Add some examples.

[openssl.git] / doc / crypto / EVP_PKEY_verifyrecover.pod

diff --git a/doc/crypto/EVP_PKEY_verifyrecover.pod b/doc/crypto/EVP_PKEY_verifyrecover.pod
index a3d997aaaf5d03c4e87260c8cb54ef41630317f8..ddc24924125aac3efaf20e374930ef3f2185a07f 100644 (file)
--- a/doc/crypto/EVP_PKEY_verifyrecover.pod
+++ b/doc/crypto/EVP_PKEY_verifyrecover.pod
@@ -53,7 +53,39 @@ indicates the operation is not supported by the public key algorithm.
 
 Recover digest originally signed using PKCS#1 and SHA256 digest:
 
-[to be added]
+ #include <openssl/evp.h>
+ #include <openssl/rsa.h>
+
+ EVP_PKEY_CTX *ctx;
+ unsigned char *rout, *sig;
+ size_t routlen, siglen; 
+ EVP_PKEY *verify_key;
+ /* NB: assumes verify_key, sig and siglen are already set up
+  * and that verify_key is an RSA public key
+  */
+ ctx = EVP_PKEY_CTX_new(verify_key);
+ if (!ctx)
+       /* Error occurred */
+ if (EVP_PKEY_verifyrecover_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_verifyrecover(ctx, rout, &routlen, sig, siglen) <= 0)
+       /* Error */
+
+ rout = OPENSSL_malloc(routlen);
+
+ if (!rout)
+       /* malloc failure */
+ 
+ if (EVP_PKEY_verifyrecover(ctx, rout, &routlen, sig, siglen) <= 0)
+       /* Error */
+
+ /* Recovered data is routlen bytes written to buffer rout */
 
 =head1 SEE ALSO