| Index: openssl/doc/crypto/EVP_PKEY_derive.pod
|
| ===================================================================
|
| --- openssl/doc/crypto/EVP_PKEY_derive.pod (revision 0)
|
| +++ openssl/doc/crypto/EVP_PKEY_derive.pod (revision 0)
|
| @@ -0,0 +1,93 @@
|
| +=pod
|
| +
|
| +=head1 NAME
|
| +
|
| +EVP_PKEY_derive_init, EVP_PKEY_derive_set_peer, EVP_PKEY_derive - derive public key algorithm shared secret.
|
| +
|
| +=head1 SYNOPSIS
|
| +
|
| + #include <openssl/evp.h>
|
| +
|
| + int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx);
|
| + int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX *ctx, EVP_PKEY *peer);
|
| + int EVP_PKEY_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen);
|
| +
|
| +=head1 DESCRIPTION
|
| +
|
| +The EVP_PKEY_derive_init() function initializes a public key algorithm
|
| +context using key B<pkey> for shared secret derivation.
|
| +
|
| +The EVP_PKEY_derive_set_peer() function sets the peer key: this will normally
|
| +be a public key.
|
| +
|
| +The EVP_PKEY_derive() derives a shared secret using B<ctx>.
|
| +If B<key> is B<NULL> then the maximum size of the output buffer is written to
|
| +the B<keylen> parameter. If B<key> is not B<NULL> then before the call the
|
| +B<keylen> parameter should contain the length of the B<key> buffer, if the call
|
| +is successful the shared secret is written to B<key> and the amount of data
|
| +written to B<keylen>.
|
| +
|
| +=head1 NOTES
|
| +
|
| +After the call to EVP_PKEY_derive_init() algorithm specific control
|
| +operations can be performed to set any appropriate parameters for the
|
| +operation.
|
| +
|
| +The function EVP_PKEY_derive() can be called more than once on the same
|
| +context if several operations are performed using the same parameters.
|
| +
|
| +=head1 RETURN VALUES
|
| +
|
| +EVP_PKEY_derive_init() and EVP_PKEY_derive() 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
|
| +
|
| +Derive shared secret (for example DH or EC keys):
|
| +
|
| + #include <openssl/evp.h>
|
| + #include <openssl/rsa.h>
|
| +
|
| + EVP_PKEY_CTX *ctx;
|
| + unsigned char *skey;
|
| + size_t skeylen;
|
| + EVP_PKEY *pkey, *peerkey;
|
| + /* NB: assumes pkey, peerkey have been already set up */
|
| +
|
| + ctx = EVP_PKEY_CTX_new(pkey);
|
| + if (!ctx)
|
| + /* Error occurred */
|
| + if (EVP_PKEY_derive_init(ctx) <= 0)
|
| + /* Error */
|
| + if (EVP_PKEY_derive_set_peer(ctx, peerkey) <= 0)
|
| + /* Error */
|
| +
|
| + /* Determine buffer length */
|
| + if (EVP_PKEY_derive(ctx, NULL, &skeylen) <= 0)
|
| + /* Error */
|
| +
|
| + skey = OPENSSL_malloc(skeylen);
|
| +
|
| + if (!skey)
|
| + /* malloc failure */
|
| +
|
| + if (EVP_PKEY_derive(ctx, skey, &skeylen) <= 0)
|
| + /* Error */
|
| +
|
| + /* Shared secret is skey bytes written to buffer skey */
|
| +
|
| +=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_verifyrecover(3)|EVP_PKEY_verifyrecover(3)>,
|
| +
|
| +=head1 HISTORY
|
| +
|
| +These functions were first added to OpenSSL 1.0.0.
|
| +
|
| +=cut
|
|
|