What is MD5 Algorithm?

The use of codes to secure information and communications in such a way that only the intended recipients can decipher and process them is known as cryptography. Hence, information access by unauthorized parties is prevented. "Cryptography" is the combination of the words "crypt" (which means "hidden") and "graphy" (which means "writing"). The methods used in cryptography to safeguard data are derived from mathematical ideas and a set of rule-based computations known as algorithms to transform communications in ways that make them difficult to decipher. These algorithms are employed in the creation of cryptographic keys, digital signatures, data privacy protection, online browsing on the internet, and the security of private transactions like debit and credit card purchases.

Techniques for Cryptography: In the era of computers, cryptography is frequently connected with the transformation of plain text into cipher text, which is text that can only be decoded by the intended recipient. This process is known as encryption. Decryption is the process of converting encrypted text into plain text.

The following list of cryptographic features:

Information may only be viewed by the intended recipient and no one else. This is known as confidentiality. Information cannot be changed while being stored or sent between a sender and the intended recipient without the addition of new information being noticed. Non-repudiation: The information creator/sender is unable to subsequently retract his desire to disseminate information. Authentication: The sender's and receiver's identities are verified. Additionally, the information's origin and destination are verified.

MD5 Algorithm

The MD5 message-digest technique, which produces a hash value of 128 bits, is a frequently used hash function. Ronald Rivest created MD5 in 1991 to replace the older hash function MD4, and it was defined in RFC 1321 in 1992.

As a checksum, MD5 may be used to ensure data integrity and protect it from accidental damage. It has been discovered that this historically used cryptographic hash algorithm has several serious flaws. It continues to be useful for various non-cryptographic tasks, such as locating the partition for a certain key in a partitioned database, and could even be favored because it requires less CPU power than more contemporary Secure Hash Algorithms.

Professor Ronald Rivest of MIT created a number of message digest algorithms, including MD5 (Rivest, 1992). Rivest created MD5 in 1991 as a secure substitute for MD4 after analytical research suggested that MD4 was probably unsafe. (Hans Dobbertin did in fact discover MD4's flaws later.)

Den Boer and Bosselaers provided an early, albeit constrained, conclusion in 1993 by identifying a "pseudo-collision" of the MD5 compression function, or two initialization vectors that yield the same digest.

The MD5 compression function collided in 1996, according to Dobbertin (Dobbertin, 1996). Although this attack did not target the whole MD5 hash algorithm, it was near enough for cryptographers to advise switching to an alternative like SHA-1 (which was also compromised). The hash value's (128 bits) size is short enough to allow for the possibility of a birthday attack. A distributed effort called MD5CRK was launched in March 2004 with the goal of showing how practically vulnerable MD5 is by locating a collision using a birthday attack.

MD5 algorithm uses:

• For file authentication, it is employed.
• It is utilized for security in online applications. For instance, secure user passwords, etc.
• We can save our password in 128-bit format using this approach.

The MD5 algorithm goes through the following steps to operations:

1. Add Padding Bits: In the first stage, padding bits are added to the original message so that the overall message length is 64 bits shorter than the precise multiple of 512. Consider receiving a message with 1000 bits. We now need to modify the original message by adding padding bits. Here, we shall pad the original message with 472 bits. The original message/output of the first step will be 1472 after the padding bits have been added, which is 64 bits less than an exact multiple of 512 (i.e., 512*3 = 1536).

Length(original message + padding bits) = 512 * i - 64 where i = 1,2,3 . . .

2. Add Length Bits: In this step, we add the length bit to the output from the previous step in order to increase the number of bits to a perfect multiple of 512. We only add the 64-bit length bit in this case to the result of the first step. i.e., the output of the first step is equal to 512 * n - 64 length bits.

We shall have 512 * n, which is an exact multiple of 512, after adding the two.

3. Initialize the MD buffer: Here, we employ the J, K, L, and M buffers. Each buffer has a 32-bit size.

4. Method The most crucial phase of the MD5 algorithm is each 512-bit block. In this case, 4 rounds and a total of 64 operations are carried out. There will be 16 operations conducted in the first round, 16 operations in the second round, 16 operations in the third round, and 16 operations in the fourth round. For example, we apply the F function for the first round, the G function for the second, the H function for the third, and the i function for the fourth. For computing functions, we use logic gates such as OR, AND, XOR, and NOT. We employ three buffers-K, L, and M-for each function.

- F(K,L,M) = (K AND L) OR (NOT K AND M)

- G(K,L,M) = (K AND L) OR (L AND NOT M)

- H(K,L,M) = K XOR L XOR M

- I(K,L,M) = L XOR (K OR NOT M)

Now that the function has been applied, we are going to do something with each block. To conduct activities, we need

5. Now take input as initialize MD buffer i.e. J, K, L, M. Output of K will be fed in L, L will be fed into M, and M will be fed into J. After doing this now we perform some operations to find the output for J.

The outcome of step J will be put into step K after all stages. The same procedures will now be followed for all G, H, and I functions. We shall obtain our message digest once all 64 operations have been completed.

OUTPUT:

After all, rounds have been performed, the buffer J, K, L, and M contains the MD5 output starting with the lower bit J and ending with Higher bits M.

OUTPUT:

```Hash of the input string:
922547e866c89b8f677312df0ccec8ee
```

Application of the MD5 Algorithm

• To authenticate and check the integrity of files, we employ message digests.
• For data security and encryption, MD5 was utilised.
• It is employed for both password verification and message digestion, regardless of message size.
• For the graphics and game boards.

Benefits of the MD5 Algorithm

• Faster and easier to comprehend is MD5.
• A 16-byte strong password is generated by the MD5 algorithm. To safeguard user passwords, all developers, including web developers, employ the MD5 algorithm.
• The MD5 method requires a relatively little amount of memory to be integrated.
• Generating a digest message from the original message is simple and quick.

Drawback of the MD5 algorithm

• For various inputs, MD5 generates the same hash function.
• Compared to SHA1, MD5 offers inferior security.
• The algorithm MD5 has been criticized for being unsafe. Therefore, we are currently switching from MD5 to SHA256.
• The algorithm MD5 is neither symmetric nor asymmetric.

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