Bug report: 'JSON beautify' operation losing numeric precision

[n1474335]

Summary

When running the 'JSON beautify' operation, numeric precision is lost for large numbers.

Example

https://gchq.github.io/CyberChef/#recipe=JSON_Beautify('%5C%5Ct')&input=eyAiYSI6IDEyMzQ1Njc4OTAxMjM0NTY3ODkgfQ

Input:

{ "a": 1234567890123456789 }

Erroneous output:

{
	"a": 1234567890123456800
}

[PhillipNordwall]

Discussion

This issue is arising due to the method of implementing the the beautification library being used.

JSON Spec

The JSON Spec allows implementations to set precision limitations numbers. https://tools.ietf.org/html/rfc7159#section-6.

Implementation

Beautification and minification are done with vkbeautify, which uses Javascript.

Javascript numbers are all represented as a 64 bit float, with a 52 bit mantissa. So the safe range for integer usage is [-2^53,2^53] = [-9007199254740992,9007199254740992]

As the spec allows for this behavior it might be better to classify this as a feature request instead of a bug.

This bug also shows up in 'JSON Minify` as it uses vkbeautify.

'JSON Minify' Example

https://gchq.github.io/CyberChef/#recipe=JSON_Minify()&input=eyAiYSI6IDkwMDcxOTkyNTQ3NDA5OTMgfQ

Input:
{ "a": 9007199254740993 }

Erroneous output:
{"a":9007199254740992}

Other uses of vkbeautify

This library gets used in the following locations. I believe that the JSON ones are the only ones that will have this particular issue as the others are likely not treating the represented numbers as anything other than a string.

• CSSBeautify.mjs
• CSSMinify.mjs
• JSONBeautify.mjs
• JSONMinify.mjs
• SQLBeautify.mjs
• SQLMinify.mjs
• XMLBeautify.mjs
• XMLMinify.mjs