Public 来自 java 私钥的密钥不正确

Question

我只有一个私钥，我需要在 java 中从中计算出 public 密钥。根据这个答案 Get public key from private in Java 我想出了以下代码：

String pemString = "full private key string here";
pemString = pemString.replace("-----BEGIN RSA PRIVATE KEY-----\n", "");
pemString = pemString.replace("-----END RSA PRIVATE KEY-----", "");
pemString = pemString.replace("\n", ""); //without this exception: Illegal base64 character a
logger.info(pemString);

byte[] decoded = Base64.getDecoder().decode(pemString);
KeyFactory kf = KeyFactory.getInstance("RSA");

PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decoded);
PrivateKey privatekey = kf.generatePrivate(keySpec);
RSAPrivateCrtKey privk = (RSAPrivateCrtKey)privatekey;

RSAPublicKeySpec publicKeySpec = new RSAPublicKeySpec(privk.getModulus(), privk.getPublicExponent());
PublicKey pubKey = kf.generatePublic(publicKeySpec);
String pubString = Base64.getEncoder().encodeToString(pubKey.getEncoded());

logger.info(pubString);

但是，如果我将代码的输出与 EC2 存储在 .ssh/authorized 键中的 public 键进行比较，结果就不一样了。我做错了什么？

我要实现ssh-keygen -y

Answer 1

您生成的密钥在 X.509 format. While the key in .ssh/authorized_keys2 is in SSH format 中。您可以使用 ssh-keygen 实用程序进行转换：

ssh-keygen -i -m PEM -f key.pem > ssh.pub

Public 来自 java 私钥的密钥不正确

Public key from private key in java is incorrect

java

cryptography

private-key

public-key

ssh-keygen