Specific secret keys identification in source code

[gaurav-mmt]

I would like to check specific set of credentials/keys are defined in source code or not. As i am defining for example this regex.json file and i have also committed the same in my source code for testing purpose.
{
"API key": "ABEFDSPUEPPDUEDE"
"API key": "ABEFDSPUEPPDUasds"
"API key": "ABEFDSPUEasdsdsdef"
}

I executed this command to figure out the trufflehog output with above API keys but i haven't received any of them in output. Please help on it

trufflehog --rules regex.json --entropy=False githuburl