Manual Pages for UNIX Operating System command usage for man ecdsa

OpenSSL                                           ecdsa(3openssl)



NNNNAAAAMMMMEEEE
     ecdsa - Elliptic Curve Digital Signature Algorithm

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      #include 

      ECDSA_SIG*     ECDSA_SIG_new(void);
      void           ECDSA_SIG_free(ECDSA_SIG *sig);
      int            i2d_ECDSA_SIG(const ECDSA_SIG *sig, unsigned char **pp);
      ECDSA_SIG*     d2i_ECDSA_SIG(ECDSA_SIG **sig, const unsigned char **pp,
                     long len);

      ECDSA_SIG*     ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
                             EC_KEY *eckey);
      ECDSA_SIG*     ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen,
                             const BIGNUM *kinv, const BIGNUM *rp,
                             EC_KEY *eckey);
      int            ECDSA_do_verify(const unsigned char *dgst, int dgst_len,
                             const ECDSA_SIG *sig, EC_KEY* eckey);
      int            ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx,
                             BIGNUM **kinv, BIGNUM **rp);
      int            ECDSA_sign(int type, const unsigned char *dgst,
                             int dgstlen, unsigned char *sig,
                             unsigned int *siglen, EC_KEY *eckey);
      int            ECDSA_sign_ex(int type, const unsigned char *dgst,
                             int dgstlen, unsigned char *sig,
                             unsigned int *siglen, const BIGNUM *kinv,
                             const BIGNUM *rp, EC_KEY *eckey);
      int            ECDSA_verify(int type, const unsigned char *dgst,
                             int dgstlen, const unsigned char *sig,
                             int siglen, EC_KEY *eckey);
      int            ECDSA_size(const EC_KEY *eckey);

      const ECDSA_METHOD*    ECDSA_OpenSSL(void);
      void           ECDSA_set_default_method(const ECDSA_METHOD *meth);
      const ECDSA_METHOD*    ECDSA_get_default_method(void);
      int            ECDSA_set_method(EC_KEY *eckey,const ECDSA_METHOD *meth);

      int            ECDSA_get_ex_new_index(long argl, void *argp,
                             CRYPTO_EX_new *new_func,
                             CRYPTO_EX_dup *dup_func,
                             CRYPTO_EX_free *free_func);
      int            ECDSA_set_ex_data(EC_KEY *d, int idx, void *arg);
      void*          ECDSA_get_ex_data(EC_KEY *d, int idx);


DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     The EEEECCCCDDDDSSSSAAAA_SSSSIIIIGGGG structure consists of two BIGNUMs for the r
     and s value of a ECDSA signature (see X9.62 or FIPS 186-2).






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OpenSSL                                           ecdsa(3openssl)



      struct
             {
             BIGNUM *r;
             BIGNUM *s;
      } ECDSA_SIG;

     ECDSA_SIG_new() allocates a new EEEECCCCDDDDSSSSAAAA_SSSSIIIIGGGG structure (note:
     this function also allocates the BIGNUMs) and initialize it.

     ECDSA_SIG_free() frees the EEEECCCCDDDDSSSSAAAA_SSSSIIIIGGGG structure ssssiiiigggg.

     i2d_ECDSA_SIG() creates the DER encoding of the ECDSA
     signature ssssiiiigggg and writes the encoded signature to ****pppppppp (note:
     if pppppppp is NULL iiii2222dddd_EEEECCCCDDDDSSSSAAAA_SSSSIIIIGGGG returns the expected length in
     bytes of the DER encoded signature). iiii2222dddd_EEEECCCCDDDDSSSSAAAA_SSSSIIIIGGGG returns
     the length of the DER encoded signature (or 0 on error).

     d2i_ECDSA_SIG() decodes a DER encoded ECDSA signature and
     returns the decoded signature in a newly allocated EEEECCCCDDDDSSSSAAAA_SSSSIIIIGGGG
     structure.  ****ssssiiiigggg points to the buffer containing the DER
     encoded signature of size lllleeeennnn.

     ECDSA_size() returns the maximum length of a DER encoded
     ECDSA signature created with the private EC key eeeecccckkkkeeeeyyyy.

     ECDSA_sign_setup() may be used to precompute parts of the
     signing operation. eeeecccckkkkeeeeyyyy is the private EC key and ccccttttxxxx is a
     pointer to BBBBNNNN_CCCCTTTTXXXX structure (or NULL). The precomputed
     values or returned in kkkkiiiinnnnvvvv and rrrrpppp and can be used in a later
     call to EEEECCCCDDDDSSSSAAAA_ssssiiiiggggnnnn_eeeexxxx or EEEECCCCDDDDSSSSAAAA_ddddoooo_ssssiiiiggggnnnn_eeeexxxx.

     ECDSA_sign() is wrapper function for ECDSA_sign_ex with kkkkiiiinnnnvvvv
     and rrrrpppp set to NULL.

