EVP Signing and Verifying - Revision history

Matt: /* Verifying HMAC */

2020-04-28T10:08:03Z

Verifying HMAC

Matt: /* Verifying HMAC */

2020-04-28T10:07:31Z

Verifying HMAC

Matt: /* Calculating HMAC */ Simplify EVP_DigestSign example, and remove double init

2020-04-28T09:58:27Z

Calculating HMAC: Simplify EVP_DigestSign example, and remove double init

Jwalton: Add CMAC note to introduction to make it obvious.

2018-01-15T13:47:55Z

Add CMAC note to introduction to make it obvious.

Kmarinushkin: Rename "HMAC signing" into "HMAC calculation", "HMAC signature" into "HMAC value" (terminology from IETF RFC 2104 and FIPS PUB 198-1); rename "Public key" into "Asymmetric key"

2017-06-07T08:07:53Z

Rename "HMAC signing" into "HMAC calculation", "HMAC signature" into "HMAC value" (terminology from IETF RFC 2104 and FIPS PUB 198-1); rename "Public key" into "Asymmetric key"

Show changes

Jwalton: Add InfoBox

2017-04-28T22:58:49Z

Add InfoBox

Jwalton: Add links to all EVP articles.

2017-04-28T22:53:54Z

Add links to all EVP articles.

Jwalton: Added note on DSA changes for 1.1.0. Its probably a better fit elsewhere, but I'm not finding a good page at the moment (e.g., no DSA or DSS page).

2016-07-02T10:30:23Z

Added note on DSA changes for 1.1.0. Its probably a better fit elsewhere, but I'm not finding a good page at the moment (e.g., no DSA or DSS page).

Richmoore: /* Signing */

2015-06-21T21:37:09Z

Signing

Jwalton at 01:25, 8 February 2015

2015-02-08T01:25:52Z

@@ Line 130: / Line 130: @@
      rc = EVP_DigestSignInit(ctx, NULL, EVP_sha256(), NULL, pkey);
-     if(rc != 1) {
+     if (rc != 1) {
          printf("EVP_DigestSignInit failed, error 0x%lx\n", ERR_get_error());
          goto err;

@@ Line 111: / Line 111: @@
 The code below performs verification of a string using an HMAC.
-<pre>int verify_it(const byte* msg, size_t mlen, const byte* val, size_t vlen, EVP_PKEY* pkey)
+<pre>int verify_it(const unsigned char *msg, size_t mlen, const unsigned char *val, size_t vlen, EVP_PKEY *pkey)
+{
      /* Returned to caller */
-     int result = -1;
+     int result = 0;
-     if(!msg || !mlen || !val || !vlen || !pkey) {
+    rc = EVP_DigestSignInit(ctx, NULL, EVP_sha256(), NULL, pkey);
-         assert(0);
+     if(rc != 1) {
-         return -1;
+         printf("EVP_DigestSignInit failed, error 0x%lx\n", ERR_get_error());
+     }
-     do
+     rc = EVP_DigestSignUpdate(ctx, msg, mlen);
+    if (rc != 1) {
-        ctx = EVP_MD_CTX_create();
+        printf("EVP_DigestSignUpdate failed, error 0x%lx\n", ERR_get_error());
-        assert(ctx != NULL);
+         goto err;
-        if(ctx == NULL) {
-     if(ctx) {
+    size = sizeof(buff);
-         EVP_MD_CTX_destroy(ctx);
+    rc = EVP_DigestSignFinal(ctx, buff, &size);
-         ctx = NULL;
+     if (rc != 1) {
+     }
-     /* Convert to 0/1 result */
+     result = (vlen == size) && (CRYPTO_memcmp(val, buff, size) == 0);
-     return !!result;
+ err:
 }</pre>

@@ Line 44: / Line 44: @@
 The code below calculates HMAC for a string.
-<pre>int hmac_it(const byte* msg, size_t mlen, byte** val, size_t* vlen, EVP_PKEY* pkey)
+<pre>int hmac_it(const unsigned char *msg, size_t mlen, unsigned char **val, size_t *vlen, EVP_PKEY *pkey)
+{
      /* Returned to caller */
-     int result = -1;
+     int result = 0;
-     if(!msg || !mlen || !val || !pkey) {
+    *val = NULL;
-         assert(0);
+    *vlen = 0;
-         return -1;
+     }
-     if(*val)
+    rc = EVP_DigestSignInit(ctx, NULL, EVP_sha256(), NULL, pkey);
-         OPENSSL_free(*val);
+     if (rc != 1) {
-     *val = NULL;
+     rc = EVP_DigestSignUpdate(ctx, msg, mlen);
-     *vlen = 0;
+     if (rc != 1) {
-     EVP_MD_CTX* ctx = NULL;
+     rc = EVP_DigestSignFinal(ctx, NULL, &req);
-     do
+     *val = OPENSSL_malloc(req);
+    if (*val == NULL) {
-        ctx = EVP_MD_CTX_create();
+        printf("OPENSSL_malloc failed, error 0x%lx\n", ERR_get_error());
-        assert(ctx != NULL);
+         goto err;
-        if(ctx == NULL) {
-     if(ctx) {
+    *vlen = req;
-         EVP_MD_CTX_destroy(ctx);
+    rc = EVP_DigestSignFinal(ctx, *val, vlen);
-         ctx = NULL;
+     if (rc != 1) {
+     }
-     /* Convert to 0/1 result */
+     result = 1;
-     return !!result;
 }</pre>

← Older revision		Revision as of 13:47, 15 January 2018
Line 7:		Line 7:

	The examples below use the new <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions to demonstarte signing and verification. The first example uses an HMAC, and the second example uses RSA key pairs. Additionally, the code for the examples are available for download.		The examples below use the new <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions to demonstarte signing and verification. The first example uses an HMAC, and the second example uses RSA key pairs. Additionally, the code for the examples are available for download.
		+
		+	'''''Note''''': CMAC is only supported since the version 1.1.0 of OpenSSL.

