Message Digest. HASH algorithms

Please, Why I calculated hash (message digest) of
word "Fausto", used java.security.MessageDigest is
5e064a44ab768f9e0d5a7e0639cc16e7 but used OpenSSL
with this same word "Fausto", result is
0de02ffc6280f4d111680373fa60c0b9????
Someone to say because happen this????
Thanks..
:-)The OpenSSL result is the value you get by taking the MD5 of "Fausto\n". I suspect you are not using the -n option with echo. i.e. you should use
echo -n Fausto | openssl md5

Similar Messages

Message digest algorithm in Archive Link

Good Morning.
We are building interface with the SAP Content Server. We require some help from you on the following items.
Referring to the SAP Content Server HTTP Interface API 4.5/4.6,
The library for checking signatures can be obtained from SAP AG. Because the standard format PKCS#7 was used for the signature, other products can also be used for decoding.
From page 8, can you lets us know where we can get them.
We would also want to know what is the message digest algorithm in Archive Link.

Hi,
SAP content server is using DSS for signing URL parameters. The NIST FIPS-180-3 specification defines which hash functions can be used in DSS. My guess is that it's using SHA1. I doubt that it's using newer version like SHA-256.
Cheers

Message Digest Algorithms

MD2, MD5, SHA-1, SHA-256, SHA-384, SHA-512
Can anyone point me the main (dis)advantages of any of those over the others? I don't want a full spec (the RFC) just if there's some obvious reason not to use one for a simple app. I care about size and performance.
Thanks!

MD2, MD4, MD5 All have output of 16 bytes
SHA1 has an output of 20 bytes
SHA256 has an output of 32 bytes
SHA384 has an output of 48 bytes
SHA512 has an output of 64 bytes
Typically, you would select a hash algorithm based on the amount of output you need. Note that all of the SHA algorithms have about the same security even though their output lengths get longer they are really not any more secure.
MD4 should not be used on ANY new applications. It is proven to be weak. In fact all of the MD algorithms are considered weaker than the SHA algorithm. MD4 is the weakest. MD5 is probably the strongest but it is also the newest meaning it has had less analysis.
If you are writing a new app I would suggest one of the SHA algorithms based on what output size you need. If you use the larger hashes for a signature for example then your privatekey size must be larger to be able to encrypt it. But if you are using the hash to generate key bytes (PKCS#5 PBE key derivation as an example) you may need or want to use one of the larger algorithms to get enough digest data back to create large keysizes.
It all really has to do with what you are trying to accomplish but SHA is considered stronger cryptographically speaking than any of the MD series. Each of the SHA algorithms are relatively speaking the same strenth.

Sha1 hash function (Message Digest)

I am trying to create a program that lists the current java programs in a directory that is run through command line arguments, ( which works) however once i have populated all the java files i need to then turn the file names into sha1 message digests for the next step. I have the relevant code for this to work but i can not get it to compile is there something i have done wrong? or put the code in the wrong place?? here is my code feel free to amend it.
Thanks Mich
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.io.File;
import java.io.FilenameFilter;
import java.util.Scanner;
public class ListDirectories implements FilenameFilter {
static Scanner sc = new Scanner(System.in);
public static void main (String [] args) throws UnsupportedEncodingException, NoSuchAlgorithmException {
String path = args [0];
ListDirectories ff = new ListDirectories();
ff.process(path);
public void process(String dir) {
String objects[] = (new File(dir)).list(this);
for (int i = 0; i < objects.length; i++) {
System.out.println("TRACE:"+objects);
public boolean accept(File dir, String s) {
if (s.endsWith(".java")) {
return true;
return false;
//public void MessageDigest(){
MessageDigest md = MessageDigest.getInstance("SHA");
try {
md.update(objects);
MessageDigest objects = md.clone();
byte[] objectsDigest = objects.digest();
md.update(objects);
} catch (CloneNotSupportedException cnse) {
throw new DigestException("couldn't make digest of partial content");

