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@@ -1,6 +1,6 @@
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#include <openssl/conf.h>
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-#include <openssl/evp.h>
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#include <openssl/err.h>
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+#include <openssl/evp.h>
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#include <stdio.h>
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#include <string.h>
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@@ -8,26 +8,17 @@
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// refer to https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption
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void handleErrors(void);
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-int gcm_encrypt(unsigned char *plaintext, int plaintext_len,
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- unsigned char *key,
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- unsigned char *iv, int iv_len,
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- unsigned char *ciphertext,
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- unsigned char *tag);
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-int gcm_decrypt(unsigned char *ciphertext, int ciphertext_len,
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- unsigned char *tag,
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- unsigned char *key,
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- unsigned char *iv, int iv_len,
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- unsigned char *plaintext);
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-
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-int main (int argc, char** argv)
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-{
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- /*
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- * Set up the key and iv. Do I need to say to not hard code these in a
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- * real application? :-)
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- */
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-
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+int gcm_encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key, unsigned char *iv, int iv_len, unsigned char *ciphertext, unsigned char *tag);
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+int gcm_decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *tag, unsigned char *key, unsigned char *iv, int iv_len, unsigned char *plaintext);
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+
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+int main(int argc, char **argv) {
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+ /*
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+ * Set up the key and iv. Do I need to say to not hard code these in a
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+ * real application? :-)
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+ */
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+
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FILE *f, *o;
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- unsigned char signature[4] = { 'C', 'C', 'A', 'T' };
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+ unsigned char signature[4] = {'C', 'C', 'A', 'T'};
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unsigned char key[32];
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unsigned char iv[12];
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unsigned char tag[16];
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@@ -35,60 +26,55 @@ int main (int argc, char** argv)
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unsigned char *cipher;
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unsigned insize, mode;
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int decryptedtext_len, ciphertext_len;
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- if(argc < 4) {
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+ if (argc < 4) {
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printf("not enough args. use %s mode key in out\n", argv[0]);
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return 1;
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}
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-
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+
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mode = strtoul(argv[1], NULL, 10);
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-
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- if(!(f = fopen(argv[2], "rb"))) {
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+
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+ if (!(f = fopen(argv[2], "rb"))) {
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printf("cannot open key\n");
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return 1;
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}
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fread(key, sizeof(key), 1, f);
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fclose(f);
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-
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- if(!(f = fopen("/dev/urandom", "rb"))) {
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+
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+ if (!(f = fopen("/dev/urandom", "rb"))) {
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printf("cannot open urandom\n");
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return 1;
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}
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fread(iv, sizeof(iv), 1, f);
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fclose(f);
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-
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- if(!(f = fopen(argv[3], "rb"))) {
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+
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+ if (!(f = fopen(argv[3], "rb"))) {
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printf("cannot open in\n");
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return 1;
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}
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- if(!(o = fopen(argv[4], "wb"))) {
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+ if (!(o = fopen(argv[4], "wb"))) {
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printf("cannot open out\n");
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return 1;
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}
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-
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-
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- if(mode) {
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+
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+ if (mode) {
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fseek(f, 0, SEEK_END);
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- insize = ftell(f)+4;
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+ insize = ftell(f) + 4;
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fseek(f, 0, SEEK_SET);
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plain = malloc(insize);
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cipher = malloc(insize);
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- fread(plain+4, insize, 1, f);
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+ fread(plain + 4, insize, 1, f);
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fclose(f);
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/* prepend signature */
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memcpy(plain, signature, 4);
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/* Encrypt the plaintext */
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- ciphertext_len = gcm_encrypt(plain, insize,
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- key,
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- iv, sizeof(iv),
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- cipher, tag);
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+ ciphertext_len = gcm_encrypt(plain, insize, key, iv, sizeof(iv), cipher, tag);
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fwrite(iv, sizeof(iv), 1, o);
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fwrite(tag, sizeof(tag), 1, o);
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fwrite(cipher, ciphertext_len, 1, o);
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fclose(o);
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- }
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- else {
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+ } else {
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fseek(f, 0, SEEK_END);
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- insize = ftell(f)-sizeof(iv)-sizeof(tag);
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+ insize = ftell(f) - sizeof(iv) - sizeof(tag);
