IPFS Encrypted Share

Current version: 1.0.0

Encrypted file uploader for IPFS, similar to Mega

Security

This use libsodium, so it should be quite safe to use. However, I’m not a cryptography expert and this code is not audited, so use it at your own risk.

Technical details

Encryption

Files are encrypted with libsodium stream encryption. The encryption key are randomly generated every time and stored as urlsafe unpadded base64 in URL fragment (not transmitted to gateway or IPFS).

Metadata

File metadata is stored at /metadata.json. It contains 2 keys:

• header: Stream header (from crypto_secretstream_xchacha20poly1305_init_push), base64 encoded without padding.
• encryptedMetadata: Encrypted metadata, base64 encoded without padding.

The encrypted metadata is the first message in the stream. It is a JSON with the following keys:

• filename: Original filename
• size: File size in bytes
• pieces: Number of file pieces

This message has the tag crypto_secretstream_xchacha20poly1305_TAG_FINAL.

File pieces

The file are splitted to pieces, each 5MB in size. (limited by libsodium.js heap size) They are encrypted and stored at /pieces/chunkId. ChunkID starts at 0 to encryptedMetadata.pieces - 1. File pieces share the same encryption stream with the metadata.

The final piece has the tag crypto_secretstream_xchacha20poly1305_TAG_FINAL. All other pieces has the tag 0.

License

Licensed under the MIT License