Tutorial on how to encrypt events

[CedarMist]

SUMMARY

Information in events is public, however developers may want the contract to output information which is only readable by whoever submitted the transaction.

ISSUE TYPE

• Feature Idea

COMPONENT NAME

Documentation

ADDITIONAL INFORMATION

Currently the deoxysii-js and related DeoxysII packages can be used to decrypt data which was encrypted using Sapphire.encrypt

In the contract you can do:

• bytes32 nonce = bytes32(Sapphire.randomBytes(32,""));
• bytes ciphertext = Sapphire.encrypt(key, nonce, abi.encode(...))
• emit Event(nonce, ciphertext)

If the transaction is encrypted the user can pass the encryption key to the contract, or the encryption key can be derived in some other way.