// // Copyright (c) 2010-2018 Antmicro // Copyright (c) 2011-2015 Realtime Embedded // // This file is licensed under the MIT License. // Full license text is available in 'licenses/MIT.txt'. // using System; using System.Collections.Generic; using System.Linq; namespace Antmicro.Renode.Peripherals.Miscellaneous { using System; using System.Security.Cryptography; using Antmicro.Renode.Core; using Antmicro.Renode.Core.Structure.Registers; using Antmicro.Renode.Logging; using Antmicro.Renode.Peripherals.Bus; public class Sha512Writer : IDoubleWordPeripheral, IBytePeripheral, IProvidesRegisterCollection, IKnownSize { public Sha512Writer(Machine machine, Sha512 sha512) { this.machine = machine; this.sha512 = sha512; } private Machine machine; private Sha512 sha512; public long Size { get { return 4096; } } public void WriteDoubleWord(long offset, uint value) { if (offset != 0) { this.Log(LogLevel.Error, "Adding word 0x{0:X} (at address 0x{1:X}) to hash", value, offset); } this.sha512.add32ToHash(value, (uint)offset); } public uint ReadDoubleWord(long offset) { return RegistersCollection.Read(offset); } public byte ReadByte(long offset) { this.Log(LogLevel.Error, "Reading byte from 0x{0:X}", offset); return 0; } public void WriteByte(long offset, byte value) { this.Log(LogLevel.Error, "Writing byte value 0x{0:X} to 0x{0:X}", value, offset); this.sha512.add8ToHash(value, (uint)offset); } public DoubleWordRegisterCollection RegistersCollection { get; private set; } public void Reset() { } } public class Sha512 : IDoubleWordPeripheral, IProvidesRegisterCollection, IKnownSize { public Sha512(Machine machine, uint memAddr, uint memSize) { this.machine = machine; var sha512Writer = new Sha512Writer(machine, this); machine.SystemBus.Register(sha512Writer, new BusRangeRegistration(memAddr, memSize)); RegistersCollection = new DoubleWordRegisterCollection(this); this.IRQ = new GPIO(); this.sha512 = new SHA512Managed(); Reset(); DefineRegisters(); } public void add32ToHash(UInt32 encounteredValue, uint address) { var inputBuffer = new byte[4]; if (!this.inputIsSwapped.Value) { inputBuffer[3] = (byte)(encounteredValue >> 0); inputBuffer[2] = (byte)(encounteredValue >> 8); inputBuffer[1] = (byte)(encounteredValue >> 16); inputBuffer[0] = (byte)(encounteredValue >> 24); } else { inputBuffer[0] = (byte)(encounteredValue >> 0); inputBuffer[1] = (byte)(encounteredValue >> 8); inputBuffer[2] = (byte)(encounteredValue >> 16); inputBuffer[3] = (byte)(encounteredValue >> 24); } if (this.usingSha256.Value) { foreach (byte b in inputBuffer) { this.Sha512_256Backing.Add(b); } } else { this.sha512.TransformBlock(inputBuffer, 0, inputBuffer.Length, null, 0); } this.digestedLength += (ulong)inputBuffer.Length * 8; } public void add8ToHash(byte encounteredValue, uint address) { var inputBuffer = new byte[1]; inputBuffer[0] = encounteredValue; if (this.usingSha256.Value) { this.Sha512_256Backing.Add(inputBuffer[0]); } else { this.sha512.TransformBlock(inputBuffer, 0, inputBuffer.Length, null, 0); } this.digestedLength += (ulong)inputBuffer.Length * 8; } private uint ResultAtOffset(int offset) { // this.Log(LogLevel.Error, "Hash is: {0} Offset[{1}]: 0x{2:X}", this.sha512, offset, this.sha512.Hash[offset + 0]); if (usingSha256.Value && offset >= 32) { offset -= 32; } // Using sha 512 var arr = this.sha512.Hash; if (this.usingSha256.Value && (this.Sha512_256Result != null)) { arr = this.Sha512_256Result.Hash; } if (outputIsSwapped.Value) { return ((uint)arr[offset + 0] << 0) | ((uint)arr[offset + 1] << 8) | ((uint)arr[offset + 2] << 16) | ((uint)arr[offset + 3] << 24); } else { return ((uint)arr[offset + 3] << 0) | ((uint)arr[offset + 2] << 8) | ((uint)arr[offset + 1] << 16) | ((uint)arr[offset + 0] << 24); } } private void DefineRegisters() { Registers.POWER.Define(this) .WithFlag(0, out powerIsOn, FieldMode.Read | FieldMode.Write, name: "ON") ; Registers.CONFIG.Define(this) .WithFlag(0, out shaIsEnabled, FieldMode.Read | FieldMode.Write, name: "SHA_EN") .WithFlag(1, out inputIsSwapped, FieldMode.Read | FieldMode.Write, name: "ENDIAN_SWAP") .WithFlag(2, out outputIsSwapped, FieldMode.Read | FieldMode.Write, name: "DIGEST_SWAP") .WithFlag(3, out usingSha256, FieldMode.Read | FieldMode.Write, name: "SELECT_256") .WithFlag(4, FieldMode.Write, name: "RESET", writeCallback: (_, doit) => { if (doit) Reset(); }) ; Registers.COMMAND.Define(this) .WithFlag(0, name: "HASH_START", writeCallback: (_, value) => { if (value) { if (this.usingSha256.Value) { // this.sha512 = SHA512Managed.Create("SHA512/256"); this.Sha512_256Backing = new List(); this.Sha512_256Result = null; } else { this.sha512 = SHA512Managed.Create("SHA512"); this.sha512.Initialize(); } this.digestedLength = 0; } }) .WithFlag(1, name: "HASH_PROCESS", writeCallback: (_, value) => { if (value) { if (this.usingSha256.Value) { this.Sha512_256Result = new SHA512_256Managed(this.Sha512_256Backing.ToArray()); this.Sha512_256Backing = null; } else { var dummy = new byte[0]; this.sha512.TransformFinalBlock(dummy, 0, 0); } sha512DoneStatus = true; UpdateInterrupts(); sha512DoneStatus = false; } }) ; Registers.DIGEST00.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(0)) ; Registers.DIGEST01.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(4)) ; Registers.DIGEST10.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(8)) ; Registers.DIGEST11.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(12)) ; Registers.DIGEST20.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(16)) ; Registers.DIGEST21.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(20)) ; Registers.DIGEST30.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(24)) ; Registers.DIGEST31.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(28)) ; Registers.DIGEST40.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(32)) ; Registers.DIGEST41.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(36)) ; Registers.DIGEST50.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(40)) ; Registers.DIGEST51.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(44)) ; Registers.DIGEST60.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(48)) ; Registers.DIGEST61.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(52)) ; Registers.DIGEST70.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(56)) ; Registers.DIGEST71.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => ResultAtOffset(60)) ; Registers.MSG_LENGTH1.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => (uint)(this.digestedLength >> 32)) ; Registers.MSG_LENGTH0.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => (uint)this.digestedLength) ; Registers.EV_STATUS.Define32(this) .WithFlag(0, FieldMode.Read, name: "ERR_VALID", valueProviderCallback: _ => errValidStatus) .WithFlag(1, FieldMode.Read, name: "FIFO_FULL", valueProviderCallback: _ => fifoFullStatus) .WithFlag(2, FieldMode.Read, name: "SHA512_DONE", valueProviderCallback: _ => sha512DoneStatus) ; Registers.EV_PENDING.Define32(this) .WithFlag(0, out errValidPending, FieldMode.Read | FieldMode.WriteOneToClear, name: "ERR_VALID", changeCallback: (_, __) => UpdateInterrupts()) .WithFlag(1, out fifoFullPending, FieldMode.Read | FieldMode.WriteOneToClear, name: "FIFO_FULL", changeCallback: (_, __) => UpdateInterrupts()) .WithFlag(2, out sha512DonePending, FieldMode.Read | FieldMode.WriteOneToClear, name: "SHA512_DONE", changeCallback: (_, __) => UpdateInterrupts()) ; Registers.EV_ENABLE.Define32(this) .WithFlag(0, out errValidEnabled, name: "ERR_VALID", changeCallback: (_, __) => UpdateInterrupts()) .WithFlag(1, out fifoFullEnabled, name: "FIFO_FULL", changeCallback: (_, __) => UpdateInterrupts()) .WithFlag(2, out sha512DoneEnabled, name: "SHA512_DONE", changeCallback: (_, __) => UpdateInterrupts()) ; Registers.FIFO.Define(this) .WithValueField(0, 32, valueProviderCallback: _ => 0) ; } private void UpdateInterrupts() { if (this.errValidStatus) { this.errValidPending.Value = true; } if (this.fifoFullStatus) { this.fifoFullPending.Value = true; } if (this.sha512DoneStatus) { this.sha512DonePending.Value = true; } IRQ.Set((this.errValidPending.Value && this.errValidEnabled.Value) || (this.fifoFullPending.Value && this.fifoFullEnabled.Value) || (this.sha512DonePending.Value && this.sha512DoneEnabled.Value)); } public void WriteDoubleWord(long address, uint value) { RegistersCollection.Write(address, value); } public uint ReadDoubleWord(long offset) { return RegistersCollection.Read(offset); } public long Size { get { return 4096; } } public DoubleWordRegisterCollection RegistersCollection { get; private set; } public void Reset() { this.sha512.Initialize(); this.digestedLength = 0; RegistersCollection.Reset(); } private readonly Machine machine; private SHA512 sha512; public GPIO IRQ { get; private set; } private List Sha512_256Backing; private SHA512_256Managed Sha512_256Result; private IFlagRegisterField powerIsOn; private IFlagRegisterField shaIsEnabled; private IFlagRegisterField inputIsSwapped; private IFlagRegisterField outputIsSwapped; private IFlagRegisterField usingSha256; private IFlagRegisterField errValidEnabled; private IFlagRegisterField errValidPending; private bool errValidStatus; private IFlagRegisterField fifoFullEnabled; private IFlagRegisterField fifoFullPending; private bool fifoFullStatus; private IFlagRegisterField sha512DoneEnabled; private IFlagRegisterField sha512DonePending; private bool sha512DoneStatus; private UInt64 digestedLength; private enum Registers { POWER = 0x00, CONFIG = 0x04, COMMAND = 0x08, DIGEST01 = 0x0c, DIGEST00 = 0x10, DIGEST11 = 0x14, DIGEST10 = 0x18, DIGEST21 = 0x1c, DIGEST20 = 0x20, DIGEST31 = 0x24, DIGEST30 = 0x28, DIGEST41 = 0x2c, DIGEST40 = 0x30, DIGEST51 = 0x34, DIGEST50 = 0x38, DIGEST61 = 0x3c, DIGEST60 = 0x40, DIGEST71 = 0x44, DIGEST70 = 0x48, MSG_LENGTH1 = 0x4c, MSG_LENGTH0 = 0x50, EV_STATUS = 0x54, EV_PENDING = 0x58, EV_ENABLE = 0x5c, FIFO = 0x60 } } } namespace Antmicro.Renode.Peripherals.Miscellaneous { using System.Globalization; using System.Diagnostics.Contracts; using System.Security.Cryptography; using Antmicro.Renode.Core; using Antmicro.Renode.Core.Structure.Registers; using Antmicro.Renode.Logging; using Antmicro.Renode.Peripherals.Bus; } public class SHA512_256Managed { UInt64[] H0Sha512_256; UInt64[] K512; public byte[] Hash; // // public constructors // public SHA512_256Managed(byte[] plaintext) { // These eight 64-bit words are obtained from GenerateInitialHashSha512t(256) // They are manually added to the array here due to bugs in the Renode C# parser. Attemtping // to use a normal array will give an error such as: // (SoC) i @peripherals/sha512.cs // Errors during compilation or loading: // Could not compile assembly: D:\Code\Xous\Core\emulation\peripherals\sha512.cs(407,5): // 14:56:16.2452 [INFO] Including script: D:\Code\Xous\Core\emulation\peripherals\sha512.cs (2) // (SoC) this.H0Sha512_256 = new UInt64[8]; this.H0Sha512_256[0] = 0x22312194fc2bf72c; this.H0Sha512_256[1] = 0x9f555fa3c84c64c2; this.H0Sha512_256[2] = 0x2393b86b6f53b151; this.H0Sha512_256[3] = 0x963877195940eabd; this.H0Sha512_256[4] = 0x96283ee2a88effe3; this.H0Sha512_256[5] = 0xbe5e1e2553863992; this.H0Sha512_256[6] = 0x2b0199fc2c85b8aa; this.H0Sha512_256[7] = 0x0eb72ddc81c52ca2; // The eighty 64-bit words in the array K512 are used in Sha-384, Sha-512, Sha-512/224, Sha-512/256. // They are obtained by taking the first 64 bits of the fractional // parts of the cube roots of the first eighty primes. // They are manually added to the array here due to bugs in the Renode C# parser. this.K512 = new UInt64[80]; this.K512[0] = 0x428a2f98d728ae22; this.K512[1] = 0x7137449123ef65cd; this.K512[2] = 0xb5c0fbcfec4d3b2f; this.K512[3] = 0xe9b5dba58189dbbc; this.K512[4] = 0x3956c25bf348b538; this.K512[5] = 0x59f111f1b605d019; this.K512[6] = 0x923f82a4af194f9b; this.K512[7] = 0xab1c5ed5da6d8118; this.K512[8] = 0xd807aa98a3030242; this.K512[9] = 0x12835b0145706fbe; this.K512[10] = 0x243185be4ee4b28c; this.K512[11] = 0x550c7dc3d5ffb4e2; this.K512[12] = 0x72be5d74f27b896f; this.K512[13] = 0x80deb1fe3b1696b1; this.K512[14] = 0x9bdc06a725c71235; this.K512[15] = 0xc19bf174cf692694; this.K512[16] = 0xe49b69c19ef14ad2; this.K512[17] = 0xefbe4786384f25e3; this.K512[18] = 0x0fc19dc68b8cd5b5; this.K512[19] = 0x240ca1cc77ac9c65; this.K512[20] = 0x2de92c6f592b0275; this.K512[21] = 0x4a7484aa6ea6e483; this.K512[22] = 0x5cb0a9dcbd41fbd4; this.K512[23] = 0x76f988da831153b5; this.K512[24] = 0x983e5152ee66dfab; this.K512[25] = 0xa831c66d2db43210; this.K512[26] = 0xb00327c898fb213f; this.K512[27] = 0xbf597fc7beef0ee4; this.K512[28] = 0xc6e00bf33da88fc2; this.K512[29] = 0xd5a79147930aa725; this.K512[30] = 0x06ca6351e003826f; this.K512[31] = 0x142929670a0e6e70; this.K512[32] = 0x27b70a8546d22ffc; this.K512[33] = 0x2e1b21385c26c926; this.K512[34] = 0x4d2c6dfc5ac42aed; this.K512[35] = 0x53380d139d95b3df; this.K512[36] = 0x650a73548baf63de; this.K512[37] = 0x766a0abb3c77b2a8; this.K512[38] = 0x81c2c92e47edaee6; this.K512[39] = 0x92722c851482353b; this.K512[40] = 0xa2bfe8a14cf10364; this.K512[41] = 0xa81a664bbc423001; this.K512[42] = 0xc24b8b70d0f89791; this.K512[43] = 0xc76c51a30654be30; this.K512[44] = 0xd192e819d6ef5218; this.K512[45] = 0xd69906245565a910; this.K512[46] = 0xf40e35855771202a; this.K512[47] = 0x106aa07032bbd1b8; this.K512[48] = 0x19a4c116b8d2d0c8; this.K512[49] = 0x1e376c085141ab53; this.K512[50] = 0x2748774cdf8eeb99; this.K512[51] = 0x34b0bcb5e19b48a8; this.K512[52] = 0x391c0cb3c5c95a63; this.K512[53] = 0x4ed8aa4ae3418acb; this.K512[54] = 0x5b9cca4f7763e373; this.K512[55] = 0x682e6ff3d6b2b8a3; this.K512[56] = 0x748f82ee5defb2fc; this.K512[57] = 0x78a5636f43172f60; this.K512[58] = 0x84c87814a1f0ab72; this.K512[59] = 0x8cc702081a6439ec; this.K512[60] = 0x90befffa23631e28; this.K512[61] = 0xa4506cebde82bde9; this.K512[62] = 0xbef9a3f7b2c67915; this.K512[63] = 0xc67178f2e372532b; this.K512[64] = 0xca273eceea26619c; this.K512[65] = 0xd186b8c721c0c207; this.K512[66] = 0xeada7dd6cde0eb1e; this.K512[67] = 0xf57d4f7fee6ed178; this.K512[68] = 0x06f067aa72176fba; this.K512[69] = 0x0a637dc5a2c898a6; this.K512[70] = 0x113f9804bef90dae; this.K512[71] = 0x1b710b35131c471b; this.K512[72] = 0x28db77f523047d84; this.K512[73] = 0x32caab7b40c72493; this.K512[74] = 0x3c9ebe0a15c9bebc; this.K512[75] = 0x431d67c49c100d4c; this.K512[76] = 0x4cc5d4becb3e42b6; this.K512[77] = 0x597f299cfc657e2a; this.K512[78] = 0x5fcb6fab3ad6faec; this.K512[79] = 0x6c44198c4a475817; this.Hash = Sha512Algorithm(plaintext, this.H0Sha512_256, 256); } byte[] Sha512Algorithm(byte[] plaintext, UInt64[] H0, int numberBits) { Block1024[] blocks = ConvertPaddedMessageToBlock1024Array(PadPlainText1024(plaintext)); // Define the hash variable and set its initial values. UInt64[] H = H0; for (int i = 0; i < blocks.Length; i++) { UInt64[] W = CreateMessageScheduleSha512(blocks[i]); // Set the working variables a,...,h to the current hash values. UInt64 a = H[0]; UInt64 b = H[1]; UInt64 c = H[2]; UInt64 d = H[3]; UInt64 e = H[4]; UInt64 f = H[5]; UInt64 g = H[6]; UInt64 h = H[7]; for (int t = 0; t < 80; t++) { UInt64 T1 = h + Sigma1_512(e) + Ch(e, f, g) + this.K512[t] + W[t]; UInt64 T2 = Sigma0_512(a) + Maj(a, b, c); h = g; g = f; f = e; e = d + T1; d = c; c = b; b = a; a = T1 + T2; } // Update the current value of the hash H after processing block i. H[0] += a; H[1] += b; H[2] += c; H[3] += d; H[4] += e; H[5] += f; H[6] += g; H[7] += h; } // Concatenate all the Word64 Hash Values byte[] hash = ShaUtilities.Word64ArrayToByteArray(H); // The number of bytes in the final output hash int numberBytes = numberBits / 8; byte[] truncatedHash = new byte[numberBytes]; Array.Copy(hash, truncatedHash, numberBytes); return truncatedHash; } static UInt32 Maj(UInt32 x, UInt32 y, UInt32 z) { return (x & y) ^ (x & z) ^ (y & z); } static UInt64 Maj(UInt64 x, UInt64 y, UInt64 z) { return (x & y) ^ (x & z) ^ (y & z); } static UInt32 Ch(UInt32 x, UInt32 y, UInt32 z) { return (x & y) ^ (~x & z); } static UInt64 Ch(UInt64 x, UInt64 y, UInt64 z) { return (x & y) ^ (~x & z); } static UInt64 Sigma0_512(UInt64 x) { return RotR(28, x) ^ RotR(34, x) ^ RotR(39, x); } static UInt64 Sigma1_512(UInt64 x) { return RotR(14, x) ^ RotR(18, x) ^ RotR(41, x); } static UInt64 sigma0_512(UInt64 x) { return RotR(1, x) ^ RotR(8, x) ^ ShR(7, x); } static UInt64 sigma1_512(UInt64 x) { return RotR(19, x) ^ RotR(61, x) ^ ShR(6, x); } static UInt64 ShR(int n, UInt64 x) { // should have 0 <= n < 64 return (x >> n); } static UInt32 RotR(int n, UInt32 x) { // should have 0 <= n < 32 return (x >> n) | (x << 32 - n); } static UInt64 RotR(int n, UInt64 x) { // should have 0 <= n < 64 return (x >> n) | (x << 64 - n); } static byte[] PadPlainText1024(byte[] plaintext) { // After padding the total