libsignal_service/
sticker_cipher.rs

1pub use crate::attachment_cipher::{
2    decrypt_in_place, encrypt_in_place, AttachmentCipherError,
3};
4
5pub fn derive_key(ikm: &[u8]) -> Result<[u8; 64], AttachmentCipherError> {
6    let mut key = [0; 64];
7    hkdf::Hkdf::<sha2::Sha256>::new(None, ikm)
8        .expand(b"Sticker Pack", &mut key)
9        .expect("valid output length");
10    Ok(key)
11}