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fseek(f, 0, SEEK_SET);
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cipher = malloc(insize);
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plain = malloc(insize);
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@@ -96,27 +82,24 @@ int main (int argc, char** argv)
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fread(tag, sizeof(tag), 1, f);
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fread(cipher, insize, 1, f);
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fclose(f);
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-
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- decryptedtext_len = gcm_decrypt(cipher, insize,
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- tag,
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- key, iv, sizeof(iv),
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- plain);
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- if(decryptedtext_len < 0) {
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+
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+ decryptedtext_len = gcm_decrypt(cipher, insize, tag, key, iv, sizeof(iv), plain);
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+ if (decryptedtext_len < 0) {
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printf("decrypt failed\n");
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fclose(o);
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remove(argv[4]);
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- }
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- else if(memcmp(plain, signature, 4)) {
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+ } else if (memcmp(plain, signature, 4)) {
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printf("signature mismatch, expected ");
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- for(int i = 0; i < sizeof(signature); i++) printf("%02x ", signature[i]);
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+ for (int i = 0; i < sizeof(signature); i++)
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+ printf("%02x ", signature[i]);
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printf("but got ");
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- for(int i = 0; i < sizeof(signature); i++) printf("%02x ", plain[i]);
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+ for (int i = 0; i < sizeof(signature); i++)
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+ printf("%02x ", plain[i]);
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printf("\n");
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fclose(o);
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remove(argv[4]);
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- }
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- else {
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- fwrite(plain+4, decryptedtext_len-4, 1, o);
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+ } else {
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+ fwrite(plain + 4, decryptedtext_len - 4, 1, o);
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fclose(o);
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}
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}
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@@ -126,126 +109,112 @@ int main (int argc, char** argv)
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return 0;
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}
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-
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-void handleErrors(void)
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-{
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- ERR_print_errors_fp(stderr);
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- abort();
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+void handleErrors(void) {
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+ ERR_print_errors_fp(stderr);
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+ abort();
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}
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+int gcm_encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key, unsigned char *iv, int iv_len, unsigned char *ciphertext, unsigned char *tag) {
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+ EVP_CIPHER_CTX *ctx;
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-int gcm_encrypt(unsigned char *plaintext, int plaintext_len,
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- unsigned char *key,
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- unsigned char *iv, int iv_len,
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- unsigned char *ciphertext,
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- unsigned char *tag)
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-{
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- EVP_CIPHER_CTX *ctx;
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+ int len;
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- int len;
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+ int ciphertext_len;
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- int ciphertext_len;
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+ /* Create and initialise the context */
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+ if (!(ctx = EVP_CIPHER_CTX_new()))
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+ handleErrors();
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+ /* Initialise the encryption operation. */
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+ if (1 != EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))
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+ handleErrors();
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- /* Create and initialise the context */
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- if(!(ctx = EVP_CIPHER_CTX_new()))
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- handleErrors();
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+ /*
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+ * Set IV length if default 12 bytes (96 bits) is not appropriate
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+ */
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+ if (1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, iv_len, NULL))
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+ handleErrors();
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- /* Initialise the encryption operation. */
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- if(1 != EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))
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- handleErrors();
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+ /* Initialise key and IV */
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+ if (1 != EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv))
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+ handleErrors();
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- /*
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- * Set IV length if default 12 bytes (96 bits) is not appropriate
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- */
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- if(1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, iv_len, NULL))
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- handleErrors();
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+ /*
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+ * Provide the message to be encrypted, and obtain the encrypted output.
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+ * EVP_EncryptUpdate can be called multiple times if necessary
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+ */
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+ if (1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len))
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+ handleErrors();
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+ ciphertext_len = len;
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- /* Initialise key and IV */
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- if(1 != EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv))
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- handleErrors();
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+ /*
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+ * Finalise the encryption. Normally ciphertext bytes may be written at
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+ * this stage, but this does not occur in GCM mode
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+ */
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+ if (1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len))
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+ handleErrors();
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+ ciphertext_len += len;
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- /*
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- * Provide the message to be encrypted, and obtain the encrypted output.