     ECDSA_sign_ex() computes a digital signature of the ddddggggssssttttlllleeeennnn
     bytes hash value ddddggggsssstttt using the private EC key eeeecccckkkkeeeeyyyy and the
     optional pre-computed values kkkkiiiinnnnvvvv and rrrrpppp. The DER encoded
     signatures is stored in ssssiiiigggg and it's length is returned in
     ssssiiiigggg_lllleeeennnn. Note: ssssiiiigggg must point to EEEECCCCDDDDSSSSAAAA_ssssiiiizzzzeeee bytes of memory.
     The parameter ttttyyyyppppeeee is ignored.

     ECDSA_verify() verifies that the signature in ssssiiiigggg of size
     ssssiiiigggglllleeeennnn is a valid ECDSA signature of the hash value value
     ddddggggsssstttt of size ddddggggssssttttlllleeeennnn using the public key eeeecccckkkkeeeeyyyy.  The
     parameter ttttyyyyppppeeee is ignored.

     ECDSA_do_sign() is wrapper function for ECDSA_do_sign_ex
     with kkkkiiiinnnnvvvv and rrrrpppp set to NULL.

     ECDSA_do_sign_ex() computes a digital signature of the
     ddddggggsssstttt_lllleeeennnn bytes hash value ddddggggsssstttt using the private key eeeecccckkkkeeeeyyyy
     and the optional pre-computed values kkkkiiiinnnnvvvv and rrrrpppp. The



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OpenSSL                                           ecdsa(3openssl)



     signature is returned in a newly allocated EEEECCCCDDDDSSSSAAAA_SSSSIIIIGGGG
     structure (or NULL on error).

     ECDSA_do_verify() verifies that the signature ssssiiiigggg is a valid
     ECDSA signature of the hash value ddddggggsssstttt of size ddddggggsssstttt_lllleeeennnn
     using the public key eeeecccckkkkeeeeyyyy.

RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEESSSS
     ECDSA_size() returns the maximum length signature or 0 on
     error.

     ECDSA_sign_setup() and ECDSA_sign() return 1 if successful
     or -1 on error.

     ECDSA_verify() and ECDSA_do_verify() return 1 for a valid
     signature, 0 for an invalid signature and -1 on error.  The
     error codes can be obtained by ERR_get_error(3).

EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS
     Creating a ECDSA signature of given SHA-1 hash value using
     the named curve secp192k1.

     First step: create a EC_KEY object (note: this part is nnnnooootttt
     ECDSA specific)

      int        ret;
      ECDSA_SIG *sig;
      EC_KEY    *eckey = EC_KEY_new();
      if (eckey == NULL)
             {
             /* error */
             }
      key->group = EC_GROUP_new_by_nid(NID_secp192k1);
      if (key->group == NULL)
             {
             /* error */
             }
      if (!EC_KEY_generate_key(eckey))
             {
             /* error */
             }

     Second step: compute the ECDSA signature of a SHA-1 hash
     value using EEEECCCCDDDDSSSSAAAA_ddddoooo_ssssiiiiggggnnnn

      sig = ECDSA_do_sign(digest, 20, eckey);
      if (sig == NULL)
             {
             /* error */
             }

     or using EEEECCCCDDDDSSSSAAAA_ssssiiiiggggnnnn



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OpenSSL                                           ecdsa(3openssl)



      unsigned char *buffer, *pp;
      int            buf_len;
      buf_len = ECDSA_size(eckey);
      buffer  = OPENSSL_malloc(buf_len);
      pp = buffer;
      if (!ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey);
             {
             /* error */
             }

     Third step: verify the created ECDSA signature using
     EEEECCCCDDDDSSSSAAAA_ddddoooo_vvvveeeerrrriiiiffffyyyy

      ret = ECDSA_do_verify(digest, 20, sig, eckey);

     or using EEEECCCCDDDDSSSSAAAA_vvvveeeerrrriiiiffffyyyy

      ret = ECDSA_verify(0, digest, 20, buffer, buf_len, eckey);

     and finally evaluate the return value:

      if (ret == -1)
             {
             /* error */
             }
      else if (ret == 0)
             {
             /* incorrect signature */
             }
      else   /* ret == 1 */
             {
             /* signature ok */
             }


CCCCOOOONNNNFFFFOOOORRRRMMMMIIIINNNNGGGG TTTTOOOO
     ANSI X9.62, US Federal Information Processing Standard FIPS
     186-2 (Digital Signature Standard, DSS)

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     dsa(3), rsa(3)

HHHHIIIISSSSTTTTOOOORRRRYYYY
     The ecdsa implementation was first introduced in OpenSSL
     0.9.8

AAAAUUUUTTTTHHHHOOOORRRR
     Nils Larsch for the OpenSSL project
     (http://www.openssl.org).






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OpenSSL                                           ecdsa(3openssl)























































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