5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
10 * Created: Wed Apr 19 17:41:39 1995 ylo
21 #include <openssl/md5.h>
28 * What kind of tripple DES are these 2 routines?
30 * Why is there a redundant initialization vector?
32 * If only iv3 was used, then, this would till effect have been
33 * outer-cbc. However, there is also a private iv1 == iv2 which
34 * perhaps makes differential analysis easier. On the other hand, the
35 * private iv1 probably makes the CRC-32 attack ineffective. This is a
36 * result of that there is no longer any known iv1 to use when
37 * choosing the X block.
40 SSH_3CBC_ENCRYPT(des_key_schedule ks1,
41 des_key_schedule ks2, des_cblock * iv2,
42 des_key_schedule ks3, des_cblock * iv3,
43 void *dest, void *src,
50 des_cbc_encrypt(src, dest, len, ks1, &iv1, DES_ENCRYPT);
51 memcpy(&iv1, dest + len - 8, 8);
53 des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_DECRYPT);
54 memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */
56 des_cbc_encrypt(dest, dest, len, ks3, iv3, DES_ENCRYPT);
57 memcpy(iv3, dest + len - 8, 8);
61 SSH_3CBC_DECRYPT(des_key_schedule ks1,
62 des_key_schedule ks2, des_cblock * iv2,
63 des_key_schedule ks3, des_cblock * iv3,
64 void *dest, void *src,
71 des_cbc_encrypt(src, dest, len, ks3, iv3, DES_DECRYPT);
72 memcpy(iv3, src + len - 8, 8);
74 des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_ENCRYPT);
75 memcpy(iv2, dest + len - 8, 8);
77 des_cbc_encrypt(dest, dest, len, ks1, &iv1, DES_DECRYPT);
78 /* memcpy(&iv1, iv2, 8); */
79 /* Note how iv1 == iv2 on entry and exit. */
83 * SSH uses a variation on Blowfish, all bytes must be swapped before
84 * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
87 swap_bytes(const unsigned char *src, unsigned char *dst_, int n)
89 /* dst must be properly aligned. */
90 u_int32_t *dst = (u_int32_t *) dst_;
96 /* Process 8 bytes every lap. */
97 for (n = n / 8; n > 0; n--) {
112 void (*cipher_attack_detected) (const char *fmt,...) = fatal;
115 detect_cbc_attack(const unsigned char *src,
120 log("CRC-32 CBC insertion attack detected");
121 cipher_attack_detected("CRC-32 CBC insertion attack detected");
125 * Names of all encryption algorithms.
126 * These must match the numbers defined in cipher.h.
128 static char *cipher_names[] =
140 * Returns a bit mask indicating which ciphers are supported by this
141 * implementation. The bit mask has the corresponding bit set of each
148 unsigned int mask = 0;
149 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */
150 mask |= 1 << SSH_CIPHER_BLOWFISH;
154 /* Returns the name of the cipher. */
157 cipher_name(int cipher)
159 if (cipher < 0 || cipher >= sizeof(cipher_names) / sizeof(cipher_names[0]) ||
160 cipher_names[cipher] == NULL)
161 fatal("cipher_name: bad cipher number: %d", cipher);
162 return cipher_names[cipher];
166 * Parses the name of the cipher. Returns the number of the corresponding
167 * cipher, or -1 on error.
171 cipher_number(const char *name)
174 for (i = 0; i < sizeof(cipher_names) / sizeof(cipher_names[0]); i++)
175 if (strcmp(cipher_names[i], name) == 0 &&
176 (cipher_mask() & (1 << i)))
182 * Selects the cipher, and keys if by computing the MD5 checksum of the
183 * passphrase and using the resulting 16 bytes as the key.
