Senior Security Engineer, Bitcoin Platform, Cash App

  • San Francisco, CA
  • Full-time

Company Description

Cash App is the fastest growing financial brand in the world. Initially built to take the pain out of peer-to-peer payments, Cash App has gone from a simple product with a single purpose to a dynamic app with over 24 million monthly active users. We are bringing a better way to send, spend, invest, and save to anyone who has ever sought an alternative to the traditional banking system.

Loved by customers and pop culture, we’ve consistently held the top spot for finance in the App Store for many years, seeing more engagement with millions of followers across social media in a day than most brands see in a year. We are building an ecosystem to redefine the world’s relationship with money by making it universally accessible.

We want to hire the best talent regardless of location. Our employment model is distributed, offering the opportunity to collaborate with teams across the world in San Francisco, New York, St. Louis, Portland, Toronto, Kitchener-Waterloo, Sydney, and Melbourne.

Interested in learning more?

Job Description

Cash App is a mobile-first bank that ranks in the top 10 free apps in the app store with a rapidly growing user base and feature set. Our mission is to provide banking services to all, in particular those that are underserved.

The Cash Security team is a hands-on engineering-driven security team that embeds security engineers within key platform and product teams across Cash. As a security team, we collaborate on building and sharing security infrastructure, principles, and guidelines.

As a Security Engineer embedded in Bitcoin Platform, you’ll work within our Bitcoin Platform team to:

  • Co-design, co-build, and co-own the security mechanisms and features that we use to protect our Bitcoin holdings in hot and cold-storage in production and at scale
  • Co-design, co-build, and co-own security mechanisms and features in our bitcoin platform production services, written in Kotlin and running on AWS
  • Maintain and develop new capabilities for Subzero, our open-source cold storage system, including the embedded enclave code that executes on our HSMs
  • Administer and maintain the offline Hardware Security Modules (HSMs) used by Subzero


You have:

  • A strong motivation to contribute to a meaningful product that will fundamentally change the way people interact with financial institutions
  • Strong desire to perform and grow as a security engineer, and mentor other engineers
  • Demonstrated technical initiative and leadership

Technologies we use and teach:

  • AWS KMS and Google’s Tink Cryptographic APIs
  • Hardware Security Modules
  • Java 11 including JUnit, Hibernate, and Guice, Kotlin, C
  • AWS, Docker, Kubernetes, Terraform

Additional Information

Cash App treats all employees and job applicants equally. Every decision is based on merit, qualifications, 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 each office’s corresponding local guidelines.