X-Git-Url: https://git.openssl.org/?p=openssl.git;a=blobdiff_plain;f=doc%2Fcrypto%2FEVP_PKEY_sign.pod;h=21974b4b1a9cf35888551beba71a278bcefbba8f;hp=63d41c9b054c66d1617036b70a942e050a42217d;hb=d64c533a207f7b6d86c3bc8ffb053e5f4d0c1ca0;hpb=ba544377fb48336b4e29fd494a7faf7c0ba6b1dc

diff --git a/doc/crypto/EVP_PKEY_sign.pod b/doc/crypto/EVP_PKEY_sign.pod
index 63d41c9b05..21974b4b1a 100644
--- a/doc/crypto/EVP_PKEY_sign.pod
+++ b/doc/crypto/EVP_PKEY_sign.pod
@@ -2,7 +2,7 @@
 
 =head1 NAME
 
-EVP_PKEY_encrypt_init, EVP_PKEY_encrypt - encrypt using a public key algorithm
+EVP_PKEY_sign_init, EVP_PKEY_sign - sign using a public key algorithm
 
 =head1 SYNOPSIS
 
@@ -28,9 +28,14 @@ B<sig> and the amount of data written to B<siglen>.
 
 =head1 NOTES
 
+EVP_PKEY_sign() does not hash the data to be signed, and therefore is
+normally used to sign digests. For signing arbitrary messages, see the
+L<EVP_DigestSignInit(3)|EVP_DigestSignInit(3)> and
+L<EVP_SignInit(3)|EVP_SignInit(3)> signing interfaces instead.
+
 After the call to EVP_PKEY_sign_init() algorithm specific control
 operations can be performed to set any appropriate parameters for the
-operation.
+operation (see L<EVP_PKEY_CTX_ctrl(3)|EVP_PKEY_CTX_ctrl(3)>).
 
 The function EVP_PKEY_sign() can be called more than once on the same
 context if several operations are performed using the same parameters.
@@ -43,21 +48,59 @@ indicates the operation is not supported by the public key algorithm.
 
 =head1 EXAMPLE
 
-Sign data using PKCS#1 and SHA256 digest:
+Sign data using RSA with PKCS#1 padding and SHA256 digest:
+
+ #include <openssl/evp.h>
+ #include <openssl/rsa.h>
+
+ EVP_PKEY_CTX *ctx;
+ /* md is a SHA-256 digest in this example. */
+ unsigned char *md, *sig;
+ size_t mdlen = 32, siglen;
+ EVP_PKEY *signing_key;
+
+ /*
+  * NB: assumes signing_key and md are set up before the next
+  * step. signing_key must be an RSA private key and md must
+  * point to the SHA-256 digest to be signed.
+  */
+ ctx = EVP_PKEY_CTX_new(signing_key, NULL /* no engine */);
+ if (!ctx)
+	/* Error occurred */
+ if (EVP_PKEY_sign_init(ctx) <= 0)
+	/* Error */
+ if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
+	/* Error */
+ if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
+	/* Error */
+
+ /* Determine buffer length */
+ if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0)
+	/* Error */
+
+ sig = OPENSSL_malloc(siglen);
+
+ if (!sig)
+	/* malloc failure */
+ 
+ if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0)
+	/* Error */
+
+ /* Signature is siglen bytes written to buffer sig */
 
-[to be added]
 
 =head1 SEE ALSO
 
 L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>,
+L<EVP_PKEY_CTX_ctrl(3)|EVP_PKEY_CTX_ctrl(3)>,
 L<EVP_PKEY_encrypt(3)|EVP_PKEY_encrypt(3)>,
 L<EVP_PKEY_decrypt(3)|EVP_PKEY_decrypt(3)>,
 L<EVP_PKEY_verify(3)|EVP_PKEY_verify(3)>,
-L<EVP_PKEY_verifyrecover(3)|EVP_PKEY_verifyrecover(3)>,
+L<EVP_PKEY_verify_recover(3)|EVP_PKEY_verify_recover(3)>,
 L<EVP_PKEY_derive(3)|EVP_PKEY_derive(3)> 
 
 =head1 HISTORY
 
-These functions were first added to OpenSSL 0.9.9.
+These functions were first added to OpenSSL 1.0.0.
 
 =cut