Struct Mpint

pub struct Mpint { /* private fields */ }

Available on crate feature alloc only.

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 input may begin with leading zeros, which will be stripped when converted to Mpint encoding.

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 ConstantTimeEq for Mpint

fn ct_eq(&self, other: &Self) -> Choice

Determine if two items are equal.

fn ct_ne(&self, other: &Self) -> Choice

Determine if two items are NOT equal.

impl Debug for Mpint

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

Formats the value using the given formatter.

impl Decode for Mpint

type Error = Error

Type returned in the event of a decoding error.

fn decode(reader: &mut impl Reader) -> Result<Self>

Attempt to decode a value of this type using the provided Reader.

impl Display for Mpint

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

Formats the value using the given formatter.

impl Encode for Mpint

fn encoded_len(&self) -> Result<usize>

Get the length of this type encoded in bytes, prior to Base64 encoding.

fn encode(&self, writer: &mut impl Writer) -> Result<()>

Encode this value using the provided Writer.

fn encoded_len_prefixed(&self) -> Result<usize, Error>

Return the length of this type after encoding when prepended with a uint32 length prefix.

fn encode_prefixed(&self, writer: &mut impl Writer) -> Result<(), Error>

Encode this value, first prepending a uint32 length prefix set to Encode::encoded_len.

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: &Self) -> 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<&BigUint> for Mpint

Available on crate features dsa or rsa only.

type Error = Error

The type returned in the event of a conversion error.

fn try_from(uint: &BigUint) -> Result<Mpint>

Performs the conversion.

impl TryFrom<&Mpint> for BigUint

Available on crate features dsa or rsa only.

type Error = Error

The type returned in the event of a conversion error.

fn try_from(mpint: &Mpint) -> Result<BigUint>

Performs the conversion.

impl TryFrom<BigUint> for Mpint

Available on crate features dsa or rsa only.

type Error = Error

The type returned in the event of a conversion error.

fn try_from(uint: BigUint) -> Result<Mpint>

Performs the conversion.

impl TryFrom<Box<[u8]>> for Mpint

type Error = Error

The type returned in the event of a conversion error.

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

Performs the conversion.

impl TryFrom<Mpint> for BigUint

Available on crate features dsa or rsa only.

type Error = Error

The type returned in the event of a conversion error.

fn try_from(mpint: Mpint) -> Result<BigUint>

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