| Index: openssl/doc/crypto/EVP_PKEY_verifyrecover.pod
|
| ===================================================================
|
| --- openssl/doc/crypto/EVP_PKEY_verifyrecover.pod (revision 0)
|
| +++ openssl/doc/crypto/EVP_PKEY_verifyrecover.pod (revision 0)
|
| @@ -0,0 +1,103 @@
|
| +=pod
|
| +
|
| +=head1 NAME
|
| +
|
| +EVP_PKEY_verifyrecover_init, EVP_PKEY_verifyrecover - recover signature using a public key algorithm
|
| +
|
| +=head1 SYNOPSIS
|
| +
|
| + #include <openssl/evp.h>
|
| +
|
| + int EVP_PKEY_verifyrecover_init(EVP_PKEY_CTX *ctx);
|
| + int EVP_PKEY_verifyrecover(EVP_PKEY_CTX *ctx,
|
| + unsigned char *rout, size_t *routlen,
|
| + const unsigned char *sig, size_t siglen);
|
| +
|
| +=head1 DESCRIPTION
|
| +
|
| +The EVP_PKEY_verifyrecover_init() function initializes a public key algorithm
|
| +context using key B<pkey> for a verify recover operation.
|
| +
|
| +The EVP_PKEY_verifyrecover() function recovers signed data
|
| +using B<ctx>. The signature is specified using the B<sig> and
|
| +B<siglen> parameters. If B<rout> is B<NULL> then the maximum size of the output
|
| +buffer is written to the B<routlen> parameter. If B<rout> is not B<NULL> then
|
| +before the call the B<routlen> parameter should contain the length of the
|
| +B<rout> buffer, if the call is successful recovered data is written to
|
| +B<rout> and the amount of data written to B<routlen>.
|
| +
|
| +=head1 NOTES
|
| +
|
| +Normally an application is only interested in whether a signature verification
|
| +operation is successful in those cases the EVP_verify() function should be
|
| +used.
|
| +
|
| +Sometimes however it is useful to obtain the data originally signed using a
|
| +signing operation. Only certain public key algorithms can recover a signature
|
| +in this way (for example RSA in PKCS padding mode).
|
| +
|
| +After the call to EVP_PKEY_verifyrecover_init() algorithm specific control
|
| +operations can be performed to set any appropriate parameters for the
|
| +operation.
|
| +
|
| +The function EVP_PKEY_verifyrecover() can be called more than once on the same
|
| +context if several operations are performed using the same parameters.
|
| +
|
| +=head1 RETURN VALUES
|
| +
|
| +EVP_PKEY_verifyrecover_init() and EVP_PKEY_verifyrecover() return 1 for success
|
| +and 0 or a negative value for failure. In particular a return value of -2
|
| +indicates the operation is not supported by the public key algorithm.
|
| +
|
| +=head1 EXAMPLE
|
| +
|
| +Recover digest originally signed using PKCS#1 and SHA256 digest:
|
| +
|
| + #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, NULL, &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
|
| +
|
| +L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>,
|
| +L<EVP_PKEY_encrypt(3)|EVP_PKEY_encrypt(3)>,
|
| +L<EVP_PKEY_decrypt(3)|EVP_PKEY_decrypt(3)>,
|
| +L<EVP_PKEY_sign(3)|EVP_PKEY_sign(3)>,
|
| +L<EVP_PKEY_verify(3)|EVP_PKEY_verify(3)>,
|
| +L<EVP_PKEY_derive(3)|EVP_PKEY_derive(3)>
|
| +
|
| +=head1 HISTORY
|
| +
|
| +These functions were first added to OpenSSL 1.0.0.
|
| +
|
| +=cut
|
|
|