Better docs for AEAD tag

This commit is contained in:
Steven Fackler 2016-11-09 18:54:29 +00:00
parent aa7c27536a
commit 7c8ae5f664
1 changed files with 10 additions and 0 deletions

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@ -287,6 +287,10 @@ impl Crypter {
/// as AES GCM. /// as AES GCM.
/// ///
/// When encrypting data with an AEAD cipher, this must be called after `finalize`. /// When encrypting data with an AEAD cipher, this must be called after `finalize`.
///
/// The size of the buffer indicates the required size of the tag. While some ciphers support a
/// range of tag sizes, it is recommended to pick the maximum size. For AES GCM, this is 16
/// bytes, for example.
pub fn get_tag(&self, tag: &mut [u8]) -> Result<(), ErrorStack> { pub fn get_tag(&self, tag: &mut [u8]) -> Result<(), ErrorStack> {
unsafe { unsafe {
assert!(tag.len() <= c_int::max_value() as usize); assert!(tag.len() <= c_int::max_value() as usize);
@ -370,6 +374,10 @@ pub fn encrypt_aead(t: Cipher,
/// ///
/// Additional Authenticated Data can be provided in the `aad` field, and the authentication tag /// Additional Authenticated Data can be provided in the `aad` field, and the authentication tag
/// should be provided in the `tag` field. /// should be provided in the `tag` field.
///
/// The size of the `tag` buffer indicates the required size of the tag. While some ciphers support
/// a range of tag sizes, it is recommended to pick the maximum size. For AES GCM, this is 16 bytes,
/// for example.
pub fn decrypt_aead(t: Cipher, pub fn decrypt_aead(t: Cipher,
key: &[u8], key: &[u8],
iv: Option<&[u8]>, iv: Option<&[u8]>,
@ -650,6 +658,8 @@ mod tests {
f4fc97416ee52abe"; f4fc97416ee52abe";
let tag = "e20b6655"; let tag = "e20b6655";
// this tag is smaller than you'd normally want, but I pulled this test from the part of
// the NIST test vectors that cover 4 byte tags.
let mut actual_tag = [0; 4]; let mut actual_tag = [0; 4];
let out = encrypt_aead(Cipher::aes_128_gcm(), let out = encrypt_aead(Cipher::aes_128_gcm(),
&key.from_hex().unwrap(), &key.from_hex().unwrap(),