Eth-Sig-Util 
A small collection of ethereum signing functions.
You can find usage examples here
Supported Signing Methods
Currently there is only one supported signing protocol. More will be added as standardized.
- Personal Sign (
personal_sign) geth thread
Installation
npm install eth-sig-util --save
Methods
concatSig(v, r, s)
All three arguments should be provided as buffers.
Returns a continuous, hex-prefixed hex value for the signature, suitable for inclusion in a JSON transaction's data field.
normalize(address)
Takes an address of either upper or lower case, with or without a hex prefix, and returns an all-lowercase, hex-prefixed address, suitable for submitting to an ethereum provider.
personalSign (privateKeyBuffer, msgParams)
msgParams should have a data key that is hex-encoded data to sign.
Returns the prefixed signature expected for calls to eth.personalSign.
recoverPersonalSignature (msgParams)
msgParams should have a data key that is hex-encoded data unsigned, and a sig key that is hex-encoded and already signed.
Returns a hex-encoded sender address.
signTypedData (privateKeyBuffer, msgParams)
Signs typed data as per EIP712.
Data should be under data key of msgParams. The method returns prefixed signature.
recoverTypedSignature ({data, sig})
Return address of a signer that did signTypedData.
Expects the same data that were used for signing. sig is a prefixed signature.
typedSignatureHash (typedData)
Return hex-encoded hash of typed data params according to EIP712 schema.
extractPublicKey (msgParams)
msgParams should have a data key that is hex-encoded data unsigned, and a sig key that is hex-encoded and already signed.
Returns a hex-encoded public key.