Compress encrypted data #231
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This is part of a push to support larger files. The focus is the switch
to using Uint8Array to store binary data. But also includes:
- When running on Node, use Buffer.from() for hex string conversions.
- To avoid large buffer copy, signedMsg as been replaced by an object
containing iv, encrypted, and hmac.
- hmac calculation has changed so it avoids copying (possibly very
large) encrypted data. See signDigest() in lib/codec.js.
- Minor cleanup
Handling hex encode/decode at the input/output boundaries and using
Uint8Array internally for representing binary data has these benefits:
- More memory efficient, allows processing of 2x larger files.
- Aligns with cryptographic best practices: hashing is now performed
on raw binary data (Uint8Array) instead of hex strings.
- Behavior is (mostly) unchanged
- scripts/index_template.html textContent is not implemented and
needs to be redesigned.
makes unnamed function more self documenting
Also removed use of recursion to improve readability (and debugability). As a bonus, function is actually shorter (LoC AND lines of text)
cuts size by 1/3 and noticeably improves performance
Refactored encrypted buffer handling to reduce memory usage Minor cleanup
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Committed a396bf0 to fix line of code that got messed up between testing and commit/push. |
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Committed a396bf0 to remove to variable definitions for vars that are no longer used. This was discovered while writing a previous pull request comment. |
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Summary
Compress data before encryption because it reduces size by about 30%, at a minimal additional compute cost compared to encryption and signing. This can produce in an encrypted file that's smaller than the original.
Resolves
Resolves #230
Details
Testing
I manually tested node encrypt, node decrypt, and HTML wrapper decrypt.
Notes for Reviewers
In an attempt to avoid, or at least limit, having 3 representations of data simultaneously in memory (file data buffer, decrypted data buffer, decompressed data buffer), we sometimes pass a reader instead of a buffer. Reader here means a callable that can read the data. See 'msgReader' in codec.js, which provides this comment: