一、微信支付敏感信息加密

为了保证通信过程中敏感信息字段（如用户的住址、银行卡号、手机号码等）的机密性，微信支付API v3要求商户对上送的敏感信息字段进行加密。

与之相对应，微信支付会对下行的敏感信息字段进行加密，商户需解密后方能得到原文。

敏感信息加密使用的RSA公钥加密算法。加密算法使用的填充方案，我们使用了相对更安全的RSAES-OAEP(Optimal Asymmetric Encryption Padding)。

敏感信息加解密-接口规则 | 微信支付商户平台文档中心

1.官方给的C#加密方案代码，但是没有给公钥apiclient_key.pem文件转成二进制的方案

/// 要加密的明文
///  -----BEGIN CERTIFICATE----- 开头的string，转为bytes 
/// 
public static string RSAEncrypt(string text, byte[] publicKey)
{using (var x509 = new X509Certificate2(publicKey)){using (var rsa = (RSACryptoServiceProvider)x509.PublicKey.Key){var buff = rsa.Encrypt(Encoding.UTF8.GetBytes(text), true);return Convert.ToBase64String(buff);}}
}

问题所在：

官网下载的apiclient_key.pem，是Java RSA版本的秘钥，没法直接转换成C#RSA秘钥

二、将Java RSA公钥转换为C#RSA公钥

1.BouncyCastle 

bouncy castle（轻量级密码术包）是一种用于 Java 平台的开放源码的轻量级密码术包；它支持大量的密码术算法，并提供JCE 1.2.1的实现。

Portable.BouncyCastle  是对应的C#版本

BouncyCastle portable version with support for .NET 4, .NET Standard 2.0

官网地址：

The Legion of the Bouncy Castle C# Cryptography APIs

2.转换方案使用 RSAUtility  源码如下： 直接复制用。

/// <summary>
/// RSA 算法工具类。
/// </summary>
public static class RSAUtility
{private const string RSA_CIPHER_ALGORITHM_ECB = "RSA/ECB";private const string RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1 = "OAEPWITHSHA1ANDMGF1PADDING";private const string RSA_SIGNER_ALGORITHM_SHA256 = "SHA-256withRSA";private static byte[] ConvertPrivateKeyPkcs8PemToByteArray(string privateKey){privateKey = privateKey.Replace("-----BEGIN PRIVATE KEY-----", string.Empty).Replace("-----END PRIVATE KEY-----", string.Empty);privateKey = Regex.Replace(privateKey, "\\s+", string.Empty);return Convert.FromBase64String(privateKey);}private static byte[] ConvertPublicKeyPkcs8PemToByteArray(string publicKey){publicKey = publicKey.Replace("-----BEGIN PUBLIC KEY-----", string.Empty).Replace("-----END PUBLIC KEY-----", string.Empty);publicKey = Regex.Replace(publicKey, "\\s+", string.Empty);return Convert.FromBase64String(publicKey);}private static X509Certificate ParseCertificatePemToX509(string certificate){using (TextReader sreader = new StringReader(certificate)){PemReader pemReader = new PemReader(sreader);return (X509Certificate)pemReader.ReadObject();}}private static RsaKeyParameters ParsePrivateKeyPemToPrivateKeyParameters(byte[] privateKeyBytes){return (RsaKeyParameters)PrivateKeyFactory.CreateKey(privateKeyBytes);}private static RsaKeyParameters ParsePublicKeyPemToPublicKeyParameters(byte[] publicKeyBytes){return (RsaKeyParameters)PublicKeyFactory.CreateKey(publicKeyBytes);}private static byte[] SignWithSHA256(RsaKeyParameters rsaPrivateKeyParams, byte[] msgBytes){ISigner signer = SignerUtilities.GetSigner(RSA_SIGNER_ALGORITHM_SHA256);signer.Init(true, rsaPrivateKeyParams);signer.BlockUpdate(msgBytes, 0, msgBytes.Length);return signer.GenerateSignature();}private static bool VerifyWithSHA256(RsaKeyParameters rsaPublicKeyParams, byte[] msgBytes, byte[] signBytes){ISigner signer = SignerUtilities.GetSigner(RSA_SIGNER_ALGORITHM_SHA256);signer.Init(false, rsaPublicKeyParams);signer.BlockUpdate(msgBytes, 0, msgBytes.Length);return signer.VerifySignature(signBytes);}private static byte[] DecryptWithECB(RsaKeyParameters rsaPrivateKeyParams, byte[] cipherBytes, string paddingMode){IBufferedCipher cipher = CipherUtilities.GetCipher($"{RSA_CIPHER_ALGORITHM_ECB}/{paddingMode}");cipher.Init(false, rsaPrivateKeyParams);return cipher.DoFinal(cipherBytes);}private static byte[] EncryptWithECB(RsaKeyParameters rsaPublicKeyParams, byte[] plainBytes, string paddingMode){IBufferedCipher cipher = CipherUtilities.GetCipher($"{RSA_CIPHER_ALGORITHM_ECB}/{paddingMode}");cipher.Init(true, rsaPublicKeyParams);return cipher.DoFinal(plainBytes);}/// <summary>/// 使用私钥基于 SHA-256 算法生成签名。/// </summary>/// <param name="privateKeyBytes">PKCS#8 私钥字节数组。</param>/// <param name="msgBytes">待签名的数据字节数组。</param>/// <returns>签名字节数组。</returns>public static byte[] SignWithSHA256(byte[] privateKeyBytes, byte[] msgBytes){if (privateKeyBytes == null) throw new ArgumentNullException(nameof(privateKeyBytes));if (msgBytes == null) throw new ArgumentNullException(nameof(msgBytes));RsaKeyParameters rsaPrivateKeyParams = ParsePrivateKeyPemToPrivateKeyParameters(privateKeyBytes);return SignWithSHA256(rsaPrivateKeyParams, msgBytes);}/// <summary>/// 使用私钥基于 SHA-256 算法生成签名。