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EVP_SIGNATURE-HMAC(7SSL) OpenSSL EVP_SIGNATURE-HMAC(7SSL)

📛 NAME

EVP_SIGNATURE-HMAC, EVP_SIGNATURE-Siphash, EVP_SIGNATURE-Poly1305, EVP_SIGNATURE-CMAC — The legacy EVP_PKEY MAC signature implementations

🚀 Quick Reference

Use Case	Command	Description
🔐 Create HMAC via legacy API	EVP_DigestSignInit(ctx, NULL, EVP_sha256(), NULL, key)	Initialise a signing operation with an HMAC key using SHA-256
🔐 Create Siphash via legacy API	EVP_DigestSignInit(ctx, NULL, NULL, NULL, siphash_key)	Initialise a signing operation with a Siphash key
🔐 Create Poly1305 via legacy API	EVP_DigestSignInit(ctx, NULL, NULL, NULL, poly1305_key)	Initialise a signing operation with a Poly1305 key
🔐 Create CMAC via legacy API	EVP_DigestSignInit(ctx, NULL, NULL, NULL, cmac_key)	Initialise a signing operation with a CMAC key
⚙️ Set signature parameters	EVP_PKEY_CTX_set_params(ctx, params)	Set MAC parameters (e.g. digest, key, salt) on the EVP_PKEY context
🆕 Preferred modern API	EVP_MAC_init(mac_ctx, key, params)	Use EVP_MAC_init instead of legacy EVP_DigestSignInit for new code

📖 DESCRIPTION

The algorithms described here have legacy support for creating MACs using EVP_DigestSignInit(3) and related functions. This is not the preferred way of creating MACs. Instead you should use the newer EVP_MAC_init(3) functions. This mechanism is provided for backwards compatibility with older versions of OpenSSL.

The same signature parameters can be set using EVP_PKEY_CTX_set_params() as can be set via EVP_MAC_CTX_set_params() for the underlying EVP_MAC. See EVP_MAC-HMAC(7), EVP_MAC-Siphash(7), EVP_MAC-Poly1305(7) and EVP_MAC-CMAC(7) for details.

See EVP_PKEY-HMAC(7), EVP_PKEY-Siphash(7), EVP_PKEY-Poly1305(7) or EVP_PKEY-CMAC(7) for details about parameters that are supported during the creation of an EVP_PKEY.

📚 SEE ALSO

• EVP_MAC_init(3)
• EVP_DigestSignInit(3)
• EVP_PKEY-HMAC(7)
• EVP_PKEY-Siphash(7)
• EVP_PKEY-Poly1305(7)
• EVP_PKEY-CMAC(7)
• EVP_MAC-HMAC(7)
• EVP_MAC-Siphash(7)
• EVP_MAC-Poly1305(7)
• EVP_MAC-CMAC(7)
• provider-signature(7)

©️ COPYRIGHT

Copyright 2020 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.

3.0.2 2026-06-02 EVP_SIGNATURE-HMAC(7SSL)

EVP_SIGNATURE-HMAC(7SSL) OpenSSL EVP_SIGNATURE-HMAC(7SSL) 📛 NAME 🚀 Quick Reference 📖 DESCRIPTION 📚 SEE ALSO ©️ COPYRIGHT