-/*
- * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
/** \file crypt.h Public crypto interface. */
+/*
+ * Asymmetric pubkey cryptosystem (apc).
+ *
+ * This is just RSA, but this fact is a hidden implementation detail.
+ */
-/** \cond used to distinguish between loading of private/public key */
-#define LOAD_PUBLIC_KEY 0
-#define LOAD_PRIVATE_KEY 1
-#define CHALLENGE_SIZE 64
-/** \endcond **/
-
-/* asymetric (public key) crypto */
+/** The size of the challenge sent to the client. */
+#define APC_CHALLENGE_SIZE 64
/** Opaque structure for public and private keys. */
struct asymmetric_key;
-int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
+/**
+ * Encrypt a buffer using asymmetric keys.
+ *
+ * \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.
+ */
+int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
unsigned len, unsigned char *outbuf);
-int priv_decrypt(const char *key_file, unsigned char *outbuf,
+
+/**
+ * Decrypt a buffer using a private key.
+ *
+ * \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.
+ *
+ * The \a outbuf must be large enough to hold at least 512 bytes.
+ *
+ * \return The size of the recovered plaintext on success, negative on errors.
+ */
+int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
unsigned char *inbuf, int inlen);
-int get_asymmetric_key(const char *key_file, int private,
- struct asymmetric_key **result);
-void free_asymmetric_key(struct asymmetric_key *key);
-/* random numbers */
+/**
+ * Read an asymmetric key from a file.
+ *
+ * \param key_file The file containing the key.
+ * \param result The key structure is returned here.
+ *
+ * \return The size of the key on success, negative on errors.
+ */
+int apc_get_pubkey(const char *key_file, struct asymmetric_key **result);
+
+/**
+ * Deallocate a public key.
+ *
+ * \param key Pointer to the key structure to free.
+ *
+ * This should be called for keys obtained by \ref apc_get_pubkey() if the key is no
+ * longer needed.
+ */
+void apc_free_pubkey(struct asymmetric_key *key);
+
+
+/**
+ * Fill a buffer with random content.
+ *
+ * \param buf The buffer to fill.
+ * \param num The size of \a buf in bytes.
+ *
+ * This function puts \a num cryptographically strong pseudo-random bytes into
+ * buf. If it can not guarantee an unpredictable byte sequence (for example
+ * because the PRNG has not been seeded with enough randomness) the function
+ * logs an error message and calls exit().
+ */
void get_random_bytes_or_die(unsigned char *buf, int num);
-void init_random_seed_or_die(void);
-/* stream cipher declarations and prototypes */
+/**
+ * Initialize the crypto backend.
+ *
+ * This function initializes the crypto library and seeds the pseudo random
+ * number generator used by random() with a random seed obtained from the
+ * crypto implementation. On errors, an error message is logged and the
+ * function calls exit().
+ *
+ * \sa \ref get_random_bytes_or_die(), srandom(3), random(3), \ref
+ * para_random().
+ */
+void crypt_init(void);
+
+/** Allocate all resources of the crypto backend. */
+void crypt_shutdown(void);
/** Opaque structure for stream ciphers. */
struct stream_cipher;
+
/** Number of bytes of the session key for stream ciphers. */
#define SESSION_KEY_LEN 32
+
/**
* Used for client-server communication encryption.
*
/** Key used for sending data. */
struct stream_cipher *send;
};
+
+/**
+ * Allocate and initialize an aes_ctr128 stream cipher structure.
+ *
+ * \param data The key.
+ * \param len The size of the key.
+ *
+ * \return A new stream cipher structure.
+ */
struct stream_cipher *sc_new(const unsigned char *data, int len);
-void sc_free(struct stream_cipher *sc);
-int sc_send_bin_buffer(struct stream_cipher_context *scc, const char *buf,
- size_t len);
-int sc_send_buffer(struct stream_cipher_context *scc, const char *buf);
-__printf_2_3 int sc_send_va_buffer(struct stream_cipher_context *scc,
- const char *fmt, ...);
-int sc_recv_bin_buffer(struct stream_cipher_context *scc, char *buf,
- size_t size);
-int sc_recv_buffer(struct stream_cipher_context *scc, char *buf, size_t size);
-/* hashing */
+/**
+ * Encrypt or decrypt a buffer using a stream cipher.
+ *
+ * \param sc Crypto key.
+ * \param src The source buffer and length.
+ * \param dst The destination buffer and length, filled out by the function.
+ *
+ * It is up to the implementation to decide whether the crypt operation is
+ * performed in place. The caller can tell by looking if the buffers given by
+ * \a src and \a dst coincide after the call. If (and only if) the crypt
+ * operation was not performed in place, the function allocated a new buffer
+ * for the result, so dst->iov_base is different from src->iov_base. In this
+ * case, the destination buffer must be freed by the caller when it is no
+ * longer needed.
+ */
+void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst);
+
+/**
+ * Wrapper for \ref sc_crypt() that can be used as a sideband transformation.
+ *
+ * \param src Passed verbatim to \ref sc_crypt().
+ * \param dst Passed verbatim to \ref sc_crypt().
+ * \param trafo_context Must point to an initialized stream cipher.
+ */
+_static_inline_ void sc_trafo(struct iovec *src, struct iovec *dst,
+ void *trafo_context)
+{
+ sc_crypt(trafo_context, src, dst);
+}
+
+/**
+ * Deallocate a stream cipher structure.
+ *
+ * \param sc A stream cipher previously obtained by sc_new().
+ */
+void sc_free(struct stream_cipher *sc);
/** Size of the hash value in bytes. */
#define HASH_SIZE 20
+/**
+ * Compute the hash of the given input data.
+ *
+ * \param data Pointer to the data to compute the hash value from.
+ * \param len The length of \a data in bytes.
+ * \param hash Result pointer.
+ *
+ * \a hash must point to an area at least \p HASH_SIZE bytes large.
+ *
+ * \sa sha(3), openssl(1).
+ * */
void hash_function(const char *data, unsigned long len, unsigned char *hash);
+
+/**
+ * Convert a hash value to ascii format.
+ *
+ * \param hash the hash value.
+ * \param asc Result pointer.
+ *
+ * \a asc must point to an area of at least 2 * \p HASH_SIZE + 1 bytes which
+ * will be filled by the function with the ascii representation of the hash
+ * value given by \a hash, and a terminating \p NULL byte.
+ */
void hash_to_asc(unsigned char *hash, char *asc);
+
+/**
+ * Compare two hashes.
+ *
+ * \param h1 Pointer to the first hash value.
+ * \param h2 Pointer to the second hash value.
+ *
+ * \return 1, -1, or zero, depending on whether \a h1 is greater than,
+ * less than or equal to h2, respectively.
+ */
int hash_compare(unsigned char *h1, unsigned char *h2);
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