| /*- |
| * Copyright 2007-2009 Colin Percival |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * |
| * This file was originally written by Colin Percival as part of the Tarsnap |
| * online backup system. |
| */ |
| #include "scrypt_platform.h" |
| |
| #include <stdint.h> |
| #include <stdlib.h> |
| |
| #include <openssl/aes.h> |
| |
| #include "sysendian.h" |
| |
| #include "crypto_aesctr.h" |
| |
| struct crypto_aesctr { |
| AES_KEY * key; |
| uint64_t nonce; |
| uint64_t bytectr; |
| uint8_t buf[16]; |
| }; |
| |
| /** |
| * crypto_aesctr_init(key, nonce): |
| * Prepare to encrypt/decrypt data with AES in CTR mode, using the provided |
| * expanded key and nonce. The key provided must remain valid for the |
| * lifetime of the stream. |
| */ |
| struct crypto_aesctr * |
| crypto_aesctr_init(AES_KEY * key, uint64_t nonce) |
| { |
| struct crypto_aesctr * stream; |
| |
| /* Allocate memory. */ |
| if ((stream = malloc(sizeof(struct crypto_aesctr))) == NULL) |
| goto err0; |
| |
| /* Initialize values. */ |
| stream->key = key; |
| stream->nonce = nonce; |
| stream->bytectr = 0; |
| |
| /* Success! */ |
| return (stream); |
| |
| err0: |
| /* Failure! */ |
| return (NULL); |
| } |
| |
| /** |
| * crypto_aesctr_stream(stream, inbuf, outbuf, buflen): |
| * Generate the next ${buflen} bytes of the AES-CTR stream and xor them with |
| * bytes from ${inbuf}, writing the result into ${outbuf}. If the buffers |
| * ${inbuf} and ${outbuf} overlap, they must be identical. |
| */ |
| void |
| crypto_aesctr_stream(struct crypto_aesctr * stream, const uint8_t * inbuf, |
| uint8_t * outbuf, size_t buflen) |
| { |
| uint8_t pblk[16]; |
| size_t pos; |
| int bytemod; |
| |
| for (pos = 0; pos < buflen; pos++) { |
| /* How far through the buffer are we? */ |
| bytemod = stream->bytectr % 16; |
| |
| /* Generate a block of cipherstream if needed. */ |
| if (bytemod == 0) { |
| be64enc(pblk, stream->nonce); |
| be64enc(pblk + 8, stream->bytectr / 16); |
| AES_encrypt(pblk, stream->buf, stream->key); |
| } |
| |
| /* Encrypt a byte. */ |
| outbuf[pos] = inbuf[pos] ^ stream->buf[bytemod]; |
| |
| /* Move to the next byte of cipherstream. */ |
| stream->bytectr += 1; |
| } |
| } |
| |
| /** |
| * crypto_aesctr_free(stream): |
| * Free the provided stream object. |
| */ |
| void |
| crypto_aesctr_free(struct crypto_aesctr * stream) |
| { |
| int i; |
| |
| /* Zero potentially sensitive information. */ |
| for (i = 0; i < 16; i++) |
| stream->buf[i] = 0; |
| stream->bytectr = stream->nonce = 0; |
| |
| /* Free the stream. */ |
| free(stream); |
| } |