Doug Anson
mbed TLS library
Dependents: HTTPClient-SSL WS_SERVER
Diff: include/polarssl/cipher.h
- Revision:
- 0:137634ff4186
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/polarssl/cipher.h Thu Jun 11 03:27:03 2015 +0000
@@ -0,0 +1,780 @@
+/**
+ * \file cipher.h
+ *
+ * \brief Generic cipher wrapper.
+ *
+ * \author Adriaan de Jong <dejong@fox-it.com>
+ *
+ * Copyright (C) 2006-2014, ARM Limited, All Rights Reserved
+ *
+ * This file is part of mbed TLS (https://tls.mbed.org)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef POLARSSL_CIPHER_H
+#define POLARSSL_CIPHER_H
+
+#if !defined(POLARSSL_CONFIG_FILE)
+#include "config.h"
+#else
+#include POLARSSL_CONFIG_FILE
+#endif
+
+#include <stddef.h>
+
+#if defined(POLARSSL_GCM_C) || defined(POLARSSL_CCM_C)
+#define POLARSSL_CIPHER_MODE_AEAD
+#endif
+
+#if defined(POLARSSL_CIPHER_MODE_CBC)
+#define POLARSSL_CIPHER_MODE_WITH_PADDING
+#endif
+
+#if defined(POLARSSL_ARC4_C)
+#define POLARSSL_CIPHER_MODE_STREAM
+#endif
+
+#if defined(_MSC_VER) && !defined(inline)
+#define inline _inline
+#else
+#if defined(__ARMCC_VERSION) && !defined(inline)
+#define inline __inline
+#endif /* __ARMCC_VERSION */
+#endif /*_MSC_VER */
+
+#define POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE -0x6080 /**< The selected feature is not available. */
+#define POLARSSL_ERR_CIPHER_BAD_INPUT_DATA -0x6100 /**< Bad input parameters to function. */
+#define POLARSSL_ERR_CIPHER_ALLOC_FAILED -0x6180 /**< Failed to allocate memory. */
+#define POLARSSL_ERR_CIPHER_INVALID_PADDING -0x6200 /**< Input data contains invalid padding and is rejected. */
+#define POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED -0x6280 /**< Decryption of block requires a full block. */
+#define POLARSSL_ERR_CIPHER_AUTH_FAILED -0x6300 /**< Authentication failed (for AEAD modes). */
+
+#define POLARSSL_CIPHER_VARIABLE_IV_LEN 0x01 /**< Cipher accepts IVs of variable length */
+#define POLARSSL_CIPHER_VARIABLE_KEY_LEN 0x02 /**< Cipher accepts keys of variable length */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum {
+ POLARSSL_CIPHER_ID_NONE = 0,
+ POLARSSL_CIPHER_ID_NULL,
+ POLARSSL_CIPHER_ID_AES,
+ POLARSSL_CIPHER_ID_DES,
+ POLARSSL_CIPHER_ID_3DES, /* Unused! */
+ POLARSSL_CIPHER_ID_CAMELLIA,
+ POLARSSL_CIPHER_ID_BLOWFISH,
+ POLARSSL_CIPHER_ID_ARC4,
+} cipher_id_t;
+
+typedef enum {
+ POLARSSL_CIPHER_NONE = 0,
+ POLARSSL_CIPHER_NULL,
+ POLARSSL_CIPHER_AES_128_ECB,
+ POLARSSL_CIPHER_AES_192_ECB,
+ POLARSSL_CIPHER_AES_256_ECB,
+ POLARSSL_CIPHER_AES_128_CBC,
+ POLARSSL_CIPHER_AES_192_CBC,
+ POLARSSL_CIPHER_AES_256_CBC,
+ POLARSSL_CIPHER_AES_128_CFB128,
+ POLARSSL_CIPHER_AES_192_CFB128,
