EIP-712 design documentation

• Provides C code for getting hash according to eip-712
• Provides examples
• Complete test case

Interface

int get_eip712_hash(eip712_data* data, uint8_t* out_hash);

Get the hash according to eip-712 through the passed parameters.

• Arg1 data: Some parameters defined according to requirements.
• Arg2 out_hash: Output the generated hash, the pointer to a buffer of length 32.
• Result: If success return 0, else return non-zero.

Struct

typedef struct _eip712_domain {
  uint8_t chain_id[EIP712_HASH_SIZE];
  char* name;
  uint8_t verifying_contract[20];
  char* version;
} eip712_domain;

typedef struct _eip712_active {
  char* action;
  char* params;
} eip712_active;

typedef struct _eip712_cell {
  char* capacity;
  char* lock;
  char* type;
  char* data;
  char* extra_data;
} eip712_cell;

typedef struct _eip712_data {
  eip712_domain domain;
  eip712_active active;
  char* transaction_das_message;
  char* inputs_capacity;
  char* outputs_capacity;
  char* fee;
  uint8_t digest[32];

  eip712_cell* inputs;
  size_t inputs_len;
  eip712_cell* outputs;
  size_t outputs_len;
} eip712_data;

Definition of eip712_data* data parameter

Implement

Modifications based on this project: eip712tool

This project is developed in C language and basically realizes all the functions of EIP-712. But it needs to be ported to risc-v. And because his parameter transfer uses Json, we will see if the situation is directly deleted later, and directly use the C structure to pass the parameters (In this, the types of eip-712 is determined).

Verification

A verification file has been completed using npm eip-712 that can be used later to verify that the results are correct.

Generate eip712 data template

In requirements, the types of eip712 are fixed, and some of these items are filled with the data of the current transaction of ckb.

Remove JSON

The parameter transmission of eip712tool uses json, but this requirement does not need to be developed with json, so it needs to be removed here.

Test

A nodejs demo to generate a real EIP-712 hash

Correct the developed version as a real version of the demo: tools/nodejs_test/test_eip_712.js. You can use the command: '''./tools/nodejs_test/test_eip_712.js ./tools/nodejs_test/data/data_dotbit.json'''

Output:

Domain hash: 0xad2ee3583cd6cfef2e2fda4f9c27bbd67b1a00408d58e4684e148fd4dc7326cf
Message hash: 0xa0096e1245f02a3563ebd75da920592ef533678e2ed5a06138c2f2cfcdb87b1f
Last message hash: 0xcce661e249e03e2e0c581e1763fa1432491863c625a4128dd966822cc5f1d2be

C testcases

Verify that the C code is executed correctly and check for memory problems, Also need to write fuzzing tests.

NOTE

• Only functions declared in eip712.h are tested
• Tests are executed directly in ckb-debugger
• All strings must be \0 terminated