Both hexadecimal and Base64 functions are used routinely to encode and decode – often called MD5 encryption and MD5 decryption – the content of the Message Digest (MD). MD5 was the fifth iteration of the concept, hence the suffix number. It replaced MD4 which was shown to have some functional vulnerabilities and MD5 algorithm was subsequently replaced with the SHA-series of hashing algorithms for similar reasons. Try our sha1 converter.

Decoding an MD5 hash without knowing the original value of the encoded string is not totally accurate, there are some values that may have a higher degree of certainty because they may form recognizable elements, such as existing words, using a dictionary approach to look-up the hash and compare with known-existing values. Some MD5 reverse look-up databases contain millions of hashes and their corresponding decoded values. This is generally considered the easiest method as it can be executed in mere fractions of a second. A second method uses a more brute-force approach by using tables – commonly known as “rainbow tables” – to analyze the encoded MD5 elements. Neither approach has 100% certainty of successful decoding, however, the possibility that it might has caused MD5 to be identified as technically insecure by National Security Agency (NSA) standards.

The MD5 reverse lookup database I use is located here: http://md5-decrypter.com/

The primary uses of the MD5 hash are for data integrity checks and generating MD5 checksums to ensure that data, such as a program or passwords, have the same content as the original. MD5 secure applications were stress-tested and found to have flaws known as “collisions,” where identical hash contents can be generated which do not have the original content. Several methodologies were employed in the attempt to salvage security, including the introduction of a “seed” – known as an MD5 salt – or multiple-pass encryption. Neither method provides sufficient protection from the feasibility of discovery.

To calculate an MD5 hash is a relatively simple process. There are a number of algorithms for various computer languages and scripts available online, either as source or an online MD5 hash calculator. Tools exist to calculate feasible content from an MD5 string or to generate an MD5 hash from a plain-text string. Most use the correct padding characters appended to a string, however, there are some scripts that may require some tweaking to be fully-compliant with accepted standards.

One of the more elegant examples of well-documented code in javascript: JavaScript implementation of the RSA Data Security

This is an example of an MD5 construct:
Plain-text data: This is a test
MD5 encrypted representation: ce114e4501d2f4e2dcea3e17b546f339
Try encoding this with our online md5 encoder

Unless this specific MD5 representation exists in an MD5 database, it is nearly impossible to derive with certainty the original plain-text data. For example, one of the most popular and insecure passwords is “secret”. The MD5 representation of “secret” is:

5ebe2294ecd0e0f08eab7690d2a6ee69

Using a commonly available MD5 reverse look-up database, it is easy to find this particular password. This is one of the more compelling reasons to have strong passwords with mixed case and embedded numeric or symbols unlikely to be guessed by a casual search.

MD5 is still in use today by many commercial businesses, however, it is with the full knowledge that it is not completely secure and there are better alternatives available. MD5 has been deprecated for US Government use and replaced by the NSA-approved SHA2 algorithms for protection of sensitive unclassified information – for example, documents with Social Security Numbers present. However, even SHA2 can be cracked and the next iteration SHA3 is currently under development.

Convert Decimal to Binary

Try our Decimal to Binary Converter
As an example, the decimal number 153 is odd.

• The rightmost binary digit – known as the Least Significant Digit or LSD – would be a “1”. If the number had been even, as 152, the LSD would be a “0”. As we record “1″ for the LSD, we now have to divide 152 (153-1)
• Divide the remainder (152) by 2. If the result is even, record a “0” to the left of the LSD. It is in this example, leaving 76, and the binary string is now “01”.
• 76 is evenly divided by 2, leaving 38, so record a “0”, the resulting binary string now being “001”.
• Divide again, resulting in an odd number, 19. Record a 1, subtract the 1 from 19 and result is now “1001.”
• Divide 18 by 2, resulting in 9. Again, it’s odd, record a 1, subtract the 1 from 9, leaving 8, the binary string is now “11001”.
• The number 8 is evenly divisible, record a 0, resulting string is now “011001″
• Divide 4 by 2, leaving 2, which is also even. Resulting string is now “0011001”.
• Divide the 2 by 2, resulting in 1. Record this as the last and Most Significant Digit. The final result is the binary string “10011001” which is the representation of the decimal number 153.

Convert Binary to Decimal

Try our Binary to Decimal converter
Conversion of binary to decimal values is equally simple.

• Start at the least significant (rightmost) digit 10011001 is odd, record a 1.
• The next leftmost bit is the number of 2s, which is none.
• The next is the number of 4s. Again, none.
• The next leftmost is the number of 8s. There is one, so record an 8.
• The next left bit is also a 1, which the number 16s. We now have recorded 1+8+16 so far.
• The next bit is the number of 32s, none.
• The next is the number of 64s, again none.
• The last, most significant digit is the number of 128s. We have 1, record that.
• Now add the decimal numbers together 1+8+16+128, resulting in the decimal number 153.

These methods are just two of several ways to accomplish the conversion. There are tables and charts which can assist in binary to decimal conversion online, as well as the opposite decimal to binary conversion. The two methods given above have the advantage of being easily done in your head without a tool, since the processes are simple addition and easy division by twos.

