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Topic: Message digest


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In the News (Sun 17 Dec 17)

  
 Cryptographic hash function - Wikipedia, the free encyclopedia
A message authentication code or MAC takes a message and a secret key and generates a "MAC tag", such that it is difficult for an attacker to generate a valid (message, tag) pair that doesn't match one they've already seen; they are used to prevent attackers forging messages, among other uses.
Determination of whether or not any changes have been made to a message (or a file), for example, can be accomplished by comparing message digests calculated before, and after, transmission (or any other event) (see Tripwire, a system using this property as a defense against malware and malfeasance).
Bits representing the length of the entire message are appended to the message and padded suitably as part of the last block.
en.wikipedia.org /wiki/Message_digest   (1431 words)

  
 MD5: Command Line Message Digest Utility
Message digest algorithms have much in common with techniques used in encryption, but to a different end; verification that data have not been altered since the signature was published.
The most commonly used present-day message digest algorithm is the 128 bit MD5 algorithm, developed by Ron Rivest of the MIT Laboratory for Computer Science and RSA Data Security, Inc.
Message digest algorithms such as MD5 are not deemed "encryption technology" and are not subject to the export controls some governments impose on other data security products.
www.fourmilab.ch /md5   (902 words)

  
 MD5 - Wikipedia, the free encyclopedia
MD5 is one of a series of message digest algorithms designed by Professor Ronald Rivest of MIT (Rivest, 1994).
The input message is broken up into chunks of 512-bit blocks; the message is padded so that its length is divisible by 512.
The processing of a message block consists of four similar stages, termed rounds; each round is composed of 16 similar operations based on a non-linear function F, modular addition, and left rotation.
en.wikipedia.org /wiki/Md5   (1163 words)

  
 [No title]
A signs the message digest and sends it with the message to B. B independently recreates the message digest from the received plaintext message.
Authentication: the message digest is signed with the private key of the sender (A).
Non-Repudiation: the message digest is signed with the private key of the sender.
www.cs.engr.uky.edu /~singhal/CS685-papers/Hash-Funct.ppt   (344 words)

  
 The MD5 Message Digest Algorithm
This page is a summary of the RFC1321 document which describes the MD5 message digest algorithm in detail and also contains a C implemtation of the algorithm.
This means that the message length is 64 bits short of being a multiple of 512.
The message digest produced as output is A, B, C, D. We begin with the low-order byte of A and end with the high-order byte of D.
www.cs.montana.edu /~kimmel/cs400/md5.htm   (489 words)

  
 Glossary   (Site not responding. Last check: 2007-11-06)
A message digest is a function that takes arbitrary-sized input data (referred to as a message) and generates a fixed-size output, called a digest (or hash).
Message digest algorithms are used to produce unique and reliable identifiers of data.
Some digital signature algorithms use a message digest algorithm to compute the hash of the data that is being signed, and then digitally sign the hash value rather than the original data, since digitally signing the original data could be very expensive.
java.sun.com /docs/books/tutorial/security1.2/summary/glossary.html   (2117 words)

  
 Figure 3: How Digital Signatures are Made   (Site not responding. Last check: 2007-11-06)
A message digest is a short summary of a message (or file) that is calculated from the message in a way that, if the message is altered at all, the altered message won't produce the same message digest as the original message.
The receiver has to be able to produce a message digest of the message as it was received, so the digesting algorithm -- a hash function -- must be public.
The calculated and encrypted message digest is the digital signature; it is attached to or stored with the original text, forming the signed text.
www.uic.edu /depts/accc/newsletter/adn26/figure3.html   (261 words)

  
 FIPS 180-1 - Secure Hash Standard
Signing the message digest rather than the message often improves the efficiency of the process because the message digest is usually much smaller in size than the message.
The message digest is used during generation of a signature for the message.
The SHA-1 is also used to compute a message digest for the received version of the message during the process of verifying the signature.
www.itl.nist.gov /fipspubs/fip180-1.htm   (2844 words)

  
 [No title]   (Site not responding. Last check: 2007-11-06)
It accepts a message as input and generates a fixed-length output, which is generally less than the length of the input message.
Then the length of the initial message is transformed to a 64-bit binary-string(if the length is greater than 264, the lower 64-bit is used) and this 64 bits is added to the tail of the message too.
It is indeed the binary representation of the length of the initial message.
www.engr.uconn.edu /~fzhang/docs/crypt.doc   (797 words)

