如何使用系统authorized_keys
文件中的条目进行java.security.PublicKey
实施?我特别想要将authorized_keys文件中的公钥与Apache SSHD PublickeyAuthenticator
接口中提供的公钥进行比较。
答案 0 :(得分:17)
我很惊讶那里没有什么明显的。我很好奇并实现了一种解码authorized_keys
文件的方法。这取决于用于Base64解码的Apache Commons Codec。
import java.io.File;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.spec.DSAPublicKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.Scanner;
import org.apache.commons.codec.binary.Base64;
public class AuthorizedKeysDecoder {
private byte[] bytes;
private int pos;
public PublicKey decodePublicKey(String keyLine) throws Exception {
bytes = null;
pos = 0;
// look for the Base64 encoded part of the line to decode
// both ssh-rsa and ssh-dss begin with "AAAA" due to the length bytes
for (String part : keyLine.split(" ")) {
if (part.startsWith("AAAA")) {
bytes = Base64.decodeBase64(part);
break;
}
}
if (bytes == null) {
throw new IllegalArgumentException("no Base64 part to decode");
}
String type = decodeType();
if (type.equals("ssh-rsa")) {
BigInteger e = decodeBigInt();
BigInteger m = decodeBigInt();
RSAPublicKeySpec spec = new RSAPublicKeySpec(m, e);
return KeyFactory.getInstance("RSA").generatePublic(spec);
} else if (type.equals("ssh-dss")) {
BigInteger p = decodeBigInt();
BigInteger q = decodeBigInt();
BigInteger g = decodeBigInt();
BigInteger y = decodeBigInt();
DSAPublicKeySpec spec = new DSAPublicKeySpec(y, p, q, g);
return KeyFactory.getInstance("DSA").generatePublic(spec);
} else {
throw new IllegalArgumentException("unknown type " + type);
}
}
private String decodeType() {
int len = decodeInt();
String type = new String(bytes, pos, len);
pos += len;
return type;
}
private int decodeInt() {
return ((bytes[pos++] & 0xFF) << 24) | ((bytes[pos++] & 0xFF) << 16)
| ((bytes[pos++] & 0xFF) << 8) | (bytes[pos++] & 0xFF);
}
private BigInteger decodeBigInt() {
int len = decodeInt();
byte[] bigIntBytes = new byte[len];
System.arraycopy(bytes, pos, bigIntBytes, 0, len);
pos += len;
return new BigInteger(bigIntBytes);
}
public static void main(String[] args) throws Exception {
AuthorizedKeysDecoder decoder = new AuthorizedKeysDecoder();
File file = new File("authorized_keys");
Scanner scanner = new Scanner(file).useDelimiter("\n");
while (scanner.hasNext()) {
System.out.println(decoder.decodePublicKey(scanner.next()));
}
scanner.close();
}
}
答案 1 :(得分:6)
如果您想要反转该过程,即将PublicKey
Java对象编码为Linux authorized_keys
条目格式,可以使用此代码:
/**
* Encode PublicKey (DSA or RSA encoded) to authorized_keys like string
*
* @param publicKey DSA or RSA encoded
* @param user username for output authorized_keys like string
* @return authorized_keys like string
* @throws IOException
*/
public static String encodePublicKey(PublicKey publicKey, String user)
throws IOException {
String publicKeyEncoded;
if(publicKey.getAlgorithm().equals("RSA")){
RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;
ByteArrayOutputStream byteOs = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(byteOs);
dos.writeInt("ssh-rsa".getBytes().length);
dos.write("ssh-rsa".getBytes());
dos.writeInt(rsaPublicKey.getPublicExponent().toByteArray().length);
dos.write(rsaPublicKey.getPublicExponent().toByteArray());
dos.writeInt(rsaPublicKey.getModulus().toByteArray().length);
dos.write(rsaPublicKey.getModulus().toByteArray());
publicKeyEncoded = new String(
Base64.encodeBase64(byteOs.toByteArray()));
return "ssh-rsa " + publicKeyEncoded + " " + user;
}
else if(publicKey.getAlgorithm().equals("DSA")){
DSAPublicKey dsaPublicKey = (DSAPublicKey) publicKey;
DSAParams dsaParams = dsaPublicKey.getParams();
ByteArrayOutputStream byteOs = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(byteOs);
dos.writeInt("ssh-dss".getBytes().length);
dos.write("ssh-dss".getBytes());
dos.writeInt(dsaParams.getP().toByteArray().length);
dos.write(dsaParams.getP().toByteArray());
dos.writeInt(dsaParams.getQ().toByteArray().length);
dos.write(dsaParams.getQ().toByteArray());
dos.writeInt(dsaParams.getG().toByteArray().length);
dos.write(dsaParams.getG().toByteArray());
dos.writeInt(dsaPublicKey.getY().toByteArray().length);
dos.write(dsaPublicKey.getY().toByteArray());
publicKeyEncoded = new String(
Base64.encodeBase64(byteOs.toByteArray()));
return "ssh-dss " + publicKeyEncoded + " " + user;
}
else{
throw new IllegalArgumentException(
"Unknown public key encoding: " + publicKey.getAlgorithm());
}
}
答案 2 :(得分:2)
致WhiteFang34,
您的代码对我来说也很棒,也很有用,但它有一个小错误。 Base64.decodeBase64方法只接收字节数组。所以我这样修好了。
for (String part : keyLine.split(" ")) {
if (part.startsWith("AAAA")) {
byte [] bytePart = part.getBytes();
bytes = Base64.decodeBase64(bytePart);
break;
}
}
无论如何,感谢您编写代码。我希望您将此代码上传到github或其他地方,或者允许我上传到我的github存储库中。
答案 3 :(得分:2)
相同的解决方案,但将decodeInt()委托给DataInputStream。 一旦知道了RSA算法,我就会从原始代码中删除KeyFactory的BouncyCastleProvider。
private static RSAPublicKey readKey(String key) throws Exception {
// key = "ssh-rsa <myBase64key> <email>"
byte[] encKey = Base64.decodeBase64(key.split(" ")[1]);
DataInputStream dis = new DataInputStream(new ByteArrayInputStream(encKey));
byte[] header = readElement(dis);
String pubKeyFormat = new String(header);
if (!pubKeyFormat.equals("ssh-rsa"))
throw new RuntimeException("Unsupported format");
byte[] publicExponent = readElement(dis);
byte[] modulus = readElement(dis);
KeySpec spec = new RSAPublicKeySpec(new BigInteger(modulus), new BigInteger(publicExponent));
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(spec);
return pubKey;
}
private static byte[] readElement(DataInput dis) throws IOException {
int len = dis.readInt();
byte[] buf = new byte[len];
dis.readFully(buf);
return buf;
}