Docs: Move deprecated ECDSA_ functions into a separate file.

Fixes #19829

Examples added for setting/getting ECDSA SIG related r and s values

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19936)

3 files changed, 252 insertions, 135 deletions

diff --git a/doc/build.info b/doc/build.info
index 4ffbcb843d..3251d27258 100644
--- a/doc/build.info
+++ b/doc/build.info
@@ -1007,6 +1007,10 @@ DEPEND[html/man3/ECDSA_SIG_new.html]=man3/ECDSA_SIG_new.pod
 GENERATE[html/man3/ECDSA_SIG_new.html]=man3/ECDSA_SIG_new.pod
 DEPEND[man/man3/ECDSA_SIG_new.3]=man3/ECDSA_SIG_new.pod
 GENERATE[man/man3/ECDSA_SIG_new.3]=man3/ECDSA_SIG_new.pod
+DEPEND[html/man3/ECDSA_sign.html]=man3/ECDSA_sign.pod
+GENERATE[html/man3/ECDSA_sign.html]=man3/ECDSA_sign.pod
+DEPEND[man/man3/ECDSA_sign.3]=man3/ECDSA_sign.pod
+GENERATE[man/man3/ECDSA_sign.3]=man3/ECDSA_sign.pod
 DEPEND[html/man3/ECPKParameters_print.html]=man3/ECPKParameters_print.pod
 GENERATE[html/man3/ECPKParameters_print.html]=man3/ECPKParameters_print.pod
 DEPEND[man/man3/ECPKParameters_print.3]=man3/ECPKParameters_print.pod
@@ -3051,6 +3055,7 @@ html/man3/DTLS_get_data_mtu.html \
 html/man3/DTLS_set_timer_cb.html \
 html/man3/DTLSv1_listen.html \
 html/man3/ECDSA_SIG_new.html \
+html/man3/ECDSA_sign.html \
 html/man3/ECPKParameters_print.html \
 html/man3/EC_GFp_simple_method.html \
 html/man3/EC_GROUP_copy.html \
@@ -3663,6 +3668,7 @@ man/man3/DTLS_get_data_mtu.3 \
 man/man3/DTLS_set_timer_cb.3 \
 man/man3/DTLSv1_listen.3 \
 man/man3/ECDSA_SIG_new.3 \
+man/man3/ECDSA_sign.3 \
 man/man3/ECPKParameters_print.3 \
 man/man3/EC_GFp_simple_method.3 \
 man/man3/EC_GROUP_copy.3 \
diff --git a/doc/man3/ECDSA_SIG_new.pod b/doc/man3/ECDSA_SIG_new.pod
index d66deab385..3266c43b55 100644
--- a/doc/man3/ECDSA_SIG_new.pod
+++ b/doc/man3/ECDSA_SIG_new.pod
@@ -2,11 +2,9 @@
 
 =head1 NAME
 
-ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0,
-ECDSA_SIG_new, ECDSA_SIG_free, ECDSA_size, ECDSA_sign, ECDSA_do_sign,
-ECDSA_verify, ECDSA_do_verify, ECDSA_sign_setup, ECDSA_sign_ex,
-ECDSA_do_sign_ex - low-level elliptic curve digital signature algorithm (ECDSA)
-functions
+ECDSA_SIG_new, ECDSA_SIG_free,
+ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0
+- Functions for creating, destroying and manipulating ECDSA_SIG objects
 
 =head1 SYNOPSIS
 
@@ -19,37 +17,18 @@ functions
  const BIGNUM *ECDSA_SIG_get0_s(const ECDSA_SIG *sig);
  int ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s);
 
-The following functions have been deprecated since OpenSSL 3.0, and can be
-hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
-see L<openssl_user_macros(7)>:
-
- int ECDSA_size(const EC_KEY *eckey);
-
- int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen,
-                unsigned char *sig, unsigned int *siglen, EC_KEY *eckey);
- ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
-                          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_do_verify(const unsigned char *dgst, int dgst_len,
-                     const ECDSA_SIG *sig, 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_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp);
- 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);
-
 =head1 DESCRIPTION
 
