Struct State 

pub struct State { /* private fields */ }

Poly1305 state for incremental authentication

This structure allows computing a Poly1305 authentication tag incrementally, which is useful when the entire message is not available at once or when processing large messages in chunks to avoid excessive memory usage.

Memory Efficiency

Using the incremental API allows processing messages of any size without needing to load the entire message into memory at once. This is particularly useful for:

• Large files that don’t fit in memory
• Streaming data from a network or other source
• Memory-constrained environments

Security Note

The security properties of Poly1305 are maintained when using the incremental API. The same tag will be produced regardless of how the message is chunked, as long as the chunks are processed in the correct order.

Implementations

impl State

pub fn new(key: &Key) -> Self

Creates a new Poly1305 authentication state

Arguments

• key - The key to use for authentication

Returns

• Self - The initialized state

Panics

This function should never panic with valid inputs. The key validity is ensured by the Key type.

pub fn update(&mut self, input: &[u8])

Updates the authentication state with more input data

Arguments

• input - The data to include in the authentication

This function cannot fail with valid inputs, and we validate inputs through the State constructor.

pub fn finalize(&mut self) -> Tag

Finalizes the authentication computation and returns the tag

Returns

• Tag - The authentication tag

This function cannot fail with valid inputs, and we validate inputs through the State constructor.