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.

Binary values are essential for the operation of computer-based systems. Reduced to its minimum functions, a computer can do only two things: add numbers and compare values – albeit very quickly. Every other computer function can be reduced to one of these two operations. In the case of arithmetic calculations, all computations are a function of addition. Subtraction is addition of negative numbers, multiplication is simply multiple addition operations, as division is multiple negative addition operations.

With one switch, two values can be represented: either zero or one. With two switches, 4 values can be represented: 00, 01, 10 and 11. With three switches, eight values are possible: 000, 001, 010, 011, 100, 101, 110, and 111. Because of the two value nature, this is referred to mathematically as “Base 2.”

Octal – or Base 8 – is the specific case of three switches – the numbers 0 through 7 are the single digit representation of the value. Without going into detail, four switches would be used to represent a single digit hexadecimal – or Base 16 – value. Decimal numbers – Base 10 – are not conveniently possible to represent without a conversion from either binary, octal or hexadecimal numeric value to an easily-grasped human number. These conversions are typically integral to every computer language by use of string operations. Since computing is a two-way process involving input and output, there are binary to decimal functions as well as decimal to binary functions.
Learn how to convert binary and decimal values

Working with long strings of ones and zeroes is a tedious process, thus the use of octal and hexadecimal symbols allow values to be more readily perceived by humans. The existence of decimal numerals is solely for the comfort of humans; they are a time- and resource-consuming inconvenience for a machine. Low-level microcode and assembly languages are generically referred to as machine code because they communicate directly with the computer without unnecessary conversion to a decimal number.

Decimal to binary conversion tools are readily available. The Microsoft operating systems – as well as virtually every other graphical user interface – have a calculator as part of the O/S package. In the case of MS Windows, the calculator has two views. One is a common function decimal calculator, the other is a more sophisticated scientific view. The second option has the ability to convert decimal to either binary, octal or hexadecimal and to perform any number of common calculations and functions in any of those formats. Handheld calculators designed for use by the engineering sciences routinely include these functions as well.

On-line tools for similar or more complex conversion of binary to decimal and decimal to binary conversion are readily available. Usually, these tools are for the more complex computer-oriented functions such as converting a numeric value to a code – such as ASCII letters and symbols – and back. Binary numbers – in hexadecimal format – are commonly used to represent levels of red, green and blue (RGB) colors.

Converting binary to decimal – commonly seen as “bin to dec” and “dec to bin” is neither difficult nor complicated once the concepts are understood.
Learn binary and decimal conversions

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!

Percent encoding is simply the substitution of a hexadecimal value for a reserved symbol or character in a URL. This is necessary to prevent some programming languages from behaving erratically when a symbol in a URL string is misinterpreted as a command to the program. Usually the URL parser can decode string elements of a URL without problems; however, in order to maintain platform-independence, URLs use an encoded string according to industry standards. This is a critical component enabling uniform web programming language conventions.

Example of Percent Encoding

An example of percent encoding is a string function simple substitution of the reserved character ampersand (&) with its hexadecimal equivalent (26) by using a string to hexadecimal conversion function. The parser needs to know when an ASCII character is encoded to decode the hexadecimal to string. The character percent (%) was selected to be followed by a two digit hexadecimal value to indicate the character. Thus, the ampersand would be represented as “%26” in the URL. Another common reserved character is the question mark (?), represented as %2F in the string. String function online programs are plentiful which provide encoding and decoding hexadecimal text and symbols. The characters are entered and the program will execute the string function online.

Shorten a URL

Another string function that is mistakenly called URL encoding is the string conversion of a portion of the URL that serves one of two purposes. The URL can be significantly shortened as is demonstrated by the widely-known “TinyURL” URL encoding online application. A target URL is encoded and stored on the site and a much smaller, more readable URL is returned. The URL decoding online is handled by the parsing engine of the TinyURL servers and passed through to the internet to complete the connection.

RSA encryption

Another string function online tool is a simple form of RSA encryption using pairs of large prime numbers and modulo arithmetic to generate a string of hexadecimal digits. This is usually done to obfuscate parameters and arguments and prevent – or at least discourage – online user alterations. Another commonly used string function is Exclusive OR (XOR) masking of a known string with any other string to return an incomprehensible result. The decryption is simply taking the result and use the XOR with the known string to return the original unencrypted string.

For those needing additional information, there are many string function tutorials which describe strings and functions in exhausting detail. Entering the type of string function and its application into any well-known search engine will turn up a number of resources available to explain the specifics of any string functions.

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.