EVP Key and Parameter Generation - Revision history

L.Habib: /* Parameter Generation */

2021-02-12T11:58:05Z

Parameter Generation

Jwalton: Add InfoBox

2017-04-28T23:01:52Z

Add InfoBox

Jwalton: Add links to all EVP articles.

2017-04-28T22:54:57Z

Add links to all EVP articles.

Matt: Added reference showing how to generate MAC codes

2013-08-19T21:01:51Z

Added reference showing how to generate MAC codes

Philippe lhardy: /* See also */

2013-03-24T17:33:05Z

Matt: Corrected error with RSA key generation

2013-03-09T13:39:22Z

Corrected error with RSA key generation

Matt: Added link to Random Number page

2013-03-09T12:45:12Z

Added link to Random Number page

Matt: Added See also section

2013-02-28T23:24:25Z

Added See also section

Matt at 23:36, 27 February 2013

2013-02-27T23:36:13Z

Matt: Created page with "The EVP functions support the ability to generate parameters and keys if required for EVP_PKEY objects. ==Parameter Generation== Parameter generation is supported for the follo…"

2013-02-27T23:35:45Z

Created page with "The EVP functions support the ability to generate parameters and keys if required for EVP_PKEY objects. ==Parameter Generation== Parameter generation is supported for the follo…"

New page

The EVP functions support the ability to generate parameters and keys if required for EVP_PKEY objects.

==Parameter Generation==

Parameter generation is supported for the following EVP_PKEY types only:
* EVP_PKEY_EC (for ECDSA and ECDH keys)
* EVP_PKEY_DSA
* EVP_PKEY_DH

The following sample code shows an example of how to generate parameters for each of these key types:

/* Create the context for generating the parameters */
if(!(pctx = EVP_PKEY_CTX_new_id(type, NULL))) goto err;
if(!EVP_PKEY_paramgen_init(pctx)) goto err;

/* Set the paramgen parameters according to the type */
switch(type)
{
case EVP_PKEY_EC:
/* Use the NID_X9_62_prime256v1 named curve - defined in obj_mac.h */
if(!EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, NID_X9_62_prime256v1)) goto err;
break;

case EVP_PKEY_DSA:
/* Set a bit length of 2048 */
if(!EVP_PKEY_CTX_set_dsa_paramgen_bits(pctx, 2048)) goto err;
break;

case EVP_PKEY_DH:
/* Set a prime length of 2048 */
if(!EVP_PKEY_CTX_set_dh_paramgen_prime_len(pctx, 2048)) goto err;
}

/* Generate parameters */
if (!EVP_PKEY_paramgen(pctx, &params)) goto err;

==Key Generation==

The following sample code shows an example of how to generate keys with the exception of EVP_PKEY_HMAC and EVP_PKEY_CMAC keys:

if(*params != NULL)
{
if(!(kctx = EVP_PKEY_CTX_new(params, NULL))) goto err;
}
else
{
/* Create context for the key generation */
if(!(kctx = EVP_PKEY_CTX_new_id(type, NULL))) goto err;
}

/* RSA keys set the key length during key generation rather than parameter generation! */
if(type == EVP_PKEY_RSA)
{
if(!EVP_PKEY_CTX_set_rsa_keygen_bits(kctx, 2048)) goto err;
}

/* Generate the key */

if(!EVP_PKEY_keygen_init(kctx)) goto err;
if (!EVP_PKEY_keygen(kctx, &key)) goto err;

CMAC keys are generated in a simlar fashion:

if(!(kctx = EVP_PKEY_CTX_new_id(type, NULL))) goto err;

if(!EVP_PKEY_keygen_init(kctx)) goto err;

/* Set the cipher to be used for the CMAC */
if (EVP_PKEY_CTX_ctrl(kctx, -1, EVP_PKEY_OP_KEYGEN,
EVP_PKEY_CTRL_CIPHER,
0, (void *)EVP_aes_256_ecb()) <= 0)
goto err;

/* Set the key data to be used for the CMAC */
if (EVP_PKEY_CTX_ctrl(kctx, -1, EVP_PKEY_OP_KEYGEN,
EVP_PKEY_CTRL_SET_MAC_KEY,
/*key length*/32, "01234567890123456789012345678901") <= 0)
goto err;

/* Generate the key */
if (!EVP_PKEY_keygen(kctx, &key)) goto err;

HMAC keys can be generated in the same way as for CMAC keys but do not take a cipher. A convenience function which wraps this process exists to simplify HMAC key generation:

key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, "password", strlen("password"));

← Older revision		Revision as of 23:01, 28 April 2017
Line 1:		Line 1:
		+	{{DocInclude
		+	\|Name=Key and Parameter Generation
		+	\|Url=http://wiki.ope
		+
	The EVP functions support the ability to generate parameters and keys if required for EVP_PKEY objects. Since these functions use random numbers you should ensure that the random number generator is appropriately seeded as discussed [[Random Numbers\|here]].		The EVP functions support the ability to generate parameters and keys if required for EVP_PKEY objects. Since these functions use random numbers you should ensure that the random number generator is appropriately seeded as discussed [[Random Numbers\|here]].

@@ Line 89: / Line 89: @@
 * [[EVP]]
 * [[Libcrypto API]]
 [[Category:Crypto API]]
 [[Category:Examples]]
 [[Category:C level]]

← Older revision		Revision as of 17:33, 24 March 2013
Line 89:		Line 89:
	* [[EVP]]		* [[EVP]]
	* [[Libcrypto API]]		* [[Libcrypto API]]
		+
		+	[[Category:Crypto API]]
		+	[[Category:Examples]]
		+	[[Category:C level]]

← Older revision		Revision as of 12:45, 9 March 2013
Line 1:		Line 1:
−	The EVP functions support the ability to generate parameters and keys if required for EVP_PKEY objects.	+	The EVP functions support the ability to generate parameters and keys if required for EVP_PKEY objects. Since these functions use random numbers you should ensure that the random number generator is appropriately seeded as discussed [[Random Numbers\|here]].

	==Parameter Generation==		==Parameter Generation==

← Older revision		Revision as of 23:24, 28 February 2013
Line 85:		Line 85:

	key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, "password", strlen("password"));		key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, "password", strlen("password"));
		+
		+	==See also==
		+	* [[EVP]]
		+	* [[Libcrypto API]]

@@ Line 15: / Line 15: @@
   /* Create the context for generating the parameters */
   if(!(pctx = EVP_PKEY_CTX_new_id(type, NULL))) goto err;
   if(!EVP_PKEY_paramgen_init(pctx)) goto err;

@@ Line 60: / Line 60: @@
   if (!EVP_PKEY_keygen(kctx, &key)) goto err;
-CMAC keys are generated in a simlar fashion:
+CMAC keys are generated in a simlar fashion (see [[EVP_Signing_and_Verifying]] for information on generating MAC codes):
   if(!(kctx = EVP_PKEY_CTX_new_id(type, NULL))) goto err;

@@ Line 48: / Line 48: @@
     if(!(kctx = EVP_PKEY_CTX_new_id(type, NULL))) goto err;
+  }
   /* RSA keys set the key length during key generation rather than parameter generation! */
@@ Line 56: / Line 58: @@
   /* Generate the key */
   if (!EVP_PKEY_keygen(kctx, &key)) goto err;