+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <syslog.h>
+#include <strings.h>
+#include <errno.h>
+#include <openssl/evp.h>
+
+/*
+ * Encrypt or decrypt buf, returning a pointer to the transformed data,
+ * or NULL on error.
+ * The returned data is the same size as the input data,
+ * which means we must turn off cipher padding, and require that buflen
+ * be a multiple of the cipher block size (8 for Blowfish).
+ * To keep things simple, the return value is a malloc'd
+ * buffer that is overwritten on each call.
+ *
+ * Ken Lalonde <ken@globalremit.com>, 2003
+ */
+char *
+cipher(char *buf, int buflen, int do_encrypt)
+{
+ static EVP_CIPHER_CTX ctx;
+ static char *out = NULL; /* return value, grown as necessary */
+ static int outlen = 0;
+ static int init = 0, which, blocksize;
+ int n;
+
+ if (!init) {
+ static const EVP_CIPHER *cipher;
+ unsigned char key[EVP_MAX_KEY_LENGTH], iv[EVP_MAX_IV_LENGTH];
+ // Read key from $HOME/.ermt.key
+ char *keyfile = ".ermt.key";
+ unsigned char buf[128];
+ FILE *fp;
+ int i;
+
+ openlog("ermt", LOG_PID, LOG_DAEMON);
+ // Not needed: OpenSSL_add_all_algorithms();
+ // Not needed: ERR_load_crypto_strings();
+ cipher = EVP_bf_cbc(); // or: EVP_aes_{128,192,256}_cbc()
+ // We want the ability to decrypt the output
+ // using "openssl enc -d -kfile K -nopad -nosalt", which
+ // means we must read the key file the same way
+ // openssl does. But be careful: if the key contains
+ // \0 or \r or \n, the effective size will be reduced.
+ if ((fp = fopen(keyfile, "r")) == NULL) {
+ syslog(LOG_ERR, "Can't open key file %s: %m", keyfile);
+ return NULL;
+ }
+ buf[0] = '\0';
+ fgets(buf, sizeof buf, fp);
+ fclose(fp);
+ i = strlen(buf);
+ if ((i > 0) &&
+ ((buf[i-1] == '\n') || (buf[i-1] == '\r')))
+ buf[--i]='\0';
+ if ((i > 0) &&
+ ((buf[i-1] == '\n') || (buf[i-1] == '\r')))
+ buf[--i]='\0';
+ if (i < 1) {
+ syslog(LOG_ERR, "zero length key");
+ errno = EINVAL;
+ return NULL;
+ }
+ EVP_BytesToKey(cipher, EVP_md5(), NULL,
+ buf, strlen(buf), 1, key, iv);
+ EVP_CIPHER_CTX_init(&ctx);
+ EVP_CipherInit_ex(&ctx, cipher, NULL, key, iv, do_encrypt);
+ EVP_CIPHER_CTX_set_padding(&ctx, 0); // -nopad
+ OPENSSL_cleanse(buf, sizeof buf);
+ OPENSSL_cleanse(key, sizeof key);
+ OPENSSL_cleanse(iv, sizeof iv);
+ blocksize = EVP_CIPHER_CTX_block_size(&ctx);
+ which = do_encrypt;
+ init = 1;
+ }
+ if (which != do_encrypt) {
+ syslog(LOG_ERR, "Cannot switch modes");
+ errno = EINVAL;
+ return NULL;
+ }
+ if ((buflen % blocksize) != 0) {
+ syslog(LOG_ERR, "Buffer size is not a multiple of cipher block size");
+ errno = EINVAL;
+ return NULL;
+ }
+ if (outlen < buflen+blocksize) {
+ outlen = (buflen+blocksize) * 2;
+ out = realloc(out, outlen);
+ }
+ if (!EVP_CipherUpdate(&ctx, out, &n, buf, buflen)) {
+ syslog(LOG_ERR, "EVP_CipherUpdate failed");
+ errno = EINVAL;
+ return NULL;
+ }
+ if (n != buflen) {
+ syslog(LOG_ERR, "EVP_CipherUpdate: %d != %d", n, buflen);
+ errno = EINVAL;
+ return NULL;
+ }
+ // assert(ctx->buf_len == 0);
+ return out;
+}
+
+/* Decrypt stdin to stdout, and exit */
+int
+decrypt()
+{
+ char buf[8*1024], *cp;
+ int n;
+
+ while ((n = fread(buf, 1, sizeof buf, stdin)) > 0) {
+ if ((cp = cipher(buf, n, 0)) == NULL) {
+ fprintf(stderr, "ermt: Error decoding input; see daemon.err syslog\n");
+ exit(1);
+ }
+ fwrite(cp, 1, n, stdout);
+ }
+ if (ferror(stdin)) {
+ perror("ermt: stdin: read");
+ exit(1);
+ }
+ if (fflush(stdout)) {
+ perror("ermt: stdout: write");
+ exit(1);
+ }
+ exit(0);
+}
git.wh0rd.org / dump.git / commitdiff
