FiSHLiM: Support for CBC mode + more commands (#2347)

plugins/fishlim/fish.c

@@ -1,6 +1,7 @@
 /*
 
   Copyright (c) 2010 Samuel Lidén Borell <samuel@kodafritt.se>
+  Copyright (c) 2019 <bakasura@protonmail.ch>
 
   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
@@ -27,15 +28,19 @@
 #define DEPRECATED_IN_MAC_OS_X_VERSION_10_7_AND_LATER
 #endif
 
+#include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <openssl/evp.h>
 #include <openssl/blowfish.h>
+#include <openssl/rand.h>
 
 #include "keystore.h"
 #include "fish.h"
 
 #define IB 64
-static const char fish_base64[64] = "./0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+static const char fish_base64[] = "./0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+static const char base64_chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
 static const signed char fish_unbase64[256] = {
     IB,IB,IB,IB,IB,IB,IB,IB,  IB,IB,IB,IB,IB,IB,IB,IB,
     IB,IB,IB,IB,IB,IB,IB,IB,  IB,IB,IB,IB,IB,IB,IB,IB,
@@ -53,6 +58,12 @@ static const signed char fish_unbase64[256] = {
     27,28,29,30,31,32,33,34,  35,36,37,IB,IB,IB,IB,IB,
 };
 
+/**
+ * Convert Int to 4 Bytes (Big-endian)
+ * 
+ * @param int   source
+ * @param char* dest
+ */
 #define GET_BYTES(dest, source) do { \
     *((dest)++) = ((source) >> 24) & 0xFF; \
     *((dest)++) = ((source) >> 16) & 0xFF; \
@@ -60,135 +71,387 @@ static const signed char fish_unbase64[256] = {
     *((dest)++) = (source) & 0xFF; \
 } while (0);
 
+/**
+ * Convert 4 Bytes to Int (Big-endian)
+ * 
+ * @param char* source
+ * @param int   dest
+ */
+#define GET_LONG(dest, source) do { \
+    dest = ((uint8_t)*((source)++) << 24); \
+    dest |= ((uint8_t)*((source)++) << 16); \
+    dest |= ((uint8_t)*((source)++) << 8); \
+    dest |= (uint8_t)*((source)++); \
+} while (0);
 
-char *fish_encrypt(const char *key, size_t keylen, const char *message) {
-    BF_KEY bfkey;
-    size_t messagelen;
-    size_t i;
-    int j;
-    char *encrypted;
-    char *end;
-    unsigned char bit;
-    unsigned char word;
-    unsigned char d;
-    BF_set_key(&bfkey, keylen, (const unsigned char*)key);
-    
-    messagelen = strlen(message);
-    if (messagelen == 0) return NULL;
-    encrypted = g_malloc(((messagelen - 1) / 8) * 12 + 12 + 1); /* each 8-byte block becomes 12 bytes */
-    end = encrypted;
-     
-    while (*message) {
-        /* Read 8 bytes (a Blowfish block) */
-        BF_LONG binary[2] = { 0, 0 };
-        unsigned char c;
-        for (i = 0; i < 8; i++) {
-            c = message[i];
-            binary[i >> 2] |= c << 8*(3 - (i&3));
-            if (c == '\0') break;
+
+/**
+ * Encode ECB FiSH Base64
+ *
+ * @param [in] message      Bytes to encode
+ * @param [in] message_len  Size of bytes to encode
+ * @return Array of char with encoded string
+ */
+char *fish_base64_encode(const char *message, size_t message_len) {
+    BF_LONG left = 0, right = 0;
+    int i, j;
+    char *encoded = NULL;
+    char *end = NULL;
+    char *msg = NULL;
+
+    if (message_len == 0)
+        return NULL;
+
+    /* Each 8-byte block becomes 12 bytes (fish base64 format) and add 1 byte for \0 */
+    encoded = g_malloc(((message_len - 1) / 8) * 12 + 12 + 1);
+    end = encoded;
+
+    /* Iterate over each 8-byte block (Blowfish block size) */
+    for (j = 0; j < message_len; j += 8) {
+        msg = (char *) message;
+
+        /* Set left and right longs */
+        GET_LONG(left, msg);
+        GET_LONG(right, msg);
+
+        for (i = 0; i < 6; ++i) {
+            *end++ = fish_base64[right & 0x3fu];
+            right = (right >> 6u);
         }
+
+        for (i = 0; i < 6; ++i) {
+            *end++ = fish_base64[left & 0x3fu];
+            left = (left >> 6u);
+        }
+
+        /* The previous for'd ensure fill all bytes of encoded, we don't need will with zeros */
         message += 8;
-        
-        /* Encrypt block */
-        BF_encrypt(binary, &bfkey);
-        
-        /* Emit FiSH-BASE64 */
-        bit = 0;
-        word = 1;
-        for (j = 0; j < 12; j++) {
-            d = fish_base64[(binary[word] >> bit) & 63];
-            *(end++) = d;
-            bit += 6;
-            if (j == 5) {
-                bit = 0;
-                word = 0;
-            }
-        }
-        
-        /* Stop if a null terminator was found */
-        if (c == '\0') break;
     }
+
     *end = '\0';
-    return encrypted;
+    return encoded;
 }
 
