openssl:如何从模数中获取公钥
问题描述：
我使用openssl生成一对密钥:
I generate a pair of keys using openssl:
shell> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/mike/.ssh/id_rsa): /path/to/test_rsa
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /path/to/test_rsa.
Your public key has been saved in /path/to/test_rsa.pub.
然后，我从私钥生成模数:
And then, I generate modulus from private key:
shell> openssl rsa -in /path/to/test_rsa -noout -modulus > /path/to/modulus.txt
现在，有什么方法可以仅从模数中获取test_rsa.pub(公钥)吗?
Now, is there any way to get test_rsa.pub(public key) just from modulus?
答
您可以使用 phpseclib，纯PHP RSA实现.例如.
<?php
include('Crypt/RSA.php');
$modulus = 'yEQs2LxSHBZgZCH0rRQQy9kmry8g2tNhQL1B9f5azNz9Ce9pXPgSRjVUo1B9Ggb/FK3jy41wWd2IfS6rse3vBzRsabMj29CVODM/19yZPmwEmjJHCgYd+AA2qweKZanDp4FLsSw/kyV5WoPN16GHEMLmLGkJFNIWtzzH5jV+S80=';
$exponent = 'AQAB';
$rsa = new Crypt_RSA();
$modulus = new Math_BigInteger(base64_decode($modulus), 256);
$exponent = new Math_BigInteger(base64_decode($exponent), 256);
$rsa->loadKey(array('n' => $modulus, 'e' => $exponent));
$rsa->setPublicKey();
echo $rsa->getPublicKey();