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/* $OpenBSD: crypto_backend.c,v 1.2 2012/08/30 21:59:46 chl Exp $ */
/*
* Copyright (c) 2012 Gilles Chehade <gilles@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.
*/
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/tree.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <imsg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <openssl/evp.h>
#include "smtpd.h"
#include "log.h"
#define CRYPTO_BUFFER_SIZE 8192
static struct crypto_params {
const EVP_CIPHER *cipher;
const EVP_MD *digest;
uint8_t key[];
} cp;
int
crypto_setup(const char *cipher, const char *digest, const char *key)
{
EVP_MD_CTX *mdctx;
int mdlen;
log_info("crypto: setting up crypto parameters");
bzero(&cp, sizeof cp);
cp.cipher = EVP_get_cipherbyname(cipher);
if (cp.cipher == NULL) {
log_warnx("crypto: unknown cipher: %s", cipher);
return 0;
}
log_info("crypto: cipher: %s", cipher);
cp.digest = EVP_get_digestbyname(digest);
if (cp.digest == NULL) {
log_warnx("crypto: unknown digest: %s", digest);
return 0;
}
log_info("crypto: digest: %s", digest);
mdctx = EVP_MD_CTX_create();
if (mdctx == NULL) {
log_warnx("crypto: unable to create digest context");
return 0;
}
EVP_DigestInit_ex(mdctx, cp.digest, NULL);
EVP_DigestUpdate(mdctx, key, strlen(key));
EVP_DigestFinal_ex(mdctx, cp.key, &mdlen);
EVP_MD_CTX_destroy(mdctx);
log_info("crypto: crypto parameters set");
return 1;
}
void
crypto_clear(void)
{
/* to be called in EVERY process *but* queue before event dispatch */
bzero(&cp, sizeof cp);
}
int
crypto_encrypt_file(FILE *in, FILE *out)
{
EVP_CIPHER_CTX ctx;
uint8_t ibuf[CRYPTO_BUFFER_SIZE];
uint8_t obuf[CRYPTO_BUFFER_SIZE];
size_t r,w;
size_t bs = EVP_CIPHER_block_size(cp.cipher);
int olen;
int ret = 0;
log_debug("crypto_encrypt_file");
/* generate IV and encrypt it */
for (r = 0; r < (size_t)EVP_CIPHER_iv_length(cp.cipher); ++r)
ibuf[r] = arc4random_uniform(0xff+1);
EVP_CIPHER_CTX_init(&ctx);
EVP_EncryptInit(&ctx, cp.cipher, cp.key, NULL);
if (! EVP_EncryptUpdate(&ctx, obuf, &olen, ibuf, r))
goto end;
if (olen && (w = fwrite(obuf, 1, olen, out)) != (size_t)olen)
goto end;
if (! EVP_EncryptFinal(&ctx, obuf, &olen))
goto end;
if (olen && (w = fwrite(obuf, 1, olen, out)) != (size_t)olen)
goto end;
/* encrypt real content */
EVP_CIPHER_CTX_init(&ctx);
EVP_EncryptInit(&ctx, cp.cipher, cp.key, ibuf);
while ((r = fread(ibuf, 1, CRYPTO_BUFFER_SIZE-bs, in)) != 0) {
if (! EVP_EncryptUpdate(&ctx, obuf, &olen, ibuf, r))
goto end;
if (olen && (w = fwrite(obuf, olen, 1, out)) != 1)
goto end;
}
if (! feof(in))
goto end;
if (! EVP_EncryptFinal(&ctx, obuf, &olen))
goto end;
if (olen && (w = fwrite(obuf, olen, 1, out)) != 1)
goto end;
fflush(out);
ret = 1;
end:
EVP_CIPHER_CTX_cleanup(&ctx);
log_debug("crypto_encrypt_file: ret=%d", ret);
return ret;
}
int
crypto_decrypt_file(FILE *in, FILE *out)
{
EVP_CIPHER_CTX ctx;
uint8_t ibuf[CRYPTO_BUFFER_SIZE];
uint8_t obuf[CRYPTO_BUFFER_SIZE];
size_t r,w;
size_t bs = EVP_CIPHER_block_size(cp.cipher);
int olen;
int ret = 0;
log_debug("crypto_decrypt_file");
/* extract and decrypt IV */