  
 RFC 1321 (rfc1321) - The MD5 Message-Digest Algorithm
That is, the message is extended so that it is just 64 bits shy of being a multiple of 512 bits long.
Padding is performed as follows: a single "1" bit is appended to the message, and then "0" bits are appended so that the length in bits of the padded message becomes congruent to 448, modulo 512.
Output The message digest produced as output is A, B, C, D. That is, we begin with the low-order byte of A, and end with the high-order byte of D. This completes the description of MD5.
www.faqs.org /rfcs/rfc1321.html   (2858 words)

  
 RSA Security - 2.1.6 What is a hash function?
If, given a message x, it is computationally infeasible to find a message y not equal to x such that H(x) = H(y), then H is said to be a weakly collision-free hash function.
The hash value represents concisely the longer message or document from which it was computed; this value is called the message digest.
In this process, a message of arbitrary length is broken into blocks whose length depends on the compression function, and ``padded'' (for security reasons) so the size of the message is a multiple of the block size.
www.rsasecurity.com /rsalabs/node.asp?id=2176   (546 words)

  
 Message Digest   (Site not responding. Last check: 2007-11-06)
The message digest of a text is a sort of a fingerprint for any text.
Computing the message digest is very useful to prevent "man in the middle" attacks.
Because there is only one digest for any given plain text, this can be used to verify the authenticity of the message.
www3.telus.net /Voiculescu/masher   (108 words)

  
 Zvon - RFC 1321 [The MD5 Message-Digest Algorithm] - MD5 Algorithm Description
A 64-bit representation of b (the length of the message before the padding bits were added) is appended to the result of the previous step.
At this point the resulting message (after padding with bits and with b) has a length that is an exact multiple of 512 bits.
The message digest produced as output is A, B, C, D. That is, we begin with the low-order byte of A, and end with the high-order byte of D. This completes the description of MD5.
www.zvon.org /tmRFC/RFC1321/Output/chapter3.html   (755 words)

  
 jGuru: What is a Message Digest?
All the information of the message is used to construct the Message Digest hash, but the message cannot be recovered from the hash.
The size of a Message Digest is always the same, independent of the size or content of the message from which it was created.
The ideal Message Digest algorithm would possibly alter 50% of the bits in the resulting hash if one bit was altered in the plaintext message.
www.jguru.com /faq/view.jsp?EID=4315   (136 words)

  
 Digest:: - Modules that calculate message digests
An important property of the digest algorithms is that the digest is likely to change if the message change in some way.
The $data provided as argument are appended to the message we calculate the digest for.
The $io_handle is read until EOF and the content is appended to the message we calculate the digest for.
www.xav.com /perl/site/lib/Digest.html   (488 words)

  
 Digest(3)
The message is simply a sequence of arbitrary bytes or bits.
An important property of the digest algorithms is that the digest is
Example: use Digest::MD5 qw(md5); $digest = md5($message); There are also versions of the functions with "_hex" or "_base64" appended to the name, which returns the digest in the indicated form.
h30097.www3.hp.com /docs/iass/OSIS_63/MAN/MAN3/0403____.HTM   (788 words)

  
 Zvon - RFC 1319 [The MD2 Message-Digest Algorithm] - MD2 Algorithm Description
The message is "padded" (extended) so that its length (in bytes) is congruent to 0, modulo 16.
Padding is performed as follows: "i" bytes of value "i" are appended to the message so that the length in bytes of the padded message becomes congruent to 0, modulo 16.
At this point the resulting message (after padding with bytes) has a length that is an exact multiple of 16 bytes.
www.zvon.org /tmRFC/RFC1319/Output/chapter3.html   (500 words)

  
 Message Authenticator Algorithm
The Message Authenticator Algorithm is, as far as the author is aware, the first Cryptographic Hash Function or Message Digest to gain widespread acceptance.
If M is the message, the authenticator is a function of K and M. It is calculated by the sender and again by the receiver.
During the process of testing and evaluation of this algorithm, it was found that its use for very long messages results in some reduction of the dependence of the authenticator on the early data in the message.
www.cix.co.uk /~klockstone/maa.htm   (4644 words)

  
 RFC 1320 (rfc1320) - The MD4 Message-Digest Algorithm
Output The message digest produced as output is A, B, C, D. That is, we begin with the low-order byte of A, and end with the high-order byte of D. This completes the description of MD4.
Summary The MD4 message-digest algorithm is simple to implement, and provides a "fingerprint" or message digest of a message of arbitrary length.
It is conjectured that the difficulty of coming up with two messages having the same message digest is on the order of 2^64 operations, and that the difficulty of coming up with any message having a given message digest is on the order of 2^128 operations.
www.faqs.org /rfcs/rfc1320.html   (2739 words)

