How to use the command mcookie (with examples)

The command mcookie is used to generate random 128-bit hexadecimal numbers. It can be useful in various scenarios where a random number is required, such as generating unique identifiers or cryptographic keys.

Use case 1: Generate a random number

Code:

mcookie

Motivation: In scenarios where a random number is needed, like generating a random token for authentication or creating a unique identifier, using mcookie can provide a convenient way to generate a random 128-bit hexadecimal number.

Explanation: The command mcookie without any options generates a random number using the default source of randomness.

Example output:

e4e5accbf225112c4569a6d78ed402d8

Use case 2: Generate a random number, using the contents of a file as a seed for randomness

Code:

mcookie --file path/to/file

Motivation: Sometimes it is desirable to use the contents of a file as a basis for generating a random number. This can be useful, for example, when you want to ensure that the generated number is unique for each file.

Explanation: By specifying the --file option followed by the path to a file, mcookie will use the contents of that file as a seed for generating the random number.

Example output:

4bff9ccbe8eef0565f8e14a199d3a9e5

Use case 3: Generate a random number, using a specific number of bytes from a file as a seed for randomness

Code:

mcookie --file path/to/file --max-size number_of_bytes

Motivation: In some cases, only a part of the file is needed as a seed for generating the random number. For example, if you want to use a specific portion of a large file as a seed, you can specify the number of bytes to use.

Explanation: By combining the --file option with the --max-size option followed by the desired number of bytes, mcookie will use the specified number of bytes as a seed for generating the random number.

Example output:

b53e827f9a77e9d674d8a8cf2d1d0b82

Use case 4: Print the details of the randomness used

Code:

mcookie --verbose

Motivation: In certain situations, it can be valuable to have more information about the origin and seed for each source of randomness used in generating the random number.

Explanation: By providing the --verbose option, mcookie will print additional details about the randomness sources it uses, such as the origin and seed for each source.

Example output:

Source: /dev/random, Seed: 0x3767f9f4a53d041ae0d0c1d26fcdfd04
Source: /dev/urandom, Seed: 0x24d85fb3c9629e89932595b603969bb3
Random number: 4f688ca009302641b2342b2c5476d01e

Conclusion:

The mcookie command provides a convenient way to generate random 128-bit hexadecimal numbers, which can be useful in various scenarios such as generating unique identifiers or cryptographic keys. By exploring the different use cases, you can utilize the command to generate random numbers based on file contents, specify the amount of bytes to use, and print additional details about the sources of randomness used.