 B<ECDSA_SIG> is an opaque structure consisting of two BIGNUMs for the
-I<r> and I<s> value of an ECDSA signature (see X9.62 or FIPS186-2).
+I<r> and I<s> value of an Elliptic Curve Digital Signature Algorithm (ECDSA) signature
+(see FIPS186-4 or X9.62).
+The B<ECDSA_SIG> object was mainly used by the deprecated low level functions described in
+L<ECDSA_sign(3)>, it is still required in order to be able to set or get the values of
+I<r> and I<s> into or from a signature. This is mainly used for testing purposes as shown
+in the L</EXAMPLES>.
 
-ECDSA_SIG_new() allocates an empty B<ECDSA_SIG> structure. Note: before
-OpenSSL 1.1.0 the: the I<r> and I<s> components were initialised.
+ECDSA_SIG_new() allocates an empty B<ECDSA_SIG> structure.
+Note: before OpenSSL 1.1.0, the I<r> and I<s> components were initialised.
 
 ECDSA_SIG_free() frees the B<ECDSA_SIG> structure I<sig>.
 
@@ -69,52 +48,6 @@ passed in should not be freed by the caller.
 See L<i2d_ECDSA_SIG(3)> and L<d2i_ECDSA_SIG(3)> for information about encoding
 and decoding ECDSA signatures to/from DER.
 
-All of the functions described below are deprecated. Applications should
-use the higher level B<EVP> interface such as L<EVP_DigestSignInit(3)>
-or L<EVP_DigestVerifyInit(3)> instead.
-
-ECDSA_size() returns the maximum length of a DER encoded ECDSA signature
-created with the private EC key I<eckey>. To obtain the actual signature
-size use L<EVP_PKEY_sign(3)> with a NULL I<sig> parameter.
-
-ECDSA_sign() computes a digital signature of the I<dgstlen> bytes hash value
-I<dgst> using the private EC key I<eckey>. The DER encoded signatures is
-stored in I<sig> and its length is returned in I<sig_len>. Note: I<sig> must
-point to ECDSA_size(eckey) bytes of memory. The parameter I<type> is currently
-ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex() with I<kinv>
-and I<rp> set to NULL.
-
-ECDSA_do_sign() is similar to ECDSA_sign() except the signature is returned
-as a newly allocated B<ECDSA_SIG> structure (or NULL on error). ECDSA_do_sign()
-is a wrapper function for ECDSA_do_sign_ex() with I<kinv> and I<rp> set to
-NULL.
-
-ECDSA_verify() verifies that the signature in I<sig> of size I<siglen> is a
-valid ECDSA signature of the hash value I<dgst> of size I<dgstlen> using the
-public key I<eckey>.  The parameter I<type> is ignored.
-
-ECDSA_do_verify() is similar to ECDSA_verify() except the signature is
-presented in the form of a pointer to an B<ECDSA_SIG> structure.
-
-The remaining functions utilise the internal I<kinv> and I<r> values used
-during signature computation. Most applications will never need to call these
-and some external ECDSA ENGINE implementations may not support them at all if
-either I<kinv> or I<r> is not NULL.
-
-ECDSA_sign_setup() may be used to precompute parts of the signing operation.
-I<eckey> is the private EC key and I<ctx> is a pointer to B<BN_CTX> structure
-(or NULL). The precomputed values or returned in I<kinv> and I<rp> and can be
-used in a later call to ECDSA_sign_ex() or ECDSA_do_sign_ex().
-
-ECDSA_sign_ex() computes a digital signature of the I<dgstlen> bytes hash value
-I<dgst> using the private EC key I<eckey> and the optional pre-computed values
-I<kinv> and I<rp>. The DER encoded signature is stored in I<sig> and its
-length is returned in I<sig_len>. Note: I<sig> must point to ECDSA_size(eckey)
-bytes of memory. The parameter I<type> is ignored.
-
-ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature is
-returned as a newly allocated B<ECDSA_SIG> structure (or NULL on error).
-
 =head1 RETURN VALUES
 
 ECDSA_SIG_new() returns NULL if the allocation fails.
@@ -124,74 +57,71 @@ ECDSA_SIG_set0() returns 1 on success or 0 on failure.
 ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s() return the corresponding value,
 or NULL if it is unset.
 
-ECDSA_size() returns the maximum length signature or 0 on error.
-
-ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful
-or 0 on error.
-
-ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated
-B<ECDSA_SIG> structure or NULL 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 L<ERR_get_error(3)>.
-
 =head1 EXAMPLES
 
-Creating an ECDSA signature of a given SHA-256 hash value using the
-named curve prime256v1 (aka P-256).
+Extract signature I<r> and I<s> values from a ECDSA I<signature>
+of size I<signaturelen>:
 
-First step: create an EC_KEY object (note: this part is B<not> ECDSA
-specific)
+ ECDSA_SIG *obj;
+ const BIGNUM *r, *s;
 
- int ret;
- ECDSA_SIG *sig;
- EC_KEY *eckey;
-
- eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
- if (eckey == NULL)
-     /* error */
- if (EC_KEY_generate_key(eckey) == 0)
+ /* Load a signature into the ECDSA_SIG object */
+ obj = d2i_ECDSA_SIG(NULL, &signature, signaturelen);
+ if (obj == NULL)
      /* error */
 
-Second step: compute the ECDSA signature of a SHA-256 hash value
-using ECDSA_do_sign():
-
- sig = ECDSA_do_sign(digest, 32, eckey);
- if (sig == NULL)
+ r = ECDSA_SIG_get0_r(obj);
+ s = ECDSA_SIG_get0_s(obj);
+ if (r == NULL || s == NULL)
      /* error */
 
-or using ECDSA_sign():
+ /* Use BN_bn2binpad() here to convert to r and s into byte arrays */
 
- unsigned char *buffer, *pp;
- int buf_len;
+ /*
+  * Do not try to access I<r> or I<s> after calling ECDSA_SIG_free(),
+  * as they are both freed by this call.
+  */
+ ECDSA_SIG_free(obj);
 
- buf_len = ECDSA_size(eckey);
- buffer = OPENSSL_malloc(buf_len);
- pp = buffer;
- if (ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey) == 0)
-     /* error */
+Convert I<r> and I<s> byte arrays into an ECDSA_SIG I<signature> of
+size I<signaturelen>:
 
-Third step: verify the created ECDSA signature using ECDSA_do_verify():
+ ECDSA_SIG *obj = NULL;
+ unsigned char *signature = NULL;
+ size_t signaturelen;
+ BIGNUM *rbn = NULL, *sbn = NULL;
 
- ret = ECDSA_do_verify(digest, 32, sig, eckey);
+ obj = ECDSA_SIG_new();
+ if (obj == NULL)
+     /* error */
+ rbn = BN_bin2bn(r, rlen, NULL);
+ sbn = BN_bin2bn(s, slen, NULL);
+ if (rbn == NULL || sbn == NULL)
+     /* error */
 
-or using ECDSA_verify():
+ if (!ECDSA_SIG_set0(obj, rbn, sbn))
+     /* error */
+ /* Set these to NULL since they are now owned by obj */
+ rbn = sbn = NULL;
 
- ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
+ signaturelen = i2d_ECDSA_SIG(obj, &signature);
+ if (signaturelen <= 0)
+     /* error */
 
-and finally evaluate the return value:
+ /*
+  * This signature could now be passed to L<EVP_DigestVerify(3)>
+  * or L<EVP_DigestVerifyFinal(3)>
+  */
 
