Implement SetIvState trait (#114)

See RustCrypto/traits#2420

Author: newpavlov

Cargo.lock

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 0.2.1 (2026-05-20)
+### Added
+- Implementation of the `SetIvState` trait ([#114])
+
+[#114]: https://github.com/RustCrypto/block-modes/pull/114
+
 ## 0.2.0 (2026-04-10)
 ## Added
 - `GenericBeltCtr` and `GenericBeltCtrCore` types ([#112])

belt-ctr/CHANGELOG.md

@@ -1,24 +1,24 @@
 [package]
 name = "belt-ctr"
-version = "0.2.0"
-description = "CTR block mode of operation specified by the BelT standard"
+version = "0.2.1"
 authors = ["RustCrypto Developers"]
-license = "MIT OR Apache-2.0"
 edition = "2024"
 rust-version = "1.85"
-readme = "README.md"
 documentation = "https://docs.rs/belt-ctr"
+readme = "README.md"
 repository = "https://github.com/RustCrypto/block-modes"
+license = "MIT OR Apache-2.0"
 keywords = ["crypto", "block-mode", "stream-cipher", "ciphers", "belt"]
 categories = ["cryptography", "no-std"]
+description = "CTR block mode of operation specified by the BelT standard"
 
 [dependencies]
-cipher = { version = "0.5", features = ["stream-wrapper"] }
+cipher = { version = "0.5.2", features = ["stream-wrapper"] }
 belt-block = "0.2"
 
 [dev-dependencies]
+cipher = { version = "0.5.2", features = ["dev"] }
 hex-literal = "1"
-cipher = { version = "0.5", features = ["dev"] }
 
 [features]
 alloc = ["cipher/alloc"]

belt-ctr/Cargo.toml

@@ -12,7 +12,7 @@ use belt_block::BeltBlock;
 use cipher::{
     AlgorithmName, Block, BlockCipherDecrypt, BlockCipherEncBackend, BlockCipherEncClosure,
     BlockCipherEncrypt, BlockSizeUser, InOut, InnerIvInit, Iv, IvSizeUser, IvState, ParBlocks,
-    ParBlocksSizeUser, StreamCipherBackend, StreamCipherClosure, StreamCipherCore,
+    ParBlocksSizeUser, SetIvState, StreamCipherBackend, StreamCipherClosure, StreamCipherCore,
     StreamCipherCoreWrapper, StreamCipherSeekCore, array::Array, common::InnerUser, consts::U16,
 };
 use core::fmt;
@@ -41,11 +41,13 @@ impl<C> StreamCipherCore for GenericBeltCtrCore<C>
 where
     C: BlockCipherEncrypt + BlockSizeUser<BlockSize = U16>,
 {
+    #[inline]
     fn remaining_blocks(&self) -> Option<usize> {
         let used = self.s.wrapping_sub(self.s_init);
         (u128::MAX - used).try_into().ok()
     }
 
+    #[inline]
     fn process_with_backend(&mut self, f: impl StreamCipherClosure<BlockSize = Self::BlockSize>) {
         struct Closure<'a, C: StreamCipherClosure<BlockSize = U16>> {
             s: &'a mut u128,
@@ -75,10 +77,12 @@ where
 {
     type Counter = u128;
 
+    #[inline]
     fn get_block_pos(&self) -> Self::Counter {
         self.s.wrapping_sub(self.s_init)
     }
 
+    #[inline]
     fn set_block_pos(&mut self, pos: Self::Counter) {
         self.s = self.s_init.wrapping_add(pos);
     }
@@ -126,17 +130,31 @@ impl<C> IvState for GenericBeltCtrCore<C>
 where
     C: BlockCipherEncrypt + BlockCipherDecrypt + BlockSizeUser<BlockSize = U16>,
 {
+    #[inline]
     fn iv_state(&self) -> Iv<Self> {
         let mut t = self.s.to_le_bytes().into();
         self.cipher.decrypt_block(&mut t);
         t
     }
 }
 
+impl<C> SetIvState for GenericBeltCtrCore<C>
+where
+    C: BlockCipherEncrypt + BlockCipherDecrypt + BlockSizeUser<BlockSize = U16>,
+{
+    #[inline]
+    fn set_iv(&mut self, iv: &Iv<Self>) {
+        let mut iv = *iv;
+        self.cipher.encrypt_block(&mut iv);
+        self.s = u128::from_le_bytes(iv.0);
+    }
+}
+
 impl<C> AlgorithmName for GenericBeltCtrCore<C>
 where
     C: BlockCipherEncrypt + BlockSizeUser<BlockSize = U16> + AlgorithmName,
 {
+    #[inline]
     fn write_alg_name(f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str("BeltCtr<")?;
         <C as AlgorithmName>::write_alg_name(f)?;
@@ -160,6 +178,7 @@ impl<C: BlockCipherEncrypt> Drop for GenericBeltCtrCore<C>
 where
     C: BlockCipherEncrypt + BlockSizeUser<BlockSize = U16>,
 {
+    #[inline]
     fn drop(&mut self) {
         #[cfg(feature = "zeroize")]
         {

belt-ctr/src/lib.rs

@@ -0,0 +1,33 @@
+//! Basic tests for `IvState` and `SetIvState` trait impls
+use belt_ctr::BeltCtrCore;
+use cipher::{IvState, KeyIvInit, SetIvState, StreamCipherCore};
+
+cipher::iv_state_test!(belt_ctr_iv_state, BeltCtrCore, apply_ks);
+
+#[test]
+fn belt_ctr_set_iv() {
+    let key = Default::default();
+    let iv = Default::default();
+    let mut mode = BeltCtrCore::new(&key, &iv);
+
+    let mut blocks = [Default::default(); 16];
+
+    mode.apply_keystream_blocks(&mut blocks);
+    let iv = mode.iv_state();
+
+    let mut buf1 = blocks;
+    let mut buf2 = blocks;
+
+    mode.peek(|m| m.apply_keystream_blocks(&mut buf1));
+    assert_eq!(mode.iv_state(), iv);
+
+    mode.apply_keystream_blocks(&mut blocks);
+    let iv2 = mode.iv_state();
+
+    mode.set_iv(&iv);
+    mode.apply_keystream_blocks(&mut buf2);
+
+    assert_eq!(blocks, buf1);
+    assert_eq!(blocks, buf2);
+    assert_eq!(mode.iv_state(), iv2);
+}

belt-ctr/tests/iv_state.rs

@@ -1,7 +1,6 @@
 //! Test vectors from the BelT standard (tables A.15 and A.16):
 //! https://apmi.bsu.by/assets/files/std/belt-spec371.pdf
-use belt_ctr::{BeltCtr, BeltCtrCore};
+use belt_ctr::BeltCtr;
 
 cipher::stream_cipher_test!(belt_ctr_core, "belt-ctr", BeltCtr);
 cipher::stream_cipher_seek_test!(belt_ctr_seek, BeltCtr);
-cipher::iv_state_test!(belt_ctr_iv_state, BeltCtrCore, apply_ks);

belt-ctr/tests/mod.rs

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 0.2.1 (2026-05-20)
+### Added
+- Implementation of the `SetIvState` trait ([#114])
+
+[#114]: https://github.com/RustCrypto/block-modes/pull/114
+
 ## 0.2.0 (2026-04-10)
 ### Removed
 - `std` feature ([#76])

cbc/CHANGELOG.md

@@ -1,24 +1,24 @@
 [package]
 name = "cbc"
-version = "0.2.0"
-description = "Cipher Block Chaining (CBC) block cipher mode of operation"
+version = "0.2.1"
 authors = ["RustCrypto Developers"]
-license = "MIT OR Apache-2.0"
 edition = "2024"
 rust-version = "1.85"
-readme = "README.md"
 documentation = "https://docs.rs/cbc"
+readme = "README.md"
 repository = "https://github.com/RustCrypto/block-modes"
+license = "MIT OR Apache-2.0"
 keywords = ["crypto", "block-mode", "ciphers"]
 categories = ["cryptography", "no-std"]
+description = "Cipher Block Chaining (CBC) block cipher mode of operation"
 
 [dependencies]
-cipher = "0.5"
+cipher = "0.5.2"
 
 [dev-dependencies]
-aes = "0.9"
-cipher = { version = "0.5", features = ["dev"] }
+cipher = { version = "0.5.2", features = ["dev"] }
 hex-literal = "1"
+aes = "0.9"
 
 [features]
 default = ["block-padding"]

cbc/Cargo.toml

@@ -2,7 +2,7 @@ use crate::xor;
 use cipher::{
     AlgorithmName, Block, BlockCipherDecBackend, BlockCipherDecClosure, BlockCipherDecrypt,
     BlockModeDecBackend, BlockModeDecClosure, BlockModeDecrypt, BlockSizeUser, InnerIvInit, Iv,
-    IvState, ParBlocks, ParBlocksSizeUser,
+    IvState, ParBlocks, ParBlocksSizeUser, SetIvState,
     array::{Array, ArraySize},
     common::{InnerUser, IvSizeUser},
     inout::InOut,
@@ -107,6 +107,16 @@ where
     }
 }
 
+impl<C> SetIvState for Decryptor<C>
+where
+    C: BlockCipherDecrypt,
+{
+    #[inline]
+    fn set_iv(&mut self, iv: &Iv<Self>) {
+        self.iv = iv.clone();
+    }
+}
+
 impl<C> AlgorithmName for Decryptor<C>
 where
     C: BlockCipherDecrypt + AlgorithmName,