Sometimes, videos make it easier to understand things. Here’s a video that explains how to convert hexadecimal to binary and how to convert binary to hexadecimal.

Enjoy!

• Html Encode
• Html Decode

Use the html encoder tool to encode any html characters into html entities.
Use the html decoder tool to decode any html encoded entities into html characters.
Hope these will be useful
Don’t forget, I add string functions on a weekly basis, so come back to check new string functions
David

The first step is to understand counting in different systems. Our usual denary system uses the digits 0 – 9. Once you reach “9” you start with 10, 11, etc back to 19. Then you move on to the 20s. Binary and hexadecimal numbering systems use the same procedure, with different digits. Binary uses only the numbers 0 and 1. Usually, these are written with four digits, so 0 in denary is 0000 in binary.

The hexadecimal numbering systems uses the number 0 – 9 and A – F. They are represented by 2 numbers or letters: 00 – FF. The letter “A” is number 10, “B” is 11, and “F” is 15. Counting in hexadecimal looks like this: 00, 01, … 09, 0A, 0B, … 0F, 10, 11, … 1A, 1B, … 1F, 20, etc.

Use this tool to convert decimal to hexadecimal. Try also the opposite tool to convert hex to decimal
Converting between binary and hexadecimal is fairly easy. A single hexadecimal number requires four binary numbers. So the binary number 0000 = hexadecimal 0, binary 0100 is hexadecimal 4, and binary 1010 is hexadecimal A.

In computer programming, you also need a way to incorporate letters. ASCII stands for American Standard Code for Information Interchange, and is based on the English alphabet. ASCII string are converted to binary or hexadecimal values, allowing words and letters to be used by computers.

The values needed to convert ASCII string to binary or hexadecimal are contained in tables. However, if you don’t have access to a table, you can manually convert ASCII to hex or binary by memorizing a few rules and applying basic counting rules. The numbers 0 – 9 begin with binary number 0011 0000, and hexadecimal number 30. Now, if you just remember the hexadecimal value (which is just 2 characters) you can convert to binary. The hexadecimal value “3” is 0011 binary, and “0” is 0000. Now you can count up through the ASCII number 9.

The capital letters A – Z begin with hexadecimal 41 and the small letters a – z begin with hexadecimal 61 and binary number 0110 0001. One more important character – a space – is hexadecimal 20 and binary 0010 0000.

Finally, here is an example with the manual conversions. To convert a string to hexadecimal, let’s take “Hi mom”, start with the “H”. “A” begins with hexadecimal value of 41, “B” is 42, …”G” is 47, and “H” is 48. Next is the letter “i”. “a” is hexadecimal 61, “b” is 62, … “h” is 68, and “i” is 69. So your first part is 48 69. Now insert the space, and the rest of the letters. Final answer: 48 69 20 6D 6F 6D

If you remember how to count, a few ASCII conversion to hex values, and a little practice, manual conversions are pretty easy.

Hexadecimal Evolution

Hexadecimal is the logical evolution from octal. Those same numbers shown in octal above would be 15C0 for 012700; FF06 for 177406; and 15C8 for 012710. This was far more convenient to enter from a keypad similar to a telephone keypad than either binary or octal. Today, octal is used in code to build masks, but rarely much else. Some remnants of octal still remain, such as the subnet masks for IP addresses, or red, blue, green (RGB) values for colors.

Hex Conversion Computer Language Functions

Converting from hexadecimal to string values or string to hexadecimal is simple. Virtually all programming languages have built-in string function manipulation and conversions. Even high-level web programming languages use hex, especially for representing colors or symbol characters.

Hex and String Conversion

By its strictest definition, a string is alphanumeric and not interpreted as a numerical representation. To perform arithmetic or logical operations using an alphanumeric requires the programmer to convert a string to hex. For example: If a city has dead people living in it, what is the population? As a string, there are no living people in the city. However, if the string “dead” is converted to hex, then there is a living population of 57005 people. Similarly, if the population is 57005 and the decimal number is first converted to hex, then the convert a string to hex function is used, the city has a dead population.

Hex Values as Alphanumeric Strings

Hexadecimal values take the form of the numbers 0 to 9 and the letters A through F – a total of 16 characters. When coders “speak” hex, many use phonetics to prevent confusion. As a hexadecimal example, the value “4D2” would be read “four delta two”. Otherwise it might sound too much like “42”.

Hex Conversion Offline and Online Tools and Tutorials

One of the included tools with Microsoft applications is a scientific calculator. It is usually set to the default of a standard calculator, however it can be easily changed by altering the “View” setting. Using the radio buttons and the keypad, it is a simple matter to convert decimal numbers to octal or hex or vice versa. Example with our hex to decimal converter

Additionally, there are a number of tools readily available online for the coder, from free string function online tools which enable the coder to execute string functions online to a wealth of knowledge contained in a wide variety of string tutorials, string function tutorials, and string to hex tutorials.

• convert a string to lowercase
• convert a string to uppercase
• convert a string to hex
• convert a hex to string
• reverse a string
• calculate a string length

These tools help a lot when making a script.

Read my tutorials to learn how to program these tools, as of today, you can check out my php tutorial.