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series-rsa-javascript

A series implementing RSA in JavaScript: BigInt maths, key sizes, and RSA inside JWTs.

2 articles
RSS

RSA in JavaScript Part 2: The JWT Is Where You'll Actually Meet It

Most JavaScript developers never call an RSA function directly. They verify an RS256 token, and two classic attacks turn that into an authentication bypass — both demonstrated here, both fixed by one line.

RSA in JavaScript: Your Numbers Are Too Small

RSA in JavaScript: Your Numbers Are Too Small

JavaScript cannot do RSA with numbers. Not slowly, not imprecisely — at all. The largest modulus a Number can handle is 26 bits and RSA needs 2048, and the failure is silent. Here's the implementation that works and why.