Add PKCS7 ECC raw sign callback support

jackctj117 · jackctj117 · commit 6d6d0ab08809 · 2026-01-28T14:44:00.000-07:00
diff --git a/.wolfssl_known_macro_extras b/.wolfssl_known_macro_extras
@@ -280,6 +280,7 @@ HAVE_INTEL_QAT_SYNC
 HAVE_INTEL_SPEEDUP
 HAVE_MDK_RTX
 HAVE_NETX_BSD
+HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK
 HAVE_PKCS7_RSA_RAW_SIGN_CALLBACK
 HAVE_POCO_LIB
 HAVE_RTP_SYS
diff --git a/tests/api/test_pkcs7.c b/tests/api/test_pkcs7.c
@@ -388,12 +388,15 @@ int test_wc_PKCS7_EncodeData(void)
 
 #if defined(HAVE_PKCS7) && defined(HAVE_PKCS7_RSA_RAW_SIGN_CALLBACK) && \
     !defined(NO_RSA) && !defined(NO_SHA256)
-/* RSA sign raw digest callback */
+/* RSA sign raw digest callback
+ * This callback demonstrates HSM/secure element use case where the private
+ * key is not passed through PKCS7 structure but obtained independently.
+ */
 static int rsaSignRawDigestCb(PKCS7* pkcs7, byte* digest, word32 digestSz,
                               byte* out, word32 outSz, byte* privateKey,
                               word32 privateKeySz, int devid, int hashOID)
 {
-    /* specific DigestInfo ASN.1 encoding prefix for a SHA2565 digest */
+    /* specific DigestInfo ASN.1 encoding prefix for a SHA256 digest */
     byte digInfoEncoding[] = {
         0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
         0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05,
@@ -407,6 +410,11 @@ static int rsaSignRawDigestCb(PKCS7* pkcs7, byte* digest, word32 digestSz,
     word32 idx = 0;
     RsaKey rsa;
 
+    /* privateKey may be NULL in HSM/secure element use case - we load it
+     * independently in this callback to simulate that scenario */
+    (void)privateKey;
+    (void)privateKeySz;
+
     /* SHA-256 required only for this example callback due to above
      * digInfoEncoding[] */
     if (pkcs7 == NULL || digest == NULL || out == NULL ||
@@ -427,7 +435,33 @@ static int rsaSignRawDigestCb(PKCS7* pkcs7, byte* digest, word32 digestSz,
         return ret;
     }
 
-    ret = wc_RsaPrivateKeyDecode(privateKey, &idx, &rsa, privateKeySz);
+    /* Load key from test buffer - simulates HSM/secure element access */
+#if defined(USE_CERT_BUFFERS_2048)
+    ret = wc_RsaPrivateKeyDecode(client_key_der_2048, &idx, &rsa,
+                                 sizeof_client_key_der_2048);
+#elif defined(USE_CERT_BUFFERS_1024)
+    ret = wc_RsaPrivateKeyDecode(client_key_der_1024, &idx, &rsa,
+                                 sizeof_client_key_der_1024);
+#else
+    {
+        XFILE fp;
+        byte keyBuf[ONEK_BUF];
+        int keySz;
+
+        fp = XFOPEN("./certs/client-key.der", "rb");
+        if (fp == XBADFILE) {
+            wc_FreeRsaKey(&rsa);
+            return -1;
+        }
+        keySz = (int)XFREAD(keyBuf, 1, sizeof(keyBuf), fp);
+        XFCLOSE(fp);
+        if (keySz <= 0) {
+            wc_FreeRsaKey(&rsa);
+            return -1;
+        }
+        ret = wc_RsaPrivateKeyDecode(keyBuf, &idx, &rsa, (word32)keySz);
+    }
+#endif
 
     /* sign DigestInfo */
     if (ret == 0) {
@@ -451,6 +485,76 @@ static int rsaSignRawDigestCb(PKCS7* pkcs7, byte* digest, word32 digestSz,
 }
 #endif
 
