text: /* ====================================================================
   * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. All advertising materials mentioning features or use of this
   *    software must display the following acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    openssl-core@OpenSSL.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com). */
  
  #ifndef OPENSSL_HEADER_ECDSA_H
  #define OPENSSL_HEADER_ECDSA_H
  
  #include <openssl/base.h>
  
  #include <openssl/ec_key.h>
  
  #if defined(__cplusplus)
  extern "C" {
  #endif
  
  
  /* ECDSA contains functions for signing and verifying with the Digital Signature
   * Algorithm over elliptic curves. */
  
  
  /* Signing and verifing. */
  
  /* ECDSA_sign signs |digest_len| bytes from |digest| with |key| and writes the
   * resulting signature to |sig|, which must have |ECDSA_size(key)| bytes of
   * space. On successful exit, |*sig_len| is set to the actual number of bytes
   * written. The |type| argument should be zero. It returns one on success and
   * zero otherwise. */
  OPENSSL_EXPORT int ECDSA_sign(int type, const uint8_t *digest,
                                size_t digest_len, uint8_t *sig,
                                unsigned int *sig_len, EC_KEY *key);
  
  /* ECDSA_verify verifies that |sig_len| bytes from |sig| constitute a valid
   * signature by |key| of |digest|. (The |type| argument should be zero.) It
   * returns one on success or zero if the signature is invalid or an error
   * occured. */
  OPENSSL_EXPORT int ECDSA_verify(int type, const uint8_t *digest,
                                  size_t digest_len, const uint8_t *sig,
                                  size_t sig_len, EC_KEY *key);
  
  /* ECDSA_size returns the maximum size of an ECDSA signature using |key|. It
   * returns zero on error. */
  OPENSSL_EXPORT size_t ECDSA_size(const EC_KEY *key);
  
  
  /* Low-level signing and verification.
   *
   * Low-level functions handle signatures as |ECDSA_SIG| structures which allow
   * the two values in an ECDSA signature to be handled separately. */
  
  struct ecdsa_sig_st {
    BIGNUM *r;
    BIGNUM *s;
  };
  
  /* ECDSA_SIG_new returns a fresh |ECDSA_SIG| structure or NULL on error. */
  OPENSSL_EXPORT ECDSA_SIG *ECDSA_SIG_new(void);
  
  /* ECDSA_SIG_free frees |sig| its member |BIGNUM|s. */
  OPENSSL_EXPORT void ECDSA_SIG_free(ECDSA_SIG *sig);
  
  /* ECDSA_sign signs |digest_len| bytes from |digest| with |key| and returns the
   * resulting signature structure, or NULL on error. */
  OPENSSL_EXPORT ECDSA_SIG *ECDSA_do_sign(const uint8_t *digest,
                                          size_t digest_len, EC_KEY *key);
  
  /* ECDSA_verify verifies that |sig| constitutes a valid signature by |key| of
   * |digest|. It returns one on success or zero if the signature is invalid or
   * on error. */
  OPENSSL_EXPORT int ECDSA_do_verify(const uint8_t *digest, size_t digest_len,
                                     const ECDSA_SIG *sig, EC_KEY *key);
  
  
  /* Signing with precomputation.
   *
   * Parts of the ECDSA signature can be independent of the message to be signed
   * thus it's possible to precompute them and reduce the signing latency.
   *
   * TODO(fork): remove support for this as it cannot support safe-randomness. */
  
  /* ECDSA_sign_setup precomputes parts of an ECDSA signing operation. It sets
   * |*kinv| and |*rp| to the precomputed values and uses the |ctx| argument, if
   * not NULL. It returns one on success and zero otherwise. */
  OPENSSL_EXPORT int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv,
                                      BIGNUM **rp);
  
  /* ECDSA_do_sign_ex is the same as |ECDSA_do_sign| but takes precomputed values
   * as generated by |ECDSA_sign_setup|. */
  OPENSSL_EXPORT ECDSA_SIG *ECDSA_do_sign_ex(const uint8_t *digest,
                                             size_t digest_len,
                                             const BIGNUM *kinv, const BIGNUM *rp,
                                             EC_KEY *eckey);
  
