1238384Sjkim=pod 2238384Sjkim 3238384Sjkim=head1 NAME 4238384Sjkim 5238384SjkimEVP_PKEY_sign_init, EVP_PKEY_sign - sign using a public key algorithm 6238384Sjkim 7238384Sjkim=head1 SYNOPSIS 8238384Sjkim 9238384Sjkim #include <openssl/evp.h> 10238384Sjkim 11238384Sjkim int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx); 12238384Sjkim int EVP_PKEY_sign(EVP_PKEY_CTX *ctx, 13238384Sjkim unsigned char *sig, size_t *siglen, 14238384Sjkim const unsigned char *tbs, size_t tbslen); 15238384Sjkim 16238384Sjkim=head1 DESCRIPTION 17238384Sjkim 18238384SjkimThe EVP_PKEY_sign_init() function initializes a public key algorithm 19238384Sjkimcontext using key B<pkey> for a signing operation. 20238384Sjkim 21238384SjkimThe EVP_PKEY_sign() function performs a public key signing operation 22238384Sjkimusing B<ctx>. The data to be signed is specified using the B<tbs> and 23238384SjkimB<tbslen> parameters. If B<sig> is B<NULL> then the maximum size of the output 24238384Sjkimbuffer is written to the B<siglen> parameter. If B<sig> is not B<NULL> then 25238384Sjkimbefore the call the B<siglen> parameter should contain the length of the 26238384SjkimB<sig> buffer, if the call is successful the signature is written to 27238384SjkimB<sig> and the amount of data written to B<siglen>. 28238384Sjkim 29238384Sjkim=head1 NOTES 30238384Sjkim 31273149SjkimEVP_PKEY_sign() does not hash the data to be signed, and therefore is 32273149Sjkimnormally used to sign digests. For signing arbitrary messages, see the 33273149SjkimL<EVP_DigestSignInit(3)|EVP_DigestSignInit(3)> and 34273149SjkimL<EVP_SignInit(3)|EVP_SignInit(3)> signing interfaces instead. 35273149Sjkim 36238384SjkimAfter the call to EVP_PKEY_sign_init() algorithm specific control 37238384Sjkimoperations can be performed to set any appropriate parameters for the 38273149Sjkimoperation (see L<EVP_PKEY_CTX_ctrl(3)|EVP_PKEY_CTX_ctrl(3)>). 39238384Sjkim 40238384SjkimThe function EVP_PKEY_sign() can be called more than once on the same 41238384Sjkimcontext if several operations are performed using the same parameters. 42238384Sjkim 43238384Sjkim=head1 RETURN VALUES 44238384Sjkim 45238384SjkimEVP_PKEY_sign_init() and EVP_PKEY_sign() return 1 for success and 0 46238384Sjkimor a negative value for failure. In particular a return value of -2 47238384Sjkimindicates the operation is not supported by the public key algorithm. 48238384Sjkim 49238384Sjkim=head1 EXAMPLE 50238384Sjkim 51238384SjkimSign data using RSA with PKCS#1 padding and SHA256 digest: 52238384Sjkim 53238384Sjkim #include <openssl/evp.h> 54238384Sjkim #include <openssl/rsa.h> 55238384Sjkim 56238384Sjkim EVP_PKEY_CTX *ctx; 57273149Sjkim /* md is a SHA-256 digest in this example. */ 58238384Sjkim unsigned char *md, *sig; 59273149Sjkim size_t mdlen = 32, siglen; 60238384Sjkim EVP_PKEY *signing_key; 61273149Sjkim 62273149Sjkim /* 63273149Sjkim * NB: assumes signing_key and md are set up before the next 64273149Sjkim * step. signing_key must be an RSA private key and md must 65273149Sjkim * point to the SHA-256 digest to be signed. 66238384Sjkim */ 67273149Sjkim ctx = EVP_PKEY_CTX_new(signing_key, NULL /* no engine */); 68238384Sjkim if (!ctx) 69238384Sjkim /* Error occurred */ 70238384Sjkim if (EVP_PKEY_sign_init(ctx) <= 0) 71238384Sjkim /* Error */ 72238384Sjkim if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) 73238384Sjkim /* Error */ 74238384Sjkim if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) 75238384Sjkim /* Error */ 76238384Sjkim 77238384Sjkim /* Determine buffer length */ 78238384Sjkim if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0) 79238384Sjkim /* Error */ 80238384Sjkim 81238384Sjkim sig = OPENSSL_malloc(siglen); 82238384Sjkim 83238384Sjkim if (!sig) 84238384Sjkim /* malloc failure */ 85238384Sjkim 86238384Sjkim if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0) 87238384Sjkim /* Error */ 88238384Sjkim 89238384Sjkim /* Signature is siglen bytes written to buffer sig */ 90238384Sjkim 91238384Sjkim 92238384Sjkim=head1 SEE ALSO 93238384Sjkim 94238384SjkimL<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>, 95273149SjkimL<EVP_PKEY_CTX_ctrl(3)|EVP_PKEY_CTX_ctrl(3)>, 96238384SjkimL<EVP_PKEY_encrypt(3)|EVP_PKEY_encrypt(3)>, 97238384SjkimL<EVP_PKEY_decrypt(3)|EVP_PKEY_decrypt(3)>, 98238384SjkimL<EVP_PKEY_verify(3)|EVP_PKEY_verify(3)>, 99246772SjkimL<EVP_PKEY_verify_recover(3)|EVP_PKEY_verify_recover(3)>, 100238384SjkimL<EVP_PKEY_derive(3)|EVP_PKEY_derive(3)> 101238384Sjkim 102238384Sjkim=head1 HISTORY 103238384Sjkim 104238384SjkimThese functions were first added to OpenSSL 1.0.0. 105238384Sjkim 106238384Sjkim=cut 107