	'''''Note''''': DSA handling changed for SSL/TLS cipher suites in OpenSSL 1.1.0. For details, see [http://groups.google.com/forum/#!topic/mailing.openssl.users/1_TFpK6XzQ4 DSA with OpenSSL-1.1] on the mailing list.		'''''Note''''': DSA handling changed for SSL/TLS cipher suites in OpenSSL 1.1.0. For details, see [http://groups.google.com/forum/#!topic/mailing.openssl.users/1_TFpK6XzQ4 DSA with OpenSSL-1.1] on the mailing list.

← Older revision		Revision as of 22:58, 28 April 2017
Line 1:		Line 1:
		+	{{DocInclude
		+	\|Name=Signing and Verifying
		+	\|Url=http://wiki.openssl.org/index.php/Manual:Evp(3)
		+	\|Include=evp.h}}
		+
	There are two APIs available to perform sign and verify operations. The first are the older <tt>EVP_Sign</tt> and <tt>EVP_Verify</tt> functions; and the second are the newer and more flexible <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions. Though the APIs are similar, new applications should use the <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions.		There are two APIs available to perform sign and verify operations. The first are the older <tt>EVP_Sign</tt> and <tt>EVP_Verify</tt> functions; and the second are the newer and more flexible <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions. Though the APIs are similar, new applications should use the <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions.

@@ Line 331: / Line 331: @@
 * [[EVP]]
 * [[Libcrypto API]]
 [[Category:Crypto API]]
 [[Category:C level]]
 [[Category:Examples]]

← Older revision		Revision as of 10:30, 2 July 2016
Line 2:		Line 2:

	The examples below use the new <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions to demonstarte signing and verification. The first example uses an HMAC, and the second example uses RSA key pairs. Additionally, the code for the examples are available for download.		The examples below use the new <tt>EVP_DigestSign</tt> and <tt>EVP_DigestVerify</tt> functions to demonstarte signing and verification. The first example uses an HMAC, and the second example uses RSA key pairs. Additionally, the code for the examples are available for download.
		+
		+	'''''Note''''': DSA handling changed for SSL/TLS cipher suites in OpenSSL 1.1.0. For details, see [http://groups.google.com/forum/#!topic/mailing.openssl.users/1_TFpK6XzQ4 DSA with OpenSSL-1.1] on the mailing list.

	==Overview==		==Overview==

← Older revision		Revision as of 21:37, 21 June 2015
Line 268:		Line 268:

	Note: There is no difference in the API between signing using an asymmetric algorithm, and generating a MAC code. In the case of CMAC no message digest function is required (NULL can be passed). Signing using the EVP_Sign* functions is very similar to the above example, except there is no support for MAC codes. Note that CMAC is only supported in the (as yet unreleased) version 1.1.0 of OpenSSL.		Note: There is no difference in the API between signing using an asymmetric algorithm, and generating a MAC code. In the case of CMAC no message digest function is required (NULL can be passed). Signing using the EVP_Sign* functions is very similar to the above example, except there is no support for MAC codes. Note that CMAC is only supported in the (as yet unreleased) version 1.1.0 of OpenSSL.
		+
		+	One gotcha to be aware of is that the first call to EVP_DigestSignFinal simply returns the maximum size of the buffer required. This will not always be the same as the size of the generated signature (specifically in the case of DSA and ECDSA). This means that you should also take account of the value of the length returned on the second call (in the slen variable in this example) when making use of the signature.

	Refer to [[Manual:EVP_DigestSignInit(3)]] for further details on the EVP_DigestSign* functions, and [[Manual:EVP_SignInit(3)]] for the EVP_Sign* functions.		Refer to [[Manual:EVP_DigestSignInit(3)]] for further details on the EVP_DigestSign* functions, and [[Manual:EVP_SignInit(3)]] for the EVP_Sign* functions.

@@ Line 1: / Line 1: @@
 There are two APIs available to perform sign and verify operations. The first are the older <tt>EVP_Sign*</tt> and <tt>EVP_Verify*</tt> functions; and the second are the newer and more flexible <tt>EVP_DigestSign*</tt> and <tt>EVP_DigestVerify*</tt> functions. Though the APIs are similar, new applications should use the <tt>EVP_DigestSign*</tt> and <tt>EVP_DigestVerify*</tt> functions.
-The examples below use the new <tt>EVP_DigestSign*</tt> and <tt>EVP_DigestVerify*</tt> functions to demonstarte signing and verification. The first example uses an HMAC, and the second example uses RSA key pairs. Additionally, the code for the example is available for download.
+The examples below use the new <tt>EVP_DigestSign*</tt> and <tt>EVP_DigestVerify*</tt> functions to demonstarte signing and verification. The first example uses an HMAC, and the second example uses RSA key pairs. Additionally, the code for the examples are available for download.
 ==Overview==