+ POLARSSL_CIPHER_AES_256_CFB128,
+ POLARSSL_CIPHER_AES_128_CTR,
+ POLARSSL_CIPHER_AES_192_CTR,
+ POLARSSL_CIPHER_AES_256_CTR,
+ POLARSSL_CIPHER_AES_128_GCM,
+ POLARSSL_CIPHER_AES_192_GCM,
+ POLARSSL_CIPHER_AES_256_GCM,
+ POLARSSL_CIPHER_CAMELLIA_128_ECB,
+ POLARSSL_CIPHER_CAMELLIA_192_ECB,
+ POLARSSL_CIPHER_CAMELLIA_256_ECB,
+ POLARSSL_CIPHER_CAMELLIA_128_CBC,
+ POLARSSL_CIPHER_CAMELLIA_192_CBC,
+ POLARSSL_CIPHER_CAMELLIA_256_CBC,
+ POLARSSL_CIPHER_CAMELLIA_128_CFB128,
+ POLARSSL_CIPHER_CAMELLIA_192_CFB128,
+ POLARSSL_CIPHER_CAMELLIA_256_CFB128,
+ POLARSSL_CIPHER_CAMELLIA_128_CTR,
+ POLARSSL_CIPHER_CAMELLIA_192_CTR,
+ POLARSSL_CIPHER_CAMELLIA_256_CTR,
+ POLARSSL_CIPHER_CAMELLIA_128_GCM,
+ POLARSSL_CIPHER_CAMELLIA_192_GCM,
+ POLARSSL_CIPHER_CAMELLIA_256_GCM,
+ POLARSSL_CIPHER_DES_ECB,
+ POLARSSL_CIPHER_DES_CBC,
+ POLARSSL_CIPHER_DES_EDE_ECB,
+ POLARSSL_CIPHER_DES_EDE_CBC,
+ POLARSSL_CIPHER_DES_EDE3_ECB,
+ POLARSSL_CIPHER_DES_EDE3_CBC,
+ POLARSSL_CIPHER_BLOWFISH_ECB,
+ POLARSSL_CIPHER_BLOWFISH_CBC,
+ POLARSSL_CIPHER_BLOWFISH_CFB64,
+ POLARSSL_CIPHER_BLOWFISH_CTR,
+ POLARSSL_CIPHER_ARC4_128,
+ POLARSSL_CIPHER_AES_128_CCM,
+ POLARSSL_CIPHER_AES_192_CCM,
+ POLARSSL_CIPHER_AES_256_CCM,
+ POLARSSL_CIPHER_CAMELLIA_128_CCM,
+ POLARSSL_CIPHER_CAMELLIA_192_CCM,
+ POLARSSL_CIPHER_CAMELLIA_256_CCM,
+} cipher_type_t;
+
+typedef enum {
+ POLARSSL_MODE_NONE = 0,
+ POLARSSL_MODE_ECB,
+ POLARSSL_MODE_CBC,
+ POLARSSL_MODE_CFB,
+ POLARSSL_MODE_OFB, /* Unused! */
+ POLARSSL_MODE_CTR,
+ POLARSSL_MODE_GCM,
+ POLARSSL_MODE_STREAM,
+ POLARSSL_MODE_CCM,
+} cipher_mode_t;
+
+typedef enum {
+ POLARSSL_PADDING_PKCS7 = 0, /**< PKCS7 padding (default) */
+ POLARSSL_PADDING_ONE_AND_ZEROS, /**< ISO/IEC 7816-4 padding */
+ POLARSSL_PADDING_ZEROS_AND_LEN, /**< ANSI X.923 padding */
+ POLARSSL_PADDING_ZEROS, /**< zero padding (not reversible!) */
+ POLARSSL_PADDING_NONE, /**< never pad (full blocks only) */
+} cipher_padding_t;
+
+typedef enum {
+ POLARSSL_OPERATION_NONE = -1,
+ POLARSSL_DECRYPT = 0,
+ POLARSSL_ENCRYPT,
+} operation_t;
+
+enum {
+ /** Undefined key length */
+ POLARSSL_KEY_LENGTH_NONE = 0,
+ /** Key length, in bits (including parity), for DES keys */
+ POLARSSL_KEY_LENGTH_DES = 64,
+ /** Key length, in bits (including parity), for DES in two key EDE */
+ POLARSSL_KEY_LENGTH_DES_EDE = 128,
+ /** Key length, in bits (including parity), for DES in three-key EDE */
+ POLARSSL_KEY_LENGTH_DES_EDE3 = 192,
+};
+
+/** Maximum length of any IV, in bytes */
+#define POLARSSL_MAX_IV_LENGTH 16
+/** Maximum block size of any cipher, in bytes */
+#define POLARSSL_MAX_BLOCK_LENGTH 16
+
+/**
+ * Base cipher information. The non-mode specific functions and values.
