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Access all hashes and MACs through the standard API.

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All the hash-specific state structures, and the functions that
directly accessed them, are now local to the source files implementing
the hashes themselves. Everywhere we previously used those types or
functions, we're now using the standard ssh_hash or ssh2_mac API.

The 'simple' functions (hmacmd5_simple, SHA_Simple etc) are now a pair
of wrappers in sshauxcrypt.c, each of which takes an algorithm
structure and can do the same conceptual thing regardless of what it
is.
This commit is contained in:
Simon Tatham
2019-01-20 16:15:14 +00:00
parent acdcf2bfaa
commit 0d2d20aad0
19 changed files with 232 additions and 274 deletions
Download Patch File Download Diff File Expand all files Collapse all files

129
import.c
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@ -495,6 +495,36 @@ static bool openssh_pem_encrypted(const Filename *filename)
return ret;
}
static void openssh_pem_derivekey(
ptrlen passphrase, const void *iv, uint8_t *keybuf)
{
/*
* Derive the encryption key for a PEM key file from the
* passphrase and iv/salt:
*
* - let block A equal MD5(passphrase || iv)
* - let block B equal MD5(A || passphrase || iv)
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
*
* (Note that only 8 bytes of the iv are used for key
* derivation, even when the key is encrypted with AES and
* hence there are 16 bytes available.)
*/
ssh_hash *h;
h = ssh_hash_new(&ssh_md5);
put_datapl(h, passphrase);
put_data(h, iv, 8);
ssh_hash_final(h, keybuf);
h = ssh_hash_new(&ssh_md5);
put_data(h, keybuf, 16);
put_datapl(h, passphrase);
put_data(h, iv, 8);
ssh_hash_final(h, keybuf + 16);
}
static ssh2_userkey *openssh_pem_read(
const Filename *filename, const char *passphrase, const char **errmsg_p)
{
@ -514,34 +544,11 @@ static ssh2_userkey *openssh_pem_read(
return NULL;
if (key->encrypted) {
/*
* Derive encryption key from passphrase and iv/salt:
*
* - let block A equal MD5(passphrase || iv)
* - let block B equal MD5(A || passphrase || iv)
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
*
* (Note that only 8 bytes of the iv are used for key
* derivation, even when the key is encrypted with AES and
* hence there are 16 bytes available.)
*/
struct MD5Context md5c;
unsigned char keybuf[32];
MD5Init(&md5c);
put_data(&md5c, passphrase, strlen(passphrase));
put_data(&md5c, key->iv, 8);
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
put_data(&md5c, keybuf, 16);
put_data(&md5c, passphrase, strlen(passphrase));
put_data(&md5c, key->iv, 8);
MD5Final(keybuf+16, &md5c);
openssh_pem_derivekey(ptrlen_from_asciz(passphrase), key->iv, keybuf);
/*
* Now decrypt the key blob.
* Decrypt the key blob.
*/
if (key->encryption == OP_E_3DES)
des3_decrypt_pubkey_ossh(keybuf, key->iv,
@ -554,7 +561,6 @@ static ssh2_userkey *openssh_pem_read(
ssh_cipher_free(cipher);
}
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}
@ -981,7 +987,6 @@ static bool openssh_pem_write(
* old-style 3DES.
*/
if (passphrase) {
struct MD5Context md5c;
unsigned char keybuf[32];
int origlen, outlen, pad, i;
@ -1008,26 +1013,11 @@ static bool openssh_pem_write(
put_padding(outblob, pad, pad);
/*
* Invent an iv. Then derive encryption key from passphrase
* and iv/salt:
*
* - let block A equal MD5(passphrase || iv)
* - let block B equal MD5(A || passphrase || iv)
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
* Invent an iv, and derive the encryption key.
*/
for (i = 0; i < 8; i++) iv[i] = random_byte();
MD5Init(&md5c);
put_data(&md5c, passphrase, strlen(passphrase));
put_data(&md5c, iv, 8);
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
put_data(&md5c, keybuf, 16);
put_data(&md5c, passphrase, strlen(passphrase));
put_data(&md5c, iv, 8);
MD5Final(keybuf+16, &md5c);
openssh_pem_derivekey(ptrlen_from_asciz(passphrase), iv, keybuf);
/*
* Now encrypt the key blob.
@ -1035,7 +1025,6 @@ static bool openssh_pem_write(
des3_encrypt_pubkey_ossh(keybuf, iv,
outblob->u, outlen);
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}
@ -1959,6 +1948,26 @@ static ptrlen BinarySource_get_mp_sshcom_as_string(BinarySource *src)
#define get_mp_sshcom_as_string(bs) \
BinarySource_get_mp_sshcom_as_string(BinarySource_UPCAST(bs))
static void sshcom_derivekey(ptrlen passphrase, uint8_t *keybuf)
{
/*
* Derive the encryption key for an ssh.com key file from the
* passphrase and iv/salt:
*
* - let block A equal MD5(passphrase)
* - let block B equal MD5(passphrase || A)
* - block C would be MD5(passphrase || A || B) and so on
* - encryption key is the first N bytes of A || B
*/
ssh_hash *h;
h = ssh_hash_new(&ssh_md5);
put_datapl(h, passphrase);
ssh_hash_final(ssh_hash_copy(h), keybuf);
put_data(h, keybuf, 16);
ssh_hash_final(h, keybuf + 16);
}
static ssh2_userkey *sshcom_read(
const Filename *filename, const char *passphrase, const char **errmsg_p)
{
@ -2035,7 +2044,6 @@ static ssh2_userkey *sshcom_read(
* - block C would be MD5(passphrase || A || B) and so on
* - encryption key is the first N bytes of A || B
*/
struct MD5Context md5c;
unsigned char keybuf[32], iv[8];
if (ciphertext.len % 8 != 0) {
@ -2044,14 +2052,7 @@ static ssh2_userkey *sshcom_read(
goto error;
}
MD5Init(&md5c);
put_data(&md5c, passphrase, strlen(passphrase));
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
put_data(&md5c, passphrase, strlen(passphrase));
put_data(&md5c, keybuf, 16);
MD5Final(keybuf+16, &md5c);
sshcom_derivekey(ptrlen_from_asciz(passphrase), keybuf);
/*
* Now decrypt the key blob in place (casting away const from
@ -2061,7 +2062,6 @@ static ssh2_userkey *sshcom_read(
des3_decrypt_pubkey_ossh(keybuf, iv,
(char *)ciphertext.ptr, ciphertext.len);
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
/*
@ -2294,25 +2294,9 @@ static bool sshcom_write(
* Encrypt the key.
*/
if (passphrase) {
/*
* Derive encryption key from passphrase and iv/salt:
*
* - let block A equal MD5(passphrase)
* - let block B equal MD5(passphrase || A)
* - block C would be MD5(passphrase || A || B) and so on
* - encryption key is the first N bytes of A || B
*/
struct MD5Context md5c;
unsigned char keybuf[32], iv[8];
MD5Init(&md5c);
put_data(&md5c, passphrase, strlen(passphrase));
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
put_data(&md5c, passphrase, strlen(passphrase));
put_data(&md5c, keybuf, 16);
MD5Final(keybuf+16, &md5c);
sshcom_derivekey(ptrlen_from_asciz(passphrase), keybuf);
/*
* Now decrypt the key blob.
@ -2320,7 +2304,6 @@ static bool sshcom_write(
memset(iv, 0, sizeof(iv));
des3_encrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen);
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}