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.tr \(*W- . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\}
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Title "dsa 3" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
dsa - Digital Signature Algorithm Header "SYNOPSIS" .Vb 2 #include <openssl/dsa.h> #include <openssl/engine.h> \& DSA * DSA_new(void); void DSA_free(DSA *dsa); \& int DSA_size(const DSA *dsa); \& DSA * DSA_generate_parameters(int bits, unsigned char *seed, int seed_len, int *counter_ret, unsigned long *h_ret, void (*callback)(int, int, void *), void *cb_arg); \& DH * DSA_dup_DH(const DSA *r); \& int DSA_generate_key(DSA *dsa); \& int DSA_sign(int dummy, 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 dummy, const unsigned char *dgst, int len, const unsigned char *sigbuf, int siglen, DSA *dsa); \& 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); const DSA_METHOD *DSA_OpenSSL(void); \& int DSA_get_ex_new_index(long argl, char *argp, int (*new_func)(), int (*dup_func)(), void (*free_func)()); int DSA_set_ex_data(DSA *d, int idx, char *arg); char *DSA_get_ex_data(DSA *d, int idx); \& DSA_SIG *DSA_SIG_new(void); void DSA_SIG_free(DSA_SIG *a); int i2d_DSA_SIG(const DSA_SIG *a, unsigned char **pp); DSA_SIG *d2i_DSA_SIG(DSA_SIG **v, unsigned char **pp, long length); \& 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); \& DSA * d2i_DSAPublicKey(DSA **a, unsigned char **pp, long length); DSA * d2i_DSAPrivateKey(DSA **a, unsigned char **pp, long length); DSA * d2i_DSAparams(DSA **a, unsigned char **pp, long length); int i2d_DSAPublicKey(const DSA *a, unsigned char **pp); int i2d_DSAPrivateKey(const DSA *a, unsigned char **pp); int i2d_DSAparams(const DSA *a,unsigned char **pp); \& int DSAparams_print(BIO *bp, const DSA *x); int DSAparams_print_fp(FILE *fp, const DSA *x); int DSA_print(BIO *bp, const DSA *x, int off); int DSA_print_fp(FILE *bp, const DSA *x, int off); .Ve Header "DESCRIPTION" These functions implement the Digital Signature Algorithm (\s-1DSA\s0). The generation of shared \s-1DSA\s0 parameters is described in \fIDSA_generate_parameters\|(3); \fIDSA_generate_key\|(3) describes how to generate a signature key. Signature generation and verification are described in DSA_sign\|(3).

The \s-1DSA\s0 structure consists of several \s-1BIGNUM\s0 components.

.Vb 10 struct { BIGNUM *p; // prime number (public) BIGNUM *q; // 160-bit subprime, q | p-1 (public) BIGNUM *g; // generator of subgroup (public) BIGNUM *priv_key; // private key x BIGNUM *pub_key; // public key y = g^x // ... } DSA; .Ve

In public keys, priv_key is \s-1NULL.\s0

Note that \s-1DSA\s0 keys may use non-standard \s-1DSA_METHOD\s0 implementations, either directly or by the use of \s-1ENGINE\s0 modules. In some cases (eg. an \s-1ENGINE\s0 providing support for hardware-embedded keys), these \s-1BIGNUM\s0 values will not be used by the implementation or may be used for alternative data storage. For this reason, applications should generally avoid using \s-1DSA\s0 structure elements directly and instead use \s-1API\s0 functions to query or modify keys.

Header "CONFORMING TO" \s-1US\s0 Federal Information Processing Standard \s-1FIPS 186 \s0(Digital Signature Standard, \s-1DSS\s0), \s-1ANSI X9.30\s0 Header "SEE ALSO" \fIbn\|(3), dh\|(3), err\|(3), rand\|(3), \fIrsa\|(3), sha\|(3), engine\|(3), \fIDSA_new\|(3), \fIDSA_size\|(3), \fIDSA_generate_parameters\|(3), \fIDSA_dup_DH\|(3), \fIDSA_generate_key\|(3), \fIDSA_sign\|(3), DSA_set_method\|(3), \fIDSA_get_ex_new_index\|(3), \fIRSA_print\|(3)