Add README

README.md

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+# eip712sign
+
+Small golang utility used to sign EIP-712 hashes. Supports:
+ - ledgers
+ - mnemonics
+ - raw private keys
+
+### Installation
+
+```shell
+go install github.com/base-org/eip712sign
+```
+
+### Flags
+
+```shell
+Usage of eip712sign:
+  -hd-paths string
+    	Hierarchical deterministic derivation path for mnemonic or ledger (default "m/44'/60'/0'/0/0")
+  -ledger
+    	Use ledger device for signing
+  -mnemonic string
+    	Mnemonic to use for signing
+  -prefix string
+    	String that prefixes the data to be signed (default "vvvvvvvv")
+  -private-key string
+    	Private key to use for signing
+  -suffix string
+    	String that suffixes the data to be signed (default "^^^^^^^^")
+  -workdir string
+    	Directory in which to run the subprocess (default ".")
+```
+
+### Usage
+
+`eip712sign` can either be run as a command wrapper, or data can be piped in via stdin.
+The former is recommended as it will only attempt to sign if the subprocess exit code is 0.
+
+```shell
+eip712sign --ledger -- <COMMAND>
+```
+or
+```shell
+<COMMAND> | eip712sign --ledger
+```
+
+Example signing some bytes output from a forge script:
+
+```shell
+eip712sign --ledger -- forge script --rpc-url <RPC_URL> SomeScript
+```
+
+`eip712sign` will parse the stdout from the subprocess, and by default, sign any hex string between the magic strings `vvvvvvvv` and `^^^^^^^^`.
+This prefix + suffix can be configured using the `-prefix` and `-suffix` flags.
+In this example, `SomeScript` should print this to the console, for example:
+
+```solidity
+function printDataToSign(bytes memory data) internal pure {
+    console.log("vvvvvvvv");
+    console.logBytes(data);
+    console.log("^^^^^^^^");
+}
+```
+...where `data` is 66 bytes in length.
+
+Example output:
+```shell
+Compiling 5 files with 0.8.15
+Solc 0.8.15 finished in 7.01s
+Compiler run successful!
+Script ran successfully.
+
+== Logs ==
+  vvvvvvvv
+  0x19011b6ca1022dcb8ee88e2ab8dd1adf6f6bfa6af586f8b074e99c952e6e3c6befadd5c5183a56f8aa2520c9522029fc20aba61ce6c6aa32aec3b00519c95eb819e8
+  ^^^^^^^^
+
+forge exited with code 0
+
+Domain hash: 0x1b6ca1022dcb8ee88e2ab8dd1adf6f6bfa6af586f8b074e99c952e6e3c6befad
+Message hash: 0xd5c5183a56f8aa2520c9522029fc20aba61ce6c6aa32aec3b00519c95eb819e8
+
+Data: 0x19011b6ca1022dcb8ee88e2ab8dd1adf6f6bfa6af586f8b074e99c952e6e3c6befadd5c5183a56f8aa2520c9522029fc20aba61ce6c6aa32aec3b00519c95eb819e8
+Signer: 0x4A02DE0C8a1C74AB99D1eCeb56d1d5f54B8293b0
+Signature: 36b6a15e3e86b1ae44bdfc9183c4d86b0eaead44c838530ecb2e43dd0618559579195d42fe63868a44ee0279feef0181b1a9ed3b0faa89bf1ebd48b0f48f54bc1c```
+```