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// Copyright (C) 2024 Vaughn Nugent
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
using System;
using System.Buffers.Binary;
using System.Runtime.InteropServices;
using VNLib.Utils.Memory;
namespace NVault.Crypto.Noscrypt
{
/// <summary>
/// Provides a set of utility methods for working with the Noscrypt library
/// </summary>
public static class Nip44Util
{
/// <summary>
/// Calculates the required NIP44 encryption buffer size for
/// the specified input data size
/// </summary>
/// <param name="dataSize">The size (in bytes) of the encoded data to encrypt</param>
/// <returns>The exact size of the padded buffer output</returns>
public static uint CalcBufferSize(uint dataSize)
{
//always add leading 2 bytes for the encoded data size
dataSize += sizeof(ushort);
//Min message size is 32 bytes
uint minSize = Math.Max(dataSize, 32);
//calculate the next power of 2
uint nextPow2 = 1;
while (nextPow2 < minSize)
{
nextPow2 <<= 1;
}
return nextPow2;
}
/// <summary>
/// Formats the plaintext data into a buffer that can be properly encrypted.
/// The output buffer must be zeroed, or can be zeroed using the
/// <paramref name="zeroOutput"/> parameter. Use <see cref="CalcBufferSize(uint)"/>
/// to determine the required output buffer size.
/// </summary>
/// <param name="plaintextData">A buffer containing plaintext data to copy to the output</param>
/// <param name="output">The output data buffer to format</param>
/// <param name="zeroOutput">A value that indicates if the buffer should be zeroed before use</param>
public static void FormatBuffer(ReadOnlySpan<byte> plaintextData, Span<byte> output, bool zeroOutput)
{
//First zero out the buffer
if (zeroOutput)
{
MemoryUtil.InitializeBlock(output);
}
//Make sure the output buffer is large enough so we dont overrun it
ArgumentOutOfRangeException.ThrowIfLessThan(output.Length, plaintextData.Length + sizeof(ushort), nameof(output));
//Write the data size to the first 2 bytes
ushort dataSize = (ushort)plaintextData.Length;
BinaryPrimitives.WriteUInt16BigEndian(output, dataSize);
//Copy the plaintext data to the output buffer after the data size
MemoryUtil.Memmove(
ref MemoryMarshal.GetReference(plaintextData),
sizeof(ushort),
ref MemoryMarshal.GetReference(output),
0,
(uint)plaintextData.Length
);
//We assume the remaining buffer is zeroed out
}
public static void Encrypt(
this INostrCrypto lib,
ref readonly NCSecretKey secretKey,
ref readonly NCPublicKey publicKey,
ReadOnlySpan<byte> nonce32,
ReadOnlySpan<byte> plainText,
Span<byte> cipherText
)
{
ArgumentNullException.ThrowIfNull(lib);
//Chacha requires the output buffer to be at-least the size of the input buffer
ArgumentOutOfRangeException.ThrowIfGreaterThan(plainText.Length, cipherText.Length, nameof(plainText));
//Nonce must be exactly 32 bytes
ArgumentOutOfRangeException.ThrowIfNotEqual(nonce32.Length, 32, nameof(nonce32));
//Encrypt data, use the plaintext buffer size as the data size
lib.Encrypt(
in secretKey,
in publicKey,
in MemoryMarshal.GetReference(nonce32),
in MemoryMarshal.GetReference(plainText),
ref MemoryMarshal.GetReference(cipherText),
(uint)plainText.Length
);
}
public static unsafe void Encrypt(
this INostrCrypto lib,
ref NCSecretKey secretKey,
ref NCPublicKey publicKey,
void* nonce32,
void* plainText,
void* cipherText,
uint size
)
{
ArgumentNullException.ThrowIfNull(plainText);
ArgumentNullException.ThrowIfNull(cipherText);
ArgumentNullException.ThrowIfNull(nonce32);
//Spans are easer to forward references from pointers without screwing up arguments
Encrypt(
lib,
in secretKey,
in publicKey,
new Span<byte>(nonce32, 32),
new Span<byte>(plainText, (int)size),
new Span<byte>(cipherText, (int)size)
);
}
public static void Decrypt(
this INostrCrypto lib,
ref readonly NCSecretKey secretKey,
ref readonly NCPublicKey publicKey,
ReadOnlySpan<byte> nonce32,
ReadOnlySpan<byte> cipherText,
Span<byte> plainText
)
{
ArgumentNullException.ThrowIfNull(lib);
//Chacha requires the output buffer to be at-least the size of the input buffer
ArgumentOutOfRangeException.ThrowIfGreaterThan(cipherText.Length, plainText.Length, nameof(cipherText));
//Nonce must be exactly 32 bytes
ArgumentOutOfRangeException.ThrowIfNotEqual(nonce32.Length, 32, nameof(nonce32));
//Decrypt data, use the ciphertext buffer size as the data size
lib.Decrypt(
in secretKey,
in publicKey,
in MemoryMarshal.GetReference(nonce32),
in MemoryMarshal.GetReference(cipherText),
ref MemoryMarshal.GetReference(plainText),
(uint)cipherText.Length
);
}
public static unsafe void Decrypt(
this INostrCrypto lib,
ref readonly NCSecretKey secretKey,
ref readonly NCPublicKey publicKey,
void* nonce32,
void* cipherText,
void* plainText,
uint size
)
{
ArgumentNullException.ThrowIfNull(nonce32);
ArgumentNullException.ThrowIfNull(cipherText);
ArgumentNullException.ThrowIfNull(plainText);
//Spans are easer to forward references from pointers without screwing up arguments
Decrypt(
lib,
in secretKey,
in publicKey,
new Span<byte>(nonce32, 32),
new Span<byte>(cipherText, (int)size),
new Span<byte>(plainText, (int)size)
);
}
}
}
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