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DigestUtil.javaAPI DocApache James 2.3.15991Fri Jan 12 12:56:26 GMT 2007org.apache.james.security

DigestUtil

public class DigestUtil extends Object
Computes and verifies digests of files and strings
version
$Revision: 494012 $

Fields Summary
Constructors Summary
private DigestUtil()
Private constructor to prevent instantiation of the class

Methods Summary
public static voiddigestFile(java.lang.String filename, java.lang.String algorithm)
Calculate digest of given file with given algorithm.
Writes digest to file named filename.algorithm .
param
filename the String name of the file to be hashed
param
algorithm the algorithm to be used to compute the digest
        byte[] b = new byte[65536];
        int count = 0;
        int read = 0;
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
            MessageDigest md = MessageDigest.getInstance(algorithm);
            fis = new FileInputStream(filename);
            while (fis.available() > 0) {
                read =  fis.read(b);
                md.update(b, 0, read);
                count += read;
            }
            byte[] digest = md.digest();
            StringBuffer fileNameBuffer =
                new StringBuffer(128)
                        .append(filename)
                        .append(".")
                        .append(algorithm);
            fos = new FileOutputStream(fileNameBuffer.toString());
            OutputStream encodedStream = MimeUtility.encode(fos, "base64");
            encodedStream.write(digest);
            fos.flush();
        } catch (Exception e) {
            System.out.println("Error computing Digest: " + e);
        } finally {
            try {
                fis.close();
                fos.close();
            } catch (Exception ignored) {}
        }
    
public static java.lang.StringdigestString(java.lang.String pass, java.lang.String algorithm)
Calculate digest of given String using given algorithm.
Encode digest in MIME-like base64.
param
pass the String to be hashed
param
algorithm the algorithm to be used
return
String Base-64 encoding of digest
throws
NoSuchAlgorithmException if the algorithm passed in cannot be found

        MessageDigest md;
        ByteArrayOutputStream bos;

        try {
            md = MessageDigest.getInstance(algorithm);
            byte[] digest = md.digest(pass.getBytes("iso-8859-1"));
            bos = new ByteArrayOutputStream();
            OutputStream encodedStream = MimeUtility.encode(bos, "base64");
            encodedStream.write(digest);
            return bos.toString("iso-8859-1");
        } catch (IOException ioe) {
            throw new RuntimeException("Fatal error: " + ioe);
        } catch (MessagingException me) {
            throw new RuntimeException("Fatal error: " + me);
        }
    
public static voidmain(java.lang.String[] args)
Command line interface. Use -help for arguments.
param
args the arguments passed in on the command line

        String alg = "SHA";
        boolean file = false;
    
        if (args.length == 0 || args.length > 4) {
            printUsage();
            return;
        }
    
        for (int i = 0; i < args.length; i++) {
            String currArg = args[i].toLowerCase(Locale.US);
            if (currArg.equals("-help")
                || currArg.equals("-usage")) {
                printUsage();
                return;
            }
            if (currArg.equals("-alg")) {
                alg = args[i+1];
            }
            if (currArg.equals("-file")) {
                file = true;
            }
        }
    
        if (file) {
            digestFile(args[args.length - 1], alg);
            return ;
        } else {
            try {
                String hash = digestString(args[args.length - 1], alg);
                System.out.println("Hash is: " + hash);
                return;
            } catch (NoSuchAlgorithmException nsae) {
                System.out.println("No such algorithm available");
            }
        }
    
public static voidprintUsage()
Print the command line usage string.
        System.out.println("Usage: " 
                           + "java org.apache.james.security.DigestUtil"
                           + " [-alg algorithm]"
                           + " [-file] filename|string");