import java.io.UnsupportedEncodingException;
import java.security.DigestException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.io.File;
import java.io.FilenameFilter;
import java.util.Scanner;
public class ListDirectories implements FilenameFilter {
     static Scanner sc = new Scanner(System.in);
     public static void main (String [] args) throws UnsupportedEncodingException, NoSuchAlgorithmException {
          String path = args [0];
          ListDirectories ff = new ListDirectories();
          ff.process(path);
     public void process(String dir) {
          String objects[] = (new File(dir)).list(this);
          for (int i = 0; i < objects.length; i++) {
               System.out.println("TRACE:"+objects);
     public boolean accept(File dir, String s) {
          if (s.endsWith(".java")) {
               return true;
          return false;
     public void MessageDigest(){
          MessageDigest md = MessageDigest.getInstance("SHA");
          try {
               MessageDigest objects = md.clone();
               md.update(objects);
               byte[] objectsDigest = objects.digest();
               md.update(objects);
          } catch (CloneNotSupportedException cnse) {
               throw new DigestException("couldn't make digest of partial content");
}this where the error occur
MessageDigest objects = md.clone();
md.update(objects);
byte[] objectsDigest = objects.digest();
md.update(objects);
The method update(byte) in the type MessageDigest is not applicable for the argumentsListDirectories.java     line 42     1187874400500     26683
The method update(byte) in the type MessageDigest is not applicable for the arguments ListDirectories.java     line 44     1187874400500     26684
Type mismatch: cannot convert from Object to MessageDigest     Test2     ListDirectories.java     line 41     1187874400500     26682

Verifying a Digital Signature using message digest

Hi, i am new to java.
I have a Digitally signed document, i wanna verify this signed document against the original one.
i got the idea from this link:
http://help.sap.com/saphelp_45b/helpdata/en/8d/517619da7d11d1a5ab0000e835363f/content.htm
i signed a pdf doc with my SmartCard. the third party signing tool passed me the PKCS7 digital signature and i stored it in database. the problem arose when i retrieved this digital signature from DB and verified against the original doc using the message digest method. the base64 result strings are always not equal.
I am sure about this:
-the retrieved digital signature was GOOD.
-the original doc was GOOD.
but why i can't get the same 2 message digests? can somebody please help?
below is part of my code:
while (rsetDs.next())
     InputStream DSName2 = rsetDs.getBinaryStream(1);
     ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
     byte[] myByte = Base64.decode(byteStream.toString());
     ByteArrayInputStream newStream = new ByteArrayInputStream(myByte);
     CertificateFactory cf = CertificateFactory.getInstance("X.509");
     Collection c = cf.generateCertificates(newStream2);
     Iterator i = c.iterator();
     while (i.hasNext())
          Certificate cert = (Certificate)i.next();
          X509Certificate cert1 = (X509Certificate)cert;
          try
               java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
               /*=============DB MD (BEGIN)==================*/
               byte [] pubkeyByte = cert1.getPublicKey().getEncoded();
               md.update(myByte);
               md.update(pubkeyByte);
               byte[] raw = md.digest();
               String db_md = Base64.encode(raw);
               /*============DB MD (end)============*/
               /*=============PDF MD (BEGIN)==================*/
               DataInputStream m_disFile = new DataInputStream(new FileInputStream("C:\\" + "original_doc.pdf"));
               int m_iNum = m_disFile.available();
               byte[] msgBytes = new byte[m_iNum];
               m_iNum = m_disFile.read(msgBytes, 0, m_iNum);
               md.update(msgBytes);
               byte[] digestMd = md.digest();
               md.reset();
               String pdf_md = Base64.encode(digestMd);
               /*=============PDF MD (END)==================*/
..thanks in advance.

