dsa - Digital Signature Algorithm
#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);
These functions implement the Digital Signature Algorithm (DSA). The generation of shared DSA parameters is described in DSA_generate_parameters(3); DSA_generate_key(3) describes how to generate a signature key. Signature generation and verification are described in DSA_sign(3). The DSA structure consists of several BIGNUM components. 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; In public keys, priv_key is NULL. Note that DSA keys may use non-standard DSA_METHOD implementations, either directly or by the use of ENGINE modules. In some cases (eg. an ENGINE providing support for hardware-embedded keys), these BIGNUM values will not be used by the implementation or may be used for alternative data storage. For this reason, applications should generally avoid using DSA structure elements directly and instead use API functions to query or modify keys.
US Federal Information Processing Standard FIPS 186 (Digital Signature Standard, DSS), ANSI X9.30
bn(3), dh(3), err(3), rand(3), rsa(3), sha(3), engine(3), DSA_new(3), DSA_size(3), DSA_generate_parameters(3), DSA_dup_DH(3), DSA_generate_key(3), DSA_sign(3), DSA_set_method(3), DSA_get_ex_new_index(3), RSA_print(3)
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.