+ */
+typedef struct {
+
+ /** Base Cipher type (e.g. POLARSSL_CIPHER_ID_AES) */
+ cipher_id_t cipher;
+
+ /** Encrypt using ECB */
+ int (*ecb_func)( void *ctx, operation_t mode,
+ const unsigned char *input, unsigned char *output );
+
+#if defined(POLARSSL_CIPHER_MODE_CBC)
+ /** Encrypt using CBC */
+ int (*cbc_func)( void *ctx, operation_t mode, size_t length,
+ unsigned char *iv, const unsigned char *input,
+ unsigned char *output );
+#endif
+
+#if defined(POLARSSL_CIPHER_MODE_CFB)
+ /** Encrypt using CFB (Full length) */
+ int (*cfb_func)( void *ctx, operation_t mode, size_t length, size_t *iv_off,
+ unsigned char *iv, const unsigned char *input,
+ unsigned char *output );
+#endif
+
+#if defined(POLARSSL_CIPHER_MODE_CTR)
+ /** Encrypt using CTR */
+ int (*ctr_func)( void *ctx, size_t length, size_t *nc_off,
+ unsigned char *nonce_counter, unsigned char *stream_block,
+ const unsigned char *input, unsigned char *output );
+#endif
+
+#if defined(POLARSSL_CIPHER_MODE_STREAM)
+ /** Encrypt using STREAM */
+ int (*stream_func)( void *ctx, size_t length,
+ const unsigned char *input, unsigned char *output );
+#endif
+
+ /** Set key for encryption purposes */
+ int (*setkey_enc_func)( void *ctx, const unsigned char *key,
+ unsigned int key_length );
+
+ /** Set key for decryption purposes */
+ int (*setkey_dec_func)( void *ctx, const unsigned char *key,
+ unsigned int key_length);
+
+ /** Allocate a new context */
+ void * (*ctx_alloc_func)( void );
+
+ /** Free the given context */
+ void (*ctx_free_func)( void *ctx );
+
+} cipher_base_t;
+
+/**
+ * Cipher information. Allows cipher functions to be called in a generic way.
+ */
+typedef struct {
+ /** Full cipher identifier (e.g. POLARSSL_CIPHER_AES_256_CBC) */
+ cipher_type_t type;
+
+ /** Cipher mode (e.g. POLARSSL_MODE_CBC) */
+ cipher_mode_t mode;
+
+ /** Cipher key length, in bits (default length for variable sized ciphers)
+ * (Includes parity bits for ciphers like DES) */
+ unsigned int key_length;
+
+ /** Name of the cipher */
+ const char * name;
+
+ /** IV/NONCE size, in bytes.
+ * For cipher that accept many sizes: recommended size */
+ unsigned int iv_size;
+
+ /** Flags for variable IV size, variable key size, etc. */
+ int flags;
+
+ /** block size, in bytes */
+ unsigned int block_size;
+
+ /** Base cipher information and functions */
+ const cipher_base_t *base;
+
+} cipher_info_t;
+
+/**
+ * Generic cipher context.
+ */
+typedef struct {
+ /** Information about the associated cipher */
+ const cipher_info_t *cipher_info;
+
+ /** Key length to use */
+ int key_length;
+
+ /** Operation that the context's key has been initialised for */
+ operation_t operation;
+
+#if defined(POLARSSL_CIPHER_MODE_WITH_PADDING)
+ /** Padding functions to use, if relevant for cipher mode */
+ void (*add_padding)( unsigned char *output, size_t olen, size_t data_len );
+ int (*get_padding)( unsigned char *input, size_t ilen, size_t *data_len );
+#endif
+
+ /** Buffer for data that hasn't been encrypted yet */
+ unsigned char unprocessed_data[POLARSSL_MAX_BLOCK_LENGTH];
+
+ /** Number of bytes that still need processing */
+ size_t unprocessed_len;
+
+ /** Current IV or NONCE_COUNTER for CTR-mode */
+ unsigned char iv[POLARSSL_MAX_IV_LENGTH];
+
+ /** IV size in bytes (for ciphers with variable-length IVs) */
+ size_t iv_size;
+
+ /** Cipher-specific context */
+ void *cipher_ctx;
+} cipher_context_t;
+
+/**
+ * \brief Returns the list of ciphers supported by the generic cipher module.
