Come caricare il certificato pubblico dal file pem ..?

Question

Stavo cercando di estrarre la chiave pubblica RES dal file sotto

-----BEGIN CERTIFICATE----- 
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 
-----END CERTIFICATE----- 

Ecco il codice che ho fatto ..

public static PublicKey loadPublicKeyFromFile(File publicKeyFile) throws Exception { 

    FileReader file = new FileReader(publicKeyFile); 
    PemReader reader = new PemReader(file); 
    X509EncodedKeySpec caKeySpec = new X509EncodedKeySpec(reader.readPemObject().getContent()); 
    KeyFactory kf = KeyFactory.getInstance("RSA"); 
    PublicKey caKey = kf.generatePublic(caKeySpec); 



    return caKey; 
} 

Ma Si tiri fuori

java.security.InvalidKeyException: IOException: ObjectIdentifier() -- data isn't an object ID 

Qual è l'appropriato modo per estrarre RES Public key da un file ..

Answer 1

A n Il certificato X.509 e un X509EncodedKeySpec sono strutture molto diverse e il tentativo di analizzare un certificato come una chiave non funzionerà. Java X509EncodedKeySpec è in realtà SubjectPublicKeyInfo di X.509, che è una piccola parte di un certificato.

Quello che devi fare è leggere e analizzare il certificato e quindi estrarre il tasto pub dal certificato. non so il modo aC per fare questo, ma SunJCE serie CertificateFactory può farlo (e può leggere o PEM o DER per l'avvio) come questo (regolare errore di pulizia e gestione di assaggiare errore):

CertificateFactory fact = CertificateFactory.getInstance("X.509"); 
    FileInputStream is = new FileInputStream (args[0]); 
    X509Certificate cer = (X509Certificate) fact.generateCertificate(is); 
    PublicKey key = cer.getPublicKey();