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Fix Blowfish-with-SSH2 combination, and enable user cipher

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selection for SSH2

[originally from svn r606]
This commit is contained in:
Simon Tatham 2000-09-20 15:15:02 +00:00
parent 9291dfc7c5
commit ea8d61f2d9
2 changed files with 126 additions and 19 deletions
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33
ssh.c
View File

@ -142,10 +142,20 @@ enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM };
extern struct ssh_cipher ssh_3des;
extern struct ssh_cipher ssh_3des_ssh2;
extern struct ssh_cipher ssh_des;
extern struct ssh_cipher ssh_blowfish;
extern struct ssh_cipher ssh_blowfish_ssh1;
extern struct ssh_cipher ssh_blowfish_ssh2;
/* for ssh 2; we miss out single-DES because it isn't supported */
struct ssh_cipher *ciphers[] = { &ssh_3des_ssh2, &ssh_blowfish };
/*
* Ciphers for SSH2. We miss out single-DES because it isn't
* supported; also 3DES and Blowfish are both done differently from
* SSH1. (3DES uses outer chaining; Blowfish has the opposite
* endianness and different-sized keys.)
*
* The first entry in this array is set up to be whatever the user
* asks for as a cipher. Thereafter there is a fixed preference
* order of fallback ciphers.
*/
struct ssh_cipher *ciphers[] = { NULL, &ssh_blowfish_ssh2, &ssh_3des_ssh2 };
extern struct ssh_kex ssh_diffiehellman;
struct ssh_kex *kex_algs[] = { &ssh_diffiehellman };
@ -1163,7 +1173,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
free(rsabuf);
cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish :
cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish_ssh1 :
cipher_type == SSH_CIPHER_DES ? &ssh_des :
&ssh_3des;
cipher->sesskey(session_key);
@ -1780,6 +1790,21 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
crBegin;
random_init();
/*
* Set up the preferred cipher.
*/
if (cfg.cipher == CIPHER_BLOWFISH) {
ciphers[0] = &ssh_blowfish_ssh2;
} else if (cfg.cipher == CIPHER_DES) {
logevent("Single DES not supported in SSH2; using 3DES");
ciphers[0] = &ssh_3des_ssh2;
} else if (cfg.cipher == CIPHER_3DES) {
ciphers[0] = &ssh_3des_ssh2;
} else {
/* Shouldn't happen, but we do want to initialise to _something_. */
ciphers[0] = &ssh_3des_ssh2;
}
begin_key_exchange:
/*
* Construct and send our key exchange packet.

112
sshblowf.c
View File

@ -25,6 +25,18 @@ typedef struct {
(cp)[2] = (value) >> 16; \
(cp)[3] = (value) >> 24; } while (0)
#define GET_32BIT_MSB_FIRST(cp) \
(((unsigned long)(unsigned char)(cp)[0] << 24) | \
((unsigned long)(unsigned char)(cp)[1] << 16) | \
((unsigned long)(unsigned char)(cp)[2] << 8) | \
((unsigned long)(unsigned char)(cp)[3]))
#define PUT_32BIT_MSB_FIRST(cp, value) do { \
(cp)[0] = (value) >> 24; \
(cp)[1] = (value) >> 16; \
(cp)[2] = (value) >> 8; \
(cp)[3] = (value); } while (0)
/*
* The Blowfish init data: hex digits of the fractional part of pi.
* (ie pi as a hex fraction is 3.243F6A8885A308D3...)
@ -287,8 +299,8 @@ static void blowfish_decrypt(word32 xL, word32 xR, word32 *output,
output[1] = xL;
}
static void blowfish_encrypt_cbc(unsigned char *blk, int len,
BlowfishContext *ctx) {
static void blowfish_lsb_encrypt_cbc(unsigned char *blk, int len,
BlowfishContext *ctx) {
word32 xL, xR, out[2], iv0, iv1;
assert((len & 7) == 0);
@ -312,8 +324,8 @@ static void blowfish_encrypt_cbc(unsigned char *blk, int len,
ctx->iv0 = iv0; ctx->iv1 = iv1;
}
static void blowfish_decrypt_cbc(unsigned char *blk, int len,
BlowfishContext *ctx) {
static void blowfish_lsb_decrypt_cbc(unsigned char *blk, int len,
BlowfishContext *ctx) {
word32 xL, xR, out[2], iv0, iv1;
assert((len & 7) == 0);
@ -337,6 +349,56 @@ static void blowfish_decrypt_cbc(unsigned char *blk, int len,
ctx->iv0 = iv0; ctx->iv1 = iv1;
}
static void blowfish_msb_encrypt_cbc(unsigned char *blk, int len,
BlowfishContext *ctx) {
word32 xL, xR, out[2], iv0, iv1;
assert((len & 7) == 0);
iv0 = ctx->iv0; iv1 = ctx->iv1;
while (len > 0) {
xL = GET_32BIT_MSB_FIRST(blk);
xR = GET_32BIT_MSB_FIRST(blk+4);
iv0 ^= xL;
iv1 ^= xR;
blowfish_encrypt(iv0, iv1, out, ctx);
iv0 = out[0];
iv1 = out[1];
PUT_32BIT_MSB_FIRST(blk, iv0);
PUT_32BIT_MSB_FIRST(blk+4, iv1);
blk += 8;
len -= 8;
}
ctx->iv0 = iv0; ctx->iv1 = iv1;
}
static void blowfish_msb_decrypt_cbc(unsigned char *blk, int len,
BlowfishContext *ctx) {
word32 xL, xR, out[2], iv0, iv1;
assert((len & 7) == 0);
iv0 = ctx->iv0; iv1 = ctx->iv1;
while (len > 0) {
xL = GET_32BIT_MSB_FIRST(blk);
xR = GET_32BIT_MSB_FIRST(blk+4);
blowfish_decrypt(xL, xR, out, ctx);
iv0 ^= out[0];
iv1 ^= out[1];
PUT_32BIT_MSB_FIRST(blk, iv0);
PUT_32BIT_MSB_FIRST(blk+4, iv1);
iv0 = xL;
iv1 = xR;
blk += 8;
len -= 8;
}
ctx->iv0 = iv0; ctx->iv1 = iv1;
}
static void blowfish_setkey(BlowfishContext *ctx,
const unsigned char *key, short keybytes) {
word32 *S0 = ctx->S0;
@ -406,14 +468,14 @@ static void blowfish_sckey(unsigned char *key)
static void blowfish_csiv(unsigned char *key)
{
ectx.iv0 = GET_32BIT_LSB_FIRST(key);
ectx.iv1 = GET_32BIT_LSB_FIRST(key+4);
ectx.iv0 = GET_32BIT_MSB_FIRST(key);
ectx.iv1 = GET_32BIT_MSB_FIRST(key+4);
}
static void blowfish_sciv(unsigned char *key)
{
dctx.iv0 = GET_32BIT_LSB_FIRST(key);
dctx.iv1 = GET_32BIT_LSB_FIRST(key+4);
dctx.iv0 = GET_32BIT_MSB_FIRST(key);
dctx.iv1 = GET_32BIT_MSB_FIRST(key+4);
}
static void blowfish_sesskey(unsigned char *key)
@ -425,22 +487,42 @@ static void blowfish_sesskey(unsigned char *key)
logevent("Initialised Blowfish encryption");
}
static void blowfish_encrypt_blk(unsigned char *blk, int len)
static void blowfish_ssh1_encrypt_blk(unsigned char *blk, int len)
{
blowfish_encrypt_cbc(blk, len, &ectx);
blowfish_lsb_encrypt_cbc(blk, len, &ectx);
}
static void blowfish_decrypt_blk(unsigned char *blk, int len)
static void blowfish_ssh1_decrypt_blk(unsigned char *blk, int len)
{
blowfish_decrypt_cbc(blk, len, &dctx);
blowfish_lsb_decrypt_cbc(blk, len, &dctx);
}
struct ssh_cipher ssh_blowfish = {
static void blowfish_ssh2_encrypt_blk(unsigned char *blk, int len)
{
blowfish_msb_encrypt_cbc(blk, len, &ectx);
}
static void blowfish_ssh2_decrypt_blk(unsigned char *blk, int len)
{
blowfish_msb_decrypt_cbc(blk, len, &dctx);
}
struct ssh_cipher ssh_blowfish_ssh1 = {
blowfish_sesskey,
blowfish_csiv, blowfish_cskey,
blowfish_sciv, blowfish_sckey,
blowfish_encrypt_blk,
blowfish_decrypt_blk,
blowfish_ssh1_encrypt_blk,
blowfish_ssh1_decrypt_blk,
"blowfish-cbc",
8
};
struct ssh_cipher ssh_blowfish_ssh2 = {
blowfish_sesskey,
blowfish_csiv, blowfish_cskey,
blowfish_sciv, blowfish_sckey,
blowfish_ssh2_encrypt_blk,
blowfish_ssh2_decrypt_blk,
"blowfish-cbc",
8
};