+ *
+ * \return a statically allocated array of ciphers, the last entry
+ * is 0.
+ */
+const int *cipher_list( void );
+
+/**
+ * \brief Returns the cipher information structure associated
+ * with the given cipher name.
+ *
+ * \param cipher_name Name of the cipher to search for.
+ *
+ * \return the cipher information structure associated with the
+ * given cipher_name, or NULL if not found.
+ */
+const cipher_info_t *cipher_info_from_string( const char *cipher_name );
+
+/**
+ * \brief Returns the cipher information structure associated
+ * with the given cipher type.
+ *
+ * \param cipher_type Type of the cipher to search for.
+ *
+ * \return the cipher information structure associated with the
+ * given cipher_type, or NULL if not found.
+ */
+const cipher_info_t *cipher_info_from_type( const cipher_type_t cipher_type );
+
+/**
+ * \brief Returns the cipher information structure associated
+ * with the given cipher id, key size and mode.
+ *
+ * \param cipher_id Id of the cipher to search for
+ * (e.g. POLARSSL_CIPHER_ID_AES)
+ * \param key_length Length of the key in bits
+ * \param mode Cipher mode (e.g. POLARSSL_MODE_CBC)
+ *
+ * \return the cipher information structure associated with the
+ * given cipher_type, or NULL if not found.
+ */
+const cipher_info_t *cipher_info_from_values( const cipher_id_t cipher_id,
+ int key_length,
+ const cipher_mode_t mode );
+
+/**
+ * \brief Initialize a cipher_context (as NONE)
+ */
+void cipher_init( cipher_context_t *ctx );
+
+/**
+ * \brief Free and clear the cipher-specific context of ctx.
+ * Freeing ctx itself remains the responsibility of the
+ * caller.
+ */
+void cipher_free( cipher_context_t *ctx );
+
+/**
+ * \brief Initialises and fills the cipher context structure with
+ * the appropriate values.
+ *
+ * \note Currently also clears structure. In future versions you
+ * will be required to call cipher_init() on the structure
+ * first.
+ *
+ * \param ctx context to initialise. May not be NULL.
+ * \param cipher_info cipher to use.
+ *
+ * \return 0 on success,
+ * POLARSSL_ERR_CIPHER_BAD_INPUT_DATA on parameter failure,
+ * POLARSSL_ERR_CIPHER_ALLOC_FAILED if allocation of the
+ * cipher-specific context failed.
+ */
+int cipher_init_ctx( cipher_context_t *ctx, const cipher_info_t *cipher_info );
+
+#if ! defined(POLARSSL_DEPRECATED_REMOVED)
+#if defined(POLARSSL_DEPRECATED_WARNING)
+#define DEPRECATED __attribute__((deprecated))
+#else
+#define DEPRECATED
+#endif
+/**
+ * \brief Free the cipher-specific context of ctx. Freeing ctx
+ * itself remains the responsibility of the caller.
+ *
+ * \deprecated Use cipher_free() instead
+ *
+ * \param ctx Free the cipher-specific context
+ *
+ * \returns 0
+ */
+int cipher_free_ctx( cipher_context_t *ctx ) DEPRECATED;
+#undef DEPRECATED
+#endif /* POLARSSL_DEPRECATED_REMOVED */
+
+/**
+ * \brief Returns the block size of the given cipher.
+ *
+ * \param ctx cipher's context. Must have been initialised.
+ *
+ * \return size of the cipher's blocks, or 0 if ctx has not been
+ * initialised.
+ */
+static inline unsigned int cipher_get_block_size( const cipher_context_t *ctx )
+{
+ if( NULL == ctx || NULL == ctx->cipher_info )
+ return 0;
+
+ return ctx->cipher_info->block_size;
+}
+
+/**
+ * \brief Returns the mode of operation for the cipher.
+ * (e.g. POLARSSL_MODE_CBC)
+ *
+ * \param ctx cipher's context. Must have been initialised.
+ *
+ * \return mode of operation, or POLARSSL_MODE_NONE if ctx
+ * has not been initialised.
