Senior Security Engineer - Bitcoin Platform

Job Description

Cash App has grown rapidly to tens of millions of users moving billions of dollars daily. To support this growth, the Security organization is expanding. The Cash Security team is a hands‑on engineering‑driven security team that embeds security engineers within key platform and product teams across Cash, collaborating on building and sharing security infrastructure, principles, and guidelines.

• Co-design, co-build, and co‑own the security mechanisms and features that we use to protect the entire lifecycle of our Bitcoin holdings 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 applications that execute on our HSMs.

You have (not all required):

• 8+ years of experience delivering quality software.
• Experience writing security‑sensitive code or using cryptographic libraries.
• Familiarity with security protocols or protocol implementation.
• Experience with embedded systems, embedded C, firmware development or embedded security.
• Experience with Secure Enclaves, Trust Zone, SGX, AWS Nitro enclaves, HSMs, nCipher HSMs or Codesafe.
• Experience building security‑sensitive applications in AWS.
• A strong motivation to contribute to a meaningful product that will fundamentally change the way people interact with a financial institution.
• Strong desire to perform and grow as a security engineer, and mentor other engineers.
• Demonstrated technical initiative and leadership.

Hardware Security Modules and nCipher Code Safe application
AWS KMS
Google’s Tink Cryptographic API
C programming

Block takes a market‑based approach to pay, and pay may vary depending on your location. U.S. locations are categorized into one of four zones based on a cost of labor index for that geographic area. The successful candidate’s starting pay will be determined based on job‑related skills, experience, qualifications, work location, and market conditions.

• Zone A: USD $198,000 - USD $297,000
• Zone B: USD $188,100 - USD $282,100
• Zone C: USD $178,200 - USD $267,400
• Zone D: USD $168,300 - USD $252,500

To find a location’s zone designation, please refer to this resource. If a location of interest is not listed, please speak with a recruiter for additional information.

Full‑time employee benefits include the following:

• Healthcare coverage (Medical, Vision and Dental insurance)
• Health Savings Account and Flexible Spending Account
• Retirement Plans including company match
• Employee Stock Purchase Program
• Wellness programs, including access to mental health, 1:1 financial planners, and a monthly wellness allowance
• Paid parental and caregiving leave
• Paid time off (including 12 paid holidays)
• Paid sick leave (1 hour per 26 hours worked (max 80 hours per calendar year to the extent legally permissible) for non‑exempt employees and covered by our Flexible Time Off policy for exempt employees)
• Learning and Development resources
• Paid Life insurance, AD&D, and disability benefits

Block is a proud equal opportunity employer. We evaluate all employees and job applicants consistently, without regard to race, color, religion, gender, national origin, age, disability, veteran status, pregnancy, gender expression or identity, sexual orientation, citizenship, or any other legally protected class. We believe in being fair, and we are committed to an inclusive interview experience, including providing reasonable accommodations to disabled applicants throughout the recruitment process.

Block will consider qualified applicants with arrest or conviction records for employment in accordance with state and local laws and "fair chance" ordinances. Because the material duties of this role involve direct or indirect access to sensitive personal or financial data, a criminal background check is required following a contingent offer of employment.