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ARIA-ECB

Algorithm​

ARIA is a 128-bit block cipher (KR standard). Electronic codebook (ECB) encrypts each 16-byte block with the same key and no initialization vector: identical plaintext blocks always produce identical ciphertext blocks, so structure in the message can leak.

These helpers require block-aligned input: length must be a multiple of 16. They do not add or remove padding; callers must align payloads or use another mode (for example ARIA-CBC).

Purpose​

Expose ARIA-ECB only for legacy interoperability, test vectors, or as a primitive inside a higher-level construction. Do not use ECB as the sole protection for formatted or long messages; prefer ARIA-CBC, ARIA-CTR, or an AEAD elsewhere in the stack when the protocol allows.

Rust API​

  • Crate: noxtls-crypto
  • Module path (conceptual): noxtls_crypto::sym (re-exported at crate root only when the feature below is enabled)
  • Primary symbols:
    • AriaCipher
    • noxtls_aria_ecb_encrypt
    • noxtls_aria_ecb_decrypt

Functions and types:

  • AriaCipher::new(key) -> Result<AriaCipher> - Parameters: key is 16, 24, or 32 bytes (128-, 192-, or 256-bit ARIA). Behavior: expands the ARIA key schedule. Returns: AriaCipher on success, or InvalidLength for unsupported key sizes.
  • noxtls_aria_ecb_encrypt(cipher, input) -> Result<Vec<u8>> - Parameters: cipher is an initialized AriaCipher; input must be block-aligned (length multiple of 16). Behavior: ARIA-ECB encryption block by block. Returns: ciphertext Vec<u8> of the same length, or InvalidLength if misaligned.
  • noxtls_aria_ecb_decrypt(cipher, input) -> Result<Vec<u8>> - Parameters: same cipher; input is ECB ciphertext, block-aligned. Behavior: ARIA-ECB decryption. Returns: plaintext Vec<u8> of the same length, or InvalidLength if misaligned.

Feature flags and policy​

noxtls_aria_ecb_encrypt and noxtls_aria_ecb_decrypt are compiled and exported only when hazardous-legacy-crypto is enabled on noxtls-crypto.

Examples​

// Requires `noxtls-crypto` with feature `hazardous-legacy-crypto`.
use noxtls_crypto::{AriaCipher, noxtls_aria_ecb_decrypt, noxtls_aria_ecb_encrypt};

let key = [0x11u8; 16];
let cipher = AriaCipher::new(&key)?;
let plaintext = [0xA5u8; 16];
let ciphertext = noxtls_aria_ecb_encrypt(&cipher, &plaintext)?;
let roundtrip = noxtls_aria_ecb_decrypt(&cipher, &ciphertext)?;
assert_eq!(roundtrip, plaintext);
# Ok::<(), noxtls_core::Error>(())

Security and compatibility​

ECB does not hide repeated plaintext blocks and provides no integrity. It is inappropriate for typical “encrypt a payload” use. If you enable this API, keep usage narrow and reviewed.