187 cipher_set_key_string(CipherContext *context, int cipher,
188 const char *passphrase, int for_encryption)
191 unsigned char digest[16];
194 MD5_Update(&md, (const unsigned char *) passphrase, strlen(passphrase));
195 MD5_Final(digest, &md);
197 cipher_set_key(context, cipher, digest, 16, for_encryption);
199 memset(digest, 0, sizeof(digest));
200 memset(&md, 0, sizeof(md));
203 /* Selects the cipher to use and sets the key. */
206 cipher_set_key(CipherContext *context, int cipher,
207 const unsigned char *key, int keylen, int for_encryption)
209 unsigned char padded[32];
211 /* Set cipher type. */
212 context->type = cipher;
214 /* Get 32 bytes of key data. Pad if necessary. (So that code
215 below does not need to worry about key size). */
216 memset(padded, 0, sizeof(padded));
217 memcpy(padded, key, keylen < sizeof(padded) ? keylen : sizeof(padded));
219 /* Initialize the initialization vector. */
221 case SSH_CIPHER_NONE:
223 * Has to stay for authfile saving of private key with no
228 case SSH_CIPHER_3DES:
230 * Note: the least significant bit of each byte of key is
231 * parity, and must be ignored by the implementation. 16
232 * bytes of key are used (first and last keys are the same).
235 error("Key length %d is insufficient for 3DES.", keylen);
236 des_set_key((void *) padded, context->u.des3.key1);
237 des_set_key((void *) (padded + 8), context->u.des3.key2);
239 des_set_key((void *) padded, context->u.des3.key3);
241 des_set_key((void *) (padded + 16), context->u.des3.key3);
242 memset(context->u.des3.iv2, 0, sizeof(context->u.des3.iv2));
243 memset(context->u.des3.iv3, 0, sizeof(context->u.des3.iv3));
246 case SSH_CIPHER_BLOWFISH:
247 BF_set_key(&context->u.bf.key, keylen, padded);
248 memset(context->u.bf.iv, 0, 8);
252 fatal("cipher_set_key: unknown cipher: %s", cipher_name(cipher));
254 memset(padded, 0, sizeof(padded));
257 /* Encrypts data using the cipher. */
260 cipher_encrypt(CipherContext *context, unsigned char *dest,
261 const unsigned char *src, unsigned int len)
264 fatal("cipher_encrypt: bad plaintext length %d", len);
266 switch (context->type) {
267 case SSH_CIPHER_NONE:
268 memcpy(dest, src, len);
271 case SSH_CIPHER_3DES:
272 SSH_3CBC_ENCRYPT(context->u.des3.key1,
273 context->u.des3.key2, &context->u.des3.iv2,
274 context->u.des3.key3, &context->u.des3.iv3,
275 dest, (void *) src, len);
278 case SSH_CIPHER_BLOWFISH:
279 swap_bytes(src, dest, len);
280 BF_cbc_encrypt(dest, dest, len,
281 &context->u.bf.key, context->u.bf.iv,
283 swap_bytes(dest, dest, len);
287 fatal("cipher_encrypt: unknown cipher: %s", cipher_name(context->type));
291 /* Decrypts data using the cipher. */
294 cipher_decrypt(CipherContext *context, unsigned char *dest,
295 const unsigned char *src, unsigned int len)
298 fatal("cipher_decrypt: bad ciphertext length %d", len);
300 switch (context->type) {
301 case SSH_CIPHER_NONE:
302 memcpy(dest, src, len);
305 case SSH_CIPHER_3DES:
307 SSH_3CBC_DECRYPT(context->u.des3.key1,
308 context->u.des3.key2, &context->u.des3.iv2,
309 context->u.des3.key3, &context->u.des3.iv3,
310 dest, (void *) src, len);
313 case SSH_CIPHER_BLOWFISH:
314 detect_cbc_attack(src, len);
315 swap_bytes(src, dest, len);
316 BF_cbc_encrypt((void *) dest, dest, len,
317 &context->u.bf.key, context->u.bf.iv,
319 swap_bytes(dest, dest, len);
323 fatal("cipher_decrypt: unknown cipher: %s", cipher_name(context->type));