• Python Generate A Unique Character Key Generator
• Python Create Unique Id
• Generate Random Id Python

Source code:Lib/uuid.py

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This module provides immutable UUID objects (the UUID class)and the functions uuid1(), uuid3(), uuid4(), uuid5() forgenerating version 1, 3, 4, and 5 UUIDs as specified in RFC 4122.

If all you want is a unique ID, you should probably call uuid1() oruuid4(). Note that uuid1() may compromise privacy since it createsa UUID containing the computer’s network address. uuid4() creates arandom UUID.

Depending on support from the underlying platform, uuid1() may or maynot return a “safe” UUID. A safe UUID is one which is generated usingsynchronization methods that ensure no two processes can obtain the sameUUID. All instances of UUID have an is_safe attributewhich relays any information about the UUID’s safety, using this enumeration:

The UUID was generated by the platform in a multiprocessing-safe way.

The UUID was not generated in a multiprocessing-safe way.

The platform does not provide information on whether the UUID wasgenerated safely or not.

Create a UUID from either a string of 32 hexadecimal digits, a string of 16bytes in big-endian order as the bytes argument, a string of 16 bytes inlittle-endian order as the bytes_le argument, a tuple of six integers(32-bit time_low, 16-bit time_mid, 16-bit time_hi_version,8-bit clock_seq_hi_variant, 8-bit clock_seq_low, 48-bit node) as thefields argument, or a single 128-bit integer as the int argument.When a string of hex digits is given, curly braces, hyphens,and a URN prefix are all optional. For example, theseexpressions all yield the same UUID:

Exactly one of hex, bytes, bytes_le, fields, or int must be given.The version argument is optional; if given, the resulting UUID will have itsvariant and version number set according to RFC 4122, overriding bits in thegiven hex, bytes, bytes_le, fields, or int.

Comparison of UUID objects are made by way of comparing theirUUID.int attributes. Comparison with a non-UUID objectraises a TypeError.

str(uuid) returns a string in the form12345678-1234-5678-1234-567812345678 where the 32 hexadecimal digitsrepresent the UUID.

UUID instances have these read-only attributes:

The UUID as a 16-byte string (containing the six integer fields in big-endianbyte order).

The UUID as a 16-byte string (with time_low, time_mid, and time_hi_versionin little-endian byte order).

A tuple of the six integer fields of the UUID, which are also available as sixindividual attributes and two derived attributes:

The UUID as a 32-character hexadecimal string.

The UUID as a 128-bit integer.

The UUID as a URN as specified in RFC 4122.

The UUID variant, which determines the internal layout of the UUID. This will beone of the constants RESERVED_NCS, RFC_4122,RESERVED_MICROSOFT, or RESERVED_FUTURE.

The UUID version number (1 through 5, meaningful only when the variant isRFC_4122).

An enumeration of SafeUUID which indicates whether the platformgenerated the UUID in a multiprocessing-safe way.

New in version 3.7.

The uuid module defines the following functions:

Get the hardware address as a 48-bit positive integer. The first time thisruns, it may launch a separate program, which could be quite slow. If allattempts to obtain the hardware address fail, we choose a random 48-bitnumber with the multicast bit (least significant bit of the first octet)set to 1 as recommended in RFC 4122. “Hardware address” means the MACaddress of a network interface. On a machine with multiple networkinterfaces, universally administered MAC addresses (i.e. where the secondleast significant bit of the first octet is unset) will be preferred overlocally administered MAC addresses, but with no other ordering guarantees.

Changed in version 3.7: Universally administered MAC addresses are preferred over locallyadministered MAC addresses, since the former are guaranteed to beglobally unique, while the latter are not.

Python Generate A Unique Character Key Generator

Generate a UUID from a host ID, sequence number, and the current time. If nodeis not given, getnode() is used to obtain the hardware address. Ifclock_seq is given, it is used as the sequence number; otherwise a random14-bit sequence number is chosen.

Generate a UUID based on the MD5 hash of a namespace identifier (which is aUUID) and a name (which is a string).

Generate a random UUID.

Generate a UUID based on the SHA-1 hash of a namespace identifier (which is aUUID) and a name (which is a string).

The uuid module defines the following namespace identifiers for use withuuid3() or uuid5().

When this namespace is specified, the name string is a fully-qualified domainname.

When this namespace is specified, the name string is a URL.

When this namespace is specified, the name string is an ISO OID.

When this namespace is specified, the name string is an X.500 DN in DER or atext output format.

The uuid module defines the following constants for the possible valuesof the variant attribute:

Reserved for NCS compatibility.

Python Create Unique Id

Specifies the UUID layout given in RFC 4122.

Reserved for Microsoft compatibility.

Reserved for future definition.

See also

This specification defines a Uniform Resource Name namespace for UUIDs, theinternal format of UUIDs, and methods of generating UUIDs.

