Files
OpenRA/OpenRA.Game/CryptoUtil.cs
RoosterDragon 5d91b678bb Use spans to improve performance in StreamExts.
Also avoid ReadBytes calls that allocate a buffer by either updating the stream position (if not interested in the bytes), by reusing an input buffer (if interested in the bytes), or using a stackalloc buffer to avoid the allocation (for small reads).
2023-11-10 10:25:39 +02:00

296 lines
8.4 KiB
C#

#region Copyright & License Information
/*
* Copyright (c) The OpenRA Developers and Contributors
* This file is part of OpenRA, which is free software. It is made
* available to you under the terms of the GNU General Public License
* as published by the Free Software Foundation, either version 3 of
* the License, or (at your option) any later version. For more
* information, see COPYING.
*/
#endregion
using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
namespace OpenRA
{
public static class CryptoUtil
{
// Fixed byte pattern for the OID header
static readonly byte[] OIDHeader = { 0x30, 0xD, 0x6, 0x9, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0xD, 0x1, 0x1, 0x1, 0x5, 0x0 };
static readonly char[] HexUpperAlphabet = "0123456789ABCDEF".ToArray();
static readonly char[] HexLowerAlphabet = "0123456789abcdef".ToArray();
public static string PublicKeyFingerprint(RSAParameters parameters)
{
// Public key fingerprint is defined as the SHA1 of the modulus + exponent bytes
return SHA1Hash(parameters.Modulus.Append(parameters.Exponent).ToArray());
}
public static string EncodePEMPublicKey(RSAParameters parameters)
{
var data = Convert.ToBase64String(EncodePublicKey(parameters));
var output = new StringBuilder();
output.AppendLine("-----BEGIN PUBLIC KEY-----");
for (var i = 0; i < data.Length; i += 64)
output.AppendLine(data.Substring(i, Math.Min(64, data.Length - i)));
output.Append("-----END PUBLIC KEY-----");
return output.ToString();
}
public static RSAParameters DecodePEMPublicKey(string key)
{
try
{
// Reconstruct original key data
var lines = key.Split('\n');
var data = Convert.FromBase64String(lines.Skip(1).Take(lines.Length - 2).JoinWith(""));
// Pull the modulus and exponent bytes out of the ASN.1 tree
// Expect this to blow up if the key is not correctly formatted
using (var s = new MemoryStream(data))
{
// SEQUENCE
s.ReadUInt8();
ReadTLVLength(s);
// SEQUENCE -> fixed header junk
s.ReadUInt8();
var headerLength = ReadTLVLength(s);
s.Position += headerLength;
// SEQUENCE -> BIT_STRING
s.ReadUInt8();
ReadTLVLength(s);
s.ReadUInt8();
// SEQUENCE -> BIT_STRING -> SEQUENCE
s.ReadUInt8();
ReadTLVLength(s);
// SEQUENCE -> BIT_STRING -> SEQUENCE -> INTEGER (modulus)
s.ReadUInt8();
var modulusLength = ReadTLVLength(s);
s.ReadUInt8();
var modulus = s.ReadBytes(modulusLength - 1);
// SEQUENCE -> BIT_STRING -> SEQUENCE -> INTEGER (exponent)
s.ReadUInt8();
var exponentLength = ReadTLVLength(s);
s.ReadUInt8();
var exponent = s.ReadBytes(exponentLength - 1);
return new RSAParameters
{
Modulus = modulus,
Exponent = exponent
};
}
}
catch (Exception e)
{
throw new InvalidDataException("Invalid PEM public key", e);
}
}
static byte[] EncodePublicKey(RSAParameters parameters)
{
using (var stream = new MemoryStream())
{
var writer = new BinaryWriter(stream);
var modExpLength = TripletFullLength(parameters.Modulus.Length + 1) + TripletFullLength(parameters.Exponent.Length + 1);
var bitStringLength = TripletFullLength(modExpLength + 1);
var sequenceLength = TripletFullLength(bitStringLength + OIDHeader.Length);
// SEQUENCE
writer.Write((byte)0x30);
WriteTLVLength(writer, sequenceLength);
// SEQUENCE -> fixed header junk
writer.Write(OIDHeader);
// SEQUENCE -> BIT_STRING
writer.Write((byte)0x03);
WriteTLVLength(writer, bitStringLength);
writer.Write((byte)0x00);
// SEQUENCE -> BIT_STRING -> SEQUENCE
writer.Write((byte)0x30);
WriteTLVLength(writer, modExpLength);
// SEQUENCE -> BIT_STRING -> SEQUENCE -> INTEGER
// Modulus is padded with a zero to avoid issues with the sign bit
writer.Write((byte)0x02);
WriteTLVLength(writer, parameters.Modulus.Length + 1);
writer.Write((byte)0);
