Add UI to puer
This commit is contained in:
Juhani Krekelä
parent
4b5ef70bce
commit
6079530e1d
216
puer.c
216
puer.c
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@ -10,6 +10,10 @@
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#include <termios.h>
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#include <unistd.h>
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// Adjusting this will render the file format incompatible
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// The minimum possible buffer size is 64
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unsigned char workbuf[8 * 1024 * 1024];
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void xxtea128(uint32_t const key[4], uint32_t block[4]) {
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// Encryption half of the XXTEA algorithm, with block size limited
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// to 128 bits or 4 words. This avoids all the weaknesses that
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@ -268,7 +272,6 @@ void hmac(unsigned char output[32], unsigned char key[], size_t keylen, unsigned
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finalize_hash(&state, output);
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}
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unsigned char workbuf[8 * 1024 * 1024];
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#define KDF_ROUNDS (sizeof(workbuf) / 32)
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void kdf(unsigned char key[16], unsigned char salt[32], unsigned char passphrase[], size_t passphraselen) {
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@ -540,54 +543,195 @@ ssize_t passphrase_prompt(unsigned char *passphrase, size_t size, const char *pr
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return index - 1;
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}
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int main(void) {
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unsigned char salt[32];
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if (getentropy(salt, 32) != 0) {
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perror("getentropy");
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void usage(char *name) {
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fprintf(stderr, "Usage: %s -d | -e [-f]\n\n", name);
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fprintf(stderr, "-d Decrypt\n");
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fprintf(stderr, "-e Encrypt\n");
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fprintf(stderr, "-f Force output to terminal\n");
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}
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int main(int argc, char *argv[]) {
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bool encrypting = false;
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bool decrypting = false;
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bool force = false;
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int opt;
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while ((opt = getopt(argc, argv, "def")) != -1) {
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switch (opt) {
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case 'd':
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decrypting = true;
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break;
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case 'e':
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encrypting = true;
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break;
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case 'f':
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force = true;
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break;
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default:
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usage(argv[0]);
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exit(1);
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}
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}
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unsigned char passphrase[128] = {0};
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if ((!encrypting && !decrypting) || (encrypting && decrypting)) {
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usage(argv[0]);
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exit(1);
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}
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FILE *infile = stdin;
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FILE *outfile = stdout;
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if (encrypting && !force && isatty(fileno(outfile))) {
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fprintf(stderr, "Refusing to print encrypted (binary) data to terminal. Use -f to force output.\n");
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exit(1);
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}
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// Get the salt for key derivation
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unsigned char salt[32];
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if (encrypting) {
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// Generate salt randomly
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if (getentropy(salt, 32) != 0) {
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perror("Could not generate salt (getentropy)");
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exit(1);
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}
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// Write salt to the beginning of the file
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if (fwrite(&salt, 32, 1, outfile) != 1) {
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fprintf(stderr, "Could not write salt\n");
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exit(1);
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}
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} else {
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// Read salt from the beginning of the file
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if (fread(&salt, 32, 1, infile) != 1) {
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fprintf(stderr, "Could not read salt\n");
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exit(1);
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}
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}
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// Read passphrase
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unsigned char passphrase[128];
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ssize_t passphrase_len = passphrase_prompt(passphrase, sizeof(passphrase), "passphrase: ");
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if (passphrase_len == -1) {
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explicit_bzero(passphrase, sizeof(passphrase));
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exit(1);
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}
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if (encrypting) {
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// Have the user confirm the passphrase if encrypting, to avoid losing data
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unsigned char confirm[128];
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ssize_t confirm_len = passphrase_prompt(confirm, sizeof(confirm), "confirm passphrase: ");
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if (confirm_len == -1) {
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explicit_bzero(passphrase, sizeof(passphrase));
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explicit_bzero(confirm, sizeof(confirm));
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exit(1);
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}
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if (confirm_len != passphrase_len || memcmp(passphrase, confirm, passphrase_len) != 0) {
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fprintf(stderr, "Passphrases do not match\n");
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explicit_bzero(passphrase, sizeof(passphrase));
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explicit_bzero(confirm, sizeof(confirm));
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exit(1);
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}
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explicit_bzero(confirm, sizeof(confirm));
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}
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// Derive key
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unsigned char key[16];
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kdf(key, salt, passphrase, passphrase_len);
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for (size_t i = 0; i < 16; i++) {