Example¶

Here are some examples of typical usage of the uuid module:

Released:

Generate randomized strings of characters using a template

Project description

Generate test data, unique ids, passwords, vouchers or other randomizedtextual data very quickly using a template language. The templatelanguage is superficially similar to regular expressions but instead ofdefining how to match or capture strings, it defines how to generaterandomized strings. A very simple invocation to produce a random stringwith word characters and digits of 10 characters length:

The purpose of this module is to save the Python developer from havingto write verbose code around the same pattern every time to generatepasswords, keys, tokens, test data, etc. of this sort:

that is:

1. Hard to read even at this simplistic level.
2. Hard to safely change quickly. Even modest additions to therequirements need unreasonably verbose solutions.
3. Doesn’t use safe encryption standards.
4. Doesn’t provide the implied minimal guarantees of characteroccurance.
5. Hard to track back to requirements (“must be between x and y inlength and have characters from sets Q, R and S”).

The template uses short forms similar to those of regular expressions.An example template for generating a strong password:

will generate something like the following:

Guarantee at least two “special” characters in a string:

You can also generate useful test data, like fake emails with plenty ofvariation:

Installation

Install as standard for Python packages from PyPi:

Usage

or to produce a list of unique strings:

Example:

The template is a string that is a sequence of one or more of thefollowing:

• Literal text (for example: UID)
• Character class (for example: [a-zs])
• Group, a combination of literals and character classes, possiblyseparated by operators and using parentheses where appropriate (forexample: (UID[d]{4}&[w]{4}))

In more detail:

Literal: <any string>

Any literal string.

Example:

Special characters need to be escaped with backslash .

Character class: [<class specification>]

Much like in regular expressions, it uses strings of characters andhyphen for defining a class of characters.

Example:

The generator will randomly choose characters from the set of lower caseletters, digits and the underscore. The number of characters generatedwill be exactly one in this case. For more, use a quantifier:

As a shortcut for commonly used character sets, a character set code maybe used. The following will render in exactly the same way:

Character Set Codes

• W: whitespace + punctuation
• a: ascii_letters
• c: lowercase
• d: digits
• h: hexdigits
• l: letters
• o: octdigits
• p: punctuation
• r: printable
• s: whitespace
• u: uppercase
• w: _ + letters + digits

Quantifier: {x:y}

Where x is lower bound and y is upper bound. This construct must alwaysfollow immediately a class with no intervening whitespace. It ispossible to write {:y} as a shorthand for {0:y} or {y} to indicate afixed length.

Example:

Generates a string from zero to 8 in length composed of lower casealphabetic characters.

Generates a string with either four lower case alphabetic characters ora string of digits that is four in length.

Using a character class and no quantifier will result in a quantifier of1. Thus:

will result always in either a, b, or c.

Variable Substitution

We provide the ${varname} syntax to enable any value to be returned.varname must be provided as a keyword argument to the render()or render_list() methods. You can use a list, function, generator.Here’s an example using a list:

Or use a range converted to a list:

Note that in Python 2.x range() returns a list. In Python 3,range() returns a range type.

Or using a function:

You can obviously pass any callable or generator that might, forinstance, randomly choose a value from a database, if that is what youwant.

Note there is a difference in handling between a callable and list type.If you use a list, StringGenerator picks an item from the list foryou, randomly. If you use a callable, StringGenerator takes and insertswhatever is returned by the callable. The callable is required to do anyrandomisation if that is what the user wants. So, if you pass a functionthat returns a list, the entire list will be inserted as a string.

Group: (<group specification>)

A group specification is a collection of literals, character classes orother groups divided by the OR operator or the shuffle operator&.

OR Operator

The binary operator can be used in a group to cause one of theoperands to be returned and the other to be ignored with an even chance.

Shuffle Operator

The binary & operator causes its operands to be combined andshuffled. This addresses the use case for many password requirements,such as, “at least 6 characters where 2 or more are digits”. Forinstance:

If a literal or a group is an operand of the shuffle operator, it willhave its character sequence shuffled with the other operand.

will produce strings like:

Concatenation and Operators

Classes, literals and groups in sequence are concatenated in the orderthey occur. Use of the or & operators always binds theoperands immediately to the left and right:

produces something like:

Generate Random Id Python

In other words, the digits occur first in sequence as expected. This isequivalent to this:

Special Characters, Escaping and Errors

There are fewer special characters than regular expressions:

They can be used as literals by escaping with backslash. All othercharacters are treated as literals. The hyphen is only special in acharacter class, when it appears within square brackets.