+#if defined(HAVE_PKCS7) && defined(HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK) && \
+    defined(HAVE_ECC) && !defined(NO_SHA256)
+/* ECC sign raw digest callback
+ * This callback demonstrates HSM/secure element use case where the private
+ * key is not passed through PKCS7 structure but obtained independently.
+ */
+static int eccSignRawDigestCb(PKCS7* pkcs7, byte* digest, word32 digestSz,
+                              byte* out, word32 outSz, byte* privateKey,
+                              word32 privateKeySz, int devid, int hashOID)
+{
+    int ret;
+    word32 idx = 0;
+    word32 sigSz = outSz;
+    ecc_key ecc;
+
+    /* privateKey may be NULL in HSM/secure element use case - we load it
+     * independently in this callback to simulate that scenario */
+    (void)privateKey;
+    (void)privateKeySz;
+    (void)hashOID;
+
+    if (pkcs7 == NULL || digest == NULL || out == NULL) {
+        return -1;
+    }
+
+    /* set up ECC key */
+    ret = wc_ecc_init_ex(&ecc, pkcs7->heap, devid);
+    if (ret != 0) {
+        return ret;
+    }
+
+    /* Load key from test buffer - simulates HSM/secure element access */
+#if defined(USE_CERT_BUFFERS_256)
+    ret = wc_EccPrivateKeyDecode(ecc_clikey_der_256, &idx, &ecc,
+                                 sizeof_ecc_clikey_der_256);
+#else
+    {
+        XFILE fp;
+        byte keyBuf[ONEK_BUF];
+        int keySz;
+
+        fp = XFOPEN("./certs/client-ecc-key.der", "rb");
+        if (fp == XBADFILE) {
+            wc_ecc_free(&ecc);
+            return -1;
+        }
+        keySz = (int)XFREAD(keyBuf, 1, sizeof(keyBuf), fp);
+        XFCLOSE(fp);
+        if (keySz <= 0) {
+            wc_ecc_free(&ecc);
+            return -1;
+        }
+        ret = wc_EccPrivateKeyDecode(keyBuf, &idx, &ecc, (word32)keySz);
+    }
+#endif
+
+    /* sign digest */
+    if (ret == 0) {
+        ret = wc_ecc_sign_hash(digest, digestSz, out, &sigSz, pkcs7->rng, &ecc);
+        if (ret == 0) {
+            ret = (int)sigSz;
+        }
+    }
+
+    wc_ecc_free(&ecc);
+
+    return ret;
+}
+#endif
+
 #if defined(HAVE_PKCS7) && defined(ASN_BER_TO_DER)
 typedef struct encodeSignedDataStream {
     byte out[FOURK_BUF*3];
@@ -757,8 +861,7 @@ int test_wc_PKCS7_EncodeSignedData(void)
     if (pkcs7 != NULL) {
         pkcs7->content = data;
         pkcs7->contentSz = (word32)sizeof(data);
-        pkcs7->privateKey = key;
-        pkcs7->privateKeySz = (word32)sizeof(key);
+        /* privateKey not set - callback simulates HSM/secure element access */
         pkcs7->encryptOID = RSAk;
         pkcs7->hashOID = SHA256h;
         pkcs7->rng = &rng;
@@ -769,6 +872,47 @@ int test_wc_PKCS7_EncodeSignedData(void)
     ExpectIntGT(wc_PKCS7_EncodeSignedData(pkcs7, output, outputSz), 0);
 #endif
 