r = fread(ibuf, 1, EVP_CIPHER_block_size(cp.cipher)*2, in);
if (r != (size_t)EVP_CIPHER_block_size(cp.cipher)*2)
goto end;
EVP_CIPHER_CTX_init(&ctx);
EVP_DecryptInit(&ctx, cp.cipher, cp.key, NULL);
if (! EVP_DecryptUpdate(&ctx, obuf, &olen, ibuf, r))
goto end;
if (! EVP_DecryptFinal(&ctx, obuf+olen, &olen))
goto end;
/* decrypt real content */
EVP_CIPHER_CTX_init(&ctx);
EVP_DecryptInit(&ctx, cp.cipher, cp.key, obuf);
while ((r = fread(ibuf, 1, CRYPTO_BUFFER_SIZE-bs, in)) != 0) {
if (! EVP_DecryptUpdate(&ctx, obuf, &olen, ibuf, r))
goto end;
if (olen && (w = fwrite(obuf, olen, 1, out)) != 1)
goto end;
}
if (! feof(in))
goto end;
if (! EVP_DecryptFinal(&ctx, obuf, &olen))
goto end;
if (olen && (w = fwrite(obuf, olen, 1, out)) != 1)
goto end;
fflush(out);
ret = 1;
end:
log_debug("crypto_decrypt_file: ret=%d", ret);
EVP_CIPHER_CTX_cleanup(&ctx);
return ret;
}
size_t
crypto_encrypt_buffer(const char *in, size_t inlen, char *out, size_t outlen)
{
EVP_CIPHER_CTX ctx;
uint8_t ibuf[CRYPTO_BUFFER_SIZE];
uint8_t obuf[CRYPTO_BUFFER_SIZE];
int olen;
ssize_t r;
int len = 0;
int ret = 0;
log_debug("crypto_encrypt_buffer");
/* out does not have enough room */
if (outlen < inlen + (EVP_CIPHER_block_size(cp.cipher) * 4))
goto end;
bzero(ibuf, sizeof ibuf);
bzero(obuf, sizeof obuf);
/* generate IV and encrypt it */
for (r = 0; r < EVP_CIPHER_iv_length(cp.cipher); ++r)
ibuf[r] = arc4random_uniform(0xff+1);
EVP_CIPHER_CTX_init(&ctx);
EVP_EncryptInit(&ctx, cp.cipher, cp.key, NULL);
if (! EVP_EncryptUpdate(&ctx, out, &olen, ibuf, r))
goto end;
if (! EVP_EncryptFinal(&ctx, out+olen, &olen))
goto end;
len += EVP_CIPHER_block_size(cp.cipher)*2;
/* encrypt real content */
EVP_CIPHER_CTX_init(&ctx);
EVP_EncryptInit(&ctx, cp.cipher, cp.key, ibuf);
if (! EVP_EncryptUpdate(&ctx, out+len, &olen, in, inlen))
goto end;
len += olen;
if (! EVP_EncryptFinal(&ctx, out+len, &olen))
goto end;
ret = len + olen;
end:
log_debug("crypto_encrypt_buffer: ret=%d", ret);
EVP_CIPHER_CTX_cleanup(&ctx);
return ret;
}
size_t
crypto_decrypt_buffer(const char *in, size_t inlen, char *out, size_t outlen)
{
EVP_CIPHER_CTX ctx;
uint8_t obuf[CRYPTO_BUFFER_SIZE];
int olen;
int len = 0;
int ret = 0;
log_debug("crypto_decrypt_buffer");
/* out does not have enough room */
if (outlen < inlen + (EVP_CIPHER_block_size(cp.cipher) * 4))
goto end;
bzero(obuf, sizeof obuf);
/* extract and decrypt IV */
EVP_CIPHER_CTX_init(&ctx);
EVP_DecryptInit(&ctx, cp.cipher, cp.key, NULL);
if (! EVP_DecryptUpdate(&ctx, obuf, &olen, in,
EVP_CIPHER_block_size(cp.cipher)*2))
goto end;
if (! EVP_DecryptFinal(&ctx, obuf+olen, &olen))
goto end;
inlen -= EVP_CIPHER_block_size(cp.cipher)*2;
in += EVP_CIPHER_block_size(cp.cipher)*2;
/* decrypt real content */
EVP_CIPHER_CTX_init(&ctx);
EVP_DecryptInit(&ctx, cp.cipher, cp.key, obuf);
if (! EVP_DecryptUpdate(&ctx, out, &olen, in, inlen))
goto end;
len += olen;
if (! EVP_DecryptFinal(&ctx, out+len, &olen))
goto end;
len += olen;
ret = len;
end:
log_debug("crypto_decrypt_buffer: ret=%d", ret);
EVP_CIPHER_CTX_cleanup(&ctx);
return ret;
}
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