PKCS#7 SignedData objects are far more complex then it looks like you are taking them. First the PKCS#7 SignedData object will contain the OID for the message digest algorithm used and for the encryption algorithm used. From the looks of your code you are simply assuming MD5.
It also contains all of the data that was signed which is typically much more than just the document. It also of course contains the public keys and signatures which singed the document. In your case it will probably only have one public certificate and one signature.
Also note that a signature is an encrypted hash. Looking at your code I do not see you use encryption at all or rather for verification decryption.
Here is the basic process a signature takes.
MessageDigest md = MessageDigest.getInstance(algOID);
byte[] digest = md.digest(message.getBytes(charEncoding));
Cipher c = Cipher.getInstance("RSA/2/PKCS1Padding");
c.init(Cipher.ENCRYPT_MODE, priKey);
byte[] signature = c.doFinal(digest);Note that the resulting byte array is not the message digest but the encrypted message digest. You must use the corresponding public key to decrypt the signature to get the message digest value. It is because the trusted public key can decrypt the correct message digest that we know it was encrypted by the holder of the private key. It is because the decrypted message digest value is equal to my computed message digest value that we know the document has not be altered...
Now PKCS#7 SignedData does not take the message digest of the document, in your case your PDF. It creates a message digest on an ASN.1 object which includes the bytes of your document plus a bunch of meta data.
For more info on the exact format of a PKCS#7 signature file check out
http://www.rsasecurity.com/rsalabs/pkcs/pkcs-7/index.html
Look through this doucment for SignedData as a starting place and follow through all of the sub objects that make up a SignedData object. This will give you an idea of what is involved.

OID And Java Hash Algorithm Output Differences?

Hi,
Can anyone tell me why I am not able to recreate the OID ldap password hash algorithm? Or can anyone tell me why I get these subtle differences between my Java created message digest and the one that is read directly from the oracle ldap hint password field? They are both based on the same original word "test".
OID Hint Password from ldap ==> {SHA}zrFqbho8VPUOnVvtyUb4c+RWF+k=
Hash created based on input ==> {SHA}zrFqbho8VPUOP1vtyUb4c+RWF+k=
Here is a little background. I am working on developing a custom forgot password feature for my web site using OID 10g R2 and Java. I am able to retrieve the oracle hint password from OID using Java JNDI as the orcladmin. This ldap password is a SHA message digest, or hash, that is base 64 encoded. Since it is a one way algorithm I can not decrypt. So instead I take the clear text password string provided by the user and create a message digest(SHA) and then encode in base 64 using Java 1.4.2 like so;
MessageDigest md = MessageDigest.getInstance("SHA");
md.update(clearTextPassword.getBytes());
String userSuppliedPassword = new String(md.digest());
BASE64Encoder base64encoder = new BASE64Encoder();
String output = "{SHA}" + base64encoder.encode(userSuppliedPassword.getBytes());
By the way, I have been able to work around this issue by performing the compare using JNDI search but was curious why this was happening. Thanks!

Hi
I am having similar issue. I have to save passwords in encrypted form to LDAP. But not working. I am prepending the encrypted password {SHA} so OID should not convert further.
Any help is appreciated
Thanks

Newbie question about message digests

I understand that a digest is a one-way process, that a message digest is a "fingerprint" of the original message but that there is no way to recover the original (I think Ronald Rivest's document says it is "conjectured to be computationally infeasible" to do so). So far so good.
But I also read this about digest algorithms: "it is virtually impossible to create a message with a predetermined digest." ( http://tinyurl.com/39thq )
What does this mean, given that a particular message will always hash to the same digest?
Thanks for any guidance.
-javahombre

Great, now I see! Thanks!
This sounds especially true now that I see the explanation. For example, I notice that even different case for the "same" string matters: "test" vs. "Test" comes out to different hash.
As for picking completely different strings that hash to the same digest, that seems almost inconceivable.
Thanks again,
javahombre

How to decrypt to get the message digest?