  /* ECDSA_sign_ex is the same as |ECDSA_sign| but takes precomputed values as
   * generated by |ECDSA_sign_setup|. */
  OPENSSL_EXPORT int ECDSA_sign_ex(int type, const uint8_t *digest,
                                   size_t digest_len, uint8_t *sig,
                                   unsigned int *sig_len, const BIGNUM *kinv,
                                   const BIGNUM *rp, EC_KEY *eckey);
  
  
  /* ASN.1 functions. */
  
  /* ECDSA_SIG_parse parses a DER-encoded ECDSA-Sig-Value structure from |cbs| and
   * advances |cbs|. It returns a newly-allocated |ECDSA_SIG| or NULL on error. */
  OPENSSL_EXPORT ECDSA_SIG *ECDSA_SIG_parse(CBS *cbs);
  
  /* ECDSA_SIG_from_bytes parses |in| as a DER-encoded ECDSA-Sig-Value structure.
   * It returns a newly-allocated |ECDSA_SIG| structure or NULL on error. */
  OPENSSL_EXPORT ECDSA_SIG *ECDSA_SIG_from_bytes(const uint8_t *in,
                                                 size_t in_len);
  
  /* ECDSA_SIG_marshal marshals |sig| as a DER-encoded ECDSA-Sig-Value and appends
   * the result to |cbb|. It returns one on success and zero on error. */
  OPENSSL_EXPORT int ECDSA_SIG_marshal(CBB *cbb, const ECDSA_SIG *sig);
  
  /* ECDSA_SIG_to_bytes marshals |sig| as a DER-encoded ECDSA-Sig-Value and, on
   * success, sets |*out_bytes| to a newly allocated buffer containing the result
   * and returns one. Otherwise, it returns zero. The result should be freed with
   * |OPENSSL_free|. */
  OPENSSL_EXPORT int ECDSA_SIG_to_bytes(uint8_t **out_bytes, size_t *out_len,
                                        const ECDSA_SIG *sig);
  
  /* ECDSA_SIG_max_len returns the maximum length of a DER-encoded ECDSA-Sig-Value
   * structure for a group whose order is represented in |order_len| bytes, or
   * zero on overflow. */
  OPENSSL_EXPORT size_t ECDSA_SIG_max_len(size_t order_len);
  
  
  /* Deprecated functions. */
  
  /* d2i_ECDSA_SIG parses an ASN.1, DER-encoded, signature from |len| bytes at
   * |*inp|. If |out| is not NULL then, on exit, a pointer to the result is in
   * |*out|. If |*out| is already non-NULL on entry then the result is written
   * directly into |*out|, otherwise a fresh |ECDSA_SIG| is allocated. On
   * successful exit, |*inp| is advanced past the DER structure. It returns the
   * result or NULL on error. */
  OPENSSL_EXPORT ECDSA_SIG *d2i_ECDSA_SIG(ECDSA_SIG **out, const uint8_t **inp,
                                          long len);
  
  /* i2d_ECDSA_SIG marshals a signature from |sig| to an ASN.1, DER
   * structure. If |outp| is not NULL then the result is written to |*outp| and
   * |*outp| is advanced just past the output. It returns the number of bytes in
   * the result, whether written or not, or a negative value on error. */
  OPENSSL_EXPORT int i2d_ECDSA_SIG(const ECDSA_SIG *sig, uint8_t **outp);
  
  
  #if defined(__cplusplus)
  }  /* extern C */
  #endif
  
  #define ECDSA_R_BAD_SIGNATURE 100
  #define ECDSA_R_MISSING_PARAMETERS 101
  #define ECDSA_R_NEED_NEW_SETUP_VALUES 102
  #define ECDSA_R_NOT_IMPLEMENTED 103
  #define ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED 104
  #define ECDSA_R_ENCODE_ERROR 105
  
  #endif  /* OPENSSL_HEADER_ECDSA_H */
  