+ */
+static inline cipher_mode_t cipher_get_cipher_mode( const cipher_context_t *ctx )
+{
+ if( NULL == ctx || NULL == ctx->cipher_info )
+ return POLARSSL_MODE_NONE;
+
+ return ctx->cipher_info->mode;
+}
+
+/**
+ * \brief Returns the size of the cipher's IV/NONCE in bytes.
+ *
+ * \param ctx cipher's context. Must have been initialised.
+ *
+ * \return If IV has not been set yet: (recommended) IV size
+ * (0 for ciphers not using IV/NONCE).
+ * If IV has already been set: actual size.
+ */
+static inline int cipher_get_iv_size( const cipher_context_t *ctx )
+{
+ if( NULL == ctx || NULL == ctx->cipher_info )
+ return 0;
+
+ if( ctx->iv_size != 0 )
+ return (int) ctx->iv_size;
+
+ return ctx->cipher_info->iv_size;
+}
+
+/**
+ * \brief Returns the type of the given cipher.
+ *
+ * \param ctx cipher's context. Must have been initialised.
+ *
+ * \return type of the cipher, or POLARSSL_CIPHER_NONE if ctx has
+ * not been initialised.
+ */
+static inline cipher_type_t cipher_get_type( const cipher_context_t *ctx )
+{
+ if( NULL == ctx || NULL == ctx->cipher_info )
+ return POLARSSL_CIPHER_NONE;
+
+ return ctx->cipher_info->type;
+}
+
+/**
+ * \brief Returns the name of the given cipher, as a string.
+ *
+ * \param ctx cipher's context. Must have been initialised.
+ *
+ * \return name of the cipher, or NULL if ctx was not initialised.
+ */
+static inline const char *cipher_get_name( const cipher_context_t *ctx )
+{
+ if( NULL == ctx || NULL == ctx->cipher_info )
+ return 0;
+
+ return ctx->cipher_info->name;
+}
+
+/**
+ * \brief Returns the key length of the cipher.
+ *
+ * \param ctx cipher's context. Must have been initialised.
+ *
+ * \return cipher's key length, in bits, or
+ * POLARSSL_KEY_LENGTH_NONE if ctx has not been
+ * initialised.
+ */
+static inline int cipher_get_key_size( const cipher_context_t *ctx )
+{
+ if( NULL == ctx || NULL == ctx->cipher_info )
+ return POLARSSL_KEY_LENGTH_NONE;
+
+ return ctx->cipher_info->key_length;
+}
+
+/**
+ * \brief Returns the operation of the given cipher.
+ *
+ * \param ctx cipher's context. Must have been initialised.
+ *
+ * \return operation (POLARSSL_ENCRYPT or POLARSSL_DECRYPT),
+ * or POLARSSL_OPERATION_NONE if ctx has not been
+ * initialised.
+ */
+static inline operation_t cipher_get_operation( const cipher_context_t *ctx )
+{
+ if( NULL == ctx || NULL == ctx->cipher_info )
+ return POLARSSL_OPERATION_NONE;
+
+ return ctx->operation;
+}
+
+/**
+ * \brief Set the key to use with the given context.
+ *
+ * \param ctx generic cipher context. May not be NULL. Must have been
+ * initialised using cipher_context_from_type or
+ * cipher_context_from_string.
+ * \param key The key to use.
+ * \param key_length key length to use, in bits.
+ * \param operation Operation that the key will be used for, either
+ * POLARSSL_ENCRYPT or POLARSSL_DECRYPT.
+ *
+ * \returns 0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if
+ * parameter verification fails or a cipher specific
+ * error code.
+ */
+int cipher_setkey( cipher_context_t *ctx, const unsigned char *key,
+ int key_length, const operation_t operation );
+
+#if defined(POLARSSL_CIPHER_MODE_WITH_PADDING)
+/**
+ * \brief Set padding mode, for cipher modes that use padding.
+ * (Default: PKCS7 padding.)
+ *
+ * \param ctx generic cipher context
+ * \param mode padding mode
+ *
+ * \returns 0 on success, POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE
+ * if selected padding mode is not supported, or
+ * POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if the cipher mode
+ * does not support padding.
