---
name: "DSA_do_sign"
section: "3ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/DSA_do_sign"
---

# DSA\_do\_sign(3ssl)

raw DSA signature operations

## NAME

DSA\_do\_sign, DSA\_do\_verify - raw DSA signature operations

## SYNOPSIS

```
 #include <openssl/dsa.h>
```

The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining **OPENSSL\_API\_COMPAT** with a suitable version value, see **openssl\_user\_macros**(7):

```
 DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
 int DSA_do_verify(const unsigned char *dgst, int dgst_len,
                   DSA_SIG *sig, DSA *dsa);
```

## DESCRIPTION

All of the functions described on this page are deprecated. Applications should instead use **EVP\_PKEY\_sign\_init**(3), **EVP\_PKEY\_sign**(3), **EVP\_PKEY\_verify\_init**(3) and **EVP\_PKEY\_verify**(3).

**DSA\_do\_sign()** computes a digital signature on the **len** byte message digest **dgst** using the private key **dsa** and returns it in a newly allocated **DSA\_SIG** structure.

**DSA\_sign\_setup**(3) may be used to precompute part of the signing operation in case signature generation is time-critical.

**DSA\_do\_verify()** verifies that the signature **sig** matches a given message digest **dgst** of size **len**.  **dsa** is the signer's public key.

## RETURN VALUES

**DSA\_do\_sign()** returns the signature, NULL on error.  **DSA\_do\_verify()** returns 1 for a valid signature, 0 for an incorrect signature and -1 on error. The error codes can be obtained by **ERR\_get\_error**(3).

## SEE ALSO

**DSA\_new**(3), **ERR\_get\_error**(3), **RAND\_bytes**(3), **DSA\_SIG\_new**(3), **DSA\_sign**(3)

## HISTORY

All of these functions were deprecated in OpenSSL 3.0.

## COPYRIGHT

Copyright 2000-2021 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\>.