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Java simple class to compute SHA-1 hash

SHA is a cryptographic message digest algorithm similar to MD5. SHA-1 hash considered to be one of the most secure hashing functions, producing a 160-bit digest (40 hex numbers) from any data with a maximum size of 264 bits. While Java has built in classes to compute SHA 1 hash, it's quite uneasy to use them for a simple task -- calculate SHA-1 hash and return 40 byte hexadecimal string.
  • Sun Java 1.4 or higher
  • We use MessageDigest class, first setting it to use SHA-1 algorithm, than feeding it with source data and getting byte array with hash value. To convert this array to hex-string we use our own method convertToHex.

    Here is AeSimpleSHA1 class, which single public static method SHA1 returns hexadecimal string representation for SHA1 hash of input argument:

    source code: Java
    public class AeSimpleSHA1 { 
        private static String convertToHex(byte[] data) { 
            StringBuffer buf = new StringBuffer();
            for (int i = 0; i < data.length; i++) { 
                int halfbyte = (data[i] >>> 4) & 0x0F;
                int two_halfs = 0;
                do { 
                    if ((0 <= halfbyte) && (halfbyte <= 9)) 
                        buf.append((char) ('0' + halfbyte));
                        buf.append((char) ('a' + (halfbyte - 10)));
                    halfbyte = data[i] & 0x0F;
                } while(two_halfs++ < 1);
            return buf.toString();
        public static String SHA1(String text) 
        throws NoSuchAlgorithmException, UnsupportedEncodingException  { 
        MessageDigest md;
        md = MessageDigest.getInstance("SHA-1");
        byte[] sha1hash = new byte[40];
        md.update(text.getBytes("iso-8859-1"), 0, text.length());
        sha1hash = md.digest();
        return convertToHex(sha1hash);

    You may use this class directly calling this method

    source code: Java
    String sha1_ad1 = AeSimpleSHA1.SHA1("Buy new mobile phone! Nokia, Sony-Ericsson, Samsung, LG, ...");                
    String sha1_ad2 = AeSimpleSHA1.SHA1("Buy geek gadgets - iPod, PDA, Notebook");

    One more example, allows user to input string from console and prints SHA1 hash

    source code: Java
    public class Ex01 { 
        public static void main(String[] args) throws IOException { 
            BufferedReader userInput = new BufferedReader (new InputStreamReader(;
            System.out.println("Enter string:");
            String rawString = userInput.readLine();
            try { 
                System.out.println("SHA1 hash of string: " + AeSimpleSHA1.SHA1(rawString));
            } catch (NoSuchAlgorithmException e) { 
                // TODO Auto-generated catch block 
            } catch (UnsupportedEncodingException e) { 
                // TODO Auto-generated catch block 
  • This class is suitable to calculate hash for small chunks of in-memory string data. To process large external files (like ISO images) you should use MessageDigest class directly
  • There may be difficulties while processing string data in encodings other than iso-8859-1.
  • tested 
  • JDK 1.5

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