Struct MPInt

pub struct MPInt { /* private fields */ }

Multiple precision integer, a.k.a. “mpint”.

This type is used for representing the big integer components of DSA and RSA keys.

Described in RFC4251 § 5:

Represents multiple precision integers in two’s complement format, stored as a string, 8 bits per byte, MSB first. Negative numbers have the value 1 as the most significant bit of the first byte of the data partition. If the most significant bit would be set for a positive number, the number MUST be preceded by a zero byte. Unnecessary leading bytes with the value 0 or 255 MUST NOT be included. The value zero MUST be stored as a string with zero bytes of data.

By convention, a number that is used in modular computations in Z_n SHOULD be represented in the range 0 <= x < n.

Examples

value (hex)	representation (hex)
0	00 00 00 00
9a378f9b2e332a7	00 00 00 08 09 a3 78 f9 b2 e3 32 a7
80	00 00 00 02 00 80
-1234	00 00 00 02 ed cc
-deadbeef	00 00 00 05 ff 21 52 41 11

Implementations

impl MPInt

pub fn from_bytes(bytes: &[u8]) -> Result<Self>

Create a new multiple precision integer from the given big endian-encoded byte slice.

Note that this method expects a leading zero on positive integers whose MSB is set, but does NOT expect a 4-byte length prefix.

pub fn from_positive_bytes(bytes: &[u8]) -> Result<Self>

Create a new multiple precision integer from the given big endian encoded byte slice representing a positive integer.

The integer should not start with any leading zeroes.

pub fn as_bytes(&self) -> &[u8]

Get the big integer data encoded as big endian bytes.

This slice will contain a leading zero if the value is positive but the MSB is also set. Use MPInt::as_positive_bytes to ensure the number is positive and strip the leading zero byte if it exists.

pub fn as_positive_bytes(&self) -> Option<&[u8]>

Get the bytes of a positive integer.

Returns

• Some(bytes) if the number is positive. The leading zero byte will be stripped.
• None if the value is negative

Trait Implementations

impl AsRef<[u8]> for MPInt

fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.

impl Clone for MPInt

fn clone(&self) -> MPInt

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for MPInt

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

Formats the value using the given formatter.

impl Display for MPInt

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

Formats the value using the given formatter.

impl LowerHex for MPInt

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

Formats the value using the given formatter.

impl Ord for MPInt

fn cmp(&self, other: &MPInt) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for MPInt

fn eq(&self, other: &MPInt) -> 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 PartialOrd for MPInt

fn partial_cmp(&self, other: &MPInt) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl TryFrom<&[u8]> for MPInt

type Error = Error

The type returned in the event of a conversion error.

fn try_from(bytes: &[u8]) -> Result<Self>

Performs the conversion.

impl TryFrom<Vec<u8>> for MPInt

type Error = Error

The type returned in the event of a conversion error.

fn try_from(bytes: Vec<u8>) -> Result<Self>

Performs the conversion.

impl UpperHex for MPInt

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

Formats the value using the given formatter.

impl Zeroize for MPInt

fn zeroize(&mut self)

Zero out this object from memory using Rust intrinsics which ensure the zeroization operation is not “optimized away” by the compiler.

impl Eq for MPInt

impl StructuralPartialEq for MPInt