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git.wh0rd.org - dump.git/blob - rmt/cipher.c
9 #include <openssl/evp.h>
12 * Encrypt or decrypt buf, returning a pointer to the transformed data,
14 * The returned data is the same size as the input data,
15 * which means we must turn off cipher padding, and require that buflen
16 * be a multiple of the cipher block size (8 for Blowfish).
17 * To keep things simple, the return value is a malloc'd
18 * buffer that is overwritten on each call.
20 * Ken Lalonde <ken@globalremit.com>, 2003
23 cipher(char *buf
, int buflen
, int do_encrypt
)
25 static EVP_CIPHER_CTX ctx
;
26 static char *out
= NULL
; /* return value, grown as necessary */
27 static int outlen
= 0;
28 static int init
= 0, which
, blocksize
;
32 static const EVP_CIPHER
*cipher
;
33 unsigned char key
[EVP_MAX_KEY_LENGTH
], iv
[EVP_MAX_IV_LENGTH
];
34 // Read key from $HOME/.ermt.key
35 char *keyfile
= ".ermt.key";
36 unsigned char buf
[128];
40 openlog("ermt", LOG_PID
, LOG_DAEMON
);
41 // Not needed: OpenSSL_add_all_algorithms();
42 // Not needed: ERR_load_crypto_strings();
43 cipher
= EVP_bf_cbc(); // or: EVP_aes_{128,192,256}_cbc()
44 // We want the ability to decrypt the output
45 // using "openssl enc -d -kfile K -nopad -nosalt", which
46 // means we must read the key file the same way
47 // openssl does. But be careful: if the key contains
48 // \0 or \r or \n, the effective size will be reduced.
49 if ((fp
= fopen(keyfile
, "r")) == NULL
) {
50 syslog(LOG_ERR
, "Can't open key file %s: %m", keyfile
);
54 fgets(buf
, sizeof buf
, fp
);
58 ((buf
[i
-1] == '\n') || (buf
[i
-1] == '\r')))
61 ((buf
[i
-1] == '\n') || (buf
[i
-1] == '\r')))
64 syslog(LOG_ERR
, "zero length key");
68 EVP_BytesToKey(cipher
, EVP_md5(), NULL
,
69 buf
, strlen(buf
), 1, key
, iv
);
70 EVP_CIPHER_CTX_init(&ctx
);
71 EVP_CipherInit_ex(&ctx
, cipher
, NULL
, key
, iv
, do_encrypt
);
72 EVP_CIPHER_CTX_set_padding(&ctx
, 0); // -nopad
73 OPENSSL_cleanse(buf
, sizeof buf
);
74 OPENSSL_cleanse(key
, sizeof key
);
75 OPENSSL_cleanse(iv
, sizeof iv
);
76 blocksize
= EVP_CIPHER_CTX_block_size(&ctx
);
80 if (which
!= do_encrypt
) {
81 syslog(LOG_ERR
, "Cannot switch modes");
85 if ((buflen
% blocksize
) != 0) {
86 syslog(LOG_ERR
, "Buffer size is not a multiple of cipher block size");
90 if (outlen
< buflen
+blocksize
) {
91 outlen
= (buflen
+blocksize
) * 2;
92 out
= realloc(out
, outlen
);
94 if (!EVP_CipherUpdate(&ctx
, out
, &n
, buf
, buflen
)) {
95 syslog(LOG_ERR
, "EVP_CipherUpdate failed");
100 syslog(LOG_ERR
, "EVP_CipherUpdate: %d != %d", n
, buflen
);
104 // assert(ctx->buf_len == 0);
108 /* Decrypt stdin to stdout, and exit */
112 char buf
[8*1024], *cp
;
115 while ((n
= fread(buf
, 1, sizeof buf
, stdin
)) > 0) {
116 if ((cp
= cipher(buf
, n
, 0)) == NULL
) {
117 fprintf(stderr
, "ermt: Error decoding input; see daemon.err syslog\n");
120 fwrite(cp
, 1, n
, stdout
);
123 perror("ermt: stdin: read");
126 if (fflush(stdout
)) {
127 perror("ermt: stdout: write");