/// </summary>/// <param name="privateKey">PKCS#8 私钥（PEM 格式）。</param>/// <param name="message">待签名的文本数据。</param>/// <returns>经 Base64 编码的签名。</returns>public static string SignWithSHA256(string privateKey, string message){if (privateKey == null) throw new ArgumentNullException(nameof(privateKey));if (message == null) throw new ArgumentNullException(nameof(message));byte[] privateKeyBytes = ConvertPrivateKeyPkcs8PemToByteArray(privateKey);byte[] msgBytes = Encoding.UTF8.GetBytes(message);byte[] signBytes = SignWithSHA256(privateKeyBytes, msgBytes);return Convert.ToBase64String(signBytes);}/// <summary>/// 使用公钥基于 SHA-256 算法验证签名。/// </summary>/// <param name="publicKeyBytes">PKCS#8 公钥字节数据。</param>/// <param name="msgBytes">待验证的数据字节数据。</param>/// <param name="signBytes">待验证的签名字节数据。</param>/// <returns>验证结果。</returns>public static bool VerifyWithSHA256(byte[] publicKeyBytes, byte[] msgBytes, byte[] signBytes){if (publicKeyBytes == null) throw new ArgumentNullException(nameof(publicKeyBytes));if (msgBytes == null) throw new ArgumentNullException(nameof(msgBytes));if (signBytes == null) throw new ArgumentNullException(nameof(signBytes));RsaKeyParameters rsaPublicKeyParams = ParsePublicKeyPemToPublicKeyParameters(publicKeyBytes);return VerifyWithSHA256(rsaPublicKeyParams, msgBytes, signBytes);}/// <summary>/// 使用公钥基于 SHA-256 算法验证签名。/// </summary>/// <param name="publicKey">PKCS#8 公钥（PEM 格式）。</param>/// <param name="message">待验证的文本数据。</param>/// <param name="signature">经 Base64 编码的待验证的签名。</param>/// <returns>验证结果。</returns>public static bool VerifyWithSHA256(string publicKey, string message, string signature){if (publicKey == null) throw new ArgumentNullException(nameof(publicKey));if (message == null) throw new ArgumentNullException(nameof(message));if (signature == null) throw new ArgumentNullException(nameof(signature));byte[] publicKeyBytes = ConvertPublicKeyPkcs8PemToByteArray(publicKey);byte[] msgBytes = Encoding.UTF8.GetBytes(message);byte[] signBytes = Convert.FromBase64String(signature);return VerifyWithSHA256(publicKeyBytes, msgBytes, signBytes);}/// <summary>/// 使用证书基于 SHA-256 算法验证签名。/// </summary>/// <param name="certificate">证书（PEM 格式）。</param>/// <param name="message">待验证的文本数据。</param>/// <param name="signature">经 Base64 编码的待验证的签名。</param>/// <returns>验证结果。</returns>public static bool VerifyWithSHA256ByCertificate(string certificate, string message, string signature){if (certificate == null) throw new ArgumentNullException(nameof(certificate));string publicKey = ExportPublicKeyFromCertificate(certificate);return VerifyWithSHA256(publicKey, message, signature);}/// <summary>/// 使用私钥基于 ECB 模式解密数据。/// </summary>/// <param name="privateKeyBytes">PKCS#8 私钥字节数据。</param>/// <param name="cipherBytes">待解密的数据字节数据。</param>/// <param name="paddingMode">填充模式。（默认值：<see cref="RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1"/>）</param>/// <returns>解密后的数据字节数组。</returns>public static byte[] DecryptWithECB(byte[] privateKeyBytes, byte[] cipherBytes, string paddingMode = RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1){if (privateKeyBytes == null) throw new ArgumentNullException(nameof(privateKeyBytes));if (cipherBytes == null) throw new ArgumentNullException(nameof(cipherBytes));RsaKeyParameters rsaPrivateKeyParams = ParsePrivateKeyPemToPrivateKeyParameters(privateKeyBytes);return DecryptWithECB(rsaPrivateKeyParams, cipherBytes, paddingMode);}/// <summary>/// 使用私钥基于 ECB 模式解密数据。/// </summary>/// <param name="privateKey">PKCS#8 私钥（PEM 格式）。</param>/// <param name="cipherText">经 Base64 编码的待解密数据。</param>/// <param name="paddingMode">填充模式。（默认值：<see cref="RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1"/>）</param>/// <returns>解密后的文本数据。</returns>public static string DecryptWithECB(string privateKey, string cipherText, string paddingMode = RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1){if (privateKey == null) throw new ArgumentNullException(nameof(privateKey));if (cipherText == null) throw new ArgumentNullException(nameof(cipherText));byte[] privateKeyBytes = ConvertPrivateKeyPkcs8PemToByteArray(privateKey);byte[] cipherBytes = Convert.FromBase64String(cipherText);byte[] plainBytes = DecryptWithECB(privateKeyBytes, cipherBytes, paddingMode);return Encoding.UTF8.GetString(plainBytes);}/// <summary>/// 使用公钥基于 ECB 模式加密数据。