Ok, I'm aware that, message digest, is a one-way hash algorithm. From what I gathered, we can decrypt then use the MessageDigest method, IsEqual to compared the hash value to ensure they are the same right?
But my problem is, right now, I has the code to encrypt and digitally signed on a xml.
But no one has used it before to decrypt. So i need to find out how.
Below is the code to generate the signed XML.
Can anyone tell me how to decrypt it?
Thanks...
    public boolean generateSignXmlDocument(String xmlDocPath, String newDocPath, KeyStore keystore, String alias, String password)
        boolean status = false;
        try
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            dbf.setNamespaceAware(true);
            DocumentBuilder builder = dbf.newDocumentBuilder();
            File f = new File(xmlDocPath);
            Document doc = builder.parse(new FileInputStream(f));
            KeyPair kp = getPrivateKey(keystore, alias, password);
            DOMSignContext dsc = new DOMSignContext(kp.getPrivate(), doc.getDocumentElement());
            String providerName = System.getProperty("jsr105Provider", "org.jcp.xml.dsig.internal.dom.XMLDSigRI");
            log.info("Creating xml sign.....");
            log.debug("Provider Name " + providerName);
            XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM", (Provider)Class.forName(providerName).newInstance());
            javax.xml.crypto.dsig.Reference ref = fac.newReference("", fac.newDigestMethod("http://www.w3.org/2000/09/xmldsig#sha1", null), Collections.singletonList(fac.newTransform("http://www.w3.org/2000/09/xmldsig#enveloped-signature", null)), null, null);
            javax.xml.crypto.dsig.SignedInfo si = fac.newSignedInfo(fac.newCanonicalizationMethod("http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments", null), fac.newSignatureMethod("http://www.w3.org/2000/09/xmldsig#rsa-sha1", null), Collections.singletonList(ref));
            KeyInfoFactory kif = fac.getKeyInfoFactory();
            javax.xml.crypto.dsig.keyinfo.KeyValue kv = kif.newKeyValue(kp.getPublic());
            javax.xml.crypto.dsig.keyinfo.KeyInfo ki = kif.newKeyInfo(Collections.singletonList(kv));
            XMLSignature signature = fac.newXMLSignature(si, ki);
            signature.sign(dsc);
            java.io.OutputStream os = new FileOutputStream(newDocPath);
            TransformerFactory tf = TransformerFactory.newInstance();
            Transformer trans = tf.newTransformer();
            trans.transform(new DOMSource(doc), new StreamResult(os));
            status = true;
        catch(Exception e)
            log.error(e);
        return status;
    }

Kyle Treece wrote:
It says that both IMAP and POP are enabled in my settings.
what settings ? in gmail webmail interface? I'm talking about how your gmail account is configured in Mail on your computer. It's configured for POP. you need to delete it from Mail and then create a new account in Mail and make it IMAP. do not use automated account setup which Mail will offer to do. that will make the account POP again. enter all server info and account type by hand.
see this link for details
http://mail.google.com/support/bin/answer.py?answer=81379
If I turn POP completely off, will it kick all the messages out of my iPhone?
as I said, this is not about turning something on or off in webmail gmail. you have to configure your email client Mail correctly. it will have no effect on your iphone.

Is message digest a strong cryptography

for strong cryptography,security is base on the key rather than algorithm itself.but I use message digest,in main I pass in a plain text(args[0]),like this:
byte[] buf= new byte[args[0].length()];
buf=args[0].getBytes();
MessageDigest algorithm=null;
try {
algorithm = MessageDigest.getInstance("SHA-1");
}catch (NoSuchAlgorithmException e) {
System.out.println(e);
algorithm.reset();
algorithm.update(buf);
byte[] digest1 = algorithm.digest();
the digest1 is the cipher text.but there looks no way to put key
so,is the message digest not a strong cryptography?or can I put key for it?

