X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=gcrypt.c;h=5d151a3cc9f7c42e6322f1748902b14281b49f1c;hb=3f6b7dd0ed39f7008ec09def9239f379b87cd7c1;hp=58fa507b6e1f96303998e0f6ba0ae47f90beb493;hpb=3699a583f3a7e9514c0f47b8b07f56b050430b67;p=paraslash.git

diff --git a/gcrypt.c b/gcrypt.c
index 58fa507b..5d151a3c 100644
--- a/gcrypt.c
+++ b/gcrypt.c
@@ -336,6 +336,26 @@ static int find_privkey_bignum_offset(const unsigned char *data, int len)
 	return p - data;
 }
 
+static int read_openssh_bignum(unsigned char *start, unsigned char *end,
+		gcry_mpi_t *bn, unsigned *bitsp)
+{
+	gcry_error_t gret;
+	size_t nscanned;
+	unsigned bits;
+
+	gret = gcry_mpi_scan(bn, GCRYMPI_FMT_SSH, start, end - start, &nscanned);
+	if (gret) {
+		PARA_ERROR_LOG("gcry_mpi_scan: %s\n",
+			gcry_strerror(gcry_err_code(gret)));
+		return -E_MPI_SCAN;
+	}
+	bits = (nscanned - 4 - (start[4] == '\0')) * 8;
+	if (bitsp)
+		*bitsp = bits;
+	PARA_DEBUG_LOG("scanned %u-bit bignum\n", bits);
+	return nscanned;
+}
+
 static int get_private_key(const char *key_file, struct asymmetric_key **result)
 {
 	struct rsa_params params;
@@ -400,10 +420,11 @@ int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
 	unsigned char *blob, *p, *end;
 	int ret;
 	gcry_error_t gret;
-	size_t nr_scanned, erroff, decoded_size;
+	size_t erroff, decoded_size;
 	gcry_mpi_t e, n;
 	gcry_sexp_t sexp;
 	struct asymmetric_key *key;
+	unsigned bits;
 
 	ret = decode_ssh_key(key_file, &blob, &decoded_size);
 	if (ret < 0)
@@ -411,23 +432,13 @@ int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
 	p = blob + ret;
 	end = blob + decoded_size;
 	PARA_DEBUG_LOG("scanning modulus and public exponent\n");
-	gret = gcry_mpi_scan(&e, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
-	if (gret) {
-		ret = -E_MPI_SCAN;
-		PARA_CRIT_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
+	ret = read_openssh_bignum(p, end, &e, NULL);
+	if (ret < 0)
 		goto free_blob;
-	}
-	PARA_DEBUG_LOG("scanned e (%zu bytes)\n", nr_scanned);
-	p += nr_scanned;
-	if (p >= end)
-		goto release_e;
-	gret = gcry_mpi_scan(&n, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
-	if (gret) {
-		ret = -E_MPI_SCAN;
-		PARA_ERROR_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
+	p += ret;
+	ret = read_openssh_bignum(p, end, &n, &bits);
+	if (ret < 0)
 		goto release_e;
-	}
-	PARA_DEBUG_LOG("scanned n (%zu bytes)\n", nr_scanned);
 	gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
 	if (gret) {
 		PARA_ERROR_LOG("offset %zu: %s\n", erroff,
@@ -435,12 +446,12 @@ int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
 		ret = -E_SEXP_BUILD;
 		goto release_n;
 	}
-	ret = ROUND_DOWN(nr_scanned, 32);
-	PARA_INFO_LOG("successfully read %d bit ssh public key\n", ret * 8);
+	PARA_INFO_LOG("successfully read %u bit ssh public key\n", bits);
 	key = para_malloc(sizeof(*key));
 	key->num_bytes = ret;
 	key->sexp = sexp;
 	*result = key;
+	ret = bits;
 release_n:
 	gcry_mpi_release(n);
 release_e: