DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures
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):
int DSA_sign(int type, const unsigned char *dgst, int len, unsigned char *sigret, unsigned int *siglen, DSA *dsa); int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp, BIGNUM **rp); int DSA_verify(int type, const unsigned char *dgst, int len, unsigned char *sigbuf, int siglen, DSA *dsa);
DSA_sign() computes a digital signature on the len byte message digest dgst using the private key dsa and places its ASN.1 DER encoding at sigret. The length of the signature is places in *siglen. sigret must point to DSA_size(dsa) bytes of memory.
DSA_sign_setup() is defined only for backward binary compatibility and should not be used. Since OpenSSL 1.1.0 the DSA type is opaque and the output of DSA_sign_setup() cannot be used anyway: calling this function will only cause overhead, and does not affect the actual signature (pre-)computation.
DSA_verify() verifies that the signature sigbuf of size siglen matches a given message digest dgst of size len. dsa is the signer's public key.
The type parameter is ignored.
The random generator must be seeded when DSA_sign() (or DSA_sign_setup()) is called. If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to external circumstances (see RAND(7)), the operation will fail.
DSA_sign() and DSA_sign_setup() return 1 on success, 0 on error. DSA_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).
US Federal Information Processing Standard FIPS 186 (Digital Signature Standard, DSS), ANSI X9.30
All of these functions were deprecated in OpenSSL 3.0.
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