Struct IvStash 

pub struct IvStash { /* private fields */ }

Remembers the IV used for each (type, plaintext, aad) triple so re-encrypting an unchanged value reproduces its exact previous ciphertext.

This is not an optimisation. sops edit decrypts, hands the tree to an editor, and re-encrypts everything; without the stash every line of the file changes on every edit, which destroys the property the whole format exists for — a readable, reviewable diff.

The type is part of the key, and leaving it out is a real bug

Upstream’s key is stashKey{plaintext interface{}, additionalData string}, and a Go map compares an interface{} by dynamic type and value — so int(1) and string("1") are two different keys there. The first version of this struct keyed on the raw plaintext bytes, which collapses exactly the pairs the encodings make indistinguishable:

these are distinct upstream	but share one byte string
1 (int) / 1.0 (float) / "1" (str)	1
true (bool) / "True" (str)	True
false (bool) / "False" (str)	False

Two such leaves under the same AAD — which is to say two elements of one list, since a sequence adds no path component — would then be handed the same nonce. The plaintext bytes are equal, so this is not the catastrophic form of GCM nonce reuse; the consequence is a file whose bytes differ from the one sops would have written, which for a tool whose entire claim is byte-parity is the bug that matters. LeafType is in the key.

The reuse that remains, stated rather than inherited

Two genuinely identical typed values at one path do still share a nonce. The plaintexts are identical, so an attacker learns only that they are equal — which any deterministic encryption concedes by construction. It is a knowing trade, confined to unchanged values, and it is the price of a reviewable diff.

Implementations

impl IvStash

pub fn new() -> Self

pub fn remember(&mut self, plaintext: &Plaintext, aad: &Aad, iv: &[u8])

Record the IV a leaf was decrypted with, so an unchanged value keeps it.

pub fn recall(&self, plaintext: &Plaintext, aad: &Aad) -> Option<Iv>

The remembered IV for this pair, if any.

pub fn len(&self) -> usize

How many pairs are remembered. Diagnostics only.

pub fn is_empty(&self) -> bool

Trait Implementations

impl Debug for IvStash

fn fmt(&self, f: &mut Formatter<'_>) -> Result

The keys of this map are plaintexts. Printing the map would leak every value in the file, so Debug prints only the count.

impl Default for IvStash

fn default() -> IvStash

Returns the “default value” for a type.