by Dinesh Thakur Category: Security

• There are a number of popular message digest algorithms known as MDn for various values of n.

• MD5 is the most popular and is fifth in a series of message digests designed by Ronald Rivest.

• The basic operation of MD5 is shown in fig.

• This algorithm operates on message 512 bits at a time.

• Messages not multiple of 512 bits are padded with:


1. A string consisting of 1 followed by zeroes, and

2. 64-bit integer that indicates the length of original message, to make the length of the composite message multiples of 512 bits.

• The message digest calculation begins with a digest value initialized to a constant.

• This value is combined with the first 512 bits of the message to produce a new value for the digest.

• The new value is than combined with the next 512 bits of the message using the same transformation.

• This process is repeated on each 512-bit block till the final value of digest is obtained from the last block of the message.

• The digest is 128-bit long for any message length.

                      Message Digest 5 (MD5)

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Dinesh ThakurDinesh Thakur holds an B.C.A, MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.