writer.Write(parameters.Modulus);
// SEQUENCE -> BIT_STRING -> SEQUENCE -> INTEGER
// Exponent is padded with a zero to avoid issues with the sign bit
writer.Write((byte)0x02);
WriteTLVLength(writer, parameters.Exponent.Length + 1);
writer.Write((byte)0);
writer.Write(parameters.Exponent);
return stream.ToArray();
}
}
static void WriteTLVLength(BinaryWriter writer, int length)
{
if (length < 0x80)
{
// Length < 128 is stored in a single byte
writer.Write((byte)length);
}
else
{
// If 128 <= length < 256**128 first byte encodes number of bytes required to hold the length
// High-bit is set as a flag to use this long-form encoding
var lengthBytes = BitConverter.GetBytes(length).Reverse().SkipWhile(b => b == 0).ToArray();
writer.Write((byte)(0x80 | lengthBytes.Length));
writer.Write(lengthBytes);
}
}
static int ReadTLVLength(Stream s)
{
var length = s.ReadUInt8();
if (length < 0x80)
return length;
Span<byte> data = stackalloc byte[4];
s.ReadBytes(data[..Math.Min(length & 0x7F, 4)]);
return BitConverter.ToInt32(data);
}
static int TripletFullLength(int dataLength)
{
if (dataLength < 0x80)
return 2 + dataLength;
return 2 + dataLength + BitConverter.GetBytes(dataLength).Reverse().SkipWhile(b => b == 0).Count();
}
public static string DecryptString(RSAParameters parameters, string data)
{
try
{
using (var rsa = new RSACryptoServiceProvider())
{
rsa.ImportParameters(parameters);
return Encoding.UTF8.GetString(rsa.Decrypt(Convert.FromBase64String(data), false));
}
}
catch (Exception e)
{
Log.Write("debug", "Failed to decrypt string with exception:");
Log.Write("debug", e);
Console.WriteLine("String decryption failed:");
Console.WriteLine(e);
return null;
}
}
public static string Sign(RSAParameters parameters, string data)
{
return Sign(parameters, Encoding.UTF8.GetBytes(data));
}
public static string Sign(RSAParameters parameters, byte[] data)
{
try
{
using (var rsa = new RSACryptoServiceProvider())
{
rsa.ImportParameters(parameters);
using (var csp = SHA1.Create())
return Convert.ToBase64String(rsa.SignHash(csp.ComputeHash(data), CryptoConfig.MapNameToOID("SHA1")));
}
}
catch (Exception e)
{
Log.Write("debug", "Failed to sign string with exception");
Log.Write("debug", e);
Console.WriteLine("String signing failed:");
Console.WriteLine(e);
return null;
}
}
public static bool VerifySignature(RSAParameters parameters, string data, string signature)
{
return VerifySignature(parameters, Encoding.UTF8.GetBytes(data), signature);
}
public static bool VerifySignature(RSAParameters parameters, byte[] data, string signature)
{
try
{
using (var rsa = new RSACryptoServiceProvider())
{
rsa.ImportParameters(parameters);
using (var csp = SHA1.Create())
return rsa.VerifyHash(csp.ComputeHash(data), CryptoConfig.MapNameToOID("SHA1"), Convert.FromBase64String(signature));
}
}
catch (Exception e)
{
Log.Write("debug", "Failed to verify signature with exception:");
Log.Write("debug", e);
Console.WriteLine("Signature validation failed:");
Console.WriteLine(e);
return false;
}
}
public static string SHA1Hash(Stream data)
{
using var csp = SHA1.Create();
return ToHex(csp.ComputeHash(data), true);
}
public static string SHA1Hash(byte[] data)
{
using var csp = SHA1.Create();
return ToHex(csp.ComputeHash(data), true);
}
public static string SHA1Hash(string data)
{
return SHA1Hash(Encoding.UTF8.GetBytes(data));
}
public static string ToHex(ReadOnlySpan<byte> source, bool lowerCase = false)
{
if (source.Length == 0)
return string.Empty;
// excessively avoid stack overflow if source is too large (considering that we're allocating a new string)
var buffer = source.Length <= 256 ? stackalloc char[source.Length * 2] : new char[source.Length * 2];
return ToHexInternal(source, buffer, lowerCase);
}
static string ToHexInternal(ReadOnlySpan<byte> source, Span<char> buffer, bool lowerCase)
{
var sourceIndex = 0;
var alphabet = lowerCase ? HexLowerAlphabet : HexUpperAlphabet;
for (var i = 0; i < buffer.Length; i += 2)
{
var b = source[sourceIndex++];
buffer[i] = alphabet[b >> 4];
buffer[i + 1] = alphabet[b & 0xF];
}
return new string(buffer);
}
}
}