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282 lines
7.4 KiB
C
282 lines
7.4 KiB
C
#define ECRYPT_VARIANT 1
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#define ECRYPT_API
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/* ecrypt-sync.h */
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/*
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* Header file for synchronous stream ciphers without authentication
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* mechanism.
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*
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* *** Please only edit parts marked with "[edit]". ***
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*/
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#ifndef ECRYPT_SYNC
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#define ECRYPT_SYNC
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#include "ecrypt-portable.h"
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/* ------------------------------------------------------------------------- */
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/* Cipher parameters */
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/*
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* The name of your cipher.
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*/
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#define ECRYPT_NAME "ChaCha20"
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#define ECRYPT_PROFILE "_____"
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/*
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* Specify which key and IV sizes are supported by your cipher. A user
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* should be able to enumerate the supported sizes by running the
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* following code:
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*
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* for (i = 0; ECRYPT_KEYSIZE(i) <= ECRYPT_MAXKEYSIZE; ++i)
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* {
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* keysize = ECRYPT_KEYSIZE(i);
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*
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* ...
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* }
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*
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* All sizes are in bits.
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*/
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#define ECRYPT_MAXKEYSIZE 256 /* [edit] */
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#define ECRYPT_KEYSIZE(i) (128 + (i)*128) /* [edit] */
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#define ECRYPT_MAXIVSIZE 64 /* [edit] */
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#define ECRYPT_IVSIZE(i) (64 + (i)*64) /* [edit] */
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/* ------------------------------------------------------------------------- */
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/* Data structures */
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/*
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* ECRYPT_ctx is the structure containing the representation of the
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* internal state of your cipher.
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*/
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typedef struct
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{
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u32 input[16]; /* could be compressed */
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/*
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* [edit]
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*
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* Put here all state variable needed during the encryption process.
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*/
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} ECRYPT_ctx;
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/* ------------------------------------------------------------------------- */
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/* Mandatory functions */
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/*
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* Key and message independent initialization. This function will be
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* called once when the program starts (e.g., to build expanded S-box
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* tables).
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*/
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void ECRYPT_init(void);
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/*
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* Key setup. It is the user's responsibility to select the values of
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* keysize and ivsize from the set of supported values specified
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* above.
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*/
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void ECRYPT_keysetup(
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ECRYPT_ctx* ctx,
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const u8* key,
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u32 keysize, /* Key size in bits. */
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u32 ivsize); /* IV size in bits. */
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/*
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* IV setup. After having called ECRYPT_keysetup(), the user is
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* allowed to call ECRYPT_ivsetup() different times in order to
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* encrypt/decrypt different messages with the same key but different
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* IV's.
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*/
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void ECRYPT_ivsetup(
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ECRYPT_ctx* ctx,
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const u8* iv);
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/*
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* Encryption/decryption of arbitrary length messages.
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*
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* For efficiency reasons, the API provides two types of
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* encrypt/decrypt functions. The ECRYPT_encrypt_bytes() function
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* (declared here) encrypts byte strings of arbitrary length, while
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* the ECRYPT_encrypt_blocks() function (defined later) only accepts
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* lengths which are multiples of ECRYPT_BLOCKLENGTH.
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*
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* The user is allowed to make multiple calls to
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* ECRYPT_encrypt_blocks() to incrementally encrypt a long message,
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* but he is NOT allowed to make additional encryption calls once he
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* has called ECRYPT_encrypt_bytes() (unless he starts a new message
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* of course). For example, this sequence of calls is acceptable:
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*
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* ECRYPT_keysetup();
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*
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* ECRYPT_ivsetup();
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* ECRYPT_encrypt_blocks();
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* ECRYPT_encrypt_blocks();
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* ECRYPT_encrypt_bytes();
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*
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* ECRYPT_ivsetup();
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* ECRYPT_encrypt_blocks();
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* ECRYPT_encrypt_blocks();
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*
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* ECRYPT_ivsetup();
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* ECRYPT_encrypt_bytes();
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*
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* The following sequence is not:
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*
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* ECRYPT_keysetup();
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* ECRYPT_ivsetup();
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* ECRYPT_encrypt_blocks();
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* ECRYPT_encrypt_bytes();
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* ECRYPT_encrypt_blocks();
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*/
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void ECRYPT_encrypt_bytes(
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ECRYPT_ctx* ctx,
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const u8* plaintext,
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u8* ciphertext,
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u32 msglen); /* Message length in bytes. */
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void ECRYPT_decrypt_bytes(
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ECRYPT_ctx* ctx,
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const u8* ciphertext,
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u8* plaintext,
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u32 msglen); /* Message length in bytes. */
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/* ------------------------------------------------------------------------- */
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/* Optional features */
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/*
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* For testing purposes it can sometimes be useful to have a function
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* which immediately generates keystream without having to provide it
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* with a zero plaintext. If your cipher cannot provide this function
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* (e.g., because it is not strictly a synchronous cipher), please
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* reset the ECRYPT_GENERATES_KEYSTREAM flag.