+#if defined(HAVE_PKCS7) && defined(HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK) && \
+    defined(HAVE_ECC) && !defined(NO_SHA256)
+    /* test ECC sign raw digest callback, if using ECC and compiled in.
+     * Example callback assumes SHA-256, so only run test if compiled in. */
+    {
+    #if defined(USE_CERT_BUFFERS_256)
+        byte        eccCert[sizeof(cliecc_cert_der_256)];
+        word32      eccCertSz = (word32)sizeof(eccCert);
+        XMEMCPY(eccCert, cliecc_cert_der_256, eccCertSz);
+    #else
+        byte        eccCert[ONEK_BUF];
+        int         eccCertSz;
+        XFILE       eccFp = XBADFILE;
+
+        ExpectTrue((eccFp = XFOPEN("./certs/client-ecc-cert.der", "rb")) !=
+            XBADFILE);
+        ExpectIntGT(eccCertSz = (int)XFREAD(eccCert, 1, ONEK_BUF, eccFp), 0);
+        if (eccFp != XBADFILE)
+            XFCLOSE(eccFp);
+    #endif
+
+        wc_PKCS7_Free(pkcs7);
+        pkcs7 = NULL;
+        ExpectNotNull(pkcs7 = wc_PKCS7_New(HEAP_HINT, testDevId));
+        ExpectIntEQ(wc_PKCS7_InitWithCert(pkcs7, eccCert, (word32)eccCertSz), 0);
+
+        if (pkcs7 != NULL) {
+            pkcs7->content = data;
+            pkcs7->contentSz = (word32)sizeof(data);
+            /* privateKey not set - callback simulates HSM/secure element access */
+            pkcs7->encryptOID = ECDSAk;
+            pkcs7->hashOID = SHA256h;
+            pkcs7->rng = &rng;
+        }
+
+        ExpectIntEQ(wc_PKCS7_SetEccSignRawDigestCb(pkcs7, eccSignRawDigestCb), 0);
+
+        ExpectIntGT(wc_PKCS7_EncodeSignedData(pkcs7, output, outputSz), 0);
+    }
+#endif
+
     wc_PKCS7_Free(pkcs7);
     DoExpectIntEQ(wc_FreeRng(&rng), 0);
 
diff --git a/wolfcrypt/src/pkcs7.c b/wolfcrypt/src/pkcs7.c
@@ -1794,6 +1794,16 @@ static int wc_PKCS7_ImportRSA(wc_PKCS7* pkcs7, RsaKey* privKey)
             }
         #endif
         }
+    #ifdef HAVE_PKCS7_RSA_RAW_SIGN_CALLBACK
+        else if (pkcs7->rsaSignRawDigestCb != NULL && pkcs7->publicKeySz > 0) {
+            /* When using raw sign callback (e.g., HSM/secure element), private
+             * key may not be available. Use public key from signer certificate
+             * for signature size calculation. */
+            idx = 0;
+            ret = wc_RsaPublicKeyDecode(pkcs7->publicKey, &idx, privKey,
+                                        pkcs7->publicKeySz);
+        }
+    #endif
         else if (pkcs7->devId == INVALID_DEVID) {
             ret = BAD_FUNC_ARG;
         }
@@ -1874,6 +1884,16 @@ static int wc_PKCS7_ImportECC(wc_PKCS7* pkcs7, ecc_key* privKey)
             }
         #endif
         }
+    #ifdef HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK
+        else if (pkcs7->eccSignRawDigestCb != NULL && pkcs7->publicKeySz > 0) {
+            /* When using raw sign callback (e.g., HSM/secure element), private
+             * key may not be available. Use public key from signer certificate
+             * for signature size calculation. */
+            idx = 0;
+            ret = wc_EccPublicKeyDecode(pkcs7->publicKey, &idx, privKey,
+                                        pkcs7->publicKeySz);
+        }
+    #endif
         else if (pkcs7->devId == INVALID_DEVID) {
             ret = BAD_FUNC_ARG;
         }
@@ -2398,6 +2418,20 @@ static int wc_PKCS7_SignedDataBuildSignature(wc_PKCS7* pkcs7,
 
