X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=gcrypt.c;h=1fde479e1be97656bd01002a2071a3d6f1b4b026;hp=751c1a4a65d4d0b3b9e5a90242462a83d3fc6cf1;hb=a826152ba51fd4813f715e5fa30e7d70407dc846;hpb=72e9bdf7c5c09ca4c20cad56c68a9a155cceff43

diff --git a/gcrypt.c b/gcrypt.c
index 751c1a4a..1fde479e 100644
--- a/gcrypt.c
+++ b/gcrypt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2014 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2011 Andre Noll <maan@tuebingen.mpg.de>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -15,18 +15,16 @@
 #include "crypt.h"
 #include "crypt_backend.h"
 #include "fd.h"
+#include "base64.h"
 
 //#define GCRYPT_DEBUG 1
 
-static bool libgcrypt_has_oaep;
-static const char *rsa_decrypt_sexp;
-
 #ifdef GCRYPT_DEBUG
 static void dump_buffer(const char *msg, unsigned char *buf, int len)
 {
 	int i;
 
-	fprintf(stderr, "%s (%u bytes): ", msg, len);
+	fprintf(stderr, "%s (%d bytes): ", msg, len);
 	for (i = 0; i < len; i++)
 		fprintf(stderr, "%02x ", buf[i]);
 	fprintf(stderr, "\n");
@@ -62,134 +60,25 @@ void get_random_bytes_or_die(unsigned char *buf, int num)
  * don't have to initialize any random seed here, but we must initialize the
  * gcrypt library. This task is performed by gcry_check_version() which can
  * also check that the gcrypt library version is at least the minimal required
- * version. This function also tells us whether we have to use our own OAEP
- * padding code.
+ * version.
  */
 void init_random_seed_or_die(void)
 {
-	const char *ver, *req_ver;
-
-	ver = gcry_check_version(NULL);
-	req_ver = "1.4.0";
-	if (!gcry_check_version(req_ver)) {
-		PARA_EMERG_LOG("fatal: need at least libgcrypt-%s, have: %s\n",
-			req_ver, ver);
-		exit(EXIT_FAILURE);
-	}
-	req_ver = "1.5.0";
-	if (gcry_check_version(req_ver)) {
-		libgcrypt_has_oaep = true;
-		rsa_decrypt_sexp = "(enc-val(flags oaep)(rsa(a %m)))";
-	} else {
-		libgcrypt_has_oaep = false;
-		rsa_decrypt_sexp = "(enc-val(rsa(a %m)))";
-	}
+	const char *req_ver = "1.5.0";
+
+	if (gcry_check_version(req_ver))
+		return;
+	PARA_EMERG_LOG("fatal: need at least libgcrypt-%s, have: %s\n",
+		req_ver, gcry_check_version(NULL));
+	exit(EXIT_FAILURE);
 }
 
