diff options
author | markm <markm@FreeBSD.org> | 2000-02-24 14:29:47 +0000 |
---|---|---|
committer | markm <markm@FreeBSD.org> | 2000-02-24 14:29:47 +0000 |
commit | fc557ff7d97438559e69347575f5aa8ef03a5f50 (patch) | |
tree | c90ea5392aa03e7619696143bde781f2bf5c0dff /crypto/openssh/cipher.c | |
download | FreeBSD-src-fc557ff7d97438559e69347575f5aa8ef03a5f50.zip FreeBSD-src-fc557ff7d97438559e69347575f5aa8ef03a5f50.tar.gz |
Vendor import of OpenSSH.
Diffstat (limited to 'crypto/openssh/cipher.c')
-rw-r--r-- | crypto/openssh/cipher.c | 320 |
1 files changed, 320 insertions, 0 deletions
diff --git a/crypto/openssh/cipher.c b/crypto/openssh/cipher.c new file mode 100644 index 0000000..552bbe3 --- /dev/null +++ b/crypto/openssh/cipher.c @@ -0,0 +1,320 @@ +/* + * + * cipher.c + * + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * + * Created: Wed Apr 19 17:41:39 1995 ylo + * + */ + +#include "includes.h" +RCSID("$Id: cipher.c,v 1.19 2000/02/22 15:19:29 markus Exp $"); + +#include "ssh.h" +#include "cipher.h" + +#include <ssl/md5.h> + +/* + * What kind of tripple DES are these 2 routines? + * + * Why is there a redundant initialization vector? + * + * If only iv3 was used, then, this would till effect have been + * outer-cbc. However, there is also a private iv1 == iv2 which + * perhaps makes differential analysis easier. On the other hand, the + * private iv1 probably makes the CRC-32 attack ineffective. This is a + * result of that there is no longer any known iv1 to use when + * choosing the X block. + */ +void +SSH_3CBC_ENCRYPT(des_key_schedule ks1, + des_key_schedule ks2, des_cblock * iv2, + des_key_schedule ks3, des_cblock * iv3, + unsigned char *dest, unsigned char *src, + unsigned int len) +{ + des_cblock iv1; + + memcpy(&iv1, iv2, 8); + + des_cbc_encrypt(src, dest, len, ks1, &iv1, DES_ENCRYPT); + memcpy(&iv1, dest + len - 8, 8); + + des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_DECRYPT); + memcpy(iv2, &iv1, 8); /* Note how iv1 == iv2 on entry and exit. */ + + des_cbc_encrypt(dest, dest, len, ks3, iv3, DES_ENCRYPT); + memcpy(iv3, dest + len - 8, 8); +} + +void +SSH_3CBC_DECRYPT(des_key_schedule ks1, + des_key_schedule ks2, des_cblock * iv2, + des_key_schedule ks3, des_cblock * iv3, + unsigned char *dest, unsigned char *src, + unsigned int len) +{ + des_cblock iv1; + + memcpy(&iv1, iv2, 8); + + des_cbc_encrypt(src, dest, len, ks3, iv3, DES_DECRYPT); + memcpy(iv3, src + len - 8, 8); + + des_cbc_encrypt(dest, dest, len, ks2, iv2, DES_ENCRYPT); + memcpy(iv2, dest + len - 8, 8); + + des_cbc_encrypt(dest, dest, len, ks1, &iv1, DES_DECRYPT); + /* memcpy(&iv1, iv2, 8); */ + /* Note how iv1 == iv2 on entry and exit. */ +} + +/* + * SSH uses a variation on Blowfish, all bytes must be swapped before + * and after encryption/decryption. Thus the swap_bytes stuff (yuk). + */ +static void +swap_bytes(const unsigned char *src, unsigned char *dst_, int n) +{ + /* dst must be properly aligned. */ + u_int32_t *dst = (u_int32_t *) dst_; + union { + u_int32_t i; + char c[4]; + } t; + + /* Process 8 bytes every lap. */ + for (n = n / 8; n > 0; n--) { + t.c[3] = *src++; + t.c[2] = *src++; + t.c[1] = *src++; + t.c[0] = *src++; + *dst++ = t.i; + + t.c[3] = *src++; + t.c[2] = *src++; + t.c[1] = *src++; + t.c[0] = *src++; + *dst++ = t.i; + } +} + +void (*cipher_attack_detected) (const char *fmt,...) = fatal; + +static inline void +detect_cbc_attack(const unsigned char *src, + unsigned int len) +{ + return; + + log("CRC-32 CBC insertion attack detected"); + cipher_attack_detected("CRC-32 CBC insertion attack detected"); +} + +/* + * Names of all encryption algorithms. + * These must match the numbers defined in cipher.h. + */ +static char *cipher_names[] = +{ + "none", + "idea", + "des", + "3des", + "tss", + "rc4", + "blowfish" +}; + +/* + * Returns a bit mask indicating which ciphers are supported by this + * implementation. The bit mask has the corresponding bit set of each + * supported cipher. + */ + +unsigned int +cipher_mask() +{ + unsigned int mask = 0; + mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ + mask |= 1 << SSH_CIPHER_BLOWFISH; + return mask; +} + +/* Returns the name of the cipher. */ + +const char * +cipher_name(int cipher) +{ + if (cipher < 0 || cipher >= sizeof(cipher_names) / sizeof(cipher_names[0]) || + cipher_names[cipher] == NULL) + fatal("cipher_name: bad cipher number: %d", cipher); + return cipher_names[cipher]; +} + +/* + * Parses the name of the cipher. Returns the number of the corresponding + * cipher, or -1 on error. + */ + +int +cipher_number(const char *name) +{ + int i; + for (i = 0; i < sizeof(cipher_names) / sizeof(cipher_names[0]); i++) + if (strcmp(cipher_names[i], name) == 0 && + (cipher_mask() & (1 << i))) + return i; + return -1; +} + +/* + * Selects the cipher, and keys if by computing the MD5 checksum of the + * passphrase and using the resulting 16 bytes as the key. + */ + +void +cipher_set_key_string(CipherContext *context, int cipher, + const char *passphrase, int for_encryption) +{ + MD5_CTX md; + unsigned char digest[16]; + + MD5_Init(&md); + MD5_Update(&md, (const unsigned char *) passphrase, strlen(passphrase)); + MD5_Final(digest, &md); + + cipher_set_key(context, cipher, digest, 16, for_encryption); + + memset(digest, 0, sizeof(digest)); + memset(&md, 0, sizeof(md)); +} + +/* Selects the cipher to use and sets the key. */ + +void +cipher_set_key(CipherContext *context, int cipher, + const unsigned char *key, int keylen, int for_encryption) +{ + unsigned char padded[32]; + + /* Set cipher type. */ + context->type = cipher; + + /* Get 32 bytes of key data. Pad if necessary. (So that code + below does not need to worry about key size). */ + memset(padded, 0, sizeof(padded)); + memcpy(padded, key, keylen < sizeof(padded) ? keylen : sizeof(padded)); + + /* Initialize the initialization vector. */ + switch (cipher) { + case SSH_CIPHER_NONE: + /* + * Has to stay for authfile saving of private key with no + * passphrase + */ + break; + + case SSH_CIPHER_3DES: + /* + * Note: the least significant bit of each byte of key is + * parity, and must be ignored by the implementation. 16 + * bytes of key are used (first and last keys are the same). + */ + if (keylen < 16) + error("Key length %d is insufficient for 3DES.", keylen); + des_set_key((void *) padded, context->u.des3.key1); + des_set_key((void *) (padded + 8), context->u.des3.key2); + if (keylen <= 16) + des_set_key((void *) padded, context->u.des3.key3); + else + des_set_key((void *) (padded + 16), context->u.des3.key3); + memset(context->u.des3.iv2, 0, sizeof(context->u.des3.iv2)); + memset(context->u.des3.iv3, 0, sizeof(context->u.des3.iv3)); + break; + + case SSH_CIPHER_BLOWFISH: + BF_set_key(&context->u.bf.key, keylen, padded); + memset(context->u.bf.iv, 0, 8); + break; + + default: + fatal("cipher_set_key: unknown cipher: %s", cipher_name(cipher)); + } + memset(padded, 0, sizeof(padded)); +} + +/* Encrypts data using the cipher. */ + +void +cipher_encrypt(CipherContext *context, unsigned char *dest, + const unsigned char *src, unsigned int len) +{ + if ((len & 7) != 0) + fatal("cipher_encrypt: bad plaintext length %d", len); + + switch (context->type) { + case SSH_CIPHER_NONE: + memcpy(dest, src, len); + break; + + case SSH_CIPHER_3DES: + SSH_3CBC_ENCRYPT(context->u.des3.key1, + context->u.des3.key2, &context->u.des3.iv2, + context->u.des3.key3, &context->u.des3.iv3, + dest, (unsigned char *) src, len); + break; + + case SSH_CIPHER_BLOWFISH: + swap_bytes(src, dest, len); + BF_cbc_encrypt(dest, dest, len, + &context->u.bf.key, context->u.bf.iv, + BF_ENCRYPT); + swap_bytes(dest, dest, len); + break; + + default: + fatal("cipher_encrypt: unknown cipher: %s", cipher_name(context->type)); + } +} + +/* Decrypts data using the cipher. */ + +void +cipher_decrypt(CipherContext *context, unsigned char *dest, + const unsigned char *src, unsigned int len) +{ + if ((len & 7) != 0) + fatal("cipher_decrypt: bad ciphertext length %d", len); + + switch (context->type) { + case SSH_CIPHER_NONE: + memcpy(dest, src, len); + break; + + case SSH_CIPHER_3DES: + /* CRC-32 attack? */ + SSH_3CBC_DECRYPT(context->u.des3.key1, + context->u.des3.key2, &context->u.des3.iv2, + context->u.des3.key3, &context->u.des3.iv3, + dest, (unsigned char *) src, len); + break; + + case SSH_CIPHER_BLOWFISH: + detect_cbc_attack(src, len); + swap_bytes(src, dest, len); + BF_cbc_encrypt((void *) dest, dest, len, + &context->u.bf.key, context->u.bf.iv, + BF_DECRYPT); + swap_bytes(dest, dest, len); + break; + + default: + fatal("cipher_decrypt: unknown cipher: %s", cipher_name(context->type)); + } +} |