/// <summary>
/// 验证字符串str的签名是否是sgin，并指定hash算法（如：SHA256）
/// </summary>
public bool Verify(string hash, string sgin, string str)
{
var byts = RSA_Unit.Base64DecodeBytes(sgin);
if (byts == null)
{
return(false);
}
return(Verify(hash, byts, Encoding.UTF8.GetBytes(str)));
}
/// <summary>
/// 解密字符串（utf-8），解密异常返回null
/// </summary>
public string DecodeOrNull(string str)
{
if (String.IsNullOrEmpty(str))
{
return(null);
}
var byts = RSA_Unit.Base64DecodeBytes(str);
if (byts == null)
{
return(null);
}
var val = DecodeOrNull(byts);
if (val == null)
{
return(null);
}
return(Encoding.UTF8.GetString(val));
}
/// <summary>
/// 用PEM格式密钥对创建RSA，支持PKCS#1、PKCS#8格式的PEM
/// </summary>
public static RSACryptoServiceProvider FromPEM(string pem)
{
var rsaParams = new CspParameters();
rsaParams.Flags = CspProviderFlags.UseMachineKeyStore;
var rsa = new RSACryptoServiceProvider(rsaParams);
var param = new RSAParameters();
var base64 = _PEMCode.Replace(pem, "");
var data = RSA_Unit.Base64DecodeBytes(base64);
if (data == null)
{
throw new Exception("PEM内容无效");
}
var idx = 0;
//读取长度
Func <byte, int> readLen = (first) => {
if (data[idx] == first)
{
idx++;
if (data[idx] == 0x81)
{
idx++;
return(data[idx++]);
}
else if (data[idx] == 0x82)
{
idx++;
return((((int)data[idx++]) << 8) + data[idx++]);
}
else if (data[idx] < 0x80)
{
return(data[idx++]);
}
}
throw new Exception("PEM未能提取到数据");
};
//读取块数据
Func <byte[]> readBlock = () => {
var len = readLen(0x02);
if (data[idx] == 0x00)
{
idx++;
len--;
}
var val = data.sub(idx, len);
idx += len;
return(val);
};
//比较data从idx位置开始是否是byts内容
Func <byte[], bool> eq = (byts) => {
for (var i = 0; i < byts.Length; i++, idx++)
{
if (idx >= data.Length)
{
return(false);
}
if (byts[i] != data[idx])
{
return(false);
}
}
return(true);
};
if (pem.Contains("PUBLIC KEY"))
{
/****使用公钥****/
//读取数据总长度
readLen(0x30);
if (!eq(_SeqOID))
{
throw new Exception("PEM未知格式");
}
//读取1长度
readLen(0x03);
idx++; //跳过0x00
//读取2长度
readLen(0x30);
//Modulus
param.Modulus = readBlock();
//Exponent
param.Exponent = readBlock();
}
else if (pem.Contains("PRIVATE KEY"))
{
/****使用私钥****/
//读取数据总长度
readLen(0x30);
//读取版本号
if (!eq(_Ver))
{
throw new Exception("PEM未知版本");
}
//检测PKCS8
var idx2 = idx;
if (eq(_SeqOID))
{
//读取1长度
readLen(0x04);
//读取2长度
readLen(0x30);
//读取版本号
if (!eq(_Ver))
{
throw new Exception("PEM版本无效");
}
}
else
{
idx = idx2;
}
//读取数据
param.Modulus = readBlock();
param.Exponent = readBlock();
param.D = readBlock();
param.P = readBlock();
param.Q = readBlock();
param.DP = readBlock();
param.DQ = readBlock();
param.InverseQ = readBlock();
}
else
{
throw new Exception("pem需要BEGIN END标头");
}
rsa.ImportParameters(param);
return(rsa);
}
