DSA_SET_METHOD(3)

💅 DSA_SET_METHOD(3) 💅

okay so this is the DSA_SET_METHOD(3) page from the Library Functions Manual, and we are about to select a DSA method. bestie, it's giving crypto internals and honestly? kinda iconic. 💖

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✨ NAME ✨

DSA_set_default_method, DSA_get_default_method, DSA_set_method, DSA_new_method, DSA_OpenSSL — select DSA method. that's the whole name situation, periodt.

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🌸 SYNOPSIS 🌸

library “libcrypto” #include <openssl/dsa.h>

void
DSA_set_default_method(const DSA_METHOD *meth);

const DSA_METHOD *
DSA_get_default_method(void);

int
DSA_set_method(DSA *dsa, const DSA_METHOD *meth);

DSA *
DSA_new_method(ENGINE *engine);

DSA_METHOD *
DSA_OpenSSL(void);

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🦋 DESCRIPTION 🦋

A DSA_METHOD object contains pointers to the functions used for DSA operations. By default, the internal implementation returned by DSA_OpenSSL() is used. By selecting another method, alternative implementations such as hardware accelerators may be used. so yes, you can swap the whole method vibe. 💫

• DSA_set_default_method() — selects meth as the default method for all DSA structures created later. future DSA structures get this method, no cap. ✨
• DSA_get_default_method() — returns a pointer to the current default method. that's it, that's the tea. 🍵
• DSA_set_method() — selects meth to perform all operations using the key dsa. This replaces the DSA_METHOD used by the DSA key. It is possible to have DSA keys that only work with certain DSA_METHOD implementations, and in such cases attempting to change the DSA_METHOD for the key can have unexpected results. ⚠️ bestie, this caveat is real — do not ignore it.
• DSA_new_method() — allocates and initializes a DSA structure. The engine argument is ignored and the default method controlled by DSA_set_default_method() is used. so engine is just sitting there, ignored, living its truth. 🙈

The DSA_METHOD structure is defined as follows:

struct {
        /* name of the implementation */
        const char *name;
        /* sign */
        DSA_SIG *(*dsa_do_sign)(const unsigned char *dgst, int dlen,
            DSA *dsa);
        /* pre-compute k^-1 and r */
        int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
            BIGNUM **rp);
        /* verify */
        int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
            DSA_SIG *sig, DSA *dsa);
        /* called at DSA_new */
        int (*init)(DSA *DSA);
        /* called at DSA_free */
        int (*finish)(DSA *DSA);
        int flags;
} DSA_METHOD;

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💖 RETURN VALUES 💖

• DSA_OpenSSL() and DSA_get_default_method() return pointers to the respective DSA_METHOD. pointers to the method, exactly like it says. 🫶
• DSA_set_method() returns 1 on success or 0 on failure. Currently, it cannot fail. so that failure path is lowkey just sitting there rn. 😭
• DSA_new_method() returns NULL and sets an error code that can be obtained by ERR_get_error(3) if the allocation fails. Otherwise it returns a pointer to the newly allocated structure. bestie, if it's NULL, go check that error. 🚨

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🔥 SEE ALSO 🔥

• DSA_meth_new(3)
• DSA_new(3)

go read these next, bestie. iykyk. 👑

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👑 HISTORY 👑

DSA_set_default_method(), DSA_get_default_method(), DSA_set_method(), DSA_new_method(), and DSA_OpenSSL() first appeared in OpenSSL 0.9.5 and have been available since OpenBSD 2.7. literally vintage. 🎀

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mwah 💋 — this page was brought to you by Debian, dated June 8, 2025. stay slaying, and remember: the vibe changes, the facts do not. 💖