# Ruslan Kiyanchuk

> Cryptography & Software Engineer

Location: San Francisco Bay Area, United States
Profile: https://flows.cv/ruslankiyanchuk

Ruslan holds MSc degree in Information and Communication Systems Security from Kharkiv National University of Radio and Electronics (Ukraine), specializing in cryptography. As a graduate he joined JSC "Institute of Information Technologies" to conduct research and development of symmetric cryptographic algorithms, where he collaborated with a team of cryptographers designing block cipher "Kalyna" adopted as a national standard of Ukraine in 2015.

## Work Experience
### Staff Software Engineer @ Navan
Jan 2022 – Present | San Francisco Bay Area
⦿ Implemented Multi Factor Authentication (MFA) for Navan platform end-to-end:
 - backend integration with Auth0 and Twilio;
 - controls in user profile on the frontend to configure MFA;
 - user-facing documentation, setting up processes for customer support.

### Information Security Consultant @ Hauki Tech
Jan 2023 – Present | Poland
Audit of cryptographic implementations, research and development of authentication, authorization, and encryption solutions.

⦿ Audited cryptographic library implementing symmetric encryption. Identified 1 major vulnerability (memory mismanagement that allows client code to override block cipher mode of operation).

⦿ Reviewed security of transport protocol used by an IoT vendor.

⦿ Research and develop authorization and encryption for a protocol for decentralized exchange and transformation of data.

### Senior Software Engineer @ Brex
Jan 2020 – Jan 2022 | San Francisco, California, United States
⦿ Implemented graph-based access authorization framework which models access as a social graph.

⦿  Identified and fixed vulnerability with activation token reuse granting an attacker full access to customer account bypassing authentication.

⦿ Implemented part of FIDO U2F specification and signature verification for JavaCard platform to enable using issued bank cards as U2F.

### Senior Software Engineer @ Symantec
Jan 2017 – Jan 2020 | San Francisco Bay Area
Enterprise Security Group

⦿  Developed framework for bare-metal servers auto-discovery and provisioning (deploying 1000 servers under 20~minutes).

⦿  Designed and implemented infrastructure asset management system for hybrid cloud environment to enable compliance monitoring.

⦿ Crypto Review Board: review and audit cryptographic solutions and implementations in company products.

### Software Engineer @ Mirantis
Jan 2014 – Jan 2017 | San Francisco Bay Area
OpenStack cloud solutions.

⦿  Developed framework for bare-metal servers auto-discovery and provisioning (deploying 1000 servers under 20~minutes).

⦿ Implemented authentication middleware for Python-based micro-services.

### Software Engineer @ Mirantis
Jan 2013 – Jan 2014 | Ukraine
⦿  Implemented plugins for OpenStack Ceilometer to collect metrics from virtual machines for monitoring and audit purposes.

⦿ Implemented CLI support for tenant admin functionality in OpenStack Keystone API v3.

⦿ Optimized OpenStack LDAP authentication backend to reduce login time from ~25s to 1-2s.

### Software Engineer @ JSC "Institute of Information Technologies"
Jan 2012 – Jan 2012 | Kharkiv, Ukraine
Research and development of symmetric cryptographic algorithms.

⦿ Analysis and implementation of block cipher "Kalyna" (Ukrainian National Encryption Standard DSTU~7624:2014 since 2015).

⦿ Algebraic cryptanalysis of symmetric block ciphers:
 - Performed algebraic cryptanalysis of GOST 28147 cipher, recovering full key after 6 rounds of encryption from only 4 pairs of plaintext and ciphertext.
 - Created reference implementation and generated test vectors for "Kalyna" block cipher.


## Education
### Master of Science (M.Sc.) in Security of Information and Communication Systems
Kharkiv National University of Radio Electronics

### Bachelor of Science (B.Sc.) in Security of Information and Communication Systems
Kharkiv National University of Radio Electronics

### Leslie High School


## Contact & Social
- LinkedIn: https://linkedin.com/in/rkiyanchuk
- GitHub: https://github.com/rkiyanchuk
- Portfolio: https://infosec.exchange/@ruslan

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Source: https://flows.cv/ruslankiyanchuk
JSON Resume: https://flows.cv/ruslankiyanchuk/resume.json
Last updated: 2026-04-12