Bug 2153470

Summary:	Backport implicit rejection for RSA PKCS#1 v1.5 encryption
Product:	[Fedora] Fedora	Reporter:	Alicja Kario <hkario>
Component:	openssl	Assignee:	Dmitry Belyavskiy <dbelyavs>
Status:	CLOSED RAWHIDE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
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Version:	rawhide	CC:	crypto-team, dbelyavs, mspacek, mturk, sahana, support.web-tv, tm
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Last Closed:	2023-01-13 18:32:48 UTC	Type:	Bug
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Description Alicja Kario 2022-12-14 16:40:35 UTC

Description of problem:
The RSA decryption API is very easy to use incorrectly, causing issues like CVE-2020-25659 in pyca/cryptography. Please backport the recently merged implementation of implicit rejection to OpenSSL so that issues like that are properly addressed.

Version-Release number of selected component (if applicable):
openssl-3.0.5-7

How reproducible:
Always

Steps to Reproduce:
1. Try to decrypt a malformed RSA ciphertext using PKCS#1 v1.5 padding

Actual results:
Usually, an error is returned.

Expected results:
A random, but static (for a given ciphertext-key pair) message is returned.

Additional info:

Comment 1 Dmitry Belyavskiy 2023-01-05 17:34:03 UTC

Added and enabled by default implicit rejection in RSA PKCS#1 v1.5 decryption as a protection against Bleichenbacher-like attacks.

The RSA decryption API will now return a randomly generated deterministic message instead of an error in case it detects an error when checking padding during PKCS#1 v1.5 decryption. This is a general protection against issues like CVE-2020-25659 and CVE-2020-25657. 

This protection can be disabled by calling `EVP_PKEY_CTX_ctrl_str(ctx, "rsa_pkcs1_implicit_rejection". "0")` on the RSA decryption context.