 /** S-expression for the public part of an RSA key. */
-#define RSA_PUBKEY_SEXP  "(public-key (rsa (n %m) (e %m)))"
+#define RSA_PUBKEY_SEXP "(public-key (rsa (n %m) (e %m)))"
 /** S-expression for a private RSA key. */
 #define RSA_PRIVKEY_SEXP "(private-key (rsa (n %m) (e %m) (d %m) (p %m) (q %m) (u %m)))"
-
-/* rfc 3447, appendix B.2 */
-static void mgf1(unsigned char *seed, size_t seed_len, unsigned result_len,
-		unsigned char *result)
-{
-	gcry_error_t gret;
-	gcry_md_hd_t handle;
-	size_t n;
-	unsigned char *md;
-	unsigned char octet_string[4], *rp = result, *end = rp + result_len;
-
-	assert(result_len / HASH_SIZE < 1ULL << 31);
-	gret = gcry_md_open(&handle, GCRY_MD_SHA1, 0);
-	assert(gret == 0);
-	for (n = 0; rp < end; n++) {
-		gcry_md_write(handle, seed, seed_len);
-		octet_string[0] = (unsigned char)((n >> 24) & 255);
-		octet_string[1] = (unsigned char)((n >> 16) & 255);
-		octet_string[2] = (unsigned char)((n >> 8)) & 255;
-		octet_string[3] = (unsigned char)(n & 255);
-		gcry_md_write(handle, octet_string, 4);
-		gcry_md_final(handle);
-		md = gcry_md_read(handle, GCRY_MD_SHA1);
-		memcpy(rp, md, PARA_MIN(HASH_SIZE, (int)(end - rp)));
-		rp += HASH_SIZE;
-		gcry_md_reset(handle);
-	}
-	gcry_md_close(handle);
-}
-
-/** The sha1 hash of an empty file. */
-static const unsigned char empty_hash[HASH_SIZE] =
-	"\xda" "\x39" "\xa3" "\xee" "\x5e"
-	"\x6b" "\x4b" "\x0d" "\x32" "\x55"
-	"\xbf" "\xef" "\x95" "\x60" "\x18"
-	"\x90" "\xaf" "\xd8" "\x07" "\x09";
-
-/* rfc3447, section 7.1.1 */
-static void pad_oaep(unsigned char *in, size_t in_len, unsigned char *out,
-		size_t out_len)
-{
-	size_t ps_len = out_len - in_len - 2 * HASH_SIZE - 2;
-	size_t n, mask_len = out_len - HASH_SIZE - 1;
-	unsigned char *seed = out + 1, *db = seed + HASH_SIZE,
-		*ps = db + HASH_SIZE, *one = ps + ps_len;
-	unsigned char *db_mask, seed_mask[HASH_SIZE];
-
-	assert(in_len <= out_len - 2 - 2 * HASH_SIZE);
-	assert(out_len > 2 * HASH_SIZE + 2);
-	PARA_DEBUG_LOG("padding %zu byte input -> %zu byte output\n",
-		in_len, out_len);
-	dump_buffer("unpadded buffer", in, in_len);
-
-	out[0] = '\0';
-	get_random_bytes_or_die(seed, HASH_SIZE);
-	memcpy(db, empty_hash, HASH_SIZE);
-	memset(ps, 0, ps_len);
-	*one = 0x01;
-	memcpy(one + 1, in, in_len);
-	db_mask = para_malloc(mask_len);
-	mgf1(seed, HASH_SIZE, mask_len, db_mask);
-	for (n = 0; n < mask_len; n++)
-		db[n] ^= db_mask[n];
-	mgf1(db, mask_len, HASH_SIZE, seed_mask);
-	for (n = 0; n < HASH_SIZE; n++)
-		seed[n] ^= seed_mask[n];
-	free(db_mask);
-	dump_buffer("padded buffer", out, out_len);
-}
-
-/* rfc 3447, section 7.1.2 */
-static int unpad_oaep(unsigned char *in, size_t in_len, unsigned char *out,
-		size_t *out_len)
-{
-	unsigned char *masked_seed = in + 1;
-	unsigned char *db = in + 1 + HASH_SIZE;
-	unsigned char seed[HASH_SIZE], seed_mask[HASH_SIZE];
-	unsigned char *db_mask, *p;
-	size_t n, mask_len = in_len - HASH_SIZE - 1;
-
-	mgf1(db, mask_len, HASH_SIZE, seed_mask);
-	for (n = 0; n < HASH_SIZE; n++)
-		seed[n] = masked_seed[n] ^ seed_mask[n];
-	db_mask = para_malloc(mask_len);
-	mgf1(seed, HASH_SIZE, mask_len, db_mask);
-	for (n = 0; n < mask_len; n++)
-		db[n] ^= db_mask[n];
-	free(db_mask);
-	if (memcmp(db, empty_hash, HASH_SIZE))
-		return -E_OEAP;
-	for (p = db + HASH_SIZE; p < in + in_len - 1; p++)
-		if (*p != '\0')
-			break;
-	if (p >= in + in_len - 1)
-		return -E_OEAP;
-	p++;
-	*out_len = in + in_len - p;
-	memcpy(out, p, *out_len);
-	return 1;
-}
+/** S-expression for decryption. */
+#define RSA_DECRYPT_SEXP "(enc-val(flags oaep)(rsa(a %m)))"
 
 struct asymmetric_key {
 	gcry_sexp_t sexp;
@@ -212,7 +101,7 @@ static int decode_key(const char *key_file, const char *header_str,
 
