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Fix two more stupid bugs in 3des-ctr:

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- We were using the first word of each block of keystream block twice and the
   second not at all.
 - We were incrementing the high-order word of the counter after every block
   rather than the low-order one.

With those fixed, our 3des-ctr implementation interoperates with the one in
Moussh.  Thanks to der Mouse for his help with the testing.

3des-ctr is now enabled by default.

[originally from svn r5699]
This commit is contained in:
Ben Harris 2005-04-28 08:21:04 +00:00
parent 61199b6a04
commit 34741dcc19
1 changed files with 3 additions and 11 deletions
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14
sshdes.c
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@ -732,7 +732,6 @@ static void des_cbc3_decrypt(unsigned char *dest, const unsigned char *src,
scheds->iv1 = iv1;
}
#ifdef ENABLE_3DES_SSH2_CTR
static void des_sdctr3(unsigned char *dest, const unsigned char *src,
unsigned int len, DESContext * scheds)
{
@ -752,16 +751,15 @@ static void des_sdctr3(unsigned char *dest, const unsigned char *src,
src += 4;
dest += 4;
tmp = GET_32BIT_MSB_FIRST(src);
PUT_32BIT_MSB_FIRST(dest, tmp ^ b[0]);
PUT_32BIT_MSB_FIRST(dest, tmp ^ b[1]);
src += 4;
dest += 4;
if ((iv0 = (iv0 + 1) & 0xffffffff) == 0)
iv1 = (iv1 + 1) & 0xffffffff;
if ((iv1 = (iv1 + 1) & 0xffffffff) == 0)
iv0 = (iv0 + 1) & 0xffffffff;
}
scheds->iv0 = iv0;
scheds->iv1 = iv1;
}
#endif
static void *des3_make_context(void)
{
@ -846,13 +844,11 @@ static void des3_ssh2_decrypt_blk(void *handle, unsigned char *blk, int len)
des_cbc3_decrypt(blk, blk, len, keys);
}
#ifdef ENABLE_3DES_SSH2_CTR
static void des3_ssh2_sdctr(void *handle, unsigned char *blk, int len)
{
DESContext *keys = (DESContext *) handle;
des_sdctr3(blk, blk, len, keys);
}
#endif
static void des_ssh2_encrypt_blk(void *handle, unsigned char *blk, int len)
{
@ -968,14 +964,12 @@ static const struct ssh2_cipher ssh_3des_ssh2 = {
8, 168, SSH_CIPHER_IS_CBC, "triple-DES CBC"
};
#ifdef ENABLE_3DES_SSH2_CTR
static const struct ssh2_cipher ssh_3des_ssh2_ctr = {
des3_make_context, des3_free_context, des3_iv, des3_key,
des3_ssh2_sdctr, des3_ssh2_sdctr,
"3des-ctr",
8, 168, 0, "triple-DES SDCTR"
};
#endif
/*
* Single DES in SSH-2. "des-cbc" is marked as HISTORIC in
@ -1006,9 +1000,7 @@ static const struct ssh2_cipher ssh_des_sshcom_ssh2 = {
* builds.
*/
static const struct ssh2_cipher *const des3_list[] = {
#ifdef ENABLE_3DES_SSH2_CTR
&ssh_3des_ssh2_ctr,
#endif
&ssh_3des_ssh2
};