+ */
+int cipher_set_padding_mode( cipher_context_t *ctx, cipher_padding_t mode );
+#endif /* POLARSSL_CIPHER_MODE_WITH_PADDING */
+
+/**
+ * \brief Set the initialization vector (IV) or nonce
+ *
+ * \param ctx generic cipher context
+ * \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
+ * \param iv_len IV length for ciphers with variable-size IV;
+ * discarded by ciphers with fixed-size IV.
+ *
+ * \returns 0 on success, or POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
+ *
+ * \note Some ciphers don't use IVs nor NONCE. For these
+ * ciphers, this function has no effect.
+ */
+int cipher_set_iv( cipher_context_t *ctx,
+ const unsigned char *iv, size_t iv_len );
+
+/**
+ * \brief Finish preparation of the given context
+ *
+ * \param ctx generic cipher context
+ *
+ * \returns 0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
+ * if parameter verification fails.
+ */
+int cipher_reset( cipher_context_t *ctx );
+
+#if defined(POLARSSL_GCM_C)
+/**
+ * \brief Add additional data (for AEAD ciphers).
+ * Currently only supported with GCM.
+ * Must be called exactly once, after cipher_reset().
+ *
+ * \param ctx generic cipher context
+ * \param ad Additional data to use.
+ * \param ad_len Length of ad.
+ *
+ * \return 0 on success, or a specific error code.
+ */
+int cipher_update_ad( cipher_context_t *ctx,
+ const unsigned char *ad, size_t ad_len );
+#endif /* POLARSSL_GCM_C */
+
+/**
+ * \brief Generic cipher update function. Encrypts/decrypts
+ * using the given cipher context. Writes as many block
+ * size'd blocks of data as possible to output. Any data
+ * that cannot be written immediately will either be added
+ * to the next block, or flushed when cipher_final is
+ * called.
+ * Exception: for POLARSSL_MODE_ECB, expects single block
+ * in size (e.g. 16 bytes for AES)
+ *
+ * \param ctx generic cipher context
+ * \param input buffer holding the input data
+ * \param ilen length of the input data
+ * \param output buffer for the output data. Should be able to hold at
+ * least ilen + block_size. Cannot be the same buffer as
+ * input!
+ * \param olen length of the output data, will be filled with the
+ * actual number of bytes written.
+ *
+ * \returns 0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if
+ * parameter verification fails,
+ * POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE on an
+ * unsupported mode for a cipher or a cipher specific
+ * error code.
+ *
+ * \note If the underlying cipher is GCM, all calls to this
+ * function, except the last one before cipher_finish(),
+ * must have ilen a multiple of the block size.
+ */
+int cipher_update( cipher_context_t *ctx, const unsigned char *input,
+ size_t ilen, unsigned char *output, size_t *olen );
+
+/**
+ * \brief Generic cipher finalisation function. If data still
+ * needs to be flushed from an incomplete block, data
+ * contained within it will be padded with the size of
+ * the last block, and written to the output buffer.
+ *
+ * \param ctx Generic cipher context
+ * \param output buffer to write data to. Needs block_size available.
+ * \param olen length of the data written to the output buffer.
+ *
+ * \returns 0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if
+ * parameter verification fails,
+ * POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption
+ * expected a full block but was not provided one,
+ * POLARSSL_ERR_CIPHER_INVALID_PADDING on invalid padding
+ * while decrypting or a cipher specific error code.
+ */
+int cipher_finish( cipher_context_t *ctx,
+ unsigned char *output, size_t *olen );
+
+#if defined(POLARSSL_GCM_C)
+/**
+ * \brief Write tag for AEAD ciphers.
+ * Currently only supported with GCM.
+ * Must be called after cipher_finish().
+ *
+ * \param ctx Generic cipher context
+ * \param tag buffer to write the tag
+ * \param tag_len Length of the tag to write
+ *
+ * \return 0 on success, or a specific error code.
+ */
+int cipher_write_tag( cipher_context_t *ctx,
+ unsigned char *tag, size_t tag_len );
+
+/**
+ * \brief Check tag for AEAD ciphers.
+ * Currently only supported with GCM.
+ * Must be called after cipher_finish().
+ *
+ * \param ctx Generic cipher context
+ * \param tag Buffer holding the tag
+ * \param tag_len Length of the tag to check
+ *
+ * \return 0 on success, or a specific error code.
