Trait tink_core::Prf

source ·

pub trait Prf: PrfBoxClone {
    // Required method
    fn compute_prf(
        &self,
        input: &[u8],
        output_length: usize
    ) -> Result<Vec<u8>, TinkError>;
}

Expand description

The Prf trait is an abstraction for an element of a pseudo random function family, selected by a key. It has the following property:

It is deterministic. compute_prf(input, length) will always return the same output if the same key is used. compute_prf(input, length1) will be a prefix of compute_prf(input, length2) if length1 < length2 and the same key is used.
It is indistinguishable from a random function: Given the evaluation of n different inputs, an attacker cannot distinguish between the PRF and random bytes on an input different from the n that are known. Use cases for PRF are deterministic redaction of PII, keyed hash functions, creating sub IDs that do not allow joining with the original dataset without knowing the key. While PRFs can be used in order to prove authenticity of a message, using the Mac interface is recommended for that use case, as it has support for verification, avoiding the security problems that often happen during verification, and having automatic support for key rotation. It also allows for non-deterministic MAC algorithms.

Required Methods§

source

fn compute_prf( &self, input: &[u8], output_length: usize ) -> Result<Vec<u8>, TinkError>

Compute the PRF selected by the underlying key on input and returns the first output_length bytes. When choosing this parameter keep the birthday paradox in mind. If you have 2^n different inputs that your system has to handle set the output length (in bytes) to at least ceil(n/4 + 4) This corresponds to 2*n + 32 bits, meaning a collision will occur with a probability less than 1:2^32. When in doubt, request a security review. Returns a non ok status if the algorithm fails or if the output of algorithm is less than outputLength.

Trait Implementations§

source §

impl From<Primitive> for Box<dyn Prf>