I have a Lambda function, written in NodeJS, that decrypts a file using the OpenPGP library. This has worked very well for the past four months but on Thursday last week it stopped decrypting the files with the following error:

{
“errorType”: “Error”,
“errorMessage”: “Error decrypting message: Decryption error”,
“stack”: [
“Error: Error decrypting message: Decryption error”,
” at /opt/node_modules/openpgp/dist/node/openpgp.min.js:2:178460″,
” at process.processTicksAndRejections (node:internal/process/task_queues:95:5)”,
” at async ju.decrypt (/opt/node_modules/openpgp/dist/node/openpgp.min.js:2:291018)”,
” at async /opt/node_modules/openpgp/dist/node/openpgp.min.js:2:345501″,
” at async Promise.all (index 0)”,
” at async /opt/node_modules/openpgp/dist/node/openpgp.min.js:2:344837″,
” at async Promise.all (index 0)”,
” at async /opt/node_modules/openpgp/dist/node/openpgp.min.js:2:344447″,
” at async Promise.all (index 0)”,
” at async Bh.decryptSessionKeys (/opt/node_modules/openpgp/dist/node/openpgp.min.js:2:344404)”
]
}

The odd thing is that when I debug the Lambda function locally it still successfully decrypts the file. I have run the function for files that were previously decrypted successfully and they no longer decrypt. I have run the code using the same libraries I’m using locally, but it still fails.

I’m wondering why this can work locally but not from AWS and also why it would have stopped working in the first place given there were no code changes.