EVP_SIGNATURE-DSA(7ossl)

📦
version 15.1 · 3 versions
, in freebsd 15.1

💜 EVP_SIGNATURE-DSA 💜

okay bestie, so this is the EVP_SIGNATURE-DSA page from the 7ossl manual — welcome to the DSA signature corner of OpenSSL 🌸 grab a strawberry drink, we're getting into it.

✨ NAME ✨

EVP_SIGNATURE-DSA — the EVP_PKEY DSA signature implementation. that's it, that's the whole name 🎀

🦋 DESCRIPTION 🦋

so basically this is your support system for computing DSA signatures. the signature you get out of EVP_PKEY_sign(3) is DER encoded ASN.1, in the form described in RFC 3279, section 2.2.2 — that's just the shape it comes in, iykyk. if you want the whole tea on DSA keys (not signatures), that's over in EVP_PKEY-DSA(7) 💅

ngl there's some FIPS lore you need to know: as part of FIPS 140-3, DSA is no longer FIPS approved for key generation and signature validation, but it's still allowed for signature verification. so like... it's giving "still invited to the party, just not to the main stage" 😭

👑 Algorithm Names

okay so in this list, names are grouped together to signify they're the same algorithm having multiple names. it also includes the OID in canonical decimal form — meaning you can actually fetch them if the caller only has a mere OID that came out in this form after a call to OBJ_obj2txt(3). handy fr fr ⭐

  • "DSA", "dsaEncryption", "1.2.840.10040.4.1" — the base signature algorithm. supported explicitly fetched with EVP_PKEY_sign_init_ex2(3), and implicitly fetched (through EC keys) with EVP_DigestSignInit(3) and EVP_DigestVerifyInit(3). lowkey important: it can't be used with EVP_PKEY_sign_message_init(3), so don't try it 🙈
  • "DSA-SHA1", "DSA-SHA-1", "dsaWithSHA1", "1.2.840.10040.4.3" — DSA signature schemes with diverse message digest algorithms. they are all supported explicitly fetched with EVP_PKEY_sign_init_ex2(3) and EVP_PKEY_sign_message_init(3).
  • "DSA-SHA2-224", "DSA-SHA224", "dsa_with_SHA224", "2.16.840.1.101.3.4.3.1" — same deal, same support ✨
  • "DSA-SHA2-256", "DSA-SHA256", "dsa_with_SHA256", "2.16.840.1.101.3.4.3.2" — same deal, same support ✨
  • "DSA-SHA2-384", "DSA-SHA384", "dsa_with_SHA384", "id-dsa-with-sha384", "1.2.840.1.101.3.4.3.3" — same deal, same support ✨
  • "DSA-SHA2-512", "DSA-SHA512", "dsa_with_SHA512", "id-dsa-with-sha512", "1.2.840.1.101.3.4.3.4" — same deal, same support ✨
  • "DSA-SHA3-224", "dsa_with_SHA3-224", "id-dsa-with-sha3-224", "2.16.840.1.101.3.4.3.5" — same deal, same support ✨
  • "DSA-SHA3-256", "dsa_with_SHA3-256", "id-dsa-with-sha3-256", "2.16.840.1.101.3.4.3.6" — same deal, same support ✨
  • "DSA-SHA3-384", "dsa_with_SHA3-384", "id-dsa-with-sha3-384", "2.16.840.1.101.3.4.3.7" — same deal, same support ✨
  • "DSA-SHA3-512", "dsa_with_SHA3-512", "id-dsa-with-sha3-512", "2.16.840.1.101.3.4.3.8" — same deal, same support ✨

🧚 Signature Parameters

these can be set using EVP_PKEY_CTX_set_params(). you can call that after EVP_PKEY_sign_init() or EVP_PKEY_verify_init(), and before calling EVP_PKEY_sign() or EVP_PKEY_verify(). you can also set them using EVP_PKEY_sign_init_ex() or EVP_PKEY_verify_init_ex(). options, options, options 💅

the settable ones:

  • "digest" (OSSL_SIGNATURE_PARAM_DIGEST) <UTF8 string> — the digest param.
  • "properties" (OSSL_SIGNATURE_PARAM_PROPERTIES) <UTF8 string> — the properties param.
  • both of those two ☝️ are not supported with the DSA signature schemes that already include a message digest algorithm — see "Algorithm Names" above, bestie, it's literally right there 🫶

and then these:

  • "nonce-type" (OSSL_SIGNATURE_PARAM_NONCE_TYPE) <unsigned integer>
  • "key-check" (OSSL_SIGNATURE_PARAM_FIPS_KEY_CHECK) <integer>
  • "digest-check" (OSSL_SIGNATURE_PARAM_FIPS_DIGEST_CHECK) <integer>
  • "sign-check" (OSSL_SIGNATURE_PARAM_FIPS_SIGN_CHECK) <int>

these settable parameters are described in provider-signature(7) — that's where the full lore lives 🔥

the following signature parameters can be retrieved using EVP_PKEY_CTX_get_params():

  • "algorithm-id" (OSSL_SIGNATURE_PARAM_ALGORITHM_ID) <octet string>
  • "digest" (OSSL_SIGNATURE_PARAM_DIGEST) <UTF8 string>
  • "nonce-type" (OSSL_SIGNATURE_PARAM_NONCE_TYPE) <unsigned integer>
  • "fips-indicator" (OSSL_SIGNATURE_PARAM_FIPS_APPROVED_INDICATOR) <integer>

and the gettable parameters are described in provider-signature(7) too 🌈

🔥 SEE ALSO 🔥

go read these next, bestie, they ate:

🌸 HISTORY 🌸

DSA Key generation and signature generation are no longer FIPS approved in OpenSSL 3.4. see "FIPS indicators" in fips_module(7) for more information — that's the receipts, periodt 👑

Copyright 2020-2026 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>.

okay that's the whole page, you're so welcome 🫶 this was 3.5.6, dated 2026-04-07 — mwah, go sign something (or verify it, since apparently that's the FIPS-approved vibe now) 💅✨

📦 where this page comes from