Skip to content

Document RSA-OAEP default padding in PKCS#11 provider #681

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
mtrojnar merged 1 commit into from
Sep 4, 2026
+24 −0
Merged

Document RSA-OAEP default padding in PKCS#11 provider #681

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions NEWS
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@ New in 0.4.21; unreleased
an ENGINE callback now leaks methods; use the bundled engine, which caches
methods per ENGINE.
* Added PKCS#11 provider support for `openssl genpkey` (Małgorzata Olszówka)
* Documented RSA-OAEP as the default padding mode for RSA encryption and
decryption in the PKCS#11 provider

New in 0.4.20; 2026-08-08; Michał Trojnara
* Added PKCS#11 3.2 interface discovery and updated the bundled header
Expand Down
22 changes: 22 additions & 0 deletions README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -218,6 +218,28 @@ OSSL_PROVIDER_add_conf_parameter(provider, "pkcs11_module",
"/path/to/pkcs11module.so");
```

## RSA asymmetric cipher padding

Since libp11-0.4.19, the PKCS#11 provider uses RSA-OAEP padding by default for
RSA encryption and decryption. OAEP is recommended by OpenSSL for new
applications because PKCS#1 v1.5 padding has known security limitations.

To decrypt data encrypted using PKCS#1 v1.5 padding, select it explicitly:
```
$ openssl pkeyutl -decrypt \
-inkey "pkcs11:object=my-key;type=private" \
-pkeyopt rsa_padding_mode:pkcs1 \
-in secret.enc
```
RSA-OAEP with SHA-256 can be selected explicitly with:
```
-pkeyopt rsa_padding_mode:oaep \
-pkeyopt rsa_oaep_md:sha256 \
-pkeyopt rsa_mgf1_md:sha256
```

See the [OpenSSL RSA documentation](https://docs.openssl.org/master/man3/RSA_public_encrypt/#description)
for details and security considerations.

# PKCS#11 engine configuration

Expand Down
Loading