/*
- * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
-/** \file crypt.c openssl-based RSA encryption/decryption routines */
+/** \file crypt.c Openssl-based encryption/decryption routines. */
#include <regex.h>
#include <dirent.h>
#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/rc4.h>
+#include <openssl/pem.h>
#include "para.h"
#include "error.h"
#include "string.h"
#include "crypt.h"
#include "fd.h"
+
+struct asymmetric_key {
+ RSA *rsa;
+};
+
/**
* Fill a buffer with random content.
*
srandom(seed);
}
+static int check_key_file(const char *file, int private)
+{
+ struct stat st;
+
+ if (stat(file, &st) != 0)
+ return -ERRNO_TO_PARA_ERROR(errno);
+ if (private != LOAD_PRIVATE_KEY)
+ return 0;
+ if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0)
+ return -E_KEY_PERM;
+ return 1;
+}
+
static EVP_PKEY *load_key(const char *file, int private)
{
BIO *key;
EVP_PKEY *pkey = NULL;
+ int ret = check_key_file(file, private);
+ if (ret < 0) {
+ PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+ return NULL;
+ }
key = BIO_new(BIO_s_file());
if (!key)
return NULL;
}
/**
- * read an RSA key from a file
+ * Read an asymmetric key from a file.
*
- * \param key_file the file containing the key
- * \param rsa RSA structure is returned here
- * \param private if non-zero, read the private key, otherwise the public key
+ * \param key_file The file containing the key.
+ * \param private if non-zero, read the private key, otherwise the public key.
+ * \param result The key structure is returned here.
*
- * \return The size of the RSA key on success, negative on errors.
+ * \return The size of the key on success, negative on errors.
*
* \sa openssl(1), rsa(1).
*/
-int get_rsa_key(char *key_file, RSA **rsa, int private)
+int get_asymmetric_key(const char *key_file, int private,
+ struct asymmetric_key **result)
{
- EVP_PKEY *key = load_key(key_file, private);
+ struct asymmetric_key *key;
+ RSA *rsa;
+ EVP_PKEY *pkey = load_key(key_file, private);
- if (!key)
+ if (!pkey)
return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
: -E_PUBLIC_KEY;
- *rsa = EVP_PKEY_get1_RSA(key);
- EVP_PKEY_free(key);
- if (!*rsa)
+ rsa = EVP_PKEY_get1_RSA(pkey);
+ EVP_PKEY_free(pkey);
+ if (!rsa)
return -E_RSA;
- return RSA_size(*rsa);
+ key = para_malloc(sizeof(*key));
+ key->rsa = rsa;
+ *result = key;
+ return RSA_size(rsa);
}
/**
- * free an RSA structure
+ * Deallocate an asymmetric key structure.
*
- * \param rsa pointer to the RSA struct to free
+ * \param key Pointer to the key structure to free.
*
- * This must be called for any key obtained by get_rsa_key().
+ * This must be called for any key obtained by get_asymmetric_key().
*/
-void rsa_free(RSA *rsa)
+void free_asymmetric_key(struct asymmetric_key *key)
{
- if (rsa)
- RSA_free(rsa);
+ if (!key)
+ return;
+ RSA_free(key->rsa);
+ free(key);
}
/**
- * decrypt a buffer using an RSA key
+ * Decrypt a buffer using a private key.
*
- * \param key_file full path of the rsa key
- * \param outbuf the output buffer
- * \param inbuf the encrypted input buffer
- * \param rsa_inlen the length of \a inbuf
+ * \param key_file Full path of the key.
+ * \param outbuf The output buffer.
+ * \param inbuf The encrypted input buffer.
+ * \param inlen The length of \a inbuf in bytes.
*
* The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
*
*
* \sa RSA_private_decrypt(3)
**/
-int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
- unsigned rsa_inlen)
+int priv_decrypt(const char *key_file, unsigned char *outbuf,
+ unsigned char *inbuf, int inlen)
{
- RSA *rsa;
- int ret, inlen = rsa_inlen;
+ struct asymmetric_key *priv;
+ int ret;
if (inlen < 0)
return -E_RSA;
- ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
+ ret = get_asymmetric_key(key_file, LOAD_PRIVATE_KEY, &priv);
if (ret < 0)
return ret;
- ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
- rsa_free(rsa);
- return (ret > 0)? ret : -E_DECRYPT;
+ /*
+ * RSA is vulnerable to timing attacks. Generate a random blinding
+ * factor to protect against this kind of attack.
+ */
+ ret = -E_BLINDING;
+ if (RSA_blinding_on(priv->rsa, NULL) == 0)
+ goto out;
+ ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
+ RSA_PKCS1_OAEP_PADDING);
+ RSA_blinding_off(priv->rsa);
+ if (ret <= 0)
+ ret = -E_DECRYPT;
+out:
+ free_asymmetric_key(priv);
+ return ret;
}
/**
- * encrypt a buffer using an RSA key
+ * Encrypt a buffer using an RSA key
*
- * \param rsa: public rsa key
- * \param inbuf the input buffer
- * \param len the length of \a inbuf
- * \param outbuf the output buffer
+ * \param pub: The public key.
+ * \param inbuf The input buffer.
+ * \param len The length of \a inbuf.
+ * \param outbuf The output buffer.
*
- * \return The size of the encrypted data on success, negative on errors
+ * \return The size of the encrypted data on success, negative on errors.
*
* \sa RSA_public_encrypt(3)
*/
-int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
+int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
unsigned len, unsigned char *outbuf)
{
int ret, flen = len; /* RSA_public_encrypt expects a signed int */
if (flen < 0)
return -E_ENCRYPT;
- ret = RSA_public_encrypt(flen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
+ ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
+ RSA_PKCS1_OAEP_PADDING);
return ret < 0? -E_ENCRYPT : ret;
}
+#define RC4_ALIGN 8
+struct stream_cipher {
+ RC4_KEY key;
+};
+
+/**
+ * Allocate and initialize a stream cipher structure.
+ *
+ * \param data The key.
+ * \param len The size of the key.
+ *
+ * \return A new stream cipher structure.
+ */
+struct stream_cipher *stream_cipher_new(const unsigned char *data, int len)
+{
+ struct stream_cipher *sc = para_malloc(sizeof(*sc));
+ RC4_set_key(&sc->key, len, data);
+ return sc;
+}
+
+/**
+ * Deallocate a stream cipher structure.
+ *
+ * \param sc A stream cipher previously obtained by stream_cipher_new().
+ */
+void stream_cipher_free(struct stream_cipher *sc)
+{
+ free(sc);
+}
+
/**
* Encrypt and send a buffer.
*
{
int ret;
unsigned char *tmp;
+ static unsigned char remainder[RC4_ALIGN];
+ size_t l1 = ROUND_DOWN(len, RC4_ALIGN), l2 = ROUND_UP(len, RC4_ALIGN);
assert(len);
- tmp = para_malloc(len);
- RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp);
+ tmp = para_malloc(l2);
+ RC4(&rc4c->send->key, l1, (const unsigned char *)buf, tmp);
+ if (len > l1) {
+ memcpy(remainder, buf + l1, len - l1);
+ RC4(&rc4c->send->key, len - l1, remainder, tmp + l1);
+ }
ret = write_all(rc4c->fd, (char *)tmp, &len);
free(tmp);
return ret;
ssize_t ret = recv(rc4c->fd, tmp, size, 0);
if (ret > 0)
- RC4(&rc4c->recv_key, ret, tmp, (unsigned char *)buf);
+ RC4(&rc4c->recv->key, ret, tmp, (unsigned char *)buf);
else if (ret < 0)
ret = -ERRNO_TO_PARA_ERROR(errno);
free(tmp);
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