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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_verify_recover(3)|EVP_PKEY_verify_recover(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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