path: root/doc/man3/EVP_SignInit.pod
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authorJung-uk Kim <jkim@FreeBSD.org>2018-09-13 19:18:07 +0000
committerJung-uk Kim <jkim@FreeBSD.org>2018-09-13 19:18:07 +0000
commita43ce912fc025d11e1395506111f75fc194d7ba5 (patch)
tree9794cf7720d75938ed0ea4f499c0dcd4b6eacdda /doc/man3/EVP_SignInit.pod
parent02be298e504b8554caca6dc85af450e1ea44d19d (diff)
Import OpenSSL 1.1.1.vendor/openssl/1.1.1
Notes: svn path=/vendor-crypto/openssl/dist/; revision=338658 svn path=/vendor-crypto/openssl/1.1.1/; revision=338659; tag=vendor/openssl/1.1.1
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+=head1 NAME
+EVP_SignInit, EVP_SignInit_ex, EVP_SignUpdate, EVP_SignFinal,
+EVP_PKEY_security_bits - EVP signing
+=head1 SYNOPSIS
+ #include <openssl/evp.h>
+ int EVP_SignInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
+ int EVP_SignUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
+ int EVP_SignFinal(EVP_MD_CTX *ctx, unsigned char *sig, unsigned int *s, EVP_PKEY *pkey);
+ void EVP_SignInit(EVP_MD_CTX *ctx, const EVP_MD *type);
+ int EVP_PKEY_size(EVP_PKEY *pkey);
+ int EVP_PKEY_security_bits(const EVP_PKEY *pkey);
+The EVP signature routines are a high level interface to digital
+EVP_SignInit_ex() sets up signing context B<ctx> to use digest
+B<type> from ENGINE B<impl>. B<ctx> must be created with
+EVP_MD_CTX_new() before calling this function.
+EVP_SignUpdate() hashes B<cnt> bytes of data at B<d> into the
+signature context B<ctx>. This function can be called several times on the
+same B<ctx> to include additional data.
+EVP_SignFinal() signs the data in B<ctx> using the private key B<pkey> and
+places the signature in B<sig>. B<sig> must be at least EVP_PKEY_size(pkey)
+bytes in size. B<s> is an OUT parameter, and not used as an IN parameter.
+The number of bytes of data written (i.e. the length of the signature)
+will be written to the integer at B<s>, at most EVP_PKEY_size(pkey) bytes
+will be written.
+EVP_SignInit() initializes a signing context B<ctx> to use the default
+implementation of digest B<type>.
+EVP_PKEY_size() returns the maximum size of a signature in bytes. The actual
+signature returned by EVP_SignFinal() may be smaller.
+EVP_PKEY_security_bits() returns the number of security bits of the given B<pkey>,
+bits of security is defined in NIST SP800-57.
+EVP_SignInit_ex(), EVP_SignUpdate() and EVP_SignFinal() return 1
+for success and 0 for failure.
+EVP_PKEY_size() returns the maximum size of a signature in bytes.
+The error codes can be obtained by L<ERR_get_error(3)>.
+EVP_PKEY_security_bits() returns the number of security bits.
+=head1 NOTES
+The B<EVP> interface to digital signatures should almost always be used in
+preference to the low level interfaces. This is because the code then becomes
+transparent to the algorithm used and much more flexible.
+When signing with DSA private keys the random number generator must be seeded
+or the operation will fail. The random number generator does not need to be
+seeded for RSA signatures.
+The call to EVP_SignFinal() internally finalizes a copy of the digest context.
+This means that calls to EVP_SignUpdate() and EVP_SignFinal() can be called
+later to digest and sign additional data.
+Since only a copy of the digest context is ever finalized the context must
+be cleaned up after use by calling EVP_MD_CTX_free() or a memory leak
+will occur.
+=head1 BUGS
+Older versions of this documentation wrongly stated that calls to
+EVP_SignUpdate() could not be made after calling EVP_SignFinal().
+Since the private key is passed in the call to EVP_SignFinal() any error
+relating to the private key (for example an unsuitable key and digest
+combination) will not be indicated until after potentially large amounts of
+data have been passed through EVP_SignUpdate().
+It is not possible to change the signing parameters using these function.
+The previous two bugs are fixed in the newer EVP_SignDigest*() function.
+=head1 SEE ALSO
+L<evp(7)>, L<HMAC(3)>, L<MD2(3)>,
+L<MD5(3)>, L<MDC2(3)>, L<RIPEMD160(3)>,
+L<SHA1(3)>, L<dgst(1)>
+Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
+Licensed under the OpenSSL license (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