Struct Ctr

pub struct Ctr<B: BlockCipher + Zeroize> { /* private fields */ }

Counter mode implementation with secure memory handling

Implementations

impl<B: BlockCipher + Zeroize> Ctr<B>

pub fn new<const N: usize>(cipher: B, nonce: &Nonce<N>) -> Result<Self>

where Nonce<N>: AesCtrCompatible,

Creates a new CTR mode instance with the default configuration

• cipher - The block cipher to use
• nonce - The nonce (must be compatible with CTR mode)

This creates a standard CTR mode with the counter in the last 4 bytes and the nonce filling the beginning of the counter block.

pub fn with_counter_params<const N: usize>( cipher: B, nonce: &Nonce<N>, counter_pos: CounterPosition, counter_size: usize, ) -> Result<Self>

where Nonce<N>: AesCtrCompatible,

Creates a new CTR mode instance with custom counter parameters

• cipher - The block cipher to use
• nonce - The nonce (must be compatible with CTR mode)
• counter_pos - Position of the counter within the counter block
• counter_size - Size of the counter in bytes (1-8)

This allows for flexible counter block layouts to match different standards and implementations.

pub fn encrypt(&mut self, plaintext: &[u8]) -> Result<Vec<u8>>

Encrypts a message using CTR mode

pub fn decrypt(&mut self, ciphertext: &[u8]) -> Result<Vec<u8>>

Decrypts a message using CTR mode In CTR mode, encryption and decryption are the same operation

pub fn process(&mut self, data: &mut [u8]) -> Result<()>

Process data in place (encrypt or decrypt)

pub fn keystream(&mut self, output: &mut [u8]) -> Result<()>

Generate keystream directly into an output buffer

pub fn seek(&mut self, block_offset: u32)

Seek to a specific block position

block_offset is the number of full blocks that have been consumed; after seeking, the next generated block will be at block_offset + 1.

pub fn set_counter(&mut self, counter: u32)

Set the counter value directly

This allows for manual control of the counter, which can be useful for seeking to specific positions in the stream.

Arguments

• counter - The new counter value

pub fn reset<const N: usize>( &mut self, nonce: Option<&Nonce<N>>, counter: u32, ) -> Result<()>

where Nonce<N>: AesCtrCompatible,

Reset to initial state with the same key and nonce

This resets the counter to 0 and clears any buffered keystream.

Arguments

• nonce - Optional new nonce to use (if not provided, keeps the current nonce)
• counter - Optional initial counter value (defaults to 0)

Trait Implementations

impl<B: Clone + BlockCipher + Zeroize> Clone for Ctr<B>

fn clone(&self) -> Ctr<B>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<B: BlockCipher + Zeroize> Drop for Ctr<B>

fn drop(&mut self)

Executes the destructor for this type.

impl<B> Zeroize for Ctr<B>

where B: Zeroize + BlockCipher,

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.