与Glibc的哈希函数

问题描述：

我一直在试图在Swift中加密字符串，但是我希望它能在linux下工作。如下面的代码（从these questions采取的答案是不行的，因为它们依赖无论是在iOS和OSX库：与Glibc的哈希函数

func sha256(data : Data) -> Data { 
    var hash = [UInt8](repeating: 0, count: Int(CC_SHA256_DIGEST_LENGTH)) 
    data.withUnsafeBytes { 
     _ = CC_SHA256($0, CC_LONG(data.count), &hash) 
    } 
    return Data(bytes: hash) 
}

那怎么可以在Linux中使用的Glibc做

答

有在glibc的土窖库，see manpage
您需要包括：。#include <crypt.h>

你必须要使用的功能是：

char *crypt(const char *key, const char *salt);

根据该手册页的SHA-256算法，因为Glibc 2.7集成并经由salt参数被选择：

The glibc2 version of this function supports additional encryption 
algorithms. 

If salt is a character string starting with the characters "$id$" 
followed by a string terminated by "$": 

     $id$salt$encrypted 

then instead of using the DES machine, id identifies the encryption 
method used and this then determines how the rest of the password 
string is interpreted. The following values of id are supported: 

     ID | Method 
     ───────────────────────────────────────────────────────── 
     1 | MD5 
     2a | Blowfish (not in mainline glibc; added in some 
      | Linux distributions) 
     5 | SHA-256 (since glibc 2.7) 
     6 | SHA-512 (since glibc 2.7) 

So $5$salt$encrypted is an SHA-256 encoded password and 
$6$salt$encrypted is an SHA-512 encoded one. 

"salt" stands for the up to 16 characters following "$id$" in the 
salt. The encrypted part of the password string is the actual 
computed password. The size of this string is fixed: 

MD5  | 22 characters 
SHA-256 | 43 characters 
SHA-512 | 86 characters 

The characters in "salt" and "encrypted" are drawn from the set 
[a-zA-Z0-9./]. In the MD5 and SHA implementations the entire key is 
significant (instead of only the first 8 bytes in DES).

在this official GNU page和this wikipedia article是解释和例子：

SHA-256的参数示例salt：
$5$9ks3nNEqv31FX.F$gdEoLFsCRsn/WRN3wxUnzfeZLoooVlzeF4WjLomTRFD

与Glibc的哈希函数

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