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44 lines
1.1 KiB
44 lines
1.1 KiB
pragma solidity ^0.4.11;
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/**
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* @title Eliptic curve signature operations
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*
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* @dev Based on https://gist.github.com/axic/5b33912c6f61ae6fd96d6c4a47afde6d
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*/
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library ECRecovery {
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/**
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* @dev Recover signer address from a message by using his signature
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* @param hash bytes32 message hash from which the signature will be recovered
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* @param sig bytes signature, the siganture is generated using web3.eth.sign()
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*/
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function recover(bytes32 hash, bytes sig) constant returns (address) {
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bytes32 r;
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bytes32 s;
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uint8 v;
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//Check the signature length
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if (sig.length != 65)
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return (address(0));
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// Divide the signature in r, s and v variables
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assembly {
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r := mload(add(sig, 32))
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s := mload(add(sig, 64))
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v := byte(0, mload(add(sig, 96)))
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}
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// Version of signature should be 27 or 28, but 0 and 1 are also possible versions
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if (v < 27)
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v += 27;
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// If the version is correct return the signer address
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if (v != 27 && v != 28)
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return (address(0));
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else
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return ecrecover(hash, v, r, s);
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}
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}
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