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Use read-only spans

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This commit is contained in:
Vitaliya Chumakova
2021-09-07 13:47:05 +03:00
parent 4e25a03f6d
commit 38ec2e4c2c
1 changed files with 9 additions and 8 deletions
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17
YandexKeyExtractor/Decryptor.cs
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@@ -8,25 +8,26 @@ namespace YandexKeyExtractor {
public static string? Decrypt(string encryptedText, string password) {
string base64Text = NormalizeBase64(encryptedText);
Span<byte> textBytes = Convert.FromBase64String(base64Text).AsSpan();
ReadOnlySpan<byte> textBytes = Convert.FromBase64String(base64Text).AsSpan();
const byte saltLength = 16;
Span<byte> textData = textBytes[..^saltLength];
Span<byte> textSalt = textBytes[^saltLength..];
ReadOnlySpan<byte> textData = textBytes[..^saltLength];
ReadOnlySpan<byte> textSalt = textBytes[^saltLength..];
byte[]? generatedPassword = SCrypt.ComputeDerivedKey(Encoding.UTF8.GetBytes(password), textSalt.ToArray(), 32768, 20, 1, null, 32);
using XSalsa20Poly1305 secureBox = new(generatedPassword);
const byte nonceLength = 24;
Span<byte> nonce = textData[..nonceLength];
Span<byte> dataWithMac = textData[nonceLength..];
ReadOnlySpan<byte> nonce = textData[..nonceLength];
ReadOnlySpan<byte> dataWithMac = textData[nonceLength..];
Span<byte> message = stackalloc byte[dataWithMac.Length];
Span<byte> message = dataWithMac.Length <= 4096 ? stackalloc byte[dataWithMac.Length] : new byte[dataWithMac.Length];
const byte macLength = 16;
Span<byte> data = dataWithMac[macLength..];
Span<byte> mac = dataWithMac[..macLength];
ReadOnlySpan<byte> data = dataWithMac[macLength..];
ReadOnlySpan<byte> mac = dataWithMac[..macLength];
return secureBox.TryDecrypt(message, data, mac, nonce) ? new string(Encoding.UTF8.GetString(message).TrimEnd('\0')) : null;
}