+/**
+ * Decode ECB FiSH Base64
+ *
+ * @param [in]  message    Base64 encoded string
+ * @param [out] final_len  Real length of message
+ * @return Array of char with decoded message
+ */
+char *fish_base64_decode(const char *message, size_t *final_len) {
+    BF_LONG left, right;
+    int i;
+    char *bytes = NULL;
+    char *msg = NULL;
+    char *byt = NULL;
+    size_t message_len;
 
-char *fish_decrypt(const char *key, size_t keylen, const char *data) {
-    BF_KEY bfkey;
-    size_t i;
-    char *decrypted;
-    char *end;
-    unsigned char bit;
-    unsigned char word;
-    unsigned char d;
-    BF_set_key(&bfkey, keylen, (const unsigned char*)key);
-    
-    decrypted = g_malloc(strlen(data) + 1);
-    end = decrypted;
-    
-    while (*data) {
-        /* Convert from FiSH-BASE64 */
-        BF_LONG binary[2] = { 0, 0 };
-        bit = 0;
-        word = 1;
-        for (i = 0; i < 12; i++) {
-            d = fish_unbase64[(const unsigned char)*(data++)];
-            if (d == IB) goto decrypt_end;
-            binary[word] |= (unsigned long)d << bit;
-            bit += 6;
-            if (i == 5) {
-                bit = 0;
-                word = 0;
-            }
-        }
-        
-        /* Decrypt block */
-        BF_decrypt(binary, &bfkey);
-        
-        /* Copy to buffer */
-        GET_BYTES(end, binary[0]);
-        GET_BYTES(end, binary[1]);
+    message_len = strlen(message);
+
+    /* Ensure blocks of 12 bytes each one and valid characters */
+    if (message_len == 0 || message_len % 12 != 0 || strspn(message, fish_base64) != message_len)
+        return NULL;
+
+    /* Each 12 bytes becomes 8-byte block and add 1 byte for \0 */
+    *final_len = ((message_len - 1) / 12) * 8 + 8 + 1;
+    (*final_len)--; /* We support binary data */
+    bytes = (char *) g_malloc0(*final_len);
+    byt = bytes;
+
+    msg = (char *) message;
+
+    while (*msg) {
+        right = 0;
+        left = 0;
+        for (i = 0; i < 6; i++) right |= (uint8_t) fish_unbase64[*msg++] << (i * 6u);
+        for (i = 0; i < 6; i++) left |= (uint8_t) fish_unbase64[*msg++] << (i * 6u);
+        GET_BYTES(byt, left);
+        GET_BYTES(byt, right);
     }
-    
-  decrypt_end:
-    *end = '\0';
-    return decrypted;
+
+    return bytes;
+}
+
+/**
+ * Encrypt or decrypt data with Blowfish cipher, support binary data.
+ *
+ * Good documentation for EVP:
+ *
+ * - https://wiki.openssl.org/index.php/EVP_Symmetric_Encryption_and_Decryption
+ *
+ * - https://stackoverflow.com/questions/5727646/what-is-the-length-parameter-of-aes-evp-decrypt
+ *
+ * - https://stackoverflow.com/questions/26345175/correct-way-to-free-allocate-the-context-in-the-openssl
+ *
+ * - https://stackoverflow.com/questions/29874150/working-with-evp-and-openssl-coding-in-c
+ *
+ * @param [in] plaintext        Bytes to encrypt or decrypt
+ * @param [in] plaintext_len    Size of plaintext
+ * @param [in] key              Bytes of key
+ * @param [in] keylen           Size of key
+ * @param [in] encode           1 or encrypt 0 for decrypt
+ * @param [in] mode             EVP_CIPH_ECB_MODE or EVP_CIPH_CBC_MODE
+ * @param [out] ciphertext_len  The bytes written
+ * @return Array of char with data encrypted or decrypted
+ */
+char *fish_cipher(const char *plaintext, size_t plaintext_len, const char *key, size_t keylen, int encode, int mode, size_t *ciphertext_len) {
+    EVP_CIPHER_CTX *ctx;
+    EVP_CIPHER *cipher = NULL;
+    int bytes_written = 0;
+    unsigned char *ciphertext = NULL;
+    unsigned char *iv_ciphertext = NULL;
+    unsigned char *iv = NULL;
+    size_t block_size = 0;
+
+    *ciphertext_len = 0;
+
+    if (plaintext_len == 0 || keylen == 0 || encode < 0 || encode > 1)
+        return NULL;
+
+    block_size = plaintext_len;
+
+    if (mode == EVP_CIPH_CBC_MODE) {
+        if (encode == 1) {
+            iv = (unsigned char *) g_malloc0(8);
+            RAND_bytes(iv, 8);
+        } else {
+            if (plaintext_len <= 8) /* IV + DATA */
+                return NULL;
+
+            iv = (unsigned char *) plaintext;
+            block_size -= 8;
+            plaintext += 8;
+            plaintext_len -= 8;
+        }
+
+        cipher = (EVP_CIPHER *) EVP_bf_cbc();
+    } else if (mode == EVP_CIPH_ECB_MODE) {
+        cipher = (EVP_CIPHER *) EVP_bf_ecb();
+    }
+
+    /* Zero Padding */
+    if (block_size % 8 != 0) {
+        block_size = block_size + 8 - (block_size % 8);
+    }
+
+    ciphertext = (unsigned char *) g_malloc0(block_size);
+    memcpy(ciphertext, plaintext, plaintext_len);
+
+    /* Create and initialise the context */
+    if (!(ctx = EVP_CIPHER_CTX_new()))
+        return NULL;
+