 	ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
 	if (ret < 0)
-		return ret;
+		goto out;
 	ret = -E_KEY_MARKER;
 	if (strncmp(map, header_str, strlen(header_str)))
 		goto unmap;
@@ -239,13 +128,11 @@ static int decode_key(const char *key_file, const char *header_str,
 		key[j++] = begin[i];
 	}
 	key[j] = '\0';
-	//PARA_CRIT_LOG("key: %s\n", key);
-	blob_size = key_size * 2;
-	blob = para_malloc(blob_size);
-	ret = base64_decode(key, blob, blob_size);
+	ret = base64_decode(key, j, (char **)&blob, &blob_size);
 	free(key);
 	if (ret < 0)
 		goto free_unmap;
+	ret = blob_size;
 	goto unmap;
 free_unmap:
 	free(blob);
@@ -258,6 +145,7 @@ unmap:
 		free(blob);
 		blob = NULL;
 	}
+out:
 	*result = blob;
 	return ret;
 }
@@ -275,14 +163,14 @@ enum asn1_types {
 /* bit 6 has value 0 */
 static inline bool is_primitive(unsigned char c)
 {
-	return ((c & (1<<6)) == 0);
+	return (c & (1<<6)) == 0;
 }
 
 static inline bool is_primitive_integer(unsigned char c)
 {
 	if (!is_primitive(c))
 		return false;
-	return ((c & 0x1f) == ASN1_TYPE_INTEGER);
+	return (c & 0x1f) == ASN1_TYPE_INTEGER;
 }
 
 /* Bit 8 is zero (and bits 7-1 give the length) */
@@ -301,64 +189,6 @@ static inline int get_long_form_num_length_bytes(unsigned char c)
 	return c & 0x7f;
 }
 
-static int find_pubkey_bignum_offset(const unsigned char *data, int len)
-{
-	const unsigned char *p = data, *end = data + len;
-
-	/* the whole thing istarts with one sequence */
-	if (*p != ASN1_TYPE_SEQUENCE)
-		return -E_ASN1_PARSE;
-	p++;
-	if (p >= end)
-		return -E_ASN1_PARSE;
-	if (is_short_form(*p))
-		p++;
-	else
-		p += 1 + get_long_form_num_length_bytes(*p);
-	if (p >= end)
-		return -E_ASN1_PARSE;
-	/* another sequence containing the object id, skip it */
-	if (*p != ASN1_TYPE_SEQUENCE)
-		return -E_ASN1_PARSE;
-	p++;
-	if (p >= end)
-		return -E_ASN1_PARSE;
-	if (!is_short_form(*p))
-		return -E_ASN1_PARSE;
-	p += 1 + get_short_form_length(*p);
-	if (p >= end)
-		return -E_ASN1_PARSE;
-	/* all numbers are wrapped in a bit string object that follows */
-	if (*p != ASN1_TYPE_BIT_STRING)
-		return -E_ASN1_PARSE;
-	p++;
-	if (p >= end)
-		return -E_ASN1_PARSE;
-	if (is_short_form(*p))
-		p++;
-	else
-		p += 1 + get_long_form_num_length_bytes(*p);
-	p++; /* skip number of unused bits in the bit string */
-	if (p >= end)
-		return -E_ASN1_PARSE;
-
-	/* next, we have a sequence of two integers (n and e) */
-	if (*p != ASN1_TYPE_SEQUENCE)
-		return -E_ASN1_PARSE;
-	p++;
-	if (p >= end)
-		return -E_ASN1_PARSE;
-	if (is_short_form(*p))
-		p++;
-	else
-		p += 1 + get_long_form_num_length_bytes(*p);
-	if (p >= end)
-		return -E_ASN1_PARSE;
-	if (*p != ASN1_TYPE_INTEGER)
-		return -E_ASN1_PARSE;
-	return p - data;
-}
-
 /*
  * Returns: Number of bytes scanned. This may differ from the value returned via
  * bn_bytes because the latter does not include the ASN.1 prefix and a leading
@@ -388,7 +218,7 @@ static int read_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
 		for (i = 0; i < num_bytes; i++, cp++)
 			bn_size = (bn_size << 8) + *cp;
 	}
-	PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, bn_size);
+	PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, (unsigned)bn_size);
 	gret = gcry_mpi_scan(bn, GCRYMPI_FMT_STD, cp, bn_size, NULL);
 	if (gret) {
 		PARA_ERROR_LOG("%s while scanning n\n",
@@ -429,7 +259,7 @@ static int find_privkey_bignum_offset(const unsigned char *data, int len)
 	if (p >= end)
 		return -E_ASN1_PARSE;
 
