Maximum length for MD5 input/output

What is the maximum length of the string that can have md5 hashed? O开发者_如何学Cr: If it has no limit, and if so what will be the max length of the md5 output value?

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MD5 processes an arbitrary-length message into a fixed-length output of 128 bits, typically represented as a sequence of 32 hexadecimal digits.

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• The length of the message is unlimited.

Append Length

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. In the unlikely event that b is greater than 2^64, then only the low-order 64 bits of b are used.

• The hash is always 128 bits. If you encode it as a hexdecimal string you can encode 4 bits per character, giving 32 characters.
• MD5 is not encryption. You cannot in general "decrypt" an MD5 hash to get the original string.

See more here.

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You can have any length, but of course, there can be a memory issue on the computer if the String input is too long. The output is always 32 characters.

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The algorithm has been designed to support arbitrary input length. I.e you can compute hashes of big files like ISO of a DVD...

If there is a limitation for the input it could come from the environment where the hash function is used. Let's say you want to compute a file and the environment has a MAX_FILE limit.

But the output string will be always the same: 32 hex chars (128 bits)!

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A 128-bit MD5 hash is represented as a sequence of 32 hexadecimal digits.

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You may want to use SHA-1 instead of MD5, as MD5 is considered broken.

You can read more about MD5 vulnerabilities in this Wikipedia article.

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There is no limit to the input of md5 that I know of. Some implementations require the entire input to be loaded into memory before passing it into the md5 function (i.e., the implementation acts on a block of memory, not on a stream), but this is not a limitation of the algorithm itself. The output is always 128 bits. Note that md5 is not an encryption algorithm, but a cryptographic hash. This means that you can use it to verify the integrity of a chunk of data, but you cannot reverse the hashing. Also note that md5 is considered broken, so you shouldn't use it for anything security-related (it's still fine to verify the integrity of downloaded files and such).

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md5 algorithm appends the message length to the last 64 bits of the last block, thus it would be fair to say that the message can be 2^64 bits long (18 e18 bits).

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Max length for MD5 input : largest definable and usable stream of bit A stream of bit definition constraints can depend on operating system, hardware constraints, programming language and more...

Length for MD5 output : Fixed-length always 128 bits For easier display, they are usually displayed in hex, which because each hex digit (0-1-2-3-4-5-6-7-8-9-A-B-C-D-E-F) takes up 4 bits of space, so its output can be displayed as 32 hex digits. 128 bits = 16 bytes = 32 hex digits

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The md5 output is always 32 characters.Therefore, when setting character limit for the password in the database, do not give a value below 32 characters. If you give a value below 32, the password will be incompletely recorded in the database and therefore users will encounter an error while logging into the system.