在使用
给定一个存储在数据库中的
将十六进制字符串转换为
将
secp256k1
曲线进行椭圆曲线加密时,我发现虽然代码和测试案例在Android Studio IDE上编译通过,但在android设备上无法编译,因为该曲线未在移动设备使用的中定义。将曲线更改为prime256v1
后,我似乎在将公钥的十六进制字符串转换为PublicKey
对象时遇到了困难。给定一个存储在数据库中的
PublicKey.getEncoded()
的十六进制字符串,我希望安卓客户端能够将byte[]
从hex
字符串转换为PublicKey
对象。我将使用X509EncodedKeySpec()
来转换byte[]
,如下所示:public static PublicKey getPublicKey(byte[] pk) throws NoSuchAlgorithmException, InvalidKeySpecException {
EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(pk);
KeyFactory kf = KeyFactory.getInstance("EC");
PublicKey pub = kf.generatePublic(publicKeySpec);
return pub;
}
将十六进制字符串转换为
byte[]
的过程如下:public static byte[] hexStringToByteArray(String hexString) {
byte[] bytes = new byte[hexString.length() / 2];
for(int i = 0; i < hexString.length(); i += 2){
String sub = hexString.substring(i, i + 2);
Integer intVal = Integer.parseInt(sub, 16);
bytes[i / 2] = intVal.byteValue();
String hex = "".format("0x%x", bytes[i / 2]);
}
return bytes;
}
将
byte[]
转换为十六进制字符串的方法如下:public static String convertBytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
for ( int j = 0; j < bytes.length; j++ ) {
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars).toLowerCase();
}
但是,当我在Android应用程序(7.0,API 24)上运行此代码时,出现以下系统错误:
W/System.err: java.security.spec.InvalidKeySpecException: java.lang.RuntimeException: error:0c0000b9:ASN.1 encoding routines:OPENSSL_internal:WRONG_TAG
at com.android.org.conscrypt.OpenSSLKey.getPublicKey(OpenSSLKey.java:295)
at com.android.org.conscrypt.OpenSSLECKeyFactory.engineGeneratePublic(OpenSSLECKeyFactory.java:47)
at java.security.KeyFactory.generatePublic(KeyFactory.java:357)
在安卓设备上将十六进制字符串转换为EC实例的PublicKey,推荐使用哪种方法?
下面是可以执行的示例代码:
ECDSA.java
public class ECDSA {
public static KeyPair generateKeyPair() throws NoSuchAlgorithmException, InvalidAlgorithmParameterException {
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("EC");
ECGenParameterSpec ecSpec = new ECGenParameterSpec("prime256v1");
SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
keyGen.initialize(ecSpec, random);
KeyPair pair = keyGen.generateKeyPair();
return pair;
}
public static PublicKey getPublicKey(byte[] pk) throws NoSuchAlgorithmException, InvalidKeySpecException {
EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(pk);
KeyFactory kf = KeyFactory.getInstance("EC");
PublicKey pub = kf.generatePublic(publicKeySpec);
return pub;
}
public static PrivateKey getPrivateKey(byte[] privk) throws NoSuchAlgorithmException, InvalidKeySpecException {
EncodedKeySpec privateKeySpec = new X509EncodedKeySpec(privk);
KeyFactory kf = KeyFactory.getInstance("EC");
PrivateKey privateKey = kf.generatePrivate(privateKeySpec);
return privateKey;
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
KeyPair keyPair = ECDSA.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();
// Converting byte[] to Hex
publicKeyHex = convertBytesToHex(publicKey.getEncoded());
privateKeyHex = convertBytesToHex(privateKey.getEncoded());
// Trying to convert Hex to PublicKey/PrivateKey objects
PublicKey pkReconstructed = ECDSA.getPublicKey(hexStringToByteArray(publicKeyHex));
PrivateKey skReconstructed = ECDSA.getPrivateKey(hexStringToByteArray(privateKeyHex));
// This throws an error when running on an android device
// because there seems to be some library mismatch with
// java.security.* vs conscrypt.OpenSSL.* on android.
}