aes Decrypt Hex - Android java.security

Android examples for java.security:AES

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Description

aes Decrypt Hex

Demo Code


import java.security.KeyFactory;
import java.security.MessageDigest;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Locale;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import android.util.Base64;

public class Main{
    // w  w  w. ja  v  a2  s .  c o m
    public static final String HEX_DIGITS = "0123456789ABCDEF";
    /**
     * UTF-8
     */
    public static final String UTF_8 = "UTF-8";
    
    public static String aesDecryptHex(String encryptHexStr, String key)
            throws Exception {
        if (StringUtils.isBlank(encryptHexStr) || StringUtils.isBlank(key)) {
            throw new Exception("illegal params.");
        }
        return new String(aes(Cipher.DECRYPT_MODE,
                hexStringToBytes(encryptHexStr), key.getBytes(UTF_8)));
    }
    
    public static byte[] aes(int opmode, byte[] content, byte[] key)
            throws Exception {
        SecureRandom secureRandom = null;
        secureRandom = SecureRandom.getInstance("SHA1PRNG", "Crypto");
        secureRandom.setSeed(key);
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        kgen.init(128, secureRandom);
        Cipher cipher = Cipher.getInstance("AES/ECB/ZeroBytePadding");
        cipher.init(opmode, new SecretKeySpec(kgen.generateKey()
                .getEncoded(), "AES"));
        return cipher.doFinal(content);
    }
    
    public static byte[] hexStringToBytes(String hexString) {
        if (StringUtils.isBlank(hexString)) {
            return null;
        }
        char[] hexChars = hexString.toUpperCase(Locale.US).toCharArray();
        int length = hexString.length() / 2;
        byte[] bytes = new byte[length];
        for (int i = 0; i < length; ++i) {
            bytes[i] = (byte) (HEX_DIGITS.indexOf(hexChars[i * 2]) << 4 | HEX_DIGITS
                    .indexOf(hexChars[i * 2 + 1]));
        }
        return bytes;
    }
}

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