ECDSA 签名的内在延展性(“重放“攻击)学习

相关推特:https://twitter.com/danielvf/status/1563169773684305921
原理文章:https://www.derpturkey.com/inherent-malleability-of-ecdsa-signatures/
签名的内在延展性，意味着可以为相同的数据创建第二有效的签名，导致如果在签名中没有加入nonce ，deadline等限制条件，攻击者可以再次提交对应交易（使用第二份签名）造成意外损失。
python验证代码:

import imp
from ellipticcurve.ecdsa import Ecdsa
from ellipticcurve.privateKey import PrivateKey
from web3 import Web3;
from ellipticcurve.signature import Signature
from ellipticcurve.curve import secp256k1, getCurveByOid
# Generate new Keys
privateKey = PrivateKey()
publicKey = privateKey.publicKey()

message = "My test message"

# Generate Signature
signature = Ecdsa.sign(message, privateKey)

# To verify if the signature is valid
print(Ecdsa.verify(message, signature, publicKey))

privateKey = PrivateKey(secret=1)
publicKey = privateKey.publicKey()
print(publicKey.toString());
message = "give to"

# Generate Signature
signature = Ecdsa.sign(message, privateKey)
print('aa:',Web3.toHex(signature.r),':   ',Web3.toHex(signature.s))
# To verify if the signature is valid
print(Ecdsa.verify(message, signature, publicKey))
print(signature._toString())
sig2=Signature(r=signature.r,s=secp256k1.N-signature.s,recoveryId=signature.recoveryId);
print('aa:',Web3.toHex(sig2.r),':   ',Web3.toHex(sig2.s))
print(Ecdsa.verify(message, sig2, publicKey))
print(Web3.toHex(secp256k1.N));

再evm合约中测试:

---

 function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public pure returns (address) {
    
    
	//删掉无关代码:
        address signer = ecrecover(hash, v, r, s);
       

        return (signer);
    }

将sig1.r 3dd21cd54e1b1178bba113b5c06b4a58c3b101eb007597fe4a0fca796daa67e7
// sig1.s 4e1bf4b3211203e356603c1a900846e8a40b0b0372aeffb6319de96ec8c25a1d
及
// sig2.r 3dd21cd54e1b1178bba113b5c06b4a58c3b101eb007597fe4a0fca796daa67e7
// sig2.s b1e40b4cdeedfc1ca99fc3e56ff7b91616a3d1e33c99a0858e34751e0773e724
分别填入对应参数:

即可返回相同address.
s的计算方式为:Secp256k1.N -sig1.s;