do not add a signature prefix for D-Trust cards

Thanks to Simon Eisenmann for the patch
http://www.opensc-project.org/pipermail/opensc-devel/2007-December/010609.html


git-svn-id: https://www.opensc-project.org/svnp/opensc/trunk@3303 c6295689-39f2-0310-b995-f0e70906c6a9

src/libopensc/card-cardos.c

@@ -802,14 +802,28 @@ cardos_compute_signature(sc_card_t *card, const u8 *data, size_t datalen,
 	 * certain key, let's try RSA_PURE etc. and see which operation
 	 * succeeds (this is not really beautiful, but currently the
 	 * only way I see) -- Nils
+	 *
+	 * We also check for several caps flags here to pervent generating
+	 * invalid signatures with duplicated hash prefixes with some cards
 	 */
-	if (ctx->debug >= 3)
-		sc_debug(ctx, "trying RSA_PURE_SIG (padded DigestInfo)\n");
-	sc_ctx_suppress_errors_on(ctx);
-	r = do_compute_signature(card, data, datalen, out, outlen);
-	sc_ctx_suppress_errors_off(ctx);
-	if (r >= SC_SUCCESS)
-		SC_FUNC_RETURN(ctx, 4, r);
+
+    if (ctx->debug >= 3) {	 
+        if (card->caps & SC_CARD_CAP_ONLY_RAW_HASH_STRIPPED)
+            sc_debug(ctx, "Forcing RAW_HASH_STRIPPED\n");        	 
+        if (card->caps & SC_CARD_CAP_ONLY_RAW_HASH)
+            sc_debug(ctx, "Forcing RAW_HASH\n");
+    }
+
+	if (!(card->caps & (SC_CARD_CAP_ONLY_RAW_HASH_STRIPPED | SC_CARD_CAP_ONLY_RAW_HASH))) {
+		if (ctx->debug >= 3)
+			sc_debug(ctx, "trying RSA_PURE_SIG (padded DigestInfo)\n");
+		sc_ctx_suppress_errors_on(ctx);
+		r = do_compute_signature(card, data, datalen, out, outlen);
+		sc_ctx_suppress_errors_off(ctx);
+		if (r >= SC_SUCCESS)
+			SC_FUNC_RETURN(ctx, 4, r);
+	}		
+
 	if (ctx->debug >= 3)
 		sc_debug(ctx, "trying RSA_SIG (just the DigestInfo)\n");
 	/* remove padding: first try pkcs1 bt01 padding */
@@ -826,13 +840,24 @@ cardos_compute_signature(sc_card_t *card, const u8 *data, size_t datalen,
 		}
 		memcpy(buf, p, tmp_len);
 	}
-	sc_ctx_suppress_errors_on(ctx);
-	r = do_compute_signature(card, buf, tmp_len, out, outlen);
-	sc_ctx_suppress_errors_off(ctx);
-	if (r >= SC_SUCCESS)	
-		SC_FUNC_RETURN(ctx, 4, r);
+
+	if (!(card->caps & (SC_CARD_CAP_ONLY_RAW_HASH_STRIPPED | SC_CARD_CAP_ONLY_RAW_HASH)) || card->caps & SC_CARD_CAP_ONLY_RAW_HASH ) {
+		if (ctx->debug >= 3)
+			sc_debug(ctx, "trying to sign raw hash value with prefix\n");	
+		sc_ctx_suppress_errors_on(ctx);
+		r = do_compute_signature(card, buf, tmp_len, out, outlen);
+		sc_ctx_suppress_errors_off(ctx);
+		if (r >= SC_SUCCESS)	
+			SC_FUNC_RETURN(ctx, 4, r);
+	}
+
+	if (card->caps & SC_CARD_CAP_ONLY_RAW_HASH) {
+	    sc_debug(ctx, "Failed to sign raw hash value with prefix when forcing\n");
+	    SC_FUNC_RETURN(ctx, 4, SC_ERROR_INVALID_ARGUMENTS);
+	}
+
 	if (ctx->debug >= 3)
-		sc_debug(ctx, "trying to sign raw hash value\n");
+		sc_debug(ctx, "trying to sign stripped raw hash value (card is responsible for prefix)\n");
 	r = sc_pkcs1_strip_digest_info_prefix(NULL,buf,tmp_len,buf,&buf_len);
 	if (r != SC_SUCCESS)
 		SC_FUNC_RETURN(ctx, 4, r);

src/libopensc/opensc.h

@@ -446,6 +446,10 @@ struct sc_reader_operations {
 /* The card supports 2048 bit RSA keys */
 #define SC_CARD_CAP_RSA_2048		0x00000020
 
+/* D-TRUST CardOS cards special flags */
+#define SC_CARD_CAP_ONLY_RAW_HASH        0x00000040
+#define SC_CARD_CAP_ONLY_RAW_HASH_STRIPPED      0x00000080
+
 typedef struct sc_card {
 	struct sc_context *ctx;
 	struct sc_reader *reader;

src/libopensc/pkcs15.c

@@ -681,6 +681,38 @@ static int sc_pkcs15_bind_internal(sc_pkcs15_card_t *p15card)
 			|| strcmp(p15card->manufacturer_id,"Prime") == 0 ))
 		p15card->flags |= SC_PKCS15_CARD_FLAG_SIGN_WITH_DECRYPT;
 
+	/* set special flags based on card meta data */
+	if (strcmp(p15card->card->driver->short_name,"cardos") == 0) {
+
+		/* D-Trust cards (D-TRUST, D-SIGN) */
+		if (strstr(p15card->label,"D-TRUST") == 0
+			|| strstr(p15card->label,"D-SIGN") == 0) {
+
+			/* D-TRUST Card 2.0 2cc (standard cards, which always add 
+			 * SHA1 prefix itself */
+			if (strstr(p15card->label, "2cc") != NULL) {
+				p15card->card->caps |= SC_CARD_CAP_ONLY_RAW_HASH_STRIPPED;
+				p15card->flags &= ~SC_PKCS15_CARD_FLAG_SIGN_WITH_DECRYPT;
+				sc_debug(p15card->card->ctx, "D-TRUST 2cc card detected, only SHA1 works with this card\n");
+				/* XXX: add detection when other hash than SHA1 is used with
+				 *      such a card, as this produces invalid signatures.
+				 */
+			}
+
+			/* D-SIGN multicard 2.0 2ca (cards working with all types of hashes 
+			 * and no addition of prefix) */
+			else if (strstr(p15card->label, "2ca") != NULL) {
+				p15card->card->caps |= SC_CARD_CAP_ONLY_RAW_HASH;
+				p15card->flags &= ~SC_PKCS15_CARD_FLAG_SIGN_WITH_DECRYPT;
+				sc_debug(p15card->card->ctx, "D-TRUST 2ca card detected\n");
+			}
+
+			/* XXX: probably there are more D-Trust card in the wild, 
+			 *      which also need these flags to produce valid signatures
+			 */
+		}
+	}
+
 	ok = 1;
 end:
 	if(buf != NULL)