http://developer.java.sun.com/developer/qow/archive/28/i ndex.html
they use messagedegist to encrypt password,do you
think this is wrong?No, they don't encrypt the password. There is no key involved. SHA-1 is a message digest, a sort of a checksum but no encryption. They just make it unreadable by storing the hash of the password. By the way, the method they use is prone to a dictionary attack.
Encryption is a two-way function. I encrypt a message M by using a key KE with an encryption function E() to produce a cipher text C:
C := E(KE, M)
I can decrypt this by using a decryption function D() with a decryption key KD:
M := D(KD, C)
This way, you can retrieve the original message from the cipher text.
The cipher text C is as long as or longer than the oroginal message M.
However, if you use a digest DS() on a message M you get a hash that has a fixed length:
H := DS(M)
This hash is not reversible! I.e. if you know the hash value H, you can not retrieve the message M. SHA-1 has a length of 20 bytes, regardless of the length of the message M. So, if you put one byte into SHA-1 or 1,000,000 bytes, H always has a length of 20 bytes. You can not retrieve the original bytes from that...
However, if you just want to store passwords in a safe way a hash is a great method for this. You simply don't need to encrypt them if you just want to know wether a user has entered a password that is the same as a stored password.
But using a hash is not enough. You also need a "salt" and an interation count. Look at PKCS#5 (http://www.rsasecurity.com/rsalabs/pkcs/pkcs-5/index.html) at the PBKDF2 chapter (5.2). It has a good introduction in chapters 1 to 4, as well.
Regards,
Frank

SHA-1 Message Digest

Hi All,
I have been given a task to create a SHA-1 (160 bit) Message Digest for a compiled executable. I have the SHA-1 string which contains 40 chars. Can someone shed some light?
Much Appreciated.
KayMan

sabre150 said:
Right, but do you know what you can do with asingle
colliiding block?The only paper I have read on this is
http://eprint.iacr.org/2004/356.pdf and it does not
fill me with dread. Maybe it should! Taken to it's
logical conclusion, any hash is flawed as soon as one
colliding block is known and dangerous once the
algorithm for creating the colliding block is
published..Yes exactly.
For some time now we have known that MD5 is flawed
and we now know that SHA1 is flawed. I expect that in
the next few years sha 256 will be found flawed. Possibly.
As I
understand it, at this time the theory of hashing is
in it's infancy and falls well behind the theory of
encryption and until the theory of hashing is more
advanced I don't expect to get really secure hashes.Yep.
Since I have now retired and only work on a very very
part time basis I don't think it will fall to me to
implement any of the upgrades.Of course; my point was to just to make a note that SHA-1 is seriously broken and should not be used if possible.

Need a 64 bit Message Digest

I need a 64 (or 96) bit message digest function that acts like MD5 or something similar, but instead of spitting out 128 bit digests, it puts out either 64 or 96 bit digests. The problem is thus, we are currently using a piece of a proprietary library to create our pretty-close-to-unique keys, which happen to be 16 byte hexidecimal keys. The company that provides the proprietary library no longer exists, and has been sold to two different companies, therefore we are looking for a replacement. The only requirement is that the key remain 16 bytes, as we have customers that rely on that key.
I've read that MD5 runs a 2^63 chance of collision.. is is possible to take the 128 bit key and simply shave off bits? does that merely increase my chance of collision to 2^47? (for 96 bit key) or 2^31 for a 64 bit key? Or is the distribution less even than that? The messages going in will be around 150 characters btw.
Any Help would be appreciated!

If you are bound by these requirements then the simplest solution is, as
you said, to lop off unecessary bits from the 16/20 byte hash returned
by MD2 or MD5. The probability of collision, all else being equal,
can be computed directly from the number of bits used. For this reason
I would suggest going for the 96 bit base 64 encoding.
Alternately you could XOR the removed bits with the reamining 96 bits
however this should not really increase the randomness if the original
function is doing its job properly. Whether it is worthwhile depends on
the quality of the original hash function.
matfud

What is mean of Message Digest ?

hi
can any one tell
what is mean of Message Digest ?
shrinath

If the OP doesn't know what a message digest is, odds
are they don''t know what a hash value is either.I don't agree, a hash function is a fairly standard IT thingie, where as a Message digest is domain specific (crypto).
But the lack of Google Fu does suggest a lack of IT knowledge. So some helpful links are included above.

Decrypting a Emcrypted Message Digest

Hi,
I have a Encrypted Message Digest which is obtained by hashing the data using SHA1 and then signed the resulted digest with private key. This is done using Entrust API's. Is there any way by which I can decrypt the Encrypted Message Digest using JAVA API's with public key.
can someone give me any idea.
Thanks in advance
Nitin

With what i could i understand,... you have an encrypted MD.(by private key). It could be like this..
MessageDigest md= MessageDigest.getInstance("SHA-1");
md.update("data".getBytes());
byte[] hash= md.digest();
Cipher c = Cipher.getInstance("RSA","BC");
c.init(Cipher.ENCRYPT_MODE,privk);
byte[] encrypted = c.doFinal(hash);
Now u can decrypt using the public key to get the original MD like this:
//initialise the cipher to decrypt mode
c.init(Cipher.DECRYPT_MODE,pubk);
byte[] decrypt= c.doFinal(encrypted);
Thats it !
Vijay

Encrypting a message digest

Hi I'm trying to encrypt a message digest using RSA Encryption. For some reason when the encrypted message digest is decrypted it does not match the original. If this is hard to follow the following code illustrates this point:
String input = "Testing message";
MessageDigest hash = MessageDigest.getInstance("SHA1");
hash.update( input.getBytes() );
generator.initialize(512, random);
KeyPair pair = generator.generateKeyPair();
Key pubKey = pair.getPublic();
Key privKey = pair.getPrivate();
cipher.init(Cipher.ENCRYPT_MODE, privKey); // encrypt
byte[] cipherText = cipher.doFinal( hash.digest() );
// now decrypt
cipher.init(Cipher.DECRYPT_MODE, pubKey);
byte[] plainText = cipher.doFinal(cipherText);Here the byte array plainText does not match the original message digest from hash.digest() Any help on how to correct this problem would be great.
thanks
-B
Edited by: BenWhethers on Dec 13, 2007 12:49 PM
Edited by: BenWhethers on Dec 13, 2007 12:50 PM

You don't provide testable code so I have made a guess as to the missing code and for me the decrypted digest is the same are the original.
        Cipher cipher = Cipher.getInstance("RSA");
        SecureRandom random = new SecureRandom();
        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
        String input = "Testing message";
        MessageDigest hash = MessageDigest.getInstance("SHA1");
        hash.update( input.getBytes() );
        generator.initialize(512, random);
        KeyPair pair = generator.generateKeyPair();
        Key pubKey = pair.getPublic();
        Key privKey = pair.getPrivate();
        cipher.init(Cipher.ENCRYPT_MODE, privKey); // encrypt
        byte[] digest = hash.digest();
        byte[] cipherText = cipher.doFinal( digest );
        // now decrypt
        cipher.init(Cipher.DECRYPT_MODE, pubKey);
        byte[] plainText = cipher.doFinal(cipherText);
        System.out.println(Arrays.equals(plainText,digest ));

Message digest -- BigInteger

Hi,
I am wondering about the encoding of a message digest output bytes (such as from SHA-1). Is it a two's complement or what? I want to convert it to a BigInteger object for further math calculation. Is there any convention or convinient way to do that?
Thanks.
Liang

Technically it is not a integer, but a bit string (read FIPS 180-1 or RFC 3174.)
But you can interpret it as a big integer (as its two's-complement binary), if you want to do so.
If the most significant bit of the SHA-1 hash is 1, the number will be negative, so if you want to use only positive numbers, you can add a 0-byte to interpret the SHA-1 as a positive number always.
Check the Javadoc.
BigInteger(byte[] val)
Translates a byte array containing the two's-complement binary representation of a BigInteger into a BigInteger.
For instance, the SHA-1 of "Hello, world!" is 943A702D 06F34599 AEE1F8DA 8EF9F729 6031D699; if you want to make the BigInteger's constructor interpret it as a positive number, copy the SHA-1 to a 21-byte array, making the first byte 0, as 00943A702D 06F34599 AEE1F8DA 8EF9F729 6031D699.

Message Digest. HASH algorithms

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