Merge pull request #434 from SparkiDev/certvfy

Low-level certificate verification examples

.gitignore

@@ -198,6 +198,10 @@ pkcs7/signedData-verifyFile
 certmanager/certloadverifybuffer
 certmanager/certverify
 
+certvfy/certvfy
+certvfy/certsigvfy
+certvfy/sigvfycert
+
 rsa/sign
 rsa/verify
 

certvfy/Makefile

@@ -0,0 +1,17 @@
+CC=gcc -g
+CFLAGS=-Wall
+LIBS= -lwolfssl
+
+all: certvfy certsigvfy sigvfycert
+
+certvfy: certvfy.o
+	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
+certsigvfy: certsigvfy.o
+	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
+sigvfycert: sigvfycert.o
+	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
+
+.PHONY: clean
+
+clean:
+	rm -f *.o certvfy certsigvfy sigvfycert

certvfy/README.md

@@ -0,0 +1,27 @@
+# wolfSSL Cert Verification Examples
+
+This directory contains:
+
+A simple example of using the low level wolfSSL APIs to verify a certificate
+in a standalone manner, separate from an SSL/TLS connection.
+
+## Compiling and Running the Example
+
+```
+$ cd wolfssl
+$ ./autogen.sh                # If downloaded from github
+$ ./configure '--enable-cryptonly' '--enable-singlethreaded' 'CFLAGS=-DWOLFSSL_SMALL_CERT_VERIFY'
+$ make all
+$ make check
+$ sudo make install
+```
+
+```
+$ cd wolfssl-examples
+$ cd certvfy
+$ make all
+$ ./certvfy
+$ ./certsigvfy
+$ ./sigvfycert
+```
+

certvfy/certsigvfy.c

@@ -0,0 +1,117 @@
+/* certsigvfy.c
+ *
+ * Copyright (C) 2006-2024 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+#include <stdio.h>
+
+#ifdef HAVE_CONFIG_H
+    #include <config.h>
+#endif
+
+#ifndef WOLFSSL_USER_SETTINGS
+    #include <wolfssl/options.h>
+#endif
+#include <wolfssl/wolfcrypt/settings.h>
+
+#include <wolfssl/wolfcrypt/asn_public.h>
+#include <wolfssl/wolfcrypt/asn.h>
+#include <wolfssl/wolfcrypt/error-crypt.h>
+
+#define MAX_DER_SZ          4096
+
+int load_file(const char* name, byte* buf, int bufSz)
+{
+    FILE* file;
+
+    file = fopen(name, "rb");
+    if (file == NULL) {
+        return 0;
+    }
+    bufSz = fread(buf, 1, bufSz, file);
+    fclose(file);
+
+    return bufSz;
+}
+
+int main(void)
+{
+    int res = 0;
+    int ret;
+
+    const char* caCert     = "../certs/ca-cert.der";
+    const char* verifyCert = "../certs/server-cert.der";
+
+    byte caDer[MAX_DER_SZ];
+    int caDerSz;
+    byte certDer[MAX_DER_SZ];
+    int certDerSz;
+
+    DecodedCert ca;
+
+    XMEMSET(&ca, 0, sizeof(ca));
+
+    wolfCrypt_Init();
+
+    /* Load the DER encoded CA certificate. */
+    caDerSz = load_file(caCert, caDer, (int)sizeof(caDer));
+    if (caDerSz == 0) {
+        printf("Failed to load CA file\n");
+        res = 1;
+        goto exit;
+    }
+
+    /* Put the CA certificate data into the object. */
+    wc_InitDecodedCert(&ca, caDer, caDerSz, NULL);
+    /* Parse fields of the certificate. */
+    ret = wc_ParseCert(&ca, CERT_TYPE, 0, NULL);
+    if (ret != 0) {
+        printf("Parsing CA failed: %s (%d)\n", wc_GetErrorString(ret), ret);
+        res = 1;
+        goto exit;
+    }
+
+    /* Load the DER encoded certificate to verify. */
+    certDerSz = load_file(verifyCert, certDer, (int)sizeof(certDer));
+    if (certDerSz == 0) {
+        printf("Failed to load certificate file\n");
+        res = 1;
+        goto exit;
+    }
+
+    /* Verify the signature of the certificate with the public key from the CA
+     * certificate.
+     */
+    ret = wc_CheckCertSigPubKey(certDer, certDerSz, NULL, ca.publicKey,
+        ca.pubKeySize, ca.keyOID);
+    if (ret != 0) {
+        printf("Signature verification failed: %s (%d)\n",
+            wc_GetErrorString(ret), ret);
+        res = 1;
+        goto exit;
+    }
+    printf("Verification Successful!\n");
+
+exit:
+    wc_FreeDecodedCert(&ca);
+    wolfCrypt_Cleanup();
+
+    return res;
+}
+

