategy, and product decisions.
  • Act as an internal security subject matter expert, advocating for better security practices throughout Square.
  • Grow your career in an engaged and creative engineering community that ships amazing products.
  • Work in any Square office location, or work remotely in the USA or Canada. Occasional travel may be required.

You have:

  • 5+ years of relevant experience
  • Success at building secure systems with broad company impact.
  • Experience designing, implementing, deploying, and monitoring highly-available, critical production systems.
  • Experience with applied cryptography or securing cloud platforms.
  • A strong desire to perform and grow as a security engineer and educate other engineers.

Some of the technologies we use:

  • Java, Go, Ruby
  • HSMs
  • AWS/GCP/Square-owned datacenter
  • Service Mesh, Envoy
  • Lambda, Kubernetes, Docker

We're active contributors to open-source! Some of the projects we developed or maintain include:

  • Keywhiz: a secrets distribution service and its client Keysync.
  • Sharkey: a service for managing certificates for use by OpenSSH.
  • Ghostunnel: TLS proxy with mutual authentication for securing non-TLS services.
  • Go-Jose: An implementation of JOSE standards (JWE, JWS, JWT) in Go (and in JavaScript, too).
  • Certigo: A utility to examine and validate certificates in a variety of formats.
  • Certstrap: Tools to bootstrap CAs, certificate requests, and signed certificates.
  • Beancounter: A scalable Bitcoin balance audit tool.
  • Subzero: Square's Bitcoin Cold Storage solution.



Additional Information

At Square, we value diversity and always treat all employees and job applicants based on merit, qualifications, competence, and talent. We do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status. We will consider for employment qualified applicants with criminal histories in a manner consistent with the requirements of the San Francisco Fair Chance Ordinance. Applicants in need of special assistance or accommodation during the interview process or in accessing our website may contact us by sending an email to assistance(at) We will treat your request as confidentially as possible. In your email, please include your name and preferred method of contact, and we will respond as soon as possible.


At Square, we want you to be well and thrive. Our global benefits package includes:
  • Healthcare coverage
  • Retirement Plans
  • Employee Stock Purchase Program
  • Wellness perks
  • Paid parental leave
  • Paid time off
  • Learning and Development resources
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