+ */
+int cipher_check_tag( cipher_context_t *ctx,
+ const unsigned char *tag, size_t tag_len );
+#endif /* POLARSSL_GCM_C */
+
+/**
+ * \brief Generic all-in-one encryption/decryption
+ * (for all ciphers except AEAD constructs).
+ *
+ * \param ctx generic cipher context
+ * \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
+ * \param iv_len IV length for ciphers with variable-size IV;
+ * discarded by ciphers with fixed-size IV.
+ * \param input buffer holding the input data
+ * \param ilen length of the input data
+ * \param output buffer for the output data. Should be able to hold at
+ * least ilen + block_size. Cannot be the same buffer as
+ * input!
+ * \param olen length of the output data, will be filled with the
+ * actual number of bytes written.
+ *
+ * \note Some ciphers don't use IVs nor NONCE. For these
+ * ciphers, use iv = NULL and iv_len = 0.
+ *
+ * \returns 0 on success, or
+ * POLARSSL_ERR_CIPHER_BAD_INPUT_DATA, or
+ * POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption
+ * expected a full block but was not provided one, or
+ * POLARSSL_ERR_CIPHER_INVALID_PADDING on invalid padding
+ * while decrypting, or
+ * a cipher specific error code.
+ */
+int cipher_crypt( cipher_context_t *ctx,
+ const unsigned char *iv, size_t iv_len,
+ const unsigned char *input, size_t ilen,
+ unsigned char *output, size_t *olen );
+
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
+/**
+ * \brief Generic autenticated encryption (AEAD ciphers).
+ *
+ * \param ctx generic cipher context
+ * \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
+ * \param iv_len IV length for ciphers with variable-size IV;
+ * discarded by ciphers with fixed-size IV.
+ * \param ad Additional data to authenticate.
+ * \param ad_len Length of ad.
+ * \param input buffer holding the input data
+ * \param ilen length of the input data
+ * \param output buffer for the output data.
+ * Should be able to hold at least ilen.
+ * \param olen length of the output data, will be filled with the
+ * actual number of bytes written.
+ * \param tag buffer for the authentication tag
+ * \param tag_len desired tag length
+ *
+ * \returns 0 on success, or
+ * POLARSSL_ERR_CIPHER_BAD_INPUT_DATA, or
+ * a cipher specific error code.
+ */
+int cipher_auth_encrypt( cipher_context_t *ctx,
+ const unsigned char *iv, size_t iv_len,
+ const unsigned char *ad, size_t ad_len,
+ const unsigned char *input, size_t ilen,
+ unsigned char *output, size_t *olen,
+ unsigned char *tag, size_t tag_len );
+
+/**
+ * \brief Generic autenticated decryption (AEAD ciphers).
+ *
+ * \param ctx generic cipher context
+ * \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
+ * \param iv_len IV length for ciphers with variable-size IV;
+ * discarded by ciphers with fixed-size IV.
+ * \param ad Additional data to be authenticated.
+ * \param ad_len Length of ad.
+ * \param input buffer holding the input data
+ * \param ilen length of the input data
+ * \param output buffer for the output data.
+ * Should be able to hold at least ilen.
+ * \param olen length of the output data, will be filled with the
+ * actual number of bytes written.
+ * \param tag buffer holding the authentication tag
+ * \param tag_len length of the authentication tag
+ *
+ * \returns 0 on success, or
+ * POLARSSL_ERR_CIPHER_BAD_INPUT_DATA, or
+ * POLARSSL_ERR_CIPHER_AUTH_FAILED if data isn't authentic,
+ * or a cipher specific error code.
+ *
+ * \note If the data is not authentic, then the output buffer
+ * is zeroed out to prevent the unauthentic plaintext to
+ * be used by mistake, making this interface safer.
+ */
+int cipher_auth_decrypt( cipher_context_t *ctx,
+ const unsigned char *iv, size_t iv_len,
+ const unsigned char *ad, size_t ad_len,
+ const unsigned char *input, size_t ilen,
+ unsigned char *output, size_t *olen,
+ const unsigned char *tag, size_t tag_len );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
+
+/**
+ * \brief Checkup routine
+ *
+ * \return 0 if successful, or 1 if the test failed
+ */
+int cipher_self_test( int verbose );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* POLARSSL_CIPHER_H */
+