字符串到PrivateKey Ed25519

Question

我有一个私钥作为字符串，我想把它转换成PrivateKey

String privateKey = "Y2E3YjYwYzRjMDRjMjk1ZDQ5ZTQzM2RlMTdjZjVkNGE0NGFjYzJmM2IzOWExNWZhMjViNGE4ZWJiZDBiMDVkYTIwNGU4MWE3ZWZmMTQ0NGE2ZmM2NjExNzRmNTY4M2I0YmYyMTk5YTkyY2UzOWRkZjdmMzhkNTFjYTNmM2Q3ZDU";

byte[] pkcs8EncodedBytes = Base64.getDecoder().decode(privateKey);

PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(pkcs8EncodedBytes);

PrivateKey pkey = KeyFactory.getInstance("Ed25519") //NoSuchAlgorithmException
                            .generatePrivate(keySpec);

但我知道这个错误：

java.security.NoSuchAlgorithmException: Ed25519 KeyFactory not available

在KeyFactory.getInstance("Ed25519")

我在用Java-10

Answer 1

发布的密钥是双重编码的，首先是十六进制，然后是Base64。请注意，不需要双重编码。如果密钥是Base64和十六进制解码，结果是一个64字节键。

从这64个字节键中，前32个字节是秘密密钥，接下来的32个字节是公钥。有关此格式的更多详细信息，请参阅这里。

使用BouncyCastle导入、签名和验证是可以使用Ed25519PrivateKeyParameters、Ed25519PublicKeyParameters和Ed25519Signer类的：

import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import org.bouncycastle.crypto.Signer;
import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters;
import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters;
import org.bouncycastle.crypto.signers.Ed25519Signer;
import org.bouncycastle.util.encoders.Hex;

// Base64, hex decode
String keyHexBase64 ="Y2E3YjYwYzRjMDRjMjk1ZDQ5ZTQzM2RlMTdjZjVkNGE0NGFjYzJmM2IzOWExNWZhMjViNGE4ZWJiZDBiMDVkYTIwNGU4MWE3ZWZmMTQ0NGE2ZmM2NjExNzRmNTY4M2I0YmYyMTk5YTkyY2UzOWRkZjdmMzhkNTFjYTNmM2Q3ZDU";
byte[] key = Hex.decode(new String(Base64.getDecoder().decode(keyHexBase64), StandardCharsets.UTF_8));

// Separate secret and public key
ByteBuffer keyBuffer = ByteBuffer.wrap(key);
byte[] secretKey = new byte[32];
keyBuffer.get(secretKey);
byte[] publicKey = new byte[keyBuffer.remaining()];
keyBuffer.get(publicKey);

// Signing
byte[] message = "The quick brown fox jumps over the lazy dog".getBytes(StandardCharsets.UTF_8);
Ed25519PrivateKeyParameters secretKeyParameters = new Ed25519PrivateKeyParameters(secretKey, 0);
Signer signer = new Ed25519Signer();
signer.init(true, secretKeyParameters);
signer.update(message, 0, message.length);
byte[] signature = signer.generateSignature();
System.out.println("Signature (hex): " + Hex.toHexString(signature));

// Verification
Ed25519PublicKeyParameters publicKeyParameters = new Ed25519PublicKeyParameters(publicKey, 0);
Signer verifier = new Ed25519Signer();
verifier.init(false, publicKeyParameters);
verifier.update(message, 0, message.length);
boolean verified = verifier.verifySignature(signature); // Signature (hex): 2aa31bb14799a00ac1129bdd6773a8481f0fd7e829d59f6fccc81021bf21e397dc5d17362d342615a5500598542586cad8891f984bdb90ec0c80b48eb638df07
System.out.println("Verification: " + verified); // Verification: true

对于BouncyCastle，需要bcprov-jdk15on，它可以从Maven储存库或BouncyCastle网站加载。