如何在Flutter中固定公钥？

Question

我想固定服务器的公共密钥，以便对服务器的任何请求都必须具有该公共密钥（这是为了防止像Charles这样的代理嗅探数据）。

我在Volley上用Android做过类似的事情。

如何使用Flutter做同样的事情？

Answer 1

创建一个SecurityContext没有可信任根的客户端，以强制执行错误的证书回调，即使是好的证书也是如此。

SecurityContext(withTrustedRoots: false);

在错误的证书回调中，使用asn1lib包解析DER编码的证书。例如：

ASN1Parser p = ASN1Parser(der);
ASN1Sequence signedCert = p.nextObject() as ASN1Sequence;
ASN1Sequence cert = signedCert.elements[0] as ASN1Sequence;
ASN1Sequence pubKeyElement = cert.elements[6] as ASN1Sequence;

ASN1BitString pubKeyBits = pubKeyElement.elements[1] as ASN1BitString;

List<int> encodedPubKey = pubKeyBits.stringValue;
// could stop here and compare the encoded key parts, or...

// parse them into their modulus/exponent parts, and test those
// (assumes RSA public key)
ASN1Parser rsaParser = ASN1Parser(encodedPubKey);
ASN1Sequence keySeq = rsaParser.nextObject() as ASN1Sequence;
ASN1Integer modulus = keySeq.elements[0] as ASN1Integer;
ASN1Integer exponent = keySeq.elements[1] as ASN1Integer;

print(modulus.valueAsBigInteger);
print(exponent);