/// </summary>/// <param name="publicKeyBytes">PKCS#8 公钥字节数据。</param>/// <param name="plainBytes">待加密的数据字节数据。</param>/// <param name="paddingMode">填充模式。（默认值：<see cref="RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1"/>）</param>/// <returns>加密后的数据字节数组。</returns>public static byte[] EncryptWithECB(byte[] publicKeyBytes, byte[] plainBytes, string paddingMode = RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1){if (publicKeyBytes == null) throw new ArgumentNullException(nameof(publicKeyBytes));if (plainBytes == null) throw new ArgumentNullException(nameof(plainBytes));RsaKeyParameters rsaPublicKeyParams = ParsePublicKeyPemToPublicKeyParameters(publicKeyBytes);return EncryptWithECB(rsaPublicKeyParams, plainBytes, paddingMode);}/// <summary>/// 使用公钥基于 ECB 模式加密数据。/// </summary>/// <param name="publicKey">PKCS#8 公钥（PEM 格式）。</param>/// <param name="plainText">待加密的文本数据。</param>/// <param name="paddingMode">填充模式。（默认值：<see cref="RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1"/>）</param>/// <returns>经 Base64 编码的加密数据。</returns>public static string EncryptWithECB(string publicKey, string plainText, string paddingMode = RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1){if (publicKey == null) throw new ArgumentNullException(nameof(publicKey));if (plainText == null) throw new ArgumentNullException(nameof(plainText));byte[] publicKeyBytes = ConvertPublicKeyPkcs8PemToByteArray(publicKey);byte[] plainBytes = Encoding.UTF8.GetBytes(plainText);byte[] cipherBytes = EncryptWithECB(publicKeyBytes, plainBytes, paddingMode);return Convert.ToBase64String(cipherBytes);}/// <summary>/// 使用证书基于 ECB 模式加密数据。/// </summary>/// <param name="certificate">证书（PEM 格式）。</param>/// <param name="plainText">待加密的文本数据。</param>/// <param name="paddingMode">填充模式。（默认值：<see cref="RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1"/>）</param>/// <returns>经 Base64 编码的加密数据。</returns>public static string EncryptWithECBByCertificate(string certificate, string plainText, string paddingMode = RSA_CIPHER_PADDING_OAEP_WITH_SHA1_AND_MGF1){if (certificate == null) throw new ArgumentNullException(nameof(certificate));string publicKey = ExportPublicKeyFromCertificate(certificate);return EncryptWithECB(publicKey, plainText, paddingMode);}/// <summary>/// <para>从 CRT/CER 证书中导出 PKCS#8 公钥。</para>/// <para>///     即从 -----BEGIN CERTIFICATE----- ... -----END CERTIFICATE-----///     转为 -----BEGIN PUBLIC KEY----- ..... -----END PUBLIC KEY-----/// </para>/// </summary>/// <param name="certificate">证书（PEM 格式）。</param>/// <returns>PKCS#8 公钥（PEM 格式）。</returns>public static string ExportPublicKeyFromCertificate(string certificate){if (certificate == null) throw new ArgumentNullException(nameof(certificate));using (TextWriter swriter = new StringWriter()){X509Certificate x509cert = ParseCertificatePemToX509(certificate);RsaKeyParameters rsaPublicKeyParams = (RsaKeyParameters)x509cert.GetPublicKey();PemWriter pemWriter = new PemWriter(swriter);pemWriter.WriteObject(rsaPublicKeyParams);pemWriter.Writer.Flush();return swriter.ToString()!;}}/// <summary>/// <para>从 CRT/CER 证书中导出证书序列号。</para>/// </summary>/// <param name="certificate">证书（PEM 格式）。</param>/// <returns>证书序列号。</returns>public static string ExportSerialNumberFromCertificate(string certificate){if (certificate == null) throw new ArgumentNullException(nameof(certificate));X509Certificate x509cert = ParseCertificatePemToX509(certificate);return x509cert.SerialNumber.ToString(16);}/// <summary>/// <para>从 CRT/CER 证书中导出证书颁发时间。</para>/// </summary>/// <param name="certificate">证书（PEM 格式）。</param>/// <returns>证书颁发时间。</returns>public static DateTimeOffset ExportEffectiveTimeFromCertificate(string certificate){if (certificate == null) throw new ArgumentNullException(nameof(certificate));X509Certificate x509cert = ParseCertificatePemToX509(certificate);return new DateTimeOffset(x509cert.NotBefore);}/// <summary>/// <para>从 CRT/CER 证书中导出证书过期时间。</para>/// </summary>/// <param name="certificate">证书（PEM 格式）。</param>/// <returns>证书过期时间。</returns>public static DateTimeOffset ExportExpireTimeFromCertificate(string certificate){if (certificate == null) throw new ArgumentNullException(nameof(certificate));X509Certificate x509cert = ParseCertificatePemToX509(certificate);return new DateTimeOffset(x509cert.NotAfter);}
}