- if (ret == 1)
-     /* signature ok */
- else if (ret == 0)
-     /* incorrect signature */
- else
-     /* error */
+ BN_free(rbn);
+ BN_free(sbn);
+ OPENSSL_free(signature);
+ ECDSA_SIG_free(obj);
 
 =head1 CONFORMING TO
 
-ANSI X9.62, US Federal Information Processing Standard FIPS186-2
+ANSI X9.62,
+US Federal Information Processing Standard FIPS186-4
 (Digital Signature Standard, DSS)
 
 =head1 SEE ALSO
@@ -201,17 +131,12 @@ L<EVP_DigestSignInit(3)>,
 L<EVP_DigestVerifyInit(3)>,
 L<EVP_PKEY_sign(3)>
 L<i2d_ECDSA_SIG(3)>,
-L<d2i_ECDSA_SIG(3)>
-
-=head1 HISTORY
-
-The ECDSA_size(), ECDSA_sign(), ECDSA_do_sign(), ECDSA_verify(),
-ECDSA_do_verify(), ECDSA_sign_setup(), ECDSA_sign_ex() and ECDSA_do_sign_ex()
-functions were deprecated in OpenSSL 3.0.
+L<d2i_ECDSA_SIG(3)>,
+L<ECDSA_sign(3)>
 
 =head1 COPYRIGHT
 
-Copyright 2004-2021 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2004-2022 The OpenSSL Project Authors. All Rights Reserved.
 
