tags: `.Net` `筆記`
# Bcrypt
> BCrypt.Net
> LINQPad8

Bcrypt 能夠對字串做雜湊加密，同一個字串也能夠雜湊出不同的內容防範駭客的入侵

## Bcrypt.Net

在 .Net 的話下面就以 [Bcrypt.Net](https://github.com/BcryptNet/bcrypt.net) 做一些例子

簡單的 hash 跟 Verify 如下

void Main()
{
    string password = "HelloWorld";
    string passwordhash = BCrypt.Net.BCrypt.HashPassword(password);
    passwordhash.Dump();
    BCrypt.Net.BCrypt.Verify(password, passwordhash).Dump();
}


在預設情況下，已經把 Salt 加入。但也可以選擇多一些客製化增加複雜度

void Main()
{
    string password = "HelloWorld";
    var salt = BCrypt.Net.BCrypt.GenerateSalt();
    string passwordhash = BCrypt.Net.BCrypt.HashPassword(password, salt);
    
    // or
    // intWorker 會影響加密的速度，依不同的情境斟酌使用
    // (用到 31 可能會跑不出結果...XD)
    var salt = BCrypt.Net.BCrypt.GenerateSalt(15, 'a');
    string passwordhash = BCrypt.Net.BCrypt.HashPassword(password, salt);
}

下面增加幾個例子來測試，同一個字串經過兩次不同的 salt 及驗證

void Main()
{
    string password = "HelloWorld";
    var salt = BCrypt.Net.BCrypt.GenerateSalt();
    string passwordhash = BCrypt.Net.BCrypt.HashPassword(password, salt);
	
    var salt2 = BCrypt.Net.BCrypt.GenerateSalt();
    string passwordhash2 = BCrypt.Net.BCrypt.HashPassword(password, salt2);
	
    passwordhash.Dump();
    passwordhash2.Dump();
	
    BCrypt.Net.BCrypt.Verify(password, passwordhash).Dump();
    BCrypt.Net.BCrypt.Verify(password, passwordhash2).Dump();
}


### Enhanced Entropy
Bcrypt.Net 提供了以下幾個增強型的方法
* EnhancedHashPassword
* EnhancedVerify

void Main()
{
    string password = "HelloWorld";
    string passwordhash = BCrypt.Net.BCrypt.EnhancedHashPassword(password);

    passwordhash.Dump();
	
    BCrypt.Net.BCrypt.Verify(password, passwordhash).Dump();
    // 記得已經使用 EnhancedHashPassword
    // 要同一併使用 EnhancedVerify
    BCrypt.Net.BCrypt.EnhancedVerify(password, passwordhash).Dump();
}