前回の記事で暗号化したパスワードを復号化するサンプルです。
入力パスワードは16進数化されています。
private String decrypt(String passwd) throws Exception {
//16進数から戻す
byte[] cipherPass = toBytes(passwd);
//ソルト
byte[] salt = {(byte)0xc7, (byte)0x73, (byte)0x21, (byte)0x8c,
(byte)0x7e, (byte)0xc8, (byte)0xee, (byte)0x99
};
// 繰り返し
int num = 128;
PBEParameterSpec pbeParam = new PBEParameterSpec(salt, num);
char[] pass = "passwordkey".toCharArray();
PBEKeySpec pbeKey = new PBEKeySpec(pass);
SecretKeyFactory secKeys = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey secKey = secKeys.generateSecret(pbeKey);
Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
cipher.init(Cipher.DECRYPT_MODE, secKey, pbeParam);
//複号化
byte[] bytepass = cipher.doFinal(cipherPass);
String decpass = new String(bytepass);
return decpass;
}
private static byte[] toBytes(String hexString) throws NumberFormatException
{
if(hexString.length()%2==1){
hexString = '0' + hexString;
}
byte[] bytes = new byte[hexString.length()/2];
for (int i = bytes.length-1; i >= 0; i--) {
String b = hexString.substring(i*2,i*2+2);
bytes[i] = (byte)Integer.parseInt(b, 16);
}
return bytes;
}
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