fourword 2.0.0

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FourWord

A new random identifier generation method capable of chronological sorting

Overview

This is a new method for generating random identifiers. It is designed for use as primary keys in databases and similar applications.

It includes a timestamp at the beginning and uses Base32 Hex as the character set for text conversion, allowing for sorting in chronological order. Since Z is used instead of = for padding, it should be usable anywhere alphanumeric characters are supported.

To minimize the possibility of collisions while also preventing overflow, the timestamp is not fixed but occupies 1/4 of the total bit length. This means that simply increasing the total bit length increases the length of the timestamp, allowing for longer continuous usage.

However, a trade-off is that increasing the bit length results in unnecessary leading zeros in the timestamp section.

Etymology

The "Four" in the name comes from the fact that the timestamp occupies 1/4 of the bit length. It is also a play on the word "Forward."

Python Library

# Install using pip
pip3 install fourword

# Install using uv
uv pip install fourword

# Add to Project using uv
uv add fourword

from fourword.lib import FourWord

fourword = FourWord(bits=256)
print(fourword.text)
print(fourword.timestamp.isoformat())

# Show usage
fourword --help
# Generate FourWord ID with default 256 bits
fourword g
# Generate FourWord ID with custom 512 bits
fourword g --bits 512
# Generate FourWord ID and Show with details
fourword g --detail
# Decode FourWord ID and Show with details
fourword i 32OD9FEO1M8G0I7A0CMGMC599N14NJQ9SQAJPT3TRATETRAMBKTGZZZZ

You can generate and analyze FourWord using the fourword library in Python.

The Python library also includes a fourword CLI command.

Specifications

FourWord is represented as the following byte sequence (big-endian):

[ (Total bits/4) bit UNIX timestamp (UTC, ns) ] + [ (Total bits/4*3) bit CSPRNG ]

For example, when the total bit length is 256 bits, the timestamp is 64 bits and the random part is 192 bits.

The ratio is fixed so that when retrieving the timestamp from an ID, the exact length can be easily determined without needing a separator.

Formats

Unlike other methods, FourWord does not strictly require text conversion. It supports multiple formats.

Text

Text conversion uses a variant of Base32 Hex.

As mentioned above, Z is used instead of = as the padding character, but otherwise, it is identical to Base32 Hex.

Example

32OD9FEO1M8G0I7A0CMGMC599N14NJQ9SQAJPT3TRATETRAMBKTGZZZZ

Compact Text

Uses Base62 (0-9A-Za-z) as the character set. The byte sequence is interpreted as a big-endian arbitrary-precision integer and converted to Base62. Zero-padded with 0 at the front so that the same bit length always produces a fixed-length output.

Approximately 76% the length of the Text format. For example, at 256 bits, the Text format is 56 characters while Compact Text fits in 43 characters.

Note that since Base62 is not a power of 2, bitwise operations cannot be used and arbitrary-precision integer arithmetic is required for decoding. It also cannot be used in case-insensitive environments.

Example

5r0NHGp8VYQuT2sVX1OZNDXn9XRg3qar5CsaahtCi7f

Readable Text

Based on the Text format, with the following modifications for human readability:

• Character set is lowercased (0-9, A-V → 0-9, a-v)
• Padding is omitted (since bit length is fixed, it can be restored during decoding)
• A hyphen (-) is inserted every 8 characters

Example

32od9feo-1m8g0i7a-0cmgmc59-9n14njq9-sqajpt3t-ratetram-bktg

Decimal

Interprets the byte sequence as a big-endian unsigned integer, adds 2^N (where N is the total bit length), and converts to decimal.

Decimal = 2^N + (byte_sequence as big-endian unsigned integer)

The result always has a fixed number of digits for a given bit length, allowing the bit length to be determined from the digit count alone during decoding.

Decoding

Determine N from the digit count, then subtract 2^N to recover the original byte sequence.

Example

126960030975124059975555195172296441085516613467993543348259724366939612929339

Hex

Simply interprets the byte sequence as a binary number and converts it to hexadecimal.

Example

18b0d4bdd80d910048ea032d0b30a94dc24bcf49e6953cf47ddabaeeed565d3b

Collision Probability

IDs with different timestamps do not collide. The values below represent the worst-case scenario (all IDs generated within the same nanosecond).

Bits	Random bit width	IDs for 10⁻¹⁸ collision prob.	IDs for 10⁻⁹ collision prob.	IDs for 50% collision prob.
256	192 bit	approx 1.12 × 10²⁰	approx 3.54 × 10²⁴	approx 9.33 × 10²⁸
512	384 bit	approx 8.88 × 10⁴⁸	approx 2.81 × 10⁵³	approx 7.39 × 10⁵⁷
768	576 bit	approx 7.03 × 10⁷⁷	approx 2.22 × 10⁸²	approx 5.85 × 10⁸⁶
1024	768 bit	approx 5.57 × 10¹⁰⁶	approx 1.76 × 10¹¹¹	approx 4.64 × 10¹¹⁵
1280	960 bit	approx 4.41 × 10¹³⁵	approx 1.40 × 10¹⁴⁰	approx 3.67 × 10¹⁴⁴
1536	1152 bit	approx 3.50 × 10¹⁶⁴	approx 1.11 × 10¹⁶⁹	approx 2.91 × 10¹⁷³
1792	1344 bit	approx 2.77 × 10¹⁹³	approx 8.76 × 10¹⁹⁷	approx 2.31 × 10²⁰²
2048	1536 bit	approx 2.20 × 10²²²	approx 6.94 × 10²²⁶	approx 1.83 × 10²³¹

Overflow Timing

Each bit length will overflow at the following times:

Bits	Timestamp bit width	Max seconds	Overflow timing (approx)
256	64 bit	approx 1.84 × 10¹⁹ s	approx 584.4 billion years AD (5.845 × 10¹¹ years)
512	128 bit	approx 3.40 × 10³⁸ s	approx 1.07 × 10³¹ years later
768	192 bit	approx 6.28 × 10⁵⁷ s	approx 1.99 × 10⁵⁰ years later
1024	256 bit	approx 1.16 × 10⁷⁷ s	approx 3.67 × 10⁶⁹ years later
1280	320 bit	approx 2.14 × 10⁹⁶ s	approx 6.77 × 10⁸⁸ years later
1536	384 bit	approx 3.94 × 10¹¹⁵ s	approx 1.25 × 10¹⁰⁸ years later
1792	448 bit	approx 7.26 × 10¹³⁴ s	approx 2.30 × 10¹²⁷ years later
2048	512 bit	approx 1.34 × 10¹⁵⁴ s	approx 4.24 × 10¹⁴⁶ years later

License

The source code and library within this repository are free to use under the MIT License.

Credit is not required for software that utilizes the FourWord specification itself or for data generated using FourWord.