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https://github.com/dirtbags/moth.git
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f5d4ef25a7
This required a fair amount of shuffling stuff around, as can be seen. Fortunately, now things ought to be able to run more or less standalone again. I also figured out a way to have the build system be a tad smarter about not rebuilding shared stuff, although you still install the exact same eris binary and /service subdirs for mcp and p2. But at least you only have to change one place in the source code now.
130 lines
2.7 KiB
C
130 lines
2.7 KiB
C
#include <stdio.h>
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#include <unistd.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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static const char magic[4] = "tea.";
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#define min(a,b) (((a)<(b))?(a):(b))
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void
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tea_encrypt(uint32_t *v, uint32_t *k) {
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uint32_t v0=v[0], v1=v[1], sum=0, i; /* set up */
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uint32_t delta=0x9e3779b9; /* a key schedule constant */
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uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3]; /* cache key */
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for (i=0; i < 32; i++) { /* basic cycle start */
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sum += delta;
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v0 += ((v1<<4) + k0) ^ (v1 + sum) ^ ((v1>>5) + k1);
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v1 += ((v0<<4) + k2) ^ (v0 + sum) ^ ((v0>>5) + k3);
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} /* end cycle */
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v[0]=v0; v[1]=v1;
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}
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/*
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* Use TEA in CTR mode to create a stream cipher.
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*/
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static void
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tea_apply(FILE *out, FILE *in, uint32_t *k, uint32_t ivec)
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{
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uint32_t count = 0;
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uint32_t v[2];
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size_t idx = sizeof v;
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char *p = (char *)v;
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while (1) {
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int c = fgetc(in);
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if (EOF == c) {
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break;
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}
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if (sizeof v == idx) {
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v[0] = ivec;
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v[1] = count++;
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tea_encrypt(v, k);
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idx = 0;
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}
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fputc(c ^ p[idx++], out);
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}
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}
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int
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tea_decrypt_stream(FILE *out, FILE *in, uint32_t *k)
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{
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uint32_t ivec;
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{
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char m[4] = {0};
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fread(m, sizeof m, 1, in);
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if (memcmp(m, magic, 4)) {
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return -1;
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}
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}
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fread(&ivec, sizeof ivec, 1, in);
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tea_apply(out, in, k, ivec);
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return 0;
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}
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int
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tea_encrypt_stream(FILE *out, FILE *in, uint32_t *k)
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{
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uint32_t ivec;
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fwrite(magic, sizeof magic, 1, out);
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{
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FILE *r = fopen("/dev/urandom", "r");
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if (! r) {
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return -1;
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}
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fread(&ivec, sizeof ivec, 1, r);
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fclose(r);
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}
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fwrite(&ivec, sizeof ivec, 1, out);
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tea_apply(out, in, k, ivec);
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return 0;
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}
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int
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usage(const char *prog)
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{
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fprintf(stderr, "Usage: %s [-e] <PLAINTEXT\n", prog);
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fprintf(stderr, "\n");
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fprintf(stderr, "You must pass in a key on fd 3 or in the environment variable KEY.\n");
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return EX_USAGE;
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}
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int
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main(int argc, char *argv[])
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{
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uint32_t key[4] = {0};
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{
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char *ekey = getenv("KEY");
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if (ekey) {
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memcpy(key, ekey, min(strlen(ekey), sizeof(key)));
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} else if (-1 == read(3, key, sizeof(key))) {
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return usage(argv[0]);
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}
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}
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if (! argv[1]) {
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tea_decrypt_stream(stdout, stdin, key);
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} else if (0 == strcmp(argv[1], "-e")) {
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tea_encrypt_stream(stdout, stdin, key);
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} else {
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return usage(argv[0]);
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}
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return 0;
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}
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