+    /* Initialise the cipher operation only with mode */
+    if (!EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, encode))
+        return NULL;
+
+    /* Set custom key length */
+    if (!EVP_CIPHER_CTX_set_key_length(ctx, keylen))
+        return NULL;
+
+    /* Finish the initiation the cipher operation */
+    if (1 != EVP_CipherInit_ex(ctx, NULL, NULL, (const unsigned char *) key, iv, encode))
+        return NULL;
+
+    /* We will manage this */
+    EVP_CIPHER_CTX_set_padding(ctx, 0);
+
+    /* Do cipher operation */
+    if (1 != EVP_CipherUpdate(ctx, ciphertext, &bytes_written, ciphertext, block_size))
+        return NULL;
+
+    *ciphertext_len = bytes_written;
+
+    /* Finalise the cipher. Further ciphertext bytes may be written at this stage */
+    if (1 != EVP_CipherFinal_ex(ctx, ciphertext + bytes_written, &bytes_written))
+        return NULL;
+
+    *ciphertext_len += bytes_written;
+
+    /* Clean up */
+    EVP_CIPHER_CTX_free(ctx);
+
+
+    if (mode == EVP_CIPH_CBC_MODE && encode == 1) {
+        /* Join IV + DATA */
+        iv_ciphertext = g_malloc0(8 + *ciphertext_len);
+
+        memcpy(iv_ciphertext, iv, 8);
+        memcpy(&iv_ciphertext[8], ciphertext, *ciphertext_len);
+        *ciphertext_len += 8;
+
+        g_free(ciphertext);
+        g_free(iv);
+
+        return (char *) iv_ciphertext;
+    } else {
+        return (char *) ciphertext;
+    }
+}
+
+/**
+ * Return a fish or standard Base64 encoded string with data encrypted
+ * is binary safe
+ * 
+ * @param [in] key          Bytes of key
+ * @param [in] keylen       Size of key
+ * @param [in] message      Bytes to encrypt
+ * @param [in] message_len  Size of message
+ * @param [in] mode         Chiper mode
+ * @return Array of char with data encrypted
+ */
+char *fish_encrypt(const char *key, size_t keylen, const char *message, size_t message_len, enum fish_mode mode) {
+    size_t ciphertext_len = 0;
+    char *ciphertext = NULL;
+    char *b64 = NULL;
+
+    if (keylen == 0 || message_len == 0)
+        return NULL;
+
+    ciphertext = fish_cipher(message, message_len, key, keylen, 1, mode, &ciphertext_len);
+
+    if (ciphertext == NULL || ciphertext_len == 0)
+        return NULL;
+
+    switch (mode) {
+        case FISH_CBC_MODE:
+            b64 = g_base64_encode((const unsigned char *) ciphertext, ciphertext_len);
+            break;
+
+        case FISH_ECB_MODE:
+            b64 = fish_base64_encode((const char *) ciphertext, ciphertext_len);
+    }
+
+    g_free(ciphertext);
+
+    if (b64 == NULL)
+        return NULL;
+
+    return b64;
+}
+
+/**
+ * Return an array of bytes with data decrypted
+ * is binary safe
+ * 
+ * @param [in] key         Bytes of key
+ * @param [in] keylen      Size of key
+ * @param [in] data        Fish or standard Base64 encoded string
+ * @param [in] mode        Chiper mode
+ * @param [out] final_len  Length of returned array
+ * @return Array of char with data decrypted
+ */
+char *fish_decrypt(const char *key, size_t keylen, const char *data, enum fish_mode mode, size_t *final_len) {
+    size_t ciphertext_len = 0;
+    char *ciphertext = NULL;
+    char *plaintext = NULL;
+
+    *final_len = 0;
+
+    if (keylen == 0 || strlen(data) == 0)
+        return NULL;
+
+    switch (mode) {
+        case FISH_CBC_MODE:
+            if (strspn(data, base64_chars) != strlen(data))
+                return NULL;
+            ciphertext = (char *) g_base64_decode(data, &ciphertext_len);
+            break;
+
+        case FISH_ECB_MODE:
+            ciphertext = fish_base64_decode(data, &ciphertext_len);
+    }
+
+    if (ciphertext == NULL || ciphertext_len == 0)
+        return NULL;
+
+    plaintext = fish_cipher(ciphertext, ciphertext_len, key, keylen, 0, mode, final_len);
+    g_free(ciphertext);
+
+    if (*final_len == 0)
+        return NULL;
+
+    return plaintext;
+}
+
+/**
+ * Similar to fish_decrypt, but pad with zeros any after the first zero in the decrypted data
+ * 
+ * @param [in] key         Bytes of key
+ * @param [in] keylen      Size of key
+ * @param [in] data        Fish or standard Base64 encoded string
+ * @param [in] mode        Chiper mode
+ * @return Array of char with data decrypted
+ */
+char *fish_decrypt_str(const char *key, size_t keylen, const char *data, enum fish_mode mode) {
+    char *decrypted = NULL;
+    char *plaintext_str = NULL;
+    size_t decrypted_len = 0;
+
+    decrypted = fish_decrypt(key, strlen(key), data, mode, &decrypted_len);
+
+    if (decrypted == NULL || decrypted_len == 0)
+        return NULL;
+
+    plaintext_str = g_strndup(decrypted, decrypted_len);
+    g_free(decrypted);
+
+    return plaintext_str;
 }
 
