raw-sha-links

raw-sha-links

Block format limited to storing a list of sha2 hashed links to raw binary blocks.

This is a very restricted block format. It is limited to representing:

• A single list of hashes.
• All hashes must link to raw blocks (does not support other multicodecs).
• All hashes must use sha2 encoding (256, 364 or 512).
• All hashes must be the same length, no mixing and matching hashes of different lengths.

This may seem like a very narrow case but it's actually quite common to create new lists of links to hashed binary blocks.

By restricting to only SHA hashes we ensure that the block encoder/decoder can be implemented as a very small JavaScript library using only the available hashing functions in crypto.subtle.digest.

By restricting to only be a linear list of hashes we can do incredibly fast parsing without a single memcopy.

And finally, by requiring a unified length we have the smallest possible block format for storing this kind of data and we can always predict the block size required to store any number of link values.

rsl.encode(values)

Encode an array of values into a new block. Every value must be an ArrayBuffer of equal length.

rsl.decode(binary[, stringEncoding])

Accepts any binary type, binary view, or string. Base64 encoded strings are supported using decode(string, 'base64').

Returns an array of DataView instances for every hash.

rsl.max(size[, algo='SHA-256'])

Returns the max number of hashes that can be contained in the target size.

rsl.size(length[, algo='SHA-256'])

Returns the block size for a block containing length number of links.

Related Libraries

For working with binary data you may want to use bytesish, especially if you're going to be copying or string encoding the DataView instances from decode().

For creating digest hashes in the you may want to use digestif. It has an incredibly small bundle size and works in Browsers and Node.js and will return you an Promise for an ArrayBuffer on both platforms which is what raw-sha-links expects.