 #ifdef HAVE_ECC
         case ECDSAk:
+        #ifdef HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK
+            if (pkcs7->eccSignRawDigestCb != NULL) {
+                /* get hash OID */
+                int eccHashOID = wc_HashGetOID(esd->hashType);
+
+                /* user signing plain digest */
+                ret = pkcs7->eccSignRawDigestCb(pkcs7,
+                           esd->contentAttribsDigest, hashSz,
+                           esd->encContentDigest, sizeof(esd->encContentDigest),
+                           pkcs7->privateKey, pkcs7->privateKeySz, pkcs7->devId,
+                           eccHashOID);
+                break;
+            }
+        #endif
             /* CMS with ECDSA does not sign DigestInfo structure
              * like PKCS#7 with RSA does */
             ret = wc_PKCS7_EcdsaSign(pkcs7, esd->contentAttribsDigest,
@@ -3986,6 +4020,30 @@ int wc_PKCS7_SetRsaSignRawDigestCb(wc_PKCS7* pkcs7, CallbackRsaSignRawDigest cb)
 }
 #endif
 
+#endif /* NO_RSA */
+
+
+#ifdef HAVE_ECC
+
+#ifdef HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK
+/* register raw ECC sign digest callback */
+int wc_PKCS7_SetEccSignRawDigestCb(wc_PKCS7* pkcs7, CallbackEccSignRawDigest cb)
+{
+    if (pkcs7 == NULL || cb == NULL) {
+        return BAD_FUNC_ARG;
+    }
+
+    pkcs7->eccSignRawDigestCb = cb;
+
+    return 0;
+}
+#endif
+
+#endif /* HAVE_ECC */
+
+
+#ifndef NO_RSA
+
 /* returns size of signature put into out, negative on error */
 static int wc_PKCS7_RsaVerify(wc_PKCS7* pkcs7, byte* sig, int sigSz,
                               byte* hash, word32 hashSz)
diff --git a/wolfssl/wolfcrypt/pkcs7.h b/wolfssl/wolfcrypt/pkcs7.h
@@ -229,6 +229,14 @@ typedef int (*CallbackRsaSignRawDigest)(wc_PKCS7* pkcs7, byte* digest,
                                    int devId, int hashOID);
 #endif
 
+#if defined(HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK) && defined(HAVE_ECC)
+/* ECC sign raw digest callback, user signs hash directly */
+typedef int (*CallbackEccSignRawDigest)(wc_PKCS7* pkcs7, byte* digest,
+                                   word32 digestSz, byte* out, word32 outSz,
+                                   byte* privateKey, word32 privateKeySz,
+                                   int devId, int hashOID);
+#endif
+
 
 /* Public Structure Warning:
  * Existing members must not be changed to maintain backwards compatibility!
@@ -376,6 +384,10 @@ struct wc_PKCS7 {
 
     CallbackAESKeyWrapUnwrap aesKeyWrapUnwrapCb;
 
+#if defined(HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK) && defined(HAVE_ECC)
+    CallbackEccSignRawDigest eccSignRawDigestCb;
+#endif
+
     /* !! NEW DATA MEMBERS MUST BE ADDED AT END !! */
 };
 
@@ -511,6 +523,11 @@ WOLFSSL_API int  wc_PKCS7_SetRsaSignRawDigestCb(wc_PKCS7* pkcs7,
         CallbackRsaSignRawDigest cb);
 #endif
 
+#if defined(HAVE_PKCS7_ECC_RAW_SIGN_CALLBACK) && defined(HAVE_ECC)
+WOLFSSL_API int  wc_PKCS7_SetEccSignRawDigestCb(wc_PKCS7* pkcs7,
+        CallbackEccSignRawDigest cb);
+#endif
+
 /* CMS/PKCS#7 EnvelopedData */
 WOLFSSL_API int  wc_PKCS7_EncodeEnvelopedData(wc_PKCS7* pkcs7,
                                           byte* output, word32 outputSz);
