--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/NaCl/crypto_stream/salsa20.cs	Mon Apr 15 00:43:48 2013 +0200
@@ -0,0 +1,123 @@
+using System;
+
+namespace UCIS.NaCl.crypto_stream {
+	static unsafe class salsa20 {
+		public const int KEYBYTES = 32;
+		public const int NONCEBYTES = 8;
+
+		static Byte[] sigma = new Byte[16] {(Byte)'e', (Byte)'x', (Byte)'p', (Byte)'a', //[16] = "expand 32-byte k";
+											(Byte)'n', (Byte)'d', (Byte)' ', (Byte)'3',
+											(Byte)'2', (Byte)'-', (Byte)'b', (Byte)'y',
+											(Byte)'t', (Byte)'e', (Byte)' ', (Byte)'k', }; 
+
+		public static void crypto_stream(Byte* c, int clen, Byte* n, Byte* k) {
+			Byte[] inv = new Byte[16];
+			Byte[] block = new Byte[64];
+			if (clen == 0) return;
+
+			for (int i = 0; i < 8; ++i) inv[i] = n[i];
+			for (int i = 8; i < 16; ++i) inv[i] = 0;
+
+			while (clen >= 64) {
+				fixed (Byte* invp = inv, sigmap = sigma) crypto_core.salsa20.crypto_core(c, invp, k, sigmap);
+
+				UInt32 u = 1;
+				for (int i = 8; i < 16; ++i) {
+					u += inv[i];
+					inv[i] = (Byte)u;
+					u >>= 8;
+				}
+
+				clen -= 64;
+				c += 64;
+			}
+
+			if (clen != 0) {
+				fixed (Byte* invp = inv, sigmap = sigma, blockp = block) crypto_core.salsa20.crypto_core(blockp, invp, k, sigmap);
+				for (int i = 0; i < clen; ++i) c[i] = block[i];
+			}
+		}
+
+		public static void crypto_stream_xor(Byte* c, Byte* m, int mlen, Byte* n, Byte* k) {
+			Byte[] inv = new Byte[16];
+			Byte[] block = new Byte[64];
+			if (mlen == 0) return;
+
+			for (int i = 0; i < 8; ++i) inv[i] = n[i];
+			for (int i = 8; i < 16; ++i) inv[i] = 0;
+
+			while (mlen >= 64) {
+				fixed (Byte* invp = inv, sigmap = sigma, blockp = block) crypto_core.salsa20.crypto_core(blockp, invp, k, sigmap);
+				for (int i = 0; i < 64; ++i) c[i] = (Byte)(m[i] ^ block[i]);
+
+				UInt32 u = 1;
+				for (int i = 8; i < 16; ++i) {
+					u += inv[i];
+					inv[i] = (Byte)u;
+					u >>= 8;
+				}
+
+				mlen -= 64;
+				c += 64;
+				m += 64;
+			}
+
+			if (mlen != 0) {
+				fixed (Byte* invp = inv, sigmap = sigma, blockp = block) crypto_core.salsa20.crypto_core(blockp, invp, k, sigmap);
+				for (int i = 0; i < mlen; ++i) c[i] = (Byte)(m[i] ^ block[i]);
+			}
+		}
+
+		internal static void crypto_stream_xor_split(Byte* mcpad, int padbytes, Byte* c, Byte* m, int mlen, Byte* n, Byte* k) {
+			Byte* inv = stackalloc Byte[16];
+			Byte* block = stackalloc Byte[64];
+
+			for (int i = 0; i < 8; ++i) inv[i] = n[i];
+			for (int i = 8; i < 16; ++i) inv[i] = 0;
+
+			if (padbytes > 0) {
+				if (padbytes > 64) throw new ArgumentOutOfRangeException("padbytes");
+				crypto_core.salsa20.crypto_core(block, inv, k, sigma);
+				if (mcpad != null) for (int i = 0; i < padbytes; ++i) mcpad[i] ^= block[i];
+				if (mlen > 0) {
+					int bleft = 64 - padbytes;
+					if (bleft > mlen) bleft = mlen;
+					for (int i = 0; i < bleft; ++i) c[i] = (Byte)(m[i] ^ block[i + padbytes]);
+					c += bleft;
+					m += bleft;
+					mlen -= bleft;
+					if (mlen >= 0) {
+						UInt32 u = 1;
+						for (int i = 8; i < 16; ++i) {
+							u += inv[i];
+							inv[i] = (Byte)u;
+							u >>= 8;
+						}
+					}
+				}
+			}
+
+			while (mlen >= 64) {
+				crypto_core.salsa20.crypto_core(block, inv, k, sigma);
+				//for (int i = 0; i < 64; ++i) c[i] = (Byte)(m[i] ^ block[i]);
+				for (int i = 0; i < 64; i += 4) *(int*)(c + i) = *(int*)(m + i) ^ *(int*)(block + i);
+
+				UInt32 u = 1;
+				for (int i = 8; i < 16; ++i) {
+					u += inv[i];
+					inv[i] = (Byte)u;
+					u >>= 8;
+				}
+
+				mlen -= 64;
+				c += 64;
+				m += 64;
+			}
+
+			if (mlen > 0) {
+				crypto_core.salsa20.crypto_core(block, inv, k, sigma);
+				for (int i = 0; i < mlen; ++i) c[i] = (Byte)(m[i] ^ block[i]);
+			}
+		}
+	}
+}
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