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161 lines
5.2 KiB
161 lines
5.2 KiB
=pod
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=head1 NAME
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EVP_PKEY_keygen_init, EVP_PKEY_keygen, EVP_PKEY_paramgen_init, EVP_PKEY_paramgen, EVP_PKEY_CTX_set_cb, EVP_PKEY_CTX_get_cb, EVP_PKEY_CTX_get_keygen_info, EVP_PKEVP_PKEY_CTX_set_app_data, EVP_PKEY_CTX_get_app_data - key and parameter generation functions
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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int EVP_PKEY_keygen_init(EVP_PKEY_CTX *ctx);
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int EVP_PKEY_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
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int EVP_PKEY_paramgen_init(EVP_PKEY_CTX *ctx);
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int EVP_PKEY_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
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typedef int EVP_PKEY_gen_cb(EVP_PKEY_CTX *ctx);
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void EVP_PKEY_CTX_set_cb(EVP_PKEY_CTX *ctx, EVP_PKEY_gen_cb *cb);
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EVP_PKEY_gen_cb *EVP_PKEY_CTX_get_cb(EVP_PKEY_CTX *ctx);
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int EVP_PKEY_CTX_get_keygen_info(EVP_PKEY_CTX *ctx, int idx);
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void EVP_PKEY_CTX_set_app_data(EVP_PKEY_CTX *ctx, void *data);
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void *EVP_PKEY_CTX_get_app_data(EVP_PKEY_CTX *ctx);
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=head1 DESCRIPTION
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The EVP_PKEY_keygen_init() function initializes a public key algorithm
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context using key B<pkey> for a key genration operation.
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The EVP_PKEY_keygen() function performs a key generation operation, the
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generated key is written to B<ppkey>.
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The functions EVP_PKEY_paramgen_init() and EVP_PKEY_paramgen() are similar
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except parameters are generated.
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The function EVP_PKEY_set_cb() sets the key or parameter generation callback
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to B<cb>. The function EVP_PKEY_CTX_get_cb() returns the key or parameter
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generation callback.
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The function EVP_PKEY_CTX_get_keygen_info() returns parameters associated
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with the generation operation. If B<idx> is -1 the total number of
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parameters available is returned. Any non negative value returns the value of
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that parameter. EVP_PKEY_CTX_gen_keygen_info() with a non-negative value for
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B<idx> should only be called within the generation callback.
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If the callback returns 0 then the key genration operation is aborted and an
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error occurs. This might occur during a time consuming operation where
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a user clicks on a "cancel" button.
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The functions EVP_PKEY_CTX_set_app_data() and EVP_PKEY_CTX_get_app_data() set
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and retrieve an opaque pointer. This can be used to set some application
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defined value which can be retrieved in the callback: for example a handle
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which is used to update a "progress dialog".
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=head1 NOTES
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After the call to EVP_PKEY_keygen_init() or EVP_PKEY_paramgen_init() algorithm
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specific control operations can be performed to set any appropriate parameters
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for the operation.
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The functions EVP_PKEY_keygen() and EVP_PKEY_paramgen() can be called more than
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once on the same context if several operations are performed using the same
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parameters.
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The meaning of the parameters passed to the callback will depend on the
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algorithm and the specifiic implementation of the algorithm. Some might not
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give any useful information at all during key or parameter generation. Others
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might not even call the callback.
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The operation performed by key or parameter generation depends on the algorithm
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used. In some cases (e.g. EC with a supplied named curve) the "generation"
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option merely sets the appropriate fields in an EVP_PKEY structure.
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In OpenSSL an EVP_PKEY structure containing a private key also contains the
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public key components and parameters (if any). An OpenSSL private key is
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equivalent to what some libraries call a "key pair". A private key can be used
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in functions which require the use of a public key or parameters.
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=head1 RETURN VALUES
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EVP_PKEY_keygen_init(), EVP_PKEY_paramgen_init(), EVP_PKEY_keygen() and
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EVP_PKEY_paramgen() return 1 for success and 0 or a negative value for failure.
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In particular a return value of -2 indicates the operation is not supported by
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the public key algorithm.
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=head1 EXAMPLES
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Generate a 2048 bit RSA key:
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#include <openssl/evp.h>
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#include <openssl/rsa.h>
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EVP_PKEY_CTX *ctx;
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EVP_PKEY *pkey = NULL;
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ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL);
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if (!ctx)
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/* Error occurred */
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if (EVP_PKEY_keygen_init(ctx) <= 0)
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/* Error */
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if (EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, 2048) <= 0)
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/* Error */
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/* Generate key */
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if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
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/* Error */
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Generate a key from a set of parameters:
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#include <openssl/evp.h>
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#include <openssl/rsa.h>
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EVP_PKEY_CTX *ctx;
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EVP_PKEY *pkey = NULL, *param;
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/* Assumed param is set up already */
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ctx = EVP_PKEY_CTX_new(param);
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if (!ctx)
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/* Error occurred */
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if (EVP_PKEY_keygen_init(ctx) <= 0)
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/* Error */
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/* Generate key */
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if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
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/* Error */
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Example of generation callback for OpenSSL public key implementations:
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/* Application data is a BIO to output status to */
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EVP_PKEY_CTX_set_app_data(ctx, status_bio);
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static int genpkey_cb(EVP_PKEY_CTX *ctx)
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{
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char c='*';
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BIO *b = EVP_PKEY_CTX_get_app_data(ctx);
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int p;
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p = EVP_PKEY_CTX_get_keygen_info(ctx, 0);
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if (p == 0) c='.';
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if (p == 1) c='+';
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if (p == 2) c='*';
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if (p == 3) c='\n';
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BIO_write(b,&c,1);
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(void)BIO_flush(b);
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return 1;
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}
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=head1 SEE ALSO
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L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>,
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L<EVP_PKEY_encrypt(3)|EVP_PKEY_encrypt(3)>,
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L<EVP_PKEY_decrypt(3)|EVP_PKEY_decrypt(3)>,
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L<EVP_PKEY_sign(3)|EVP_PKEY_sign(3)>,
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L<EVP_PKEY_verify(3)|EVP_PKEY_verify(3)>,
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L<EVP_PKEY_verifyrecover(3)|EVP_PKEY_verifyrecover(3)>,
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L<EVP_PKEY_derive(3)|EVP_PKEY_derive(3)>
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=head1 HISTORY
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These functions were first added to OpenSSL 1.0.0.
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=cut
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