EVP\_CIPHER-NULL(7ossl) OpenSSL EVP\_CIPHER-NULL(7ossl)

# [NAME](#NAME)

EVP\_CIPHER-NULL - The NULL EVP\_CIPHER implementation

# [DESCRIPTION](#DESCRIPTION)

Support for a NULL symmetric encryption using the **EVP\_CIPHER** API. This is used when the TLS cipher suite is TLS\_NULL\_WITH\_NULL\_NULL. This does no encryption (just copies the data) and has a mac size of zero.

## [Algorithm Name](#Algorithm_Name)

The following algorithm is available in the default provider:

"NULL"

## [Parameters](#Parameters)

This implementation supports the following parameters:

*Gettable EVP\_CIPHER parameters*

See "Gettable EVP\_CIPHER parameters" in [**EVP\_EncryptInit**(3)](/man/os/openssl/EVP_EncryptInit.3)

*Gettable EVP\_CIPHER\_CTX parameters*

"keylen" (**OSSL\_CIPHER\_PARAM\_KEYLEN**) <unsigned integer>

"ivlen" (**OSSL\_CIPHER\_PARAM\_IVLEN** and <**OSSL\_CIPHER\_PARAM\_AEAD\_IVLEN**) <unsigned integer>

"tls-mac" (**OSSL\_CIPHER\_PARAM\_TLS\_MAC**) <octet ptr>

See "PARAMETERS" in [**EVP\_EncryptInit**(3)](/man/os/openssl/EVP_EncryptInit.3) for further information.

*Settable EVP\_CIPHER\_CTX parameters*

"tls-mac-size" (**OSSL\_CIPHER\_PARAM\_TLS\_MAC\_SIZE**) <unsigned integer>

See "PARAMETERS" in [**EVP\_EncryptInit**(3)](/man/os/openssl/EVP_EncryptInit.3) for further information.

# [CONFORMING TO](#CONFORMING_TO)

RFC 5246 section-6.2.3.1

# [SEE ALSO](#SEE_ALSO)

[**provider-cipher**(7)](/man/os/openssl/provider-cipher.7), [**OSSL\_PROVIDER-default**(7)](/man/os/openssl/OSSL_PROVIDER-default.7)

# [COPYRIGHT](#COPYRIGHT)

Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

2026-09-29 3.6.5

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Document: EVP_CIPHER-NULL(7ossl) from openssl 3.6.5-r2 (Chainguard OS)
Source: https://github.com/openssl/openssl