diff --git a/contracts/ECRecovery.sol b/contracts/ECRecovery.sol new file mode 100644 index 000000000..2e846fc11 --- /dev/null +++ b/contracts/ECRecovery.sol @@ -0,0 +1,68 @@ +pragma solidity ^0.4.11; + + +/** + * Eliptic curve signature operations + * Based on https://gist.github.com/axic/5b33912c6f61ae6fd96d6c4a47afde6d + */ +library ECRecovery { + + // Duplicate Solidity's ecrecover, but catching the CALL return value + function safeRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal returns (bool, address) { + // We do our own memory management here. Solidity uses memory offset + // 0x40 to store the current end of memory. We write past it (as + // writes are memory extensions), but don't update the offset so + // Solidity will reuse it. The memory used here is only needed for + // this context. + + bool ret; + address addr; + + assembly { + let size := mload(0x40) + mstore(size, hash) + mstore(add(size, 32), v) + mstore(add(size, 64), r) + mstore(add(size, 96), s) + + // NOTE: we can reuse the request memory because we deal with + // the return code + ret := call(3000, 1, 0, size, 128, size, 32) + addr := mload(size) + } + + return (ret, addr); + } + + function recover(bytes32 hash, bytes sig) internal returns (address) { + bytes32 r; + bytes32 s; + uint8 v; + + if (sig.length != 65) + return (address(0)); + + assembly { + r := mload(add(sig, 32)) + s := mload(add(sig, 64)) + v := byte(0, mload(add(sig, 96))) + } + + // albeit non-transactional signatures are not specified by the YP, one would expect it + // to match the YP range of [27, 28] + // + // geth uses [0, 1] and some clients have followed. This might change, see: + // https://github.com/ethereum/go-ethereum/issues/2053 + if (v < 27) + v += 27; + + if (v != 27 && v != 28) + return (address(0)); + + bool ret; + address addr; + (ret, addr) = safeRecover(hash, v, r, s); + return addr; + } + +} diff --git a/docs/source/ecrecovery.rst b/docs/source/ecrecovery.rst new file mode 100644 index 000000000..0e96819c9 --- /dev/null +++ b/docs/source/ecrecovery.rst @@ -0,0 +1,14 @@ +ECReovery +============================================= + +Recover the signer address of messages using elliptic curve signatures. + +safeRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal returns (bool, address) +""""""""""""""""""""""""""""""""""""""""""""""""" + +Returns the signer of the the hash using the signature divided in v, r, and s values. + +recover(bytes32 hash, bytes sig) internal returns (address) +""""""""""""""""""""""""""""""""""""""""""""""""" + +Returns the signer of the the hash using the signature that provides the web3.sign() method. diff --git a/test/ECRecovery.js b/test/ECRecovery.js new file mode 100644 index 000000000..d412e2085 --- /dev/null +++ b/test/ECRecovery.js @@ -0,0 +1,51 @@ +var ECRecoveryMock = artifacts.require("./helpers/ECRecoveryMock.sol"); + +contract('ECRecovery', function(accounts) { + + let ecrecovery; + + before(async function() { + ecrecovery = await ECRecoveryMock.new(); + }); + + it("recover v0", async function() { + let signer = '0x2cc1166f6212628a0deef2b33befb2187d35b86c'; + let message = '0x7dbaf558b0a1a5dc7a67202117ab143c1d8605a983e4a743bc06fcc03162dc0d'; // web3.sha3('OpenZeppelin') + let signature = '0x5d99b6f7f6d1f73d1a26497f2b1c89b24c0993913f86e9a2d02cd69887d9c94f3c880358579d811b21dd1b7fd9bb01c1d81d10e69f0384e675c32b39643be89200'; + await ecrecovery.recover(message, signature); + assert.equal(signer, await ecrecovery.signer()); + }); + + it("recover v1", async function() { + let signer = '0x1e318623ab09fe6de3c9b8672098464aeda9100e'; + let message = '0x7dbaf558b0a1a5dc7a67202117ab143c1d8605a983e4a743bc06fcc03162dc0d'; // web3.sha3('OpenZeppelin') + let signature = '0x331fe75a821c982f9127538858900d87d3ec1f9f737338ad67cad133fa48feff48e6fa0c18abc62e42820f05943e47af3e9fbe306ce74d64094bdf1691ee53e001'; + await ecrecovery.recover(message, signature); + assert.equal(signer, await ecrecovery.signer()); + }); + + it("safeRecover v0", async function() { + let signer = '0x58d5f9f841bcf9e502b438cc81d1ea3ba3f8f7f3'; + let message = '0x7dbaf558b0a1a5dc7a67202117ab143c1d8605a983e4a743bc06fcc03162dc0d'; // web3.sha3('OpenZeppelin') + let signature = '3690f285f30200dfacd35b9ee9af4beaf2c2f4b7880d93dd9bdf776e8fdbec6a095d00c80e20e95a68c8effc038707dd740aabf94a6ca37c09733874f772d6e000'; + let v = (signature.substring(128,130) == '01') ? 28 : 27; + let r = '0x'+signature.substring(0,64); + let s = '0x'+signature.substring(64,128); + await ecrecovery.safeRecover(message, v, r, s); + assert.equal(signer, await ecrecovery.signer()); + assert.equal(true, await ecrecovery.result()); + }); + + it("safeRecover v1", async function() { + let signer = '0x0b8124c2429c44e8ca31e7db6f85845abf146415'; + let message = '0x7dbaf558b0a1a5dc7a67202117ab143c1d8605a983e4a743bc06fcc03162dc0d'; // web3.sha3('OpenZeppelin') + let signature = '7696f87b3f14e2f1c408c552c0005479bfe35df3a9efb493a2ad2bdf25d95c8c605b6f83699faca9bcbc3c665b434ed8d9c717aa71a1916f054fc41671dd38ad01'; + let v = (signature.substring(128,130) == '01') ? 28 : 27; + let r = '0x'+signature.substring(0,64); + let s = '0x'+signature.substring(64,128); + await ecrecovery.safeRecover(message, v, r, s); + assert.equal(signer, await ecrecovery.signer()); + assert.equal(true, await ecrecovery.result()); + }); + +}); diff --git a/test/helpers/ECRecoveryMock.sol b/test/helpers/ECRecoveryMock.sol new file mode 100644 index 000000000..95ed0dcec --- /dev/null +++ b/test/helpers/ECRecoveryMock.sol @@ -0,0 +1,20 @@ +pragma solidity ^0.4.11; + + +import '../../contracts/ECRecovery.sol'; + + +contract ECRecoveryMock { + + bool public result; + address public signer; + + function safeRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) { + (result, signer) = ECRecovery.safeRecover(hash, v, r, s); + } + + function recover(bytes32 hash, bytes sig) { + signer = ECRecovery.recover(hash, sig); + } + +}