 /**
  * Encrypts a message (see fish_decrypt). The key is searched for in the
  * key store.
  */
-char *fish_encrypt_for_nick(const char *nick, const char *data) {
+char *fish_encrypt_for_nick(const char *nick, const char *data, enum fish_mode *omode) {
     char *key;
-    char *encrypted;
+    char *encrypted, *encrypted_cbc = NULL;
+    enum fish_mode mode;
 
     /* Look for key */
-    key = keystore_get_key(nick);
+    key = keystore_get_key(nick, &mode);
     if (!key) return NULL;
-    
+
+    *omode = mode;
+
     /* Encrypt */
-    encrypted = fish_encrypt(key, strlen(key), data);
-    
+    encrypted = fish_encrypt(key, strlen(key), data, strlen(data), mode);
+
     g_free(key);
-    return encrypted;
+
+    if (encrypted == NULL || mode == FISH_ECB_MODE)
+        return encrypted;
+
+    /* Add '*' for CBC */
+    encrypted_cbc = g_strdup_printf("*%s",encrypted);
+    g_free(encrypted);
+
+    return encrypted_cbc;
 }
 
 /**
  * Decrypts a message (see fish_decrypt). The key is searched for in the
  * key store.
  */
-char *fish_decrypt_from_nick(const char *nick, const char *data) {
+char *fish_decrypt_from_nick(const char *nick, const char *data, enum fish_mode *omode) {
     char *key;
     char *decrypted;
+    enum fish_mode mode;
+
     /* Look for key */
-    key = keystore_get_key(nick);
+    key = keystore_get_key(nick, &mode);
     if (!key) return NULL;
-    
+
+    *omode = mode;
+
+    if (mode == FISH_CBC_MODE)
+        ++data;
+
     /* Decrypt */
-    decrypted = fish_decrypt(key, strlen(key), data);
-    
+    decrypted = fish_decrypt_str(key, strlen(key), data, mode);
     g_free(key);
+
     return decrypted;
 }