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*/
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#define ECRYPT_GENERATES_KEYSTREAM
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#ifdef ECRYPT_GENERATES_KEYSTREAM
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void ECRYPT_keystream_bytes(
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ECRYPT_ctx* ctx,
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u8* keystream,
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u32 length); /* Length of keystream in bytes. */
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#endif
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/* ------------------------------------------------------------------------- */
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/* Optional optimizations */
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/*
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* By default, the functions in this section are implemented using
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* calls to functions declared above. However, you might want to
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* implement them differently for performance reasons.
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*/
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/*
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* All-in-one encryption/decryption of (short) packets.
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*
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* The default definitions of these functions can be found in
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* "ecrypt-sync.c". If you want to implement them differently, please
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* undef the ECRYPT_USES_DEFAULT_ALL_IN_ONE flag.
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*/
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#define ECRYPT_USES_DEFAULT_ALL_IN_ONE /* [edit] */
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void ECRYPT_encrypt_packet(
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ECRYPT_ctx* ctx,
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const u8* iv,
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const u8* plaintext,
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u8* ciphertext,
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u32 msglen);
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void ECRYPT_decrypt_packet(
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ECRYPT_ctx* ctx,
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const u8* iv,
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const u8* ciphertext,
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u8* plaintext,
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u32 msglen);
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/*
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* Encryption/decryption of blocks.
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*
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* By default, these functions are defined as macros. If you want to
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* provide a different implementation, please undef the
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* ECRYPT_USES_DEFAULT_BLOCK_MACROS flag and implement the functions
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* declared below.
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*/
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#define ECRYPT_BLOCKLENGTH 64 /* [edit] */
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#define ECRYPT_USES_DEFAULT_BLOCK_MACROS /* [edit] */
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#ifdef ECRYPT_USES_DEFAULT_BLOCK_MACROS
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#define ECRYPT_encrypt_blocks(ctx, plaintext, ciphertext, blocks) \
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ECRYPT_encrypt_bytes(ctx, plaintext, ciphertext, \
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(blocks) * ECRYPT_BLOCKLENGTH)
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#define ECRYPT_decrypt_blocks(ctx, ciphertext, plaintext, blocks) \
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ECRYPT_decrypt_bytes(ctx, ciphertext, plaintext, \
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(blocks) * ECRYPT_BLOCKLENGTH)
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#ifdef ECRYPT_GENERATES_KEYSTREAM
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#define ECRYPT_keystream_blocks(ctx, keystream, blocks) \
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ECRYPT_keystream_bytes(ctx, keystream, \
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(blocks) * ECRYPT_BLOCKLENGTH)
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#endif
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#else
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void ECRYPT_encrypt_blocks(
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ECRYPT_ctx* ctx,
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const u8* plaintext,
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u8* ciphertext,
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u32 blocks); /* Message length in blocks. */
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void ECRYPT_decrypt_blocks(
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ECRYPT_ctx* ctx,
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const u8* ciphertext,
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u8* plaintext,
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u32 blocks); /* Message length in blocks. */
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#ifdef ECRYPT_GENERATES_KEYSTREAM
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void ECRYPT_keystream_blocks(
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ECRYPT_ctx* ctx,
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const u8* keystream,
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u32 blocks); /* Keystream length in blocks. */
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#endif
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#endif
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/*
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* If your cipher can be implemented in different ways, you can use
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* the ECRYPT_VARIANT parameter to allow the user to choose between
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* them at compile time (e.g., gcc -DECRYPT_VARIANT=3 ...). Please
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* only use this possibility if you really think it could make a
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* significant difference and keep the number of variants
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* (ECRYPT_MAXVARIANT) as small as possible (definitely not more than
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* 10). Note also that all variants should have exactly the same
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* external interface (i.e., the same ECRYPT_BLOCKLENGTH, etc.).
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*/
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#define ECRYPT_MAXVARIANT 1 /* [edit] */
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#ifndef ECRYPT_VARIANT
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#define ECRYPT_VARIANT 1
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#endif
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#if (ECRYPT_VARIANT > ECRYPT_MAXVARIANT)
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#error this variant does not exist
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#endif
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/* ------------------------------------------------------------------------- */
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#endif
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