-	/* Skip next integer  */
+	/* skip next integer */
 	if (*p != ASN1_TYPE_INTEGER)
 		return -E_ASN1_PARSE;
 	p++;
@@ -460,6 +290,7 @@ static int get_private_key(const char *key_file, struct asymmetric_key **result)
 	gcry_sexp_t sexp;
 	struct asymmetric_key *key;
 
+	*result = NULL;
 	ret = decode_key(key_file, PRIVATE_KEY_HEADER, PRIVATE_KEY_FOOTER,
 		&blob);
 	if (ret < 0)
@@ -538,64 +369,6 @@ free_blob:
 	return ret;
 }
 
-/** Public keys start with this header. */
-#define PUBLIC_KEY_HEADER "-----BEGIN PUBLIC KEY-----"
-/** Public keys end with this footer. */
-#define PUBLIC_KEY_FOOTER "-----END PUBLIC KEY-----"
-
-static int get_asn_public_key(const char *key_file, struct asymmetric_key **result)
-{
-	gcry_mpi_t n = NULL, e = NULL;
-	unsigned char *blob, *cp, *end;
-	int blob_size, ret, n_size;
-	gcry_error_t gret;
-	size_t erroff;
-	gcry_sexp_t sexp;
-	struct asymmetric_key *key;
-
-	ret = decode_key(key_file, PUBLIC_KEY_HEADER, PUBLIC_KEY_FOOTER,
-		&blob);
-	if (ret < 0)
-		return ret;
-	blob_size = ret;
-	end = blob + blob_size;
-	ret = find_pubkey_bignum_offset(blob, blob_size);
-	if (ret < 0)
-		goto free_blob;
-	PARA_DEBUG_LOG("decoding public RSA params at offset %d\n", ret);
-	cp = blob + ret;
-
-	ret = read_bignum(cp, end, &n, &n_size);
-	if (ret < 0)
-		goto free_blob;
-	cp += ret;
-
-	ret = read_bignum(cp, end, &e, NULL);
-	if (ret < 0)
-		goto release_n;
-
-	gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
-	if (gret) {
-		PARA_ERROR_LOG("offset %zu: %s\n", erroff,
-			gcry_strerror(gcry_err_code(gret)));
-		ret = -E_SEXP_BUILD;
-		goto release_e;
-	}
-	key = para_malloc(sizeof(*key));
-	key->sexp = sexp;
-	*result = key;
-	ret = n_size;
-	PARA_INFO_LOG("successfully read %u bit asn public key\n", n_size * 8);
-
-release_e:
-	gcry_mpi_release(e);
-release_n:
-	gcry_mpi_release(n);
-free_blob:
-	free(blob);
-	return ret;
-}
-
 static int get_ssh_public_key(unsigned char *data, int size, gcry_sexp_t *result)
 {
 	int ret;
@@ -604,14 +377,10 @@ static int get_ssh_public_key(unsigned char *data, int size, gcry_sexp_t *result
 	size_t nr_scanned, erroff, decoded_size;
 	gcry_mpi_t e = NULL, n = NULL;
 
-	PARA_DEBUG_LOG("decoding %d byte  public rsa-ssh key\n", size);
-	if (size > INT_MAX / 4)
-		return -ERRNO_TO_PARA_ERROR(EOVERFLOW);
-	blob = para_malloc(2 * size);
-	ret = uudecode((char *)data, blob, 2 * size);
+	PARA_DEBUG_LOG("decoding %d byte public rsa-ssh key\n", size);
+	ret = uudecode((char *)data, size, (char **)&blob, &decoded_size);
 	if (ret < 0)
 		goto free_blob;
-	decoded_size = ret;
 	end = blob + decoded_size;
 	dump_buffer("decoded key", blob, decoded_size);
 	ret = check_ssh_key_header(blob, decoded_size);
@@ -651,7 +420,7 @@ static int get_ssh_public_key(unsigned char *data, int size, gcry_sexp_t *result
 		goto release_n;
 	}
 	ret = nr_scanned / 32 * 32;
-	PARA_INFO_LOG("successfully read %u bit ssh public key\n", ret * 8);
+	PARA_INFO_LOG("successfully read %d bit ssh public key\n", ret * 8);
 release_n:
 	gcry_mpi_release(n);
 release_e:
@@ -661,8 +430,7 @@ free_blob:
 	return ret;
 }
 
