Senior Security Engineer - Bitcoin Platform

Company Description
It all started with an idea at Block in 2013. 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 ecosystem, developing unique financial products, including Afterpay/Clearpay, to provide a better way to send, spend, invest, borrow and save to our 47 million monthly active customers. We want to redefine the world's relationship with money to make it more relatable, instantly available, and universally accessible.
Today, Cash App has thousands of employees working globally across office and remote locations, with a culture geared toward innovation, collaboration and impact. We've been a distributed team since day one, and many of our roles can be done remotely from the countries where Cash App operates. No matter the location, we tailor our experience to ensure our employees are creative, productive, and happy.
Check out our locations, benefits, and more at cash.app/careers.
Job Description
Cash App has grown rapidly to tens of million of users moving billions of dollars daily. To support this incredible growth, we are growing the Security organization.
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 Engineering, you'll work within our Bitcoin Platform Engineering team to:

• 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

Qualifications
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, TrustZone, 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 financial institution
• Strong desire to perform and grow as a security engineer, and mentor other engineers
• Demonstrated technical initiative and leadership

Technologies we use and teach:

• Hardware Security Modules and nCipher CodeSafe application
• AWS KMS
• Google's Tink Cryptographic API
• C programming

Additional Information
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. These ranges may be modified in the future.
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

These benefits are further detailed in Block's policies. This role is also eligible to participate in Block's equity plan subject to the terms of the applicable plans and policies, and may be eligible for a sign-on bonus. Sales roles may be eligible to participate in a commission plan subject to the terms of the applicable plans and policies. Pay and benefits are subject to change at any time, consistent with the terms of any applicable compensation or benefit plans.
We're working to build a more inclusive economy where our customers have equal access to opportunity, and we strive to live by these same values in building our workplace. Block is a proud equal opportunity employer. We work hard to 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 are committed to an inclusive interview experience, including providing reasonable accommodations to disabled applicants throughout the recruitment process. We encourage applicants to share any needed accommodations with their recruiter, who will treat these requests as confidentially as possible. Want to learn more about what we're doing to build a workplace that is fair and square? Check out our I+D page .
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.
While there is no specific deadline to apply for this role, on average, U.S. open roles are posted for 70 days before being filled by a successful candidate.
Block, Inc. (NYSE: SQ) is a global technology company with a focus on financial services. Made up of Square, Cash App, Spiral, TIDAL, and TBD, we build tools to help more people access the economy. Square helps sellers run and grow their businesses with its integrated ecosystem of commerce solutions, business software, and banking services. With Cash App, anyone can easily send, spend, or invest their money in stocks or Bitcoin. Spiral (formerly Square Crypto) builds and funds free, open-source Bitcoin projects. Artists use TIDAL to help them succeed as entrepreneurs and connect more deeply with fans. TBD is building an open developer platform to make it easier to access Bitcoin and other blockchain technologies without having to go through an institution.