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- * EVP_EncryptUpdate can be called multiple times if necessary
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- */
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- if(1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len))
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- handleErrors();
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- ciphertext_len = len;
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+ /* Get the tag */
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+ if (1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, tag))
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+ handleErrors();
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- /*
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- * Finalise the encryption. Normally ciphertext bytes may be written at
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- * this stage, but this does not occur in GCM mode
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- */
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- if(1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len))
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- handleErrors();
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- ciphertext_len += len;
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+ /* Clean up */
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+ EVP_CIPHER_CTX_free(ctx);
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- /* Get the tag */
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- if(1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, tag))
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- handleErrors();
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-
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- /* Clean up */
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- EVP_CIPHER_CTX_free(ctx);
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-
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- return ciphertext_len;
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+ return ciphertext_len;
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}
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-
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-int gcm_decrypt(unsigned char *ciphertext, int ciphertext_len,
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- unsigned char *tag,
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- unsigned char *key,
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- unsigned char *iv, int iv_len,
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- unsigned char *plaintext)
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-{
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- EVP_CIPHER_CTX *ctx;
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- int len;
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- int plaintext_len;
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- int ret;
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-
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- /* Create and initialise the context */
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- if(!(ctx = EVP_CIPHER_CTX_new()))
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- handleErrors();
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-
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- /* Initialise the decryption operation. */
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- if(!EVP_DecryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))
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- handleErrors();
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-
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- /* Set IV length. Not necessary if this is 12 bytes (96 bits) */
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- if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, iv_len, NULL))
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- handleErrors();
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-
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- /* Initialise key and IV */
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- if(!EVP_DecryptInit_ex(ctx, NULL, NULL, key, iv))
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- handleErrors();
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-
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- /*
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- * Provide the message to be decrypted, and obtain the plaintext output.
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- * EVP_DecryptUpdate can be called multiple times if necessary
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- */
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- if(!EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len))
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- handleErrors();
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- plaintext_len = len;
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-
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- /* Set expected tag value. Works in OpenSSL 1.0.1d and later */
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- if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16, tag))
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- handleErrors();
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-
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- /*
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- * Finalise the decryption. A positive return value indicates success,
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- * anything else is a failure - the plaintext is not trustworthy.
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- */
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- ret = EVP_DecryptFinal_ex(ctx, plaintext + len, &len);
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-
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- /* Clean up */
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- EVP_CIPHER_CTX_free(ctx);
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-
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- if(ret > 0) {
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- /* Success */
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- plaintext_len += len;
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- return plaintext_len;
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- } else {
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- /* Verify failed */
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- return -1;
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- }
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+int gcm_decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *tag, unsigned char *key, unsigned char *iv, int iv_len,
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+ unsigned char *plaintext) {
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+ EVP_CIPHER_CTX *ctx;
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+ int len;
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+ int plaintext_len;
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+ int ret;
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+
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+ /* Create and initialise the context */
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+ if (!(ctx = EVP_CIPHER_CTX_new()))
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+ handleErrors();
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+
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+ /* Initialise the decryption operation. */
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+ if (!EVP_DecryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))
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+ handleErrors();
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+
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+ /* Set IV length. Not necessary if this is 12 bytes (96 bits) */
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+ if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, iv_len, NULL))
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+ handleErrors();
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+
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+ /* Initialise key and IV */
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+ if (!EVP_DecryptInit_ex(ctx, NULL, NULL, key, iv))
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+ handleErrors();
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+
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+ /*
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+ * Provide the message to be decrypted, and obtain the plaintext output.
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+ * EVP_DecryptUpdate can be called multiple times if necessary
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+ */
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+ if (!EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len))
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+ handleErrors();
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+ plaintext_len = len;
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+
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+ /* Set expected tag value. Works in OpenSSL 1.0.1d and later */
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+ if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16, tag))
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+ handleErrors();
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+
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+ /*
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+ * Finalise the decryption. A positive return value indicates success,
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+ * anything else is a failure - the plaintext is not trustworthy.
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+ */
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+ ret = EVP_DecryptFinal_ex(ctx, plaintext + len, &len);
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+
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+ /* Clean up */
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+ EVP_CIPHER_CTX_free(ctx);
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+
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+ if (ret > 0) {
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+ /* Success */
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+ plaintext_len += len;
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+ return plaintext_len;
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+ } else {
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+ /* Verify failed */
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+ return -1;
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+ }
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}
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Jonas Pflanzer