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RUSTSEC-2023-0068

Sequential calls of encryption API (encrypt, wrap, and dump) result in nonce reuse
Reported
Issued
Package
cocoon (crates.io)
Type
Vulnerability
Categories
Keywords
#nonce #stream-cipher
Aliases
References
CVSS Score
4.5 MEDIUM
CVSS Details
Attack vector
Local
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
CVSS Vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Patched
  • >=0.4.0
Affected Functions
Version
cocoon::Cocoon::dump
  • <=0.3.3
cocoon::Cocoon::encrypt
  • <=0.3.3
cocoon::Cocoon::wrap
  • <=0.3.3
cocoon::MiniCocoon::dump
  • <=0.3.3
cocoon::MiniCocoon::encrypt
  • <=0.3.3
cocoon::MiniCocoon::wrap
  • <=0.3.3

Description

Problem: Trying to create a new encrypted message with the same cocoon object generates the same ciphertext. It mostly affects MiniCocoon and Cocoon objects with custom seeds and RNGs (where StdRng is used under the hood).

Note: The issue does NOT affect objects created with Cocoon::new which utilizes ThreadRng.

Cause: StdRng produces the same nonce because StdRng::clone resets its state.

Measure: Make encryption API mutable (encrypt, wrap, and dump).

Workaround: Create a new cocoon object with a new seed per each encryption.

How to Reproduce

let cocoon = MiniCocoon::from_password(b"password", &[1; 32]);
let mut data1 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data1)?;

let mut data2 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data2)?;

// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]
// data2: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]

Workaround

For cocoon <= 0.3.3, create a new cocoon with a different seed per each encrypt/wrap/dump call.

let cocoon = MiniCocoon::from_password(b"password", &[1; 32]);
let mut data1 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data1)?;

// Another seed: &[2; 32].
let cocoon = MiniCocoon::from_password(b"password", &[2; 32]);
let mut data2 = "my secret data".to_owned().into_bytes();
let _ = cocoon.encrypt(&mut data2)?;

// data1: [23, 217, 251, 151, 179, 62, 85, 15, 253, 92, 192, 112, 200, 52]
// data2: [53, 223, 209, 96, 130, 99, 209, 108, 83, 189, 123, 81, 19, 1]

Advisory available under CC0-1.0 license.