java-spring-oidc-example/src/main/java/com/onegini/oidc/encryption/JweKeyGenerator.java at master · onewelcome/java-spring-oidc-example · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
package com.onegini.oidc.encryption;

import static com.nimbusds.jose.jwk.Curve.P_256;
import static com.nimbusds.jose.jwk.KeyType.EC;
import static com.nimbusds.jose.jwk.KeyType.RSA;
import static com.nimbusds.jose.jwk.KeyUse.ENCRYPTION;

import java.security.InvalidAlgorithmParameterException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.ECPrivateKey;
import java.security.interfaces.ECPublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.UUID;

import org.springframework.stereotype.Service;

import com.nimbusds.jose.JWEAlgorithm;
import com.nimbusds.jose.jwk.ECKey;
import com.nimbusds.jose.jwk.JWK;
import com.nimbusds.jose.jwk.RSAKey;
import lombok.extern.slf4j.Slf4j;

@Service
@Slf4j
class JweKeyGenerator {

  private static final int RSA_KEY_SIZE = 2048;

  JWK generateKey(final JWEAlgorithm jweAlgorithm) {
    if (JWEAlgorithm.Family.RSA.contains(jweAlgorithm)) {
      return generateRSAKey(jweAlgorithm);
    }
    if (JWEAlgorithm.Family.ECDH_ES.contains(jweAlgorithm)) {
      return generateECKey(jweAlgorithm);
    }
    log.error("Unsupported Algorithm ({})", jweAlgorithm);
    return null;
  }

  private JWK generateRSAKey(final JWEAlgorithm jweAlgorithm) {
    try {
      final KeyPairGenerator gen = KeyPairGenerator.getInstance(RSA.getValue());
      gen.initialize(RSA_KEY_SIZE);
      final KeyPair keyPair = gen.generateKeyPair();

      return new RSAKey.Builder((RSAPublicKey) keyPair.getPublic())
          .privateKey((RSAPrivateKey) keyPair.getPrivate())
          .keyUse(ENCRYPTION)
          .keyID(UUID.randomUUID().toString())
          .algorithm(jweAlgorithm)
          .build();
    } catch (final NoSuchAlgorithmException e) {
      log.error("Generating a RSA key failed.", e);
    }
    return null;
  }

  private JWK generateECKey(final JWEAlgorithm jweAlgorithm) {
    try {
      final KeyPairGenerator gen = KeyPairGenerator.getInstance(EC.getValue());
      gen.initialize(P_256.toECParameterSpec());
      final KeyPair keyPair = gen.generateKeyPair();

      return new ECKey.Builder(P_256, (ECPublicKey) keyPair.getPublic())
          .privateKey((ECPrivateKey) keyPair.getPrivate())
          .keyUse(ENCRYPTION)
          .keyID(UUID.randomUUID().toString())
          .algorithm(jweAlgorithm)
          .build();
    } catch (final NoSuchAlgorithmException | InvalidAlgorithmParameterException e) {
      log.error("Generating a EC key failed.", e);
    }
    return null;
  }
}