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printf("%02hhx ", key[i]);
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}
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printf("\n\n");
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explicit_bzero(passphrase, sizeof(passphrase));
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char *message = "Syökää parsaa ja palvokaa saatanaa";
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unsigned char buf[64];
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memset(buf, 0xab, sizeof(buf));
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strcpy((char*)buf, message);
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for (size_t i = 0; i < sizeof(buf); i++) {
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printf("%02hhx ", buf[i]);
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if (i % 16 == 15) printf("\n");
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}
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printf("\n");
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uint64_t messageindex = 0;
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if (encrypting) {
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for (;;) {
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// Leave space for the MAC in the work buffer
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size_t bytes = fread(workbuf, 1, sizeof(workbuf) - 16, infile);
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if (bytes == 0 && ferror(infile)) {
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perror("Failure reading");
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explicit_bzero(key, sizeof(key));
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exit(1);
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}
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ccm_encrypt(key, 25, buf, strlen(message), &buf[48]);
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for (size_t i = 0; i < sizeof(buf); i++) {
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printf("%02hhx ", buf[i]);
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if (i % 16 == 15) printf("\n");
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}
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printf("\n");
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// MAC is after the message
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unsigned char *mac = &workbuf[bytes];
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memset(&buf[strlen(message)], 0x0f, 48-strlen(message));
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for (size_t i = 0; i < sizeof(buf); i++) {
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printf("%02hhx ", buf[i]);
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if (i % 16 == 15) printf("\n");
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}
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printf("\n");
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ccm_encrypt(key, messageindex++, workbuf, bytes, mac);
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bool auth = ccm_decrypt(key, 25, buf, strlen(message), &buf[48]);
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printf("auth %s\n", auth ? "succeeded" : "failed");
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for (size_t i = 0; i < sizeof(buf); i++) {
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printf("%02hhx ", buf[i]);
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if (i % 16 == 15) printf("\n");
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size_t written = fwrite(workbuf, 1, bytes + 16, outfile);
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if (written != bytes + 16) {
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perror("Failure writing");
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explicit_bzero(key, sizeof(key));
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exit(1);
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}
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// If this chunk was short, that means we're done
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if (bytes < sizeof(workbuf) - 16) {
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break;
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}
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if (messageindex == 0) {
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// We will not run into this, but I feel like it's cleaner to check
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fprintf(stderr, "Chunk counter overflow\n");
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explicit_bzero(key, sizeof(key));
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exit(1);
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}
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}
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} else {
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for (;;) {
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size_t bytes = fread(workbuf, 1, sizeof(workbuf), infile);
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if (bytes == 0 && ferror(infile)) {
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perror("Failure reading");
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explicit_bzero(key, sizeof(key));
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exit(1);
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} else if (bytes < 16) {
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fprintf(stderr, "Chunk too short. File likely corrupt.\n");
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explicit_bzero(key, sizeof(key));
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exit(1);
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}
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// MAC is after the message
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unsigned char *mac = &workbuf[bytes - 16];
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bool auth = ccm_decrypt(key, messageindex++, workbuf, bytes - 16, mac);
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if (!auth) {
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if (messageindex == 1) {
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// First chunk
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fprintf(stderr, "Authentication failed. Either the passphrase is wrong or the file is corrupt.\n");
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} else {
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fprintf(stderr, "Authentication failed. The file is likely corrupt.\n");
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}
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explicit_bzero(key, sizeof(key));
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exit(1);
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}
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size_t written = fwrite(workbuf, 1, bytes - 16, outfile);
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if (written != bytes - 16) {
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perror("Failure writing");
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explicit_bzero(key, sizeof(key));
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exit(1);
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}
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// If this chunk was short, that means we're done
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if (bytes < sizeof(workbuf)) {
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break;
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}
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if (messageindex == 0) {
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// We will not run into this, but I feel like it's cleaner to check
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fprintf(stderr, "Chunk counter overflow\n");
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explicit_bzero(key, sizeof(key));
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exit(1);
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}
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}
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}
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// Remove the key from memory
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explicit_bzero(key, sizeof(key));
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if (fflush(stdout) != 0) {
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perror("Failure writing");
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exit(1);
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}
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return 0;
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}
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