 Licensed under the Apache License 2.0 (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy
diff --git a/doc/man3/ECDSA_sign.pod b/doc/man3/ECDSA_sign.pod
new file mode 100644
index 0000000000..7e56466653
--- /dev/null
+++ b/doc/man3/ECDSA_sign.pod
@@ -0,0 +1,186 @@
+=pod
+
+=head1 NAME
+
+ECDSA_size, ECDSA_sign, ECDSA_do_sign,
+ECDSA_verify, ECDSA_do_verify, ECDSA_sign_setup, ECDSA_sign_ex,
+ECDSA_do_sign_ex - deprecated low-level elliptic curve digital signature algorithm
+(ECDSA) functions
+
+=head1 SYNOPSIS
+
+ #include <openssl/ecdsa.h>
+
+The following functions have been deprecated since OpenSSL 3.0, and can be
+hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
+see L<openssl_user_macros(7)>:
+
+ int ECDSA_size(const EC_KEY *eckey);
+
+ int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen,
+                unsigned char *sig, unsigned int *siglen, EC_KEY *eckey);
+ ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
+                          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_do_verify(const unsigned char *dgst, int dgst_len,
+                     const ECDSA_SIG *sig, 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_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp);
+ 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);
+
+=head1 DESCRIPTION
+
+See L<ECDSA_SIG_new(3)> for a description of the B<ECDSA_SIG> object.
+
+See L<i2d_ECDSA_SIG(3)> and L<d2i_ECDSA_SIG(3)> for information about encoding
+and decoding ECDSA signatures to/from DER.
+
+All of the functions described below are deprecated. Applications should
+use the higher level B<EVP> interface such as L<EVP_DigestSignInit(3)>
+or L<EVP_DigestVerifyInit(3)> instead.
+
+ECDSA_size() returns the maximum length of a DER encoded ECDSA signature
+created with the private EC key I<eckey>. To obtain the actual signature
+size use L<EVP_PKEY_sign(3)> with a NULL I<sig> parameter.
+
+ECDSA_sign() computes a digital signature of the I<dgstlen> bytes hash value
+I<dgst> using the private EC key I<eckey>. The DER encoded signatures is
+stored in I<sig> and its length is returned in I<sig_len>. Note: I<sig> must
+point to ECDSA_size(eckey) bytes of memory. The parameter I<type> is currently
+ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex() with I<kinv>
+and I<rp> set to NULL.
+
+ECDSA_do_sign() is similar to ECDSA_sign() except the signature is returned
+as a newly allocated B<ECDSA_SIG> structure (or NULL on error). ECDSA_do_sign()
+is a wrapper function for ECDSA_do_sign_ex() with I<kinv> and I<rp> set to
+NULL.
+
+ECDSA_verify() verifies that the signature in I<sig> of size I<siglen> is a
+valid ECDSA signature of the hash value I<dgst> of size I<dgstlen> using the
+public key I<eckey>.  The parameter I<type> is ignored.
+
+ECDSA_do_verify() is similar to ECDSA_verify() except the signature is
+presented in the form of a pointer to an B<ECDSA_SIG> structure.
+
+The remaining functions utilise the internal I<kinv> and I<r> values used
+during signature computation. Most applications will never need to call these
+and some external ECDSA ENGINE implementations may not support them at all if
+either I<kinv> or I<r> is not NULL.
+
+ECDSA_sign_setup() may be used to precompute parts of the signing operation.
+I<eckey> is the private EC key and I<ctx> is a pointer to B<BN_CTX> structure
+(or NULL). The precomputed values or returned in I<kinv> and I<rp> and can be
+used in a later call to ECDSA_sign_ex() or ECDSA_do_sign_ex().
+
+ECDSA_sign_ex() computes a digital signature of the I<dgstlen> bytes hash value
+I<dgst> using the private EC key I<eckey> and the optional pre-computed values
+I<kinv> and I<rp>. The DER encoded signature is stored in I<sig> and its
+length is returned in I<sig_len>. Note: I<sig> must point to ECDSA_size(eckey)
+bytes of memory. The parameter I<type> is ignored.
+
+ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature is
+returned as a newly allocated B<ECDSA_SIG> structure (or NULL on error).
+
+=head1 RETURN VALUES
+
+ECDSA_size() returns the maximum length signature or 0 on error.
+
+ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful
+or 0 on error.
+
+ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated
+B<ECDSA_SIG> structure or NULL 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 L<ERR_get_error(3)>.
+
+=head1 EXAMPLES
+
+Creating an ECDSA signature of a given SHA-256 hash value using the
+named curve prime256v1 (aka P-256).
+This example uses deprecated functionality. See L</DESCRIPTION>.
+
+First step: create an EC_KEY object (note: this part is B<not> ECDSA
+specific)
+
+ int ret;
+ ECDSA_SIG *sig;
+ EC_KEY *eckey;
+
+ eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
+ if (eckey == NULL)
+     /* error */
+ if (EC_KEY_generate_key(eckey) == 0)
+     /* error */
+
+Second step: compute the ECDSA signature of a SHA-256 hash value
+using ECDSA_do_sign():
+
+ sig = ECDSA_do_sign(digest, 32, eckey);
+ if (sig == NULL)
+     /* error */
+
+or using ECDSA_sign():
+
+ 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) == 0)
+     /* error */
+
+Third step: verify the created ECDSA signature using ECDSA_do_verify():
+
+ ret = ECDSA_do_verify(digest, 32, sig, eckey);
+
+or using ECDSA_verify():
+
+ ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
+
+and finally evaluate the return value:
+
+ if (ret == 1)
+     /* signature ok */
+ else if (ret == 0)
+     /* incorrect signature */
+ else
+     /* error */
+
+=head1 CONFORMING TO
+
+ANSI X9.62, US Federal Information Processing Standard FIPS186-2
+(Digital Signature Standard, DSS)
+
+=head1 SEE ALSO
+
+L<EC_KEY_new(3)>,
+L<EVP_DigestSignInit(3)>,
+L<EVP_DigestVerifyInit(3)>,
+L<EVP_PKEY_sign(3)>
+L<i2d_ECDSA_SIG(3)>,
+L<d2i_ECDSA_SIG(3)>
+
+=head1 HISTORY
+
+All functionality described here was deprecated in OpenSSL 3.0.
+
+=head1 COPYRIGHT
+
+Copyright 2004-2022 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the Apache License 2.0 (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut