Unable to decrypt readableStreamBody from Azure Blob Storage - Misformed Armored Text

[ed-whittle]

Hi All,

I'm having trouble decrypting a Blob from Azure Storage.

Package Versions:
openpgp: 5.11.0
node: 18.6.0
@azure/storage-blob: 12.17.0

Related Documentation
https://learn.microsoft.com/en-gb/javascript/api/%40azure/storage-blob/blobclient?view=azure-node-latest#@azure-storage-blob-blobclient-download

When I print the blob to the console, I get this result

    const downloadBlockBlobResponse = await inboundBlobClient.download(0);

    console.log(await streamToString(downloadBlockBlobResponse.readableStreamBody))

....

async function streamToString(readableStream) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    readableStream.on("data", data => {
      chunks.push(data.toString());
    });
    readableStream.on("end", () => {
      resolve(chunks.join(""));
    });
    readableStream.on("error", reject);
  })
}

-----BEGIN PGP MESSAGE-----
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=7+Uy
-----END PGP MESSAGE-----

However when decrypting the stream using the decrypt function

    const { data } = await openpgp.decrypt({
      message: await openpgp.readMessage({
        armoredMessage: downloadBlockBlobResponse.readableStreamBody,
      }),
      decryptionKeys: [privateKey], // for decryption,
    });

Error: Misformed armored text
    at <my local path>/gpg-encrypt/node_modules/openpgp/dist/node/openpgp.min.js:2:26344
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

Testing with the binaryMessage, I get a different output

    const { data } = await openpgp.decrypt({
      message: await openpgp.readMessage({
        binaryMessage: downloadBlockBlobResponse.readableStreamBody,
      }),
      decryptionKeys: [privateKey], // for decryption,
    });

Error: Error during parsing. This message / key probably does not conform to a valid OpenPGP format.

I convert the stream to a string using the helper function above, the file prints successfully to the console

    const downloadBlockBlobResponse = await inboundBlobClient.download(0);

    const dataAsString = await streamToString(downloadBlockBlobResponse.readableStreamBody);

    const { data } = await openpgp.decrypt({
      message: await openpgp.readMessage({
        armoredMessage: dataAsString,
      }),
      decryptionKeys: [privateKey], // for decryption,
    });

    console.log(data); // Prints the payload successfully

I have no problems with a similar implementation for encryption performed in a different function

    const ciphertext = await openpgp.encrypt({
      message: await openpgp.createMessage({
        binary: downloadBlockBlobResponse.readableStreamBody
      }),
      encryptionKeys: publicKey,
    });

I need to keep the blob downloaded from Blob storage as a stream for large file support. Any help would be greatly appreciated.

[ed-whittle]

Fixed, the issue was to set the encoding as utf8

The working example is

    const downloadBlobResponse = await inboundBlobClient.download();
    downloadBlobResponse.readableStreamBody.setEncoding('utf8')

    const message = await openpgp.readMessage({
      armoredMessage: downloadBlobResponse.readableStreamBody as any
    });

    console.log('Decrypting');
    const { data } = await openpgp.decrypt({
      message,
      decryptionKeys: [privateKey], // for decryption,
    });

    console.log('Starting Upload');
    outboundBlockBlobClient.uploadStream(data as any);