三、C# 微信支付敏感信息加解 案例

string CERTIFICATE = "-----BEGIN CERTIFICATE-----xxxxxxxxxxxx----END CERTIFICATE-----\r\n";
//公钥转换
string actualPublicKey = RSAUtility.ExportPublicKeyFromCertificate(CERTIFICATE).Replace("\r", "").Replace("\n", "");
//执行加密
string result = RSAUtility.EncryptWithECB(actualPublicKey, "张三丰");
Console.WriteLine(result); //加密结果 LHcAhbGJz2+j8SSK51NaOibntvd19YxgoNlaCM89dVRchkcopWN+EQgIgOS3Qtcc+cD4lPpMvUaclDNRu3a6Y+bIAVWzmZCudEjRV9MmTSh/XIMgqTTTu0rV4PLAzywp+LaGHqNRbvaicWDRAF1F+gHDSJSOxlIHBIhgimuaoa04xQdztA71p3RJuXG0TYs2oRb+6QJQKj11nbIx7/fgx5VMePyqlqShzd1MTfrw4zqc/+dGL+euVhSwQNV8JYt6ZogtLraRlRVlRinH875P81uhKwUVrxtvv6pwNN+p+yph1CaDOK4qCT7XsDtsatS102L/AGf95wQ87o4Ym9WpfA==

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