Issue 7 envvar

.gitignore

@@ -1,7 +1,10 @@
 kr
+*.bak
+*.exe
 *.o
 *.profraw
 *.profdata
+*~
 tmp
 test.out
 cov

README.md

@@ -8,7 +8,7 @@ AEAD interface of Monocypher to encrypt/decrypt files using
 `kr` offers two modes of operation:
 
 - Keyfile-based: a private key is stored on the user's machine and is used to
-  encrypt and decrypt files. 
+  encrypt and decrypt files.
 
 - Passphrase-based: an encryption/decryption key is generated, on the fly, using
   Argon2i (with a random salt).
@@ -65,7 +65,7 @@ _same_ pair (passphrase, userID) on every invocation. For example:
 ```
 $ kr -guUSERID -p"PASS PHRASE" ~/key.sec
 ```
- Or 
+ Or
 
 ```
 $ kr -g --uid=USERID --passphrase="PASS PHRASE" ~/key.sec
@@ -133,7 +133,7 @@ $ kr --decrypt --keyfile ~/.key.sec inputfile outputfile
 
 Instead of using key files, we can use passphrases as follows:
 
-##### Encryption `-e -p`
+##### Encryption `-e -p` / `-e -E`
 
 ```
 $ kr -e -p"PASS PHRASE" inputfile outputfile
@@ -149,7 +149,15 @@ We can also use the long options:
 $ kr --encrypt --passphrase="PASS PHRASE" inputfile outputfile
 ```
 
-##### Decryption `-d -p`
+Alternatively use `-E` / `--envvar` to pick up password from an operating
+system environment variable:
+
+```
+$ env PASSPHRASE="PASS PHRASE" kr --encrypt       -E=PASSPHRASE inputfile outputfile
+$ env PASSPHRASE="PASS PHRASE" kr --encrypt --envvar=PASSPHRASE inputfile outputfile
+```
+
+##### Decryption `-d -p` / `-d -E`
 
 ```
 $ kr -d -p"PASS PHRASE" inputfile outputfile
@@ -165,6 +173,15 @@ Or using the long options:
 $ kr --decrypt --passphrase="PASS PHRASE" inputfile outputfile
 ```
 
+Alternatively use `-E` / `--envvar` to pick up password from an operating
+system environment variable:
+
+```
+$ env PASSPHRASE="PASS PHRASE" kr --decrypt       -E=PASSPHRASE inputfile outputfile
+$ env PASSPHRASE="PASS PHRASE" kr --decrypt --envvar=PASSPHRASE inputfile outputfile
+```
+
+
 ### Support for streams
 
 `kr` is able to process streams as well. For instance, these examples with
@@ -173,7 +190,7 @@ pipes:
 ```
 $ echo 'Hello, world!' | kr -epPASS | kr -dpPASS
 ```
-or with keyfiles 
+or with keyfiles
 
 ```
 $ echo 'Hello, world!' | kr -ek ~/.key.sec | kr -dk ~/.key.sec

kr.1

@@ -63,6 +63,10 @@ Use the passphrase \fB[pass]\fR for for operations. If the passphrase is not
 specified, prompt the user to type it (Twice for encryption and keyfile
 generation. Once for decryption).
 .TP
+\fB\-E\fR, \fB\-\-envvar\fR \fI[pass]\fP
+Use the passphrase contained in the operating system environment variable
+\fB[pass]\fR for operations.
+.TP
 \fB\-u\fR, \fB\-\-uid\fR \fI<uid>\fP
 Use \fB<uid>\fR for key generation (\fB\-g\fR). Use \fB<uid>\fR for
 reproductible key generation (\-g). When used, the program will ask for a

src/kr.c

@@ -50,7 +50,7 @@
 // backward compatibility issues.
 
 #define PROG "kr"
-#define PROG_VERSION "0.2" // The program's version.
+#define PROG_VERSION "0.3" // The program's version.
 #define FILE_VERSION 0 // Encrypted files format version.
 #define KEYFILE_VERSION 0 // keyfiles format version.
 #define KEY_SIZE 32
@@ -221,6 +221,10 @@ static const char *usage[] = {
 "                             user to type it (Twice for encryption and",
 "                             keyfile generation. Once for decryption).",
 "",
+"   -E | --envvar=[pass]      Use the passphrase contained in the operating",
+"                             system environment variable [pass] for operations.",
+"                             TODO doc priority versus passphrase",
+"",
 "   -u | --uid=<uid>          Use <uid> for key generation (-g).",
 "                             When used, the program will ask for a passphrase",
 "                             in order to generate a deterministic key, i.e., ",
@@ -264,7 +268,7 @@ static enum error encrypt(FILE *in, FILE *out, const uint8_t key[KEY_SIZE],
         uint8_t *ad = (eof) ? END_TAG : NULL; // if last chunk, tag it.
         size_t adlen = (eof) ? 4 : 0;
 
