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Add Bleichenbacher attack warning about PKCS#1 v1.5 #637

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Merged
tarcieri merged 1 commit into from
Jan 24, 2026
Merged

Add Bleichenbacher attack warning about PKCS#1 v1.5 #637

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11 changes: 11 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,12 @@
//! ```
//!
//! ## PKCS#1 v1.5 encryption
//!
//! <div class="warning">
//! <b>Warning:</b>
//! See security notes in the <code><a href="./pkcs1v15/index.html">pkcs1v15</a></code> module.
//! </div>
//!
//! ```
//! use rsa::{RsaPrivateKey, RsaPublicKey, Pkcs1v15Encrypt};
//!
Expand All @@ -66,6 +72,11 @@
//!
//! ## PKCS#1 v1.5 signatures
//!
//! <div class="warning">
//! <b>Warning:</b>
//! See security notes in the <code><a href="./pkcs1v15/index.html">pkcs1v15</a></code> module.
//! </div>
//!
//! Note: requires `sha2` feature of `rsa` crate is enabled.
//!
#![cfg_attr(feature = "sha2", doc = "```")]
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20 changes: 20 additions & 0 deletions src/pkcs1v15.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,25 @@
//! PKCS#1 v1.5 support as described in [RFC8017 § 8.2].
//!
//! <div class="warning">
//! <b>Warning</b>
//!
//! PKCS#1 v1.5 padding has a longstanding history of issues generally classed as
//! [Bleichenbacher Attacks] which were originally discovered in 1998 but keep reappearing in
//! various forms again and again over the course of decades, including most recently in the 2023
//! [Marvin Attack], which the `rsa` crate is [still vulnerable] to.
//!
//! These attacks can result in complete plaintext recovery for encryption, or signature forgery,
//! leading to a total failure of either confidentiality or integrity.
//!
//! Unless explicitly needed for compatibility reasons, we recommend against using PKCS#1 v1.5,
//! and suggest using [PSS][`super::pss`] or [OAEP][`super::oaep`] instead (if there is a
//! requirement to use RSA).
//! </div>
//!
//! [Bleichenbacher Attacks]: https://en.wikipedia.org/wiki/Adaptive_chosen-ciphertext_attack#Practical_attacks
//! [Marvin Attack]: https://people.redhat.com/~hkario/marvin/
//! [still vulnerable]: https://github.com/RustCrypto/RSA/issues/626
//!
//! # Usage
//!
//! See [code example in the toplevel rustdoc](../index.html#pkcs1-v15-signatures).
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