我正在寻找OpenSSL EVP_BytesToKey函数的直接.NET实现。我找到的最接近的东西是System.Security.Cryptography.PasswordDeriveBytes类(和Rfc2898DeriveBytes),但它似乎略有不同,并且不会生成与EVP_BytesToKey 相同的 键 和 iv 。
我还发现此实现似乎是一个不错的开始,但没有考虑迭代计数。
我意识到这里有OpenSSL.NET,但这只是本机openssl DLL的包装,而不是“真正的” .NET实现。
我找到了 EVP_BytesToKey 方法的伪代码说明(在openssl源代码的/doc/ssleay.txt中):
/* M[] is an array of message digests * MD() is the message digest function */ M[0]=MD(data . salt); for (i=1; i<count; i++) M[0]=MD(M[0]); i=1 while (data still needed for key and iv) { M[i]=MD(M[i-1] . data . salt); for (i=1; i<count; i++) M[i]=MD(M[i]); i++; } If the salt is NULL, it is not used. The digests are concatenated together. M = M[0] . M[1] . M[2] .......
因此,基于此,我能够提出这种C#方法(该方法似乎可以满足我的目的,并假定使用32字节的密钥和16字节的iv):
private static void DeriveKeyAndIV(byte[] data, byte[] salt, int count, out byte[] key, out byte[] iv) { List<byte> hashList = new List<byte>(); byte[] currentHash = new byte[0]; int preHashLength = data.Length + ((salt != null) ? salt.Length : 0); byte[] preHash = new byte[preHashLength]; System.Buffer.BlockCopy(data, 0, preHash, 0, data.Length); if (salt != null) System.Buffer.BlockCopy(salt, 0, preHash, data.Length, salt.Length); MD5 hash = MD5.Create(); currentHash = hash.ComputeHash(preHash); for (int i = 1; i < count; i++) { currentHash = hash.ComputeHash(currentHash); } hashList.AddRange(currentHash); while (hashList.Count < 48) // for 32-byte key and 16-byte iv { preHashLength = currentHash.Length + data.Length + ((salt != null) ? salt.Length : 0); preHash = new byte[preHashLength]; System.Buffer.BlockCopy(currentHash, 0, preHash, 0, currentHash.Length); System.Buffer.BlockCopy(data, 0, preHash, currentHash.Length, data.Length); if (salt != null) System.Buffer.BlockCopy(salt, 0, preHash, currentHash.Length + data.Length, salt.Length); currentHash = hash.ComputeHash(preHash); for (int i = 1; i < count; i++) { currentHash = hash.ComputeHash(currentHash); } hashList.AddRange(currentHash); } hash.Clear(); key = new byte[32]; iv = new byte[16]; hashList.CopyTo(0, key, 0, 32); hashList.CopyTo(32, iv, 0, 16); }
更新 :这里更多/更少相同的实现,但是使用.NET DeriveBytes接口:https ://gist.github.com/1339719
OpenSSL 1.1.0c更改了某些内部组件中使用的摘要算法。以前使用MD5,并且1.1.0切换到SHA256。小心的变化不影响你在这两个EVP_BytesToKey和命令状openssl enc。
EVP_BytesToKey
openssl enc