bits of the output will be divisible by 1024. int numberBits = plaintext.Length * 8; int t = (numberBits + 8 + 128) / 1024; // Note that 1024 * (t + 1) is the least multiple of 1024 greater than (numberBits + 8 + 128) // Therefore the number of zero bits we need to add is int k = 1024 * (t + 1) - (numberBits + 8 + 128); // Since numberBits % 8 = 0, we know k % 8 = 0. So n = k / 8 is the number of zero bytes to add. int n = k / 8; List paddedtext = plaintext.ToList(); // Start the padding by concatenating 1000_0000 = 0x80 = 128 paddedtext.Add(0x80); // Next add n zero bytes for (int i = 0; i < n; i++) { paddedtext.Add(0); } // Now add 16 bytes (128 bits) to represent the length of the message in bits. // C# does not have 128 bit integer. // For now just add 8 zero bytes and then 8 bytes to represent the int for (int i = 0; i < 8; i++) { paddedtext.Add(0); } byte[] B = BitConverter.GetBytes((ulong)numberBits); Array.Reverse(B); for (int i = 0; i < B.Length; i++) { paddedtext.Add(B[i]); } return paddedtext.ToArray(); } static Block1024[] ConvertPaddedMessageToBlock1024Array(byte[] M) { // We are assuming M is padded, so the number of bits in M is divisible by 1024 int numberBlocks = (M.Length * 8) / 1024; // same as: M.Length / 128 Block1024[] blocks = new Block1024[numberBlocks]; for (int i = 0; i < numberBlocks; i++) { // First extract the relavant subarray from M byte[] B = new byte[128]; // 128 * 8 = 1024 for (int j = 0; j < 128; j++) { B[j] = M[i * 128 + j]; } UInt64[] words = ShaUtilities.ByteArrayToWord64Array(B); blocks[i] = new Block1024(words); } return blocks; } static UInt64[] CreateMessageScheduleSha512(Block1024 block) { // The message schedule. UInt64[] W = new UInt64[80]; // Prepare the message schedule W. // The first 16 words in W are the same as the words of the block. // The remaining 80-16 =64 words in W are functions of the previously defined words. for (int t = 0; t < 80; t++) { if (t < 16) { W[t] = block.words[t]; } else { W[t] = sigma1_512(W[t - 2]) + W[t - 7] + sigma0_512(W[t - 15]) + W[t - 16]; } } return W; } class Block1024 { // A Block1024 consists of an array of 16 elements of type Word64. public UInt64[] words; public Block1024(UInt64[] words) { if (words.Length == 16) { this.words = words; } else { Console.WriteLine("ERROR: A block must be 16 words"); this.words = null; } } } static class ShaUtilities { public static UInt64[] ByteArrayToWord64Array(byte[] B) { // We assume B is not null, is not empty and number elements is divisible by 8 int numberWords = B.Length / 8; // 8 bytes for each Word32 UInt64[] word64Array = new UInt64[numberWords]; for (int i = 0; i < numberWords; i++) { word64Array[i] = ByteArrayToWord64(B, 8 * i); } return word64Array; } public static UInt64 ByteArrayToWord64(byte[] B, int startIndex) { // We assume: 0 <= startIndex < B. Length, and startIndex + 8 <= B.Length UInt64 c = 256; UInt64 output = 0; for (int i = startIndex; i < startIndex + 8; i++) { output = output * c + B[i]; } return output; } // Returns an array of 8 bytes. public static byte[] Word64ToByteArray(UInt64 x) { byte[] b = BitConverter.GetBytes(x); Array.Reverse(b); return b; } public static byte[] Word64ArrayToByteArray(UInt64[] words) { List b = new List(); for (int i = 0; i < words.Length; i++) { b.AddRange(Word64ToByteArray(words[i])); } return b.ToArray(); } } }