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dsa


  1. dsa.1.man
  2. dsa.3.man


1. dsa.1.man

Manpage of DSA

DSA

Section: OpenSSL (1)
Updated: 2003-01-30
Index Return to Main Contents
 

NAME

dsa - DSA key processing  

SYNOPSIS

openssl dsa [-inform PEM|DER] [-outform PEM|DER] [-in filename] [-passin arg] [-out filename] [-passout arg] [-des] [-des3] [-idea] [-text] [-noout] [-modulus] [-pubin] [-pubout] [-engine id]  

DESCRIPTION

The dsa command processes DSA keys. They can be converted between various forms and their components printed out. Note This command uses the traditional SSLeay compatible format for private key encryption: newer applications should use the more secure PKCS#8 format using the pkcs8  

COMMAND OPTIONS

-inform DER|PEM
This specifies the input format. The DER option with a private key uses an ASN1 DER encoded form of an ASN.1 SEQUENCE consisting of the values of version (currently zero), p, q, g, the public and private key components respectively as ASN.1 INTEGERs. When used with a public key it uses a SubjectPublicKeyInfo structure: it is an error if the key is not DSA.

The PEM form is the default format: it consists of the DER format base64 encoded with additional header and footer lines. In the case of a private key PKCS#8 format is also accepted.

-outform DER|PEM
This specifies the output format, the options have the same meaning as the -inform option.
-in filename
This specifies the input filename to read a key from or standard input if this option is not specified. If the key is encrypted a pass phrase will be prompted for.
-passin arg
the input file password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
-out filename
This specifies the output filename to write a key to or standard output by is not specified. If any encryption options are set then a pass phrase will be prompted for. The output filename should not be the same as the input filename.
-passout arg
the output file password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
-des|-des3|-idea
These options encrypt the private key with the DES, triple DES, or the IDEA ciphers respectively before outputting it. A pass phrase is prompted for. If none of these options is specified the key is written in plain text. This means that using the dsa utility to read in an encrypted key with no encryption option can be used to remove the pass phrase from a key, or by setting the encryption options it can be use to add or change the pass phrase. These options can only be used with PEM format output files.
-text
prints out the public, private key components and parameters.
-noout
this option prevents output of the encoded version of the key.
-modulus
this option prints out the value of the public key component of the key.
-pubin
by default a private key is read from the input file: with this option a public key is read instead.
-pubout
by default a private key is output. With this option a public key will be output instead. This option is automatically set if the input is a public key.
-engine id
specifying an engine (by it's unique id string) will cause req to attempt to obtain a functional reference to the specified engine, thus initialising it if needed. The engine will then be set as the default for all available algorithms.
 

NOTES

The PEM private key format uses the header and footer lines:

 -----BEGIN DSA PRIVATE KEY-----
 -----END DSA PRIVATE KEY-----

The PEM public key format uses the header and footer lines:

 -----BEGIN PUBLIC KEY-----
 -----END PUBLIC KEY-----

 

EXAMPLES

To remove the pass phrase on a DSA private key:

 openssl dsa -in key.pem -out keyout.pem

To encrypt a private key using triple DES:

 openssl dsa -in key.pem -des3 -out keyout.pem

To convert a private key from PEM to DER format:

 openssl dsa -in key.pem -outform DER -out keyout.der

To print out the components of a private key to standard output:

 openssl dsa -in key.pem -text -noout

To just output the public part of a private key:

 openssl dsa -in key.pem -pubout -out pubkey.pem

 

SEE ALSO

dsaparam(1), gendsa(1), rsa(1), genrsa(1)


 

Index

NAME
SYNOPSIS
DESCRIPTION
COMMAND OPTIONS
NOTES
EXAMPLES
SEE ALSO

This document was created by man2html using the manual pages.
Time: 17:30:46 GMT, October 23, 2013

2. dsa.3.man

Manpage of dsa

dsa

Section: OpenSSL (3)
Updated: 2002-08-05
Index Return to Main Contents
 

NAME

dsa - Digital Signature Algorithm  

SYNOPSIS

 #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);

 

DESCRIPTION

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.  

CONFORMING TO

US Federal Information Processing Standard FIPS 186 (Digital Signature Standard, DSS), ANSI X9.30  

SEE ALSO

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)


 

Index

NAME
SYNOPSIS
DESCRIPTION
CONFORMING TO
SEE ALSO

This document was created by man2html using the manual pages.
Time: 17:30:46 GMT, October 23, 2013

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