How to Load RSA Private Key From File
Two things. First, you must base64 decode the mykey.pem
file yourself. Second, the openssl private key format is specified in PKCS#1 as the RSAPrivateKey
ASN.1 structure. It is not compatible with java's PKCS8EncodedKeySpec
, which is based on the SubjectPublicKeyInfo
ASN.1 structure. If you are willing to use the bouncycastle library you can use a few classes in the bouncycastle provider and bouncycastle PKIX libraries to make quick work of this.
import java.io.BufferedReader;
import java.io.FileReader;
import java.security.KeyPair;
import java.security.Security;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
// ...
String keyPath = "mykey.pem";
BufferedReader br = new BufferedReader(new FileReader(keyPath));
Security.addProvider(new BouncyCastleProvider());
PEMParser pp = new PEMParser(br);
PEMKeyPair pemKeyPair = (PEMKeyPair) pp.readObject();
KeyPair kp = new JcaPEMKeyConverter().getKeyPair(pemKeyPair);
pp.close();
samlResponse.sign(Signature.getInstance("SHA1withRSA").toString(), kp.getPrivate(), certs);
You need to convert your private key to PKCS8 format using following command:
openssl pkcs8 -topk8 -inform PEM -outform DER -in private_key_file -nocrypt > pkcs8_key
After this your java program can read it.