  
 GoatEye.Com - Message Digest Madness   (Site not responding. Last check: 2007-11-06)
as output a 128-bit "fingerprint" or "message digest" of the input.
message having a given prespecified target message digest.
So created a MD5 dictionary from this file with LDIR, that is i created the Message Digest for each line in that dictionary and now have a huge MD5 dictionary, woot.
www.goateye.com /arch/000023.html   (331 words)

  
 2.2 RSA-MD5 Message Digest Algorithm   (Site not responding. Last check: 2007-11-06)
The RSA-MD5 message digest is computed using the algorithm defined in RFC 1321 [10].
When symmetric key management is employed with this MIC algorithm, the symmetrically encrypted MD5 message digest is represented in the fourth argument of a "Key-Info:" header field as a contiguous string of 32 ASCII hexadecimal digits (corresponding to a 128-bit MD5 message digest).
To avoid any potential ambiguity regarding the ordering of the octets of a MD5 message digest that is input as an RSA data value to the RSA encryption process, the following holds true.
www.freesoft.org /CIE/RFC/1423/5.htm   (259 words)

  
 MD4, Message-Digest Algorithm.   (Site not responding. Last check: 2007-11-06)
The algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input.
It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest.
The MD4 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA.
filibusta.crema.unimi.it /docs/rfc/md4.htm   (150 words)

  
 Message Digest
A Message Digest is used to guarantee data integrity.
Computing Message digest from a piece of plain text is much faster than encrypting that Plaintext with a public key algorithm, so message digest can be used to speed up digital signature algorithms
The Allies could decrypt these messages given time, however by the time they had decrypted them most were obsolete.
ganges.cs.tcd.ie /mepeirce/Dce/99/oldcrypto/Backup_of_MessageDigest.wbk   (902 words)

  
 15.2 md5 -- MD5 message digest algorithm
The size of the resulting digest in bytes.
except the digest is returned as a string of length 32, containing only hexadecimal digits.
This can be used to efficiently compute the digests of strings that share a common initial substring.
www.python.org /doc/current/lib/module-md5.html   (240 words)

  
 How SSL   (Site not responding. Last check: 2007-11-06)
Bob has signed a message generated by Alice, and in doing so he has taken a step that is just about as dangerous as encrypting a random value originated by Alice.
Now when Alice receives Bob's first message, she can examine the certificate, check the signature (as above, using a digest and public key decryption), and then check the subject (that is, Bob's name) and see that it is indeed Bob.
He can garble messages all he wants, but the MAC computations will reveal him for the fraud he is. Alice or Bob can discover the bogus MAC value and stop talking.
www.info.lk /techweb/security/how_ssl.htm   (1488 words)

  
 Digest::MD4 - Perl interface to the RSA Data Security Inc. MD4 Message-Digest Algorithm   (Site not responding. Last check: 2007-11-06)
The final message digest value is returned by the digest operation as a 16-byte binary string.
Note that the digest operation is effectively a destructive, read-once operation.
The hexdigest operation calls digest and returns the result as a printable string of hexdecimal digits.
perlhelp.web.cern.ch /PerlHelp/site/lib/Digest/MD4.html   (698 words)

  
 Cotse - Connected: An Internet Encyclopedia - 2.1 RSA-MD2 Message Digest Algorithm
The RSA-MD2 message digest is computed using the algorithm defined in RFC 1319 [9].
The RSA-MD2 message digest algorithm accepts as input a message of any length and produces as output a 16-octet quantity.
When symmetric key management is employed with this MIC algorithm, the symmetrically encrypted MD2 message digest is represented in a the fourth argument of a "Key-Info:" header field as a contiguous string of 32 ASCII hexadecimal digits (corresponding to a 128-bit MD2 message digest).
www.cotse.com /CIE/RFC/1423/4.htm   (447 words)

  
 [No title]
Append Padding Bytes The message is "padded" (extended) so that its length (in bytes) is congruent to 0, modulo 16.
Initialize MD Buffer A 48-byte buffer X is used to compute the message digest.
Summary The MD2 message-digest algorithm is simple to implement, and provides a "fingerprint" or message digest of a message of arbitrary length.
www.ietf.org /rfc/rfc1319.txt   (1864 words)

  
 search.cpan.org: Digest::MD5 - Perl interface to the MD5 Algorithm
The algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input.
It is useful when you do not want to destroy the digests state, but need an intermediate value of the digest, e.g.
This means that we are no longer limited to have space for the whole message in memory, i.e.
search.cpan.org /~gaas/Digest-MD5-2.33/MD5.pm   (1192 words)

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