certvfy/certvfy.c

@@ -0,0 +1,124 @@
+/* certvfy.c
+ *
+ * Copyright (C) 2006-2024 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL.
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
+ */
+
+#include <stdio.h>
+
+#ifdef HAVE_CONFIG_H
+    #include <config.h>
+#endif
+
+#ifndef WOLFSSL_USER_SETTINGS
+    #include <wolfssl/options.h>
+#endif
+#include <wolfssl/wolfcrypt/settings.h>
+
+#include <wolfssl/wolfcrypt/asn_public.h>
+#include <wolfssl/wolfcrypt/asn.h>
+#include <wolfssl/wolfcrypt/error-crypt.h>
+
+#define MAX_DER_SZ          4096
+
+int load_file(const char* name, byte* buf, int bufSz)
+{
+    FILE* file;
+
+    file = fopen(name, "rb");
+    if (file == NULL) {
+        return 0;
+    }
+    bufSz = fread(buf, 1, bufSz, file);
+    fclose(file);
+
+    return bufSz;
+}
+
+int main(void)
+{
+    int res = 0;
+    int ret;
+
+    const char* caCert     = "../certs/ca-cert.der";
+    const char* verifyCert = "../certs/server-cert.der";
+
+    byte caDer[MAX_DER_SZ];
+    int caDerSz;
+    byte certDer[MAX_DER_SZ];
+    int certDerSz;
+
+    DecodedCert ca;
+    Signer caSigner;
+    DecodedCert cert;
+
+    XMEMSET(&ca, 0, sizeof(ca));
+    XMEMSET(&caSigner, 0, sizeof(caSigner));
+    XMEMSET(&cert, 0, sizeof(cert));
+
+    wolfCrypt_Init();
+
+    /* Load the DER encoded CA certificate. */
+    caDerSz = load_file(caCert, caDer, (int)sizeof(caDer));
+    if (caDerSz == 0) {
+        printf("Failed to load CA file\n");
+        res = 1;
+        goto exit;
+    }
+
+    /* Put the CA certificate data into the object. */
+    wc_InitDecodedCert(&ca, caDer, caDerSz, NULL);
+    /* Parse fields of the certificate. */
+    ret = wc_ParseCert(&ca, CERT_TYPE, 0, NULL);
+    if (ret != 0) {
+        printf("Parsing CA failed: %s (%d)\n", wc_GetErrorString(ret), ret);
+        res = 1;
+        goto exit;
+    }
+    /* Put fields into CA signer object. */
+    caSigner.publicKey  = ca.publicKey;
+    caSigner.pubKeySize = ca.pubKeySize;
+    caSigner.keyOID     = ca.keyOID;
+    XMEMCPY(caSigner.subjectNameHash, ca.subjectHash, KEYID_SIZE);
+
+    /* Load the DER encoded certificate to verify. */
+    certDerSz = load_file(verifyCert, certDer, (int)sizeof(certDer));
+    if (certDerSz == 0) {
+        printf("Failed to load certificate file\n");
+        res = 1;
+        goto exit;
+    }
+
+    /* Put the certificate data into the object. */
+    wc_InitDecodedCert(&cert, certDer, certDerSz, NULL);
+    /* Parse and verify the certificate. */
+    ret = wc_ParseCert(&cert, CERT_TYPE, 1, &caSigner);
+    if (ret != 0) {
+        printf("Verification failed: %s (%d)\n", wc_GetErrorString(ret), ret);
+        res = 1;
+        goto exit;
+    }
+    printf("Verification Successful!\n");
+
+exit:
+    wc_FreeDecodedCert(&cert);
+    wc_FreeDecodedCert(&ca);
+    wolfCrypt_Cleanup();
+    return res;
+}
+