text: /* $OpenBSD: e_chacha.c,v 1.3 2014/06/12 15:49:29 deraadt Exp $ */
  /*
   * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #ifndef OPENSSL_NO_CHACHA
  
  #include <openssl/chacha.h>
  #include <openssl/evp.h>
  #include <openssl/objects.h>
  
  #include "evp_locl.h"
  
  static int chacha_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
      const unsigned char *in, size_t len);
  static int chacha_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
      const unsigned char *iv, int enc);
  
  static const EVP_CIPHER chacha20_cipher = {
  	.nid = NID_chacha20,
  	.block_size = 1,
  	.key_len = 32,
  	.iv_len = 8,
  	.flags = EVP_CIPH_STREAM_CIPHER,
  	.init = chacha_init,
  	.do_cipher = chacha_cipher,
  	.ctx_size = sizeof(ChaCha_ctx)
  };
  
  const EVP_CIPHER *
  EVP_chacha20(void)
  {
  	return (&chacha20_cipher);
  }
  
  static int
  chacha_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
      const unsigned char *iv, int enc)
  {
  	ChaCha_set_key((ChaCha_ctx *)ctx->cipher_data, key,
  	    EVP_CIPHER_CTX_key_length(ctx) * 8);
  	ChaCha_set_iv((ChaCha_ctx *)ctx->cipher_data, iv, NULL);
  	return 1;
  }
  
  static int
  chacha_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, const unsigned char *in,
      size_t len)
  {
  	ChaCha((ChaCha_ctx *)ctx->cipher_data, out, in, len);
  	return 1;
  }
  
  #endif
  