-int get_asymmetric_key(const char *key_file, int private,
-		struct asymmetric_key **result)
+int get_public_key(const char *key_file, struct asymmetric_key **result)
 {
 	int ret, ret2;
 	void *map;
@@ -671,17 +439,13 @@ int get_asymmetric_key(const char *key_file, int private,
 	gcry_sexp_t sexp;
 	struct asymmetric_key *key;
 
-	if (private)
-		return get_private_key(key_file, result);
 	ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
 	if (ret < 0)
 		return ret;
 	ret = is_ssh_rsa_key(map, map_size);
 	if (!ret) {
-		ret = para_munmap(map, map_size);
-		if (ret < 0)
-			return ret;
-		return get_asn_public_key(key_file, result);
+		para_munmap(map, map_size);
+		return -E_SSH_PARSE;
 	}
 	start = map + ret;
 	end = map + map_size;
@@ -702,7 +466,7 @@ unmap:
 	return ret;
 }
 
-void free_asymmetric_key(struct asymmetric_key *key)
+void free_public_key(struct asymmetric_key *key)
 {
 	if (!key)
 		return;
@@ -710,83 +474,34 @@ void free_asymmetric_key(struct asymmetric_key *key)
 	free(key);
 }
 
-static int decode_rsa(gcry_sexp_t sexp, int key_size, unsigned char *outbuf,
-		size_t *nbytes)
+static int decode_rsa(gcry_sexp_t sexp, unsigned char *outbuf, size_t *nbytes)
 {
-	int ret;
-	gcry_error_t gret;
-	unsigned char oaep_buf[512];
-	gcry_mpi_t out_mpi;
-
-	if (libgcrypt_has_oaep) {
-		const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
-
-		if (!p) {
-			PARA_ERROR_LOG("could not get data from list\n");
-			return -E_OEAP;
-		}
-		memcpy(outbuf, p, *nbytes);
-		return 1;
-	}
-	out_mpi = gcry_sexp_nth_mpi(sexp, 0, GCRYMPI_FMT_USG);
-	if (!out_mpi)
-		return -E_SEXP_FIND;
-	gret = gcry_mpi_print(GCRYMPI_FMT_USG, oaep_buf, sizeof(oaep_buf),
-		nbytes, out_mpi);
-	if (gret) {
-		PARA_ERROR_LOG("mpi_print: %s\n", gcrypt_strerror(gret));
-		ret = -E_MPI_PRINT;
-		goto out_mpi_release;
-	}
-	/*
-	 * An oaep-encoded buffer always starts with at least one zero byte.
-	 * However, leading zeroes in an mpi are omitted in the output of
-	 * gcry_mpi_print() when using the GCRYMPI_FMT_USG format. The
-	 * alternative, GCRYMPI_FMT_STD, does not work either because here the
-	 * leading zero(es) might also be omitted, depending on the value of
-	 * the second byte.
-	 *
-	 * To circumvent this, we shift the oaep buffer to the right. But first
-	 * we check that the buffer actually started with a zero byte, i.e. that
-	 * nbytes < key_size. Otherwise a decoding error occurred.
-	 */
-	ret = -E_SEXP_DECRYPT;
-	if (*nbytes >= key_size)
-		goto out_mpi_release;
-	memmove(oaep_buf + key_size - *nbytes, oaep_buf, *nbytes);
-	memset(oaep_buf, 0, key_size - *nbytes);
+	const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
 
-	PARA_DEBUG_LOG("decrypted buffer before unpad (%d bytes):\n",
-		key_size);
-	dump_buffer("non-unpadded decrypted buffer", oaep_buf, key_size);
-	ret = unpad_oaep(oaep_buf, key_size, outbuf, nbytes);
-	if (ret < 0)
-		goto out_mpi_release;
-	PARA_DEBUG_LOG("decrypted buffer after unpad (%zu bytes):\n",
-		*nbytes);
-	dump_buffer("unpadded decrypted buffer", outbuf, *nbytes);
-	ret = 1;
-out_mpi_release:
-	gcry_mpi_release(out_mpi);
-	return ret;
+	if (!p)
+		return -E_RSA_DECODE;
+	memcpy(outbuf, p, *nbytes);
+	return 1;
 }
 
 int priv_decrypt(const char *key_file, unsigned char *outbuf,
 		unsigned char *inbuf, int inlen)
 {
 	gcry_error_t gret;
-	int ret, key_size;
+	int ret;
 	struct asymmetric_key *priv;
 	gcry_mpi_t in_mpi = NULL;
 	gcry_sexp_t in, out, priv_key;
 	size_t nbytes;
 