One special case is the escape character itself, backslash ’’. To escapethis, you will need at least two backslashes to escape it. So, threealltogether: one for Python’s string interpretation and one forStringGenerator’s escaping. If for some exotic reason you want twoliteral backslashes in a row, you need a total of eight backslashes. Theforegoing presupposes the template is a string in a file. If you areusing the template in a shell command line or shell script, you’ll needto make any changes required by your specific shell.

The template parser tries to raise exceptions when syntax errors aremade, but not every error will be caught, like having space between aclass and quantifier.

Spaces

Do not use any spaces in the template unless you intend to use them ascharacters in the output:

Character Classes and Quantifiers

Use a colon in the curly braces to indicate a range. There are sensibledefaults:

As of version 0.1.7, quantifier ranges can alternatively be specifiedwith a hyphen:

Here’s an example of generating a syntactically valid but, hopefully,spurious email address:

The first name will be exactly 10 lower case characters; the last namewill be 5-10 characters of lower case letters, each separated by eithera dot or underscore. The domain name without domain class will be 3 - 12lower case characters and the domain type will be one of‘.com’,‘.net’,‘.org’.

The following will produce strings that tend to have more letters,because the set of letters (52) is larger than the set of digits (10):

Using multiple character set codes repeatedly will increase theprobability of a character from that set occuring in the result string:

This will provide a string that is three times more likely to contain adigit than the previous example.

Uniqueness

When using the unique=True flag in the render_list() method,it’s possible the generator cannot possibly produce the required numberof unique strings. For instance:

This will generate an exception but not before attempting to generatethe strings.

The number of times the generator needs to render new strings to satisfythe list length and uniqueness is not determined at parse time. Themaximum number of times it will try is by default n x 10 where n is therequested length of the list. Therefore, taking the above example, thegenerator will attempt to generate the unique list of 0’s and 1’s 100 x10 = 1000 times before giving up.

Progress

When using the progress_callback parameter of the render_list()method, it’s possible to inform others about the progress of stringgeneration. This is especially useful when generating a large number ofstrings.

The callback function obtains two int parameters: (current, total),which define the current progress and the total amount of requestedstrings.

By using that, callers of render_list() are able to implement aprogress indicator suitable for informing end users about the progressof string generation.

Unicode

Unicode is supported for both the template and output.

Character Sets

Character sets used for backslashed character codes are exactly thePython character sets from the string package. While the module isdesigned to work on pre- Python 3, we use only those member variablesfrom the string module that are present in Python 3. This avoids thelocale-dependent sets of characters in Python 2.x.

Randomness Methods

The generator tries to use random.SystemRandom() for randint,shuffle, etc. It falls back to random.randint and associatedmethods if it can’t use SystemRandom.

Debugging

Call the dump() method on the class instance to get useful information:

• Version of strgen module
• Version of Python
• The class name used for random methods
• The parse tree
• The output from one invocation of the render() method

The output looks something like the following:

Rationale and Design Goals

In Python, the need to generate random strings comes up frequently andis accomplished usually (though not always) via something like thefollowing code snippet:

This generates a string that is 10 characters made of uppercase lettersand digits. Unfortunately, this solution becomes cumbersome whenreal-world requirements are added. Take for example, the typicalrequirement to generate a password: “a password shall have 6 - 20characters of which at least one must be a digit and at least one mustbe a special character”. The above solution then becomes much morecomplicated and changing the requirements is an error-prone andunnecessarily complex task.

The equivalent using the strgen package:

strgen is far more compact, flexible and feature-rich than using thestandard solution:

• It tries to use a better entropy mechanism and falls back gracefullyif this is not available on the host OS.

• The user can easily modify the specification (template) with minimaleffort without the fear of introducing hard-to-test code paths.

• It covers a broader set of use cases: unique ids, persistent uniquefilenames, test data, etc.

• The template syntax is easy to learn for anyone familiar with regularexpressions while being much simpler.

• It supports unicode.

• It works on Python 2.6, 2.7 and 3.x.

• It proposes a standard way of expressing common requirements, like “apassword shall have 6 - 20 characters of which at least one must be adigit and at least one must be a special character”:

This package is designed with the following goals in mind:

• Provide an abstract template language that does not depend on aspecific implementation language.
• Reduce dependencies on other packages.
• Keep syntax as simple as possible while being useful.
• Provide an implementation design with associated behaviour thatstrikes the right balance between ease-of-implementation andease-of-use.
• Superficially similar to regular expressions to enable developers toquickly pick up the template syntax.
• Support non-ASCII languages (unicode).

Testing

For running the unit tests, you might want to try:

Acknowledgements

Thanks to Robert LeBlanc who caught some important errors in escapingspecial characters. Thanks to Andreas Motl for the progress counter.

Original Author: paul.wolf@yewleaf.com

Release historyRelease notifications

0.3.3

0.3.2

0.3.1

0.3.0

0.2.1

0.2.0

0.1.9

Aws generate key pair putty. 0.1.8

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