22df2e7fcb
Renamed a variable Implemented a custom AES function as "Rijndael128" - Built in key derivation at the moment (PBKDF2-HMAC-SHA1) - Added built-in string encryption/decryption - All encryption functions compute the results using the underlying mathematical models instead of using tables, simply to demonstrate the inner workings of AES Simplified some methods for readability and convenience Removed unnecessary use of BigInteger Replaced manually (and terribly) calculated Galois field arithmetic with Galois2 methods to make the code simpler and more understandable
61 lines
2.0 KiB
C#
61 lines
2.0 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Tofvesson.Crypto
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{
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// Class for key derivation
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public static class KDF
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{
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public delegate byte[] HashFunction(byte[] message);
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public static byte[] HMAC(byte[] key, byte[] message, HashFunction func, int blockSizeBytes)
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{
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if (key.Length > blockSizeBytes) key = func(key);
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else if (key.Length < blockSizeBytes)
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{
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byte[] b = new byte[blockSizeBytes];
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Array.Copy(key, b, key.Length);
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key = b;
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}
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byte[] o_key_pad = new byte[blockSizeBytes];
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byte[] i_key_pad = new byte[blockSizeBytes];
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for (int i = 0; i < blockSizeBytes; ++i)
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{
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o_key_pad[i] = (byte)(key[i] ^ 0x5c);
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i_key_pad[i] = (byte)(key[i] ^ 0x36);
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}
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return func(Support.Concatenate(o_key_pad, func(Support.Concatenate(i_key_pad, message))));
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}
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public static byte[] HMAC_SHA1(byte[] key, byte[] message) => HMAC(key, message, SHA.SHA1, 64);
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public delegate byte[] PRF(byte[] key, byte[] salt);
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public static byte[] PBKDF2(PRF function, byte[] password, byte[] salt, int iterations, int dklen)
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{
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byte[] dk = new byte[0];
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uint iter = 1;
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while (dk.Length < dklen)
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{
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// F-function
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byte[] u = function(password, Support.Concatenate(salt, Support.WriteToArray(new byte[4], Support.SwapEndian(iter), 0)));
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byte[] ures = new byte[u.Length];
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Array.Copy(u, ures, u.Length);
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for(int i = 1; i<iterations; ++i)
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{
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u = function(password, u);
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for (int j = 0; j < u.Length; ++j) ures[j] ^= u[j];
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}
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dk = Support.Concatenate(dk, ures);
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++iter;
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}
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return dk.ToLength(dklen);
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}
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}
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}
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