import java.io.*;
import java.security.*;

public class MessageDigestEncoder {
  static private byte [] loadByteData (String filename) {
    FileInputStream fis = null;
    try {
      fis = new FileInputStream (filename);
      BufferedInputStream bis = new BufferedInputStream (fis);
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      int ch;
      while ((ch = bis.read()) != -1) {
        baos.write (ch);
      }
      return baos.toByteArray();
    } catch (IOException e) {
      if (fis != null) {
        try {
          fis.close();
        } catch (IOException ee) {
          // ignore
        }
      }
      return null;
    }
  }
  static private String hexDigit(byte x) {
    StringBuffer sb = new StringBuffer();
    char c;
    // First nibble
    c = (char) ((x >> 4) & 0xf);
    if (c > 9) {
      c = (char) ((c - 10) + 'a');
    } else {
      c = (char) (c + '0');
    }
    sb.append (c);
    // Second nibble
    c = (char) (x & 0xf);
    if (c > 9) {
      c = (char)((c - 10) + 'a');
    } else {
      c = (char)(c + '0');
    }
    sb.append (c);
    return sb.toString();
  }
  static private String computeDigest (MessageDigest algorithm, String filename) {
    byte[] content = loadByteData (filename);
    if (content != null) {
      algorithm.reset();
      algorithm.update (content);
      byte digest[] = algorithm.digest();
      StringBuffer hexString = new StringBuffer();
      int digestLength = digest.length;
      for (int i=0;i<digestLength;i++) {
        hexString.append (hexDigit(digest[i]));
        hexString.append (" ");
      }
      return hexString.toString();
    } else {
      return "";
    }
  }
  public static void main (String args[]) {
    MessageDigest algorithm = null;
    if (args.length < 2) {
      System.err.println ("java MessageDigestEncoder SHA-1|MD5 filename(s)");
      System.exit (-1);
    }
    try {
      algorithm = MessageDigest.getInstance (args[0]);
    } catch (NoSuchAlgorithmException e) {
      System.err.println ("Invalid algorithm");
      System.err.println ("java MessageDigestEncoder SHA-1|MD5 filename(s)");
      System.exit (-2);
    }
    int argsLength = args.length;
    for (int i=1;i<argsLength;i++) {
      String digest = computeDigest (algorithm, args[i]);
      System.out.println ("filename: " + args[i]);
      System.out.println (digest);
      System.out.println();
    }
  }
}