Feature request: Multihash

[nileshtrivedi]

There's a standard for self-describing hashes called Multihash.

A multihash follows the TLV (type-length-value) pattern.

• the type is an unsigned variable integer identifying the hash function. There is a default table, and it is configurable. The default table is the multicodec table.
• the length is an unsigned variable integer counting the length of the digest, in bytes
• the value is the hash function digest, with a length of exactly bytes.

For example, the multihash value 122041dd7b6443542e75701aa98a0c235951a28a0d851b11564d20022ab11d2589a8 indicates:

• 12 indicates that the hash function variant is sha2-256
• 20 indicates that hash length is 32 bytes
• 41dd7b6443542e75701aa98a0c235951a28a0d851b11564d20022ab11d2589a8 is the hash value

This is already used in IPFS, but is intended for wider adoption to support portability and future-proofing.

It would be great to have an encoding block for producing a multihash of a byte string.