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C++ ethereum ecRecover function using libsecp256k1 (with recovery module enabled) and keccak-tiny. Returns public eth address from signed message. Used to prove ownership of an eth address for logging in, etc.
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| #include "keccak-tiny.h" | |
| #include "secp256k1.h" | |
| #include "secp256k1_recovery.h" | |
| std::string bytes_to_hex_string(const uint8_t *str, const uint64_t s) | |
| { | |
| std::ostringstream ret; | |
| for (size_t i = 0; i < s; ++i) | |
| ret << std::hex << std::setfill('0') << std::setw(2) << std::nouppercase << (int) str[i]; | |
| return ret.str(); | |
| } | |
| std::string hex_to_string(const std::string& input) | |
| { | |
| static const char* const lut = "0123456789abcdef"; | |
| size_t len = input.length(); | |
| if (len & 1) throw std::invalid_argument("odd length"); | |
| std::string output; | |
| output.reserve(len / 2); | |
| for (size_t i = 0; i < len; i += 2) | |
| { | |
| char a = input[i]; | |
| const char* p = std::lower_bound(lut, lut + 16, a); | |
| if (*p != a) throw std::invalid_argument("not a hex digit"); | |
| char b = input[i + 1]; | |
| const char* q = std::lower_bound(lut, lut + 16, b); | |
| if (*q != b) throw std::invalid_argument("not a hex digit"); | |
| output.push_back(((p - lut) << 4) | (q - lut)); | |
| } | |
| return output; | |
| } | |
| std::string ecrecover(std::string sig, std::string msg) // hex-encoded sig, plain text msg | |
| { | |
| std::string _sig = hex_to_string(sig.substr(2)); // strip 0x | |
| if(_sig.size() != 65) | |
| return ("0x00000000000000000000000000000000"); | |
| int v = _sig[64]; | |
| _sig = _sig.substr(0,64); | |
| if(v>3) | |
| v-=27; | |
| auto* ctx = secp256k1_context_create( SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY ); | |
| secp256k1_ecdsa_recoverable_signature rawSig; | |
| if(!secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &rawSig, (unsigned char*)_sig.data(), v)) | |
| return ("0x00000000000000000000000000000000"); | |
| std::array<uint8_t,32> hash; | |
| keccak_256(hash.data(), hash.size(), (unsigned char*)msg.data(), msg.length()); // hash message | |
| msg = string("\x19")+"Ethereum Signed Message:\n32"+string(hash.begin(),hash.end()); // wrap message hash | |
| keccak_256(hash.data(), hash.size(), (unsigned char*)msg.data(), msg.length()); // hash wrapped message hash | |
| secp256k1_pubkey rawPubkey; | |
| if(!secp256k1_ecdsa_recover(ctx, &rawPubkey, &rawSig, hash.data())) // 32 bit hash | |
| return ("0x00000000000000000000000000000000"); | |
| std::array<uint8_t,65> pubkey; | |
| size_t biglen = 65; | |
| secp256k1_ec_pubkey_serialize(ctx, pubkey.data(), &biglen, &rawPubkey, SECP256K1_EC_UNCOMPRESSED); | |
| std::string out = std::string(pubkey.begin(),pubkey.end()).substr(1); | |
| keccak_256(hash.data(), hash.size(), (const unsigned char*)out.data(), out.length()); | |
| return("0x"+bytes_to_hex_string(hash.data(),hash.size()).substr(24)); | |
| } |
Author
Would you be willing to share your included files? Got a project I'm working on and been struggling to implement this functionality. I can't find this tiny-keccak or the secp256k files.
I believe these are the ones I used:
https://github.com/urbit/secp256k1
https://github.com/coruus/keccak-tiny
Author
GitHub - coruus/keccak-tiny: A tiny implementation of SHA-3, SHAKE, Keccak, and sha3sum
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GitHub - coruus/keccak-tiny: A tiny implementation of SHA-3, SHAKE, Kecc...
A tiny implementation of SHA-3, SHAKE, Keccak, and sha3sum - GitHub - coruus/keccak-tiny: A tiny implementation ...
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On Wednesday, March 16, 2022, 01:44:48 PM MST, Daniel Taghavi ***@***.***> wrote:
@dtaghavi commented on this gist.
You got this keccak-tiny somewhere?
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Would you be willing to share your included files? Got a project I'm working on and been struggling to implement this functionality.
I can't find this tiny-keccak or the secp256k files.