BlobStore is a smart contract for Ethereum blockchains that permanently stores blobs of data. It will be the principle contract of the Link Blockchain.


BlobStore has the following properties:

  • World-readable
    Every blob published can be read by anyone who connects to the blockchain it was published on. The only way to avoid this would be to encrypt the blob before publishing it.
  • Immutable
    While a blob can be “retracted”, it can never really be deleted because the transaction that created it will be archived for eternity on full nodes.
  • Revisioned
    BlobStore has a rudimentary revisioning system built-in where a blob can have multiple revisions, e.g. for editing posts. More sophisticated revisioning systems can be built on top of BlobStore where each blob is a revision.
  • Ownership
    Each blob can have an owner. Only the owner can modify a blob, change blob settings, or transfer ownership to another address.
  • Configurable
    Each blob has the following flags that can be set:
    • Updatable
      The contents of the blob can be changed. Once disabled it cannot be re-enabled.
    • Enfore Revisions
      When updating the blob a new revision must be created. It is not possible to retract revisions. Once enabled, this flag cannot be disabled.
    • Retractable
      The blob in its entirety can be retracted. This is unaffected by Enforce Revisions. The blobId of a retracted blob can never be used again. Once disabled it cannot be re-enabled.
    • Transferable
      The blob can be transfered to another user (if they accept it), or disowned completely. Once disabled it cannot be re-enabled. At creation time blobs can also be flaged as anonymous to not have an owner associated. An alternative to transferable blobs is to use a proxy account with transferable ownership as the blob owner.
  • Light client support
    Blobs are stored in Ethereum log storage so can be retrieved by light clients.
  • Scalable
    Currently every Ethereum full node processes every transaction, limiting the scalability of BlobStore. However, in future Ethereum blockchains will become “sharded”, effectively providing unlimited scalability.
  • Low latency
    Searching Ethereum logs is not normally instantaneous because they are not fully indexed like state entries. However, BlobStore stores in state the block number that each log is stored in. This allows for instantaneous retrieval.
  • Expensive
    While cheaper than contract state, BlobStore is still considerably more expensive than other decentralized storage systems. This is because it is fully immutable. BlobStore is not cost effective for very large blobs of data or for a large number of blobs that are of low value. As Ethereum blockchains become more scalable BlobStore will become better value.
  • Anti-spam
    Because each blob that is stored in the system must paid for spam is not profitable.
  • Upgradability
    BlobStore is an upgradable system. Due to a security vulnerability, new features, or performance improvements a new BlobStore contract may be deployed.
  • Unit tests
    BlobStore has tests written in Solidity using the Dapple framework.
  • JavaScript library
    BlobStore has a simple library to ease the process of reading and writing blobs.
  • Multiple blockchains
    BlobStore will be deployed on all Ethereum blockchains, i.e. Ethereum, Ethereum Classic, Expanse and Link.

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