在C#中进行公钥加密/私钥解密，需要用RSACryptoServiceProvider，但是它不支持由OpenSSL生成的公钥/私钥字符串。
比如这样的公钥/私钥对（ 公私钥生成方法见 http://travistidwell.com/jsencrypt/ ）：
公钥
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC7PyjMEuniN6BPn8oqzIZ6AO1N
jSTO9R3adCCIwKfKIEoWXXM+tHDpktdPKSaAsWJPTNAGvEvtxOfzXib/EMXKqD0e
Uy5MatfpRjRdf1hJVimmfrb09Qx2j7CsKLy7nD23m4xubdYBwvkjMwt/L3JxB5D6
qryW1wei/j1c+/OCxQIDAQAB
-----END PUBLIC KEY-----
私钥
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
网上有牛人通过解析公钥/私钥字符串，将之导入到RSACryptoServiceProvider中（原文链接已不存在）。
我们就是使用这位牛人的代码解决了这个问题，实际使用的代码如下：
public class RSACryptoService
{
private RSACryptoServiceProvider _privateKeyRsaProvider;
private RSACryptoServiceProvider _publicKeyRsaProvider; public RSACryptoService(string privateKey, string publicKey = null)
{
if (!string.IsNullOrEmpty(privateKey))
{
_privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(privateKey);
} if (!string.IsNullOrEmpty(publicKey))
{
_publicKeyRsaProvider = CreateRsaProviderFromPublicKey(publicKey);
}
} public string Decrypt(string cipherText)
{
if (_privateKeyRsaProvider == null)
{
throw new Exception("_privateKeyRsaProvider is null");
}
return Encoding.UTF8.GetString(_privateKeyRsaProvider.Decrypt(System.Convert.FromBase64String(cipherText), false));
} public string Encrypt(string text)
{
if (_publicKeyRsaProvider == null)
{
throw new Exception("_publicKeyRsaProvider is null");
}
return Convert.ToBase64String(_publicKeyRsaProvider.Encrypt(Encoding.UTF8.GetBytes(text), false));
} private RSACryptoServiceProvider CreateRsaProviderFromPrivateKey(string privateKey)
{
var privateKeyBits = System.Convert.FromBase64String(privateKey); var RSA = new RSACryptoServiceProvider();
var RSAparams = new RSAParameters(); using (BinaryReader binr = new BinaryReader(new MemoryStream(privateKeyBits)))
{
byte bt = ;
ushort twobytes = ;
twobytes = binr.ReadUInt16();
if (twobytes == 0x8130)
binr.ReadByte();
else if (twobytes == 0x8230)
binr.ReadInt16();
else
throw new Exception("Unexpected value read binr.ReadUInt16()"); twobytes = binr.ReadUInt16();
if (twobytes != 0x0102)
throw new Exception("Unexpected version"); bt = binr.ReadByte();
if (bt != 0x00)
throw new Exception("Unexpected value read binr.ReadByte()"); RSAparams.Modulus = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.Exponent = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.D = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.P = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.Q = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.DP = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.DQ = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.InverseQ = binr.ReadBytes(GetIntegerSize(binr));
} RSA.ImportParameters(RSAparams);
return RSA;
} private int GetIntegerSize(BinaryReader binr)
{
byte bt = ;
byte lowbyte = 0x00;
byte highbyte = 0x00;
int count = ;
bt = binr.ReadByte();
if (bt != 0x02)
return ;
bt = binr.ReadByte(); if (bt == 0x81)
count = binr.ReadByte();
else
if (bt == 0x82)
{
highbyte = binr.ReadByte();
lowbyte = binr.ReadByte();
byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
count = BitConverter.ToInt32(modint, );
}
else
{
count = bt;
} while (binr.ReadByte() == 0x00)
{
count -= ;
}
binr.BaseStream.Seek(-, SeekOrigin.Current);
return count;
} private RSACryptoServiceProvider CreateRsaProviderFromPublicKey(string publicKeyString)
{
// encoded OID sequence for PKCS #1 rsaEncryption szOID_RSA_RSA = "1.2.840.113549.1.1.1"
byte[] SeqOID = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
byte[] x509key;
byte[] seq = new byte[];
int x509size; x509key = Convert.FromBase64String(publicKeyString);
x509size = x509key.Length; // --------- Set up stream to read the asn.1 encoded SubjectPublicKeyInfo blob ------
using (MemoryStream mem = new MemoryStream(x509key))
{
using (BinaryReader binr = new BinaryReader(mem)) //wrap Memory Stream with BinaryReader for easy reading
{
byte bt = ;
ushort twobytes = ; twobytes = binr.ReadUInt16();
if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
binr.ReadByte(); //advance 1 byte
else if (twobytes == 0x8230)
binr.ReadInt16(); //advance 2 bytes
else
return null; seq = binr.ReadBytes(); //read the Sequence OID
if (!CompareBytearrays(seq, SeqOID)) //make sure Sequence for OID is correct
return null; twobytes = binr.ReadUInt16();
if (twobytes == 0x8103) //data read as little endian order (actual data order for Bit String is 03 81)
binr.ReadByte(); //advance 1 byte
else if (twobytes == 0x8203)
binr.ReadInt16(); //advance 2 bytes
else
return null; bt = binr.ReadByte();
if (bt != 0x00) //expect null byte next
return null; twobytes = binr.ReadUInt16();
if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
binr.ReadByte(); //advance 1 byte
else if (twobytes == 0x8230)
binr.ReadInt16(); //advance 2 bytes
else
return null; twobytes = binr.ReadUInt16();
byte lowbyte = 0x00;
byte highbyte = 0x00; if (twobytes == 0x8102) //data read as little endian order (actual data order for Integer is 02 81)
lowbyte = binr.ReadByte(); // read next bytes which is bytes in modulus
else if (twobytes == 0x8202)
{
highbyte = binr.ReadByte(); //advance 2 bytes
lowbyte = binr.ReadByte();
}
else
return null;
byte[] modint = { lowbyte, highbyte, 0x00, 0x00 }; //reverse byte order since asn.1 key uses big endian order
int modsize = BitConverter.ToInt32(modint, ); int firstbyte = binr.PeekChar();
if (firstbyte == 0x00)
{ //if first byte (highest order) of modulus is zero, don't include it
binr.ReadByte(); //skip this null byte
modsize -= ; //reduce modulus buffer size by 1
} byte[] modulus = binr.ReadBytes(modsize); //read the modulus bytes if (binr.ReadByte() != 0x02) //expect an Integer for the exponent data
return null;
int expbytes = (int)binr.ReadByte(); // should only need one byte for actual exponent data (for all useful values)
byte[] exponent = binr.ReadBytes(expbytes); // ------- create RSACryptoServiceProvider instance and initialize with public key -----
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
RSAParameters RSAKeyInfo = new RSAParameters();
RSAKeyInfo.Modulus = modulus;
RSAKeyInfo.Exponent = exponent;
RSA.ImportParameters(RSAKeyInfo); return RSA;
} }
} private bool CompareBytearrays(byte[] a, byte[] b)
{
if (a.Length != b.Length)
return false;
int i = ;
foreach (byte c in a)
{
if (c != b[i])
return false;
i++;
}
return true;
}
}
【相关博问】
C#如何通过已有私钥进行RSA解密
C#中如何使用openssl的公钥进行加密