-        // Arguments order: 
+        // Arguments order:
         // ctx, cipher_text, mac, ad, ad_size, plain_text, text_size.
         // The mac comes after the encrypted chunk, thus:
         // - the mac is located at buf_out + len, and
@@ -318,7 +322,7 @@ static enum error decrypt(FILE *in, FILE *out, const uint8_t key[KEY_SIZE],
         uint8_t *ad = (eof) ? END_TAG : 0; // last chunk should've been tagged.
         size_t adlen = (eof) ? 4 : 0;
 
-        // Arguments order: 
+        // Arguments order:
         // ctx, plain_text, mac, ad, ad_size, cipher_text, text_size.
         // The read 'len' bytes from 'in' already includes the mac, thus:
         // - the mac is located at buf_in + len - MAC_SIZE, and
@@ -343,7 +347,7 @@ static enum error decrypt(FILE *in, FILE *out, const uint8_t key[KEY_SIZE],
 }
 
 // Generate a key_size bytes key from a passphrase and a salt (random)
-// using Argon2i (with configuration in 'config', inputs (password and salt) 
+// using Argon2i (with configuration in 'config', inputs (password and salt)
 // data in 'inputs'), and extras (key and ad). This needs a work area that
 // has to be allocated. If this allocation fails, securely wipe inputs and
 // extras and exit.
@@ -448,7 +452,7 @@ static enum error read_keyfile(FILE *kf, uint8_t key[KEY_SIZE])
     // Inspect the protection-version byte, and get its MSB.
     int protected = *version >> 7;
     if (!protected) {
-        // Key is not protected. Copy the last KEY_SIZE bytes. 
+        // Key is not protected. Copy the last KEY_SIZE bytes.
         memcpy(key, fkey, KEY_SIZE);
     } else {
         // Ask the user to provide a passphrase to decrypt the key.
@@ -581,6 +585,7 @@ int main(int argc, char *argv[])
         {"decrypt", 'd', OPTPARSE_NONE},
         {"keyfile", 'k', OPTPARSE_REQUIRED},
         {"passphrase", 'p', OPTPARSE_OPTIONAL},
+        {"envvar", 'E', OPTPARSE_OPTIONAL},
         {"uid", 'u', OPTPARSE_REQUIRED},
         {"keyedit", 'm', OPTPARSE_REQUIRED},
         {"help", 'h', OPTPARSE_NONE},
@@ -602,6 +607,7 @@ int main(int argc, char *argv[])
     char *keyfile = NULL;
     char *infile = NULL;
     char *outfile = NULL;
+    char *passphrase_env_ptr = NULL;
     FILE *kf = NULL;
     FILE *in = NULL;
     FILE *out = NULL;
@@ -643,6 +649,20 @@ int main(int argc, char *argv[])
                     memcpy(passphrase, options.optarg, pwlen);
                 }
                 break;
+            case 'E':
+                use_passphrase = 1;
+                if (options.optarg) {
+                    passphrase_env_ptr = getenv(options.optarg);
+                    if (passphrase_env_ptr == NULL) {
+                        BAIL(ERR_PASS_READ_FAIL);
+                    }
+                    pwlen = strlen(passphrase_env_ptr) + 1;
+                    if (pwlen > MAXPASS) {
+                        BAIL(ERR_PASS_TOO_BIG);
+                    }
+                    memcpy(passphrase, passphrase_env_ptr, pwlen);
+                }
+                break;
             case 'u':
                 use_passphrase = 1;
                 if (options.optarg) {
@@ -722,7 +742,7 @@ int main(int argc, char *argv[])
                 BAIL(ERR_NO_RANDOM);
             }
             // If the key to be generated depends on a uid and a passphrase,
-            // generate a deterministic one with the same value when given 
+            // generate a deterministic one with the same value when given
             // the same uid and passphrase.
             if (use_passphrase) {
                 // Hash the uid to use it as a salt for key derivation.
@@ -830,7 +850,7 @@ int main(int argc, char *argv[])
     }
 
 // Clean everything and exit.
-bail: 
+bail:
     // Safely wipe sensitive info.
     crypto_wipe(key, KEY_SIZE);
     crypto_wipe(passphrase, MAXPASS);

tests/tests.c

@@ -266,7 +266,7 @@ static int p_encrypt_decrypt(void)
             fsize = 0;
         }
         if (DEBUG) {
-            printf(YELLOW "\tFile size:" BLUE " %lu bytes\n", fsize);
+            printf(YELLOW "\tFile size:" BLUE " %" PRIu64 " bytes\n", fsize);
         }
         fillrand(data, fsize);
         fillrand(key, KEY_SIZE);
@@ -428,7 +428,7 @@ int p_password_enc_dec(void)
         }
 
         if (DEBUG) {
-            printf(YELLOW "\tFile size:" BLUE " %lu bytes\n", fsize);
+            printf(YELLOW "\tFile size:" BLUE " %" PRIu64 " bytes\n", fsize);
         }
 
         fillrand(data, fsize);