tlsfuzzer/tlslite-ng

RSA blinding factor may not have an inverse mod n

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#426 opened on Oct 18, 2020

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buggood first issuehelp wanted

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Description

In RSA code we generate a blinding factor as simple integer mod n: https://github.com/tomato42/tlslite-ng/blob/9951ec1c769617247a80aa1cae661ec0edc68823/tlslite/utils/python_rsakey.py#L65-L70

we should verify that it's relatively prime to n (by calculating gcd() and checking if it is 1) before using it.

Contributor guide

Research direction
Inspect the code at the linked line (L65-70) in python rsakey.py and add a gcd check to ensure the blinding factor is relatively prime to n before using it.
Tech stack
python
Domain
securitycryptography
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RSA basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80