Struct FuzzyHashLengthEncoding 

pub struct FuzzyHashLengthEncoding { /* private fields */ }

Approximated input data length encoded as 8-bits in a fuzzy hash.

On TLSH, it compresses a 32-bit input size to an approximated encoding of 8-bits. This enables to distinguish statistically similar files with large differences in the size.

This struct can have a:

1. A valid encoding for a valid input size,
2. A “valid” encoding for an invalid input size (only appears when the input is smaller than the TLSH’s lower limit), or
3. An invalid encoding (does not correspond any of the 32-bit size).

This struct only handles the validness of its encoding. So, the case 2 above is considered “valid” in this type.

Implementations

impl FuzzyHashLengthEncoding

pub const MAX_DISTANCE: u32 = 1_536u32

The maximum distance between two length encodings.

pub fn new(len: u32) -> Option<Self>

Encode the 32-bit data length as rough 8-bit representation.

pub fn value(&self) -> u8

Returns the raw encoding.

pub fn is_valid(&self) -> bool

Returns whether the encoding is valid.

Note that, if the encoding only appears when the input size is too small, it also returns true because the encoding itself is still valid. On the other hand, if the encoding exceeds the upper limit, it will return false because it will not correspond to any of 32-bit input size.

pub fn compare(&self, other: &FuzzyHashLengthEncoding) -> u32

Compare against another length encoding and return the distance between them.

pub fn range(&self) -> Option<RangeInclusive<u32>>

Decode the encoded 8-bit length approximation as an inclusive 32-bit input size range that will produce the given encoding.

It will return None if there’s no valid 32-bit size for given encoding.

Trait Implementations

impl Clone for FuzzyHashLengthEncoding

fn clone(&self) -> FuzzyHashLengthEncoding

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FuzzyHashLengthEncoding

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for FuzzyHashLengthEncoding

fn eq(&self, other: &FuzzyHashLengthEncoding) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl TryFrom<u32> for FuzzyHashLengthEncoding

type Error = ParseError

The type returned in the event of a conversion error.

fn try_from(len: u32) -> Result<Self, Self::Error>

Performs the conversion.

impl Copy for FuzzyHashLengthEncoding

impl Eq for FuzzyHashLengthEncoding

impl StructuralPartialEq for FuzzyHashLengthEncoding