+	ret = check_private_key_file(key_file);
+	if (ret < 0)
+		return ret;
 	PARA_INFO_LOG("decrypting %d byte input\n", inlen);
 	/* key_file -> asymmetric key priv */
 	ret = get_private_key(key_file, &priv);
 	if (ret < 0)
 		return ret;
-	key_size = ret / 8;
 
 	/* asymmetric key priv -> sexp priv_key */
 	ret = -E_SEXP_FIND;
@@ -803,7 +518,7 @@ int priv_decrypt(const char *key_file, unsigned char *outbuf,
 		goto key_release;
 	}
 	/* in_mpi -> in sexp */
-	gret = gcry_sexp_build(&in, NULL, rsa_decrypt_sexp, in_mpi);
+	gret = gcry_sexp_build(&in, NULL, RSA_DECRYPT_SEXP, in_mpi);
 	if (gret) {
 		PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
 		ret = -E_SEXP_BUILD;
@@ -817,7 +532,7 @@ int priv_decrypt(const char *key_file, unsigned char *outbuf,
 		ret = -E_SEXP_DECRYPT;
 		goto in_release;
 	}
-	ret = decode_rsa(out, key_size, outbuf, &nbytes);
+	ret = decode_rsa(out, outbuf, &nbytes);
 	if (ret < 0)
 		goto out_release;
 	PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
@@ -831,7 +546,8 @@ in_mpi_release:
 key_release:
 	gcry_sexp_release(priv_key);
 free_key:
-	free_asymmetric_key(priv);
+	gcry_sexp_release(priv->sexp);
+	free(priv);
 	return ret;
 }
 
@@ -850,18 +566,7 @@ int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
 	pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
 	if (!pub_key)
 		return -E_SEXP_FIND;
-	if (libgcrypt_has_oaep) {
-		gret = gcry_sexp_build(&in, NULL,
-			"(data(flags oaep)(value %b))", len, inbuf);
-	} else {
-		unsigned char padded_input[256];
-		const size_t pad_size = 256;
-		/* inbuf -> padded inbuf */
-		pad_oaep(inbuf, len, padded_input, pad_size);
-		/* padded inbuf -> in sexp */
-		gret = gcry_sexp_build(&in, NULL,
-			"(data(flags raw)(value %b))", pad_size, padded_input);
-	}
+	gret = gcry_sexp_build(&in, NULL, "(data(flags oaep)(value %b))", len, inbuf);
 	if (gret) {
 		PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
 		ret = -E_SEXP_BUILD;
@@ -912,33 +617,20 @@ struct stream_cipher {
 	gcry_cipher_hd_t handle;
 };
 
-struct stream_cipher *sc_new(const unsigned char *data, int len,
-		bool use_aes)
+struct stream_cipher *sc_new(const unsigned char *data, int len)
 {
 	gcry_error_t gret;
 	struct stream_cipher *sc = para_malloc(sizeof(*sc));
 
-	if (use_aes) {
-		assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
-		gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
-			GCRY_CIPHER_MODE_CTR, 0);
-		assert(gret == 0);
-		gret = gcry_cipher_setkey(sc->handle, data,
-			AES_CRT128_BLOCK_SIZE);
-		assert(gret == 0);
-		gret = gcry_cipher_setctr(sc->handle,
-			data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
-		assert(gret == 0);
-		return sc;
-	}
-	gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_ARCFOUR,
-		GCRY_CIPHER_MODE_STREAM, 0);
-	if (gret) {
-		PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
-		free(sc);
-		return NULL;
-	}
-	gret = gcry_cipher_setkey(sc->handle, data, (size_t)len);
+	assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
+	gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
+		GCRY_CIPHER_MODE_CTR, 0);
+	assert(gret == 0);
+	gret = gcry_cipher_setkey(sc->handle, data,
+		AES_CRT128_BLOCK_SIZE);
+	assert(gret == 0);
+	gret = gcry_cipher_setctr(sc->handle,
+		data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
 	assert(gret == 0);
 	return sc;
 }