1 files changed, 377 insertions, 0 deletions

diff --git a/libsylph/ssl.c b/libsylph/ssl.c
index 8413925..5a76b8b 100644
--- a/libsylph/ssl.c
+++ b/libsylph/ssl.c
@@ -32,6 +32,11 @@
 #include "ssl.h"
 #include "ssl_hostname_validation.h"
 
+#define SALT_SIZE 16
+#define CIPHER EVP_aes_256_cfb()
+#define KEY_HASH EVP_sha256()
+#define DIGEST_HASH EVP_sha256()
+
 static SSL_CTX *ssl_ctx_SSLv23 = NULL;
 static SSL_CTX *ssl_ctx_TLSv1 = NULL;
 
@@ -402,4 +407,376 @@ void ssl_set_verify_func(SSLVerifyFunc func)
         verify_ui_func = func;
 }
 
+/* master password related functions */
+static gint secure_derive_key(guchar *key,
+                              gint length_key,
+                              const gchar *passphrase,
+                              const guchar *salt) {
+
+    guint length_buffer, length_hash;
+    guchar *buffer, *ptr_hash;
+
+    EVP_MD_CTX *mdctx;
+
+    OPENSSL_cleanse(key, length_key);
+
+    length_buffer = SALT_SIZE + strlen(passphrase);
+    buffer = OPENSSL_malloc(length_buffer);
+    OPENSSL_cleanse(buffer, length_buffer);
+
+        memcpy(buffer, salt, SALT_SIZE);
+        memcpy(buffer + SALT_SIZE, passphrase, strlen(passphrase));
+
+    mdctx = EVP_MD_CTX_create();
+    EVP_DigestInit_ex(mdctx, KEY_HASH, NULL);
+    EVP_DigestUpdate(mdctx, buffer, length_buffer);
+    OPENSSL_cleanse(buffer, length_buffer);
+
+    ptr_hash = OPENSSL_malloc(EVP_MD_size(KEY_HASH));
+    EVP_DigestFinal_ex(mdctx, ptr_hash, &length_hash);
+
+    memcpy(key,
+           ptr_hash,
+           (length_hash > length_key) ? length_key : length_hash);
+
+    OPENSSL_cleanse(ptr_hash, length_hash);
+    OPENSSL_free(ptr_hash);
+    OPENSSL_free(buffer);
+    EVP_MD_CTX_destroy(mdctx);
+
+    return RC_OK;
+
+}
+
+
+gint encrypt_data(gchar **encrypted,
+                  gint *length_encrypted,
+                  const gchar *data,
+                  const gchar *passphrase,
+                  gint length_data,
+                  guint min_data_length,
+                  gboolean rnd_salt) {
+
+    gint crypt_buffer_cnt, rc;
+    guint key_size, length_hash;
+    guint length_cleartext, length_ciphertext, length_total;
+    guchar salt[SALT_SIZE];
+    guchar *ciphertext_buffer, *total_buffer;
+    /* sensitive buffers and counters */
+    guint length_data_payload, length_padding;
+    gchar str_data_size[3];
+    guchar *data_payload_buffer, *hash_buffer, *padding_buffer, *key;
+    guchar *cleartext_buffer;
+
+    EVP_CIPHER_CTX *ctx;
+    EVP_MD_CTX *mdctx;
+
+    rc = RC_ERROR;
+
+    if (length_data < 1) {
+        return -1;
+    }
+    if (rnd_salt) {
+        if (RAND_bytes(salt, SALT_SIZE) != 1) {
+            debug_print("Random problems...\n");
+            goto cleanup;
+        }
+    } else {
+        strncpy((gchar *)salt, "FOR TESTING ONLY", SALT_SIZE);
+    }
+
+    key_size = EVP_CIPHER_key_length(CIPHER);
+    key = OPENSSL_malloc(key_size);
+    OPENSSL_cleanse(key, key_size);
+    if (secure_derive_key(key,
+                      key_size,
+                      passphrase,
+                          salt) != RC_OK) {
+        OPENSSL_cleanse(key, key_size);
+        debug_print("Could not generate secure key\n");
+        goto cleanup;
+    }
+
+    /* prepare the data-buffer */
+    length_padding = 0;
+    if (length_data < min_data_length) {
+        g_snprintf(str_data_size, 3, "%02d", length_data);
+        length_padding = min_data_length - length_data;
+        padding_buffer = OPENSSL_malloc(length_padding);
+        OPENSSL_cleanse(padding_buffer, length_padding);
+        if (RAND_bytes(padding_buffer, length_padding) != 1) {
+            debug_print("Random problems...\n");
+            goto cleanup;
+        }
+    } else {
+        g_snprintf(str_data_size, 3, "-1");
+    }
+
+    length_data_payload = 2 + length_data + length_padding;
+    data_payload_buffer = OPENSSL_malloc(length_data_payload);
+    OPENSSL_cleanse(data_payload_buffer, length_data_payload);
+
+    memcpy(data_payload_buffer, str_data_size, 2);
+    memcpy(data_payload_buffer + 2, data, length_data);
+    if (length_padding > 0) {
+        memcpy(data_payload_buffer + (2 + length_data),
+               padding_buffer,
+               length_padding);
+    }
+
+    mdctx = EVP_MD_CTX_create();
+    EVP_DigestInit_ex(mdctx, DIGEST_HASH, NULL);
+    EVP_DigestUpdate(mdctx, data_payload_buffer, length_data_payload);
+
+    length_hash = EVP_MD_size(DIGEST_HASH);
+    hash_buffer = OPENSSL_malloc(length_hash);
+    OPENSSL_cleanse(hash_buffer, length_hash);
+    EVP_DigestFinal_ex(mdctx, hash_buffer, NULL);
+
+    length_cleartext = length_hash + length_data_payload;
+    
+    cleartext_buffer = OPENSSL_malloc(length_cleartext);
+    OPENSSL_cleanse(cleartext_buffer, length_cleartext);
+
+    /* assemble cleartext-buffer */
+    memcpy(cleartext_buffer, hash_buffer, length_hash);
+    memcpy(cleartext_buffer + length_hash,
+           data_payload_buffer,
+           length_data_payload);
+    OPENSSL_cleanse(data_payload_buffer, length_data_payload); /* sensitive */
+
+    /* encryption */
+    if (!(ctx = EVP_CIPHER_CTX_new())) {
+        debug_print("New ctx failed\n");
+        goto cleanup;
+    }
+
+    length_ciphertext = 0;
+    if (EVP_EncryptInit_ex(ctx, CIPHER, NULL, key, salt) != 1) {
+        debug_print("EVP_EncryptInit_ex failed\n");
+        goto cleanup;
+    }
+
+    ciphertext_buffer = OPENSSL_malloc(length_cleartext);
+
+    crypt_buffer_cnt = 0;
+    while(1) {
+        if (EVP_EncryptUpdate(ctx,
+                              ciphertext_buffer + length_ciphertext,
+                              &crypt_buffer_cnt,
+                              cleartext_buffer + length_ciphertext,
+                              1) != 1) { /* one byte at a time */
+            debug_print("EVP_EncryptUpdate failed\n");
+            goto cleanup;
+        }
+
+        if (crypt_buffer_cnt != 1) { /* paranoia */
+            debug_print("The sizes of enc and dec text do not correspond\n");
+            goto cleanup;
+        }
+
+        ++length_ciphertext;
+
+        if (length_ciphertext >= length_cleartext) {
+            break;
+        }
+    }
+    /* No padding required for the CFB mode */
+
+    OPENSSL_cleanse(cleartext_buffer, length_cleartext); /* sensitive */
+    length_total = SALT_SIZE + length_ciphertext;
+    total_buffer = OPENSSL_malloc(length_total);
+
+    memcpy(total_buffer, salt, SALT_SIZE);
+    memcpy(total_buffer + SALT_SIZE, ciphertext_buffer, length_ciphertext);
+
+    *encrypted = g_base64_encode(total_buffer, length_total);
+    *length_encrypted = strlen(*encrypted);
+
+    rc = RC_OK;
+
+cleanup:
+    /* key */
+    OPENSSL_cleanse(key, key_size);
+    OPENSSL_free(key);
+    /* cleartext buffer */
+    OPENSSL_cleanse(cleartext_buffer, length_cleartext);
+    OPENSSL_free(cleartext_buffer);
+    /* payload buffer */
+    OPENSSL_cleanse(data_payload_buffer, length_data_payload);
+    OPENSSL_free(data_payload_buffer);
+    /* hash */
+    OPENSSL_cleanse(hash_buffer, length_hash);
+    OPENSSL_free(hash_buffer);
+    /* padding */
+    if (length_padding > 0) {
+        OPENSSL_cleanse(padding_buffer, length_padding);
+        OPENSSL_free(padding_buffer);
+    }
+
+    OPENSSL_cleanse(str_data_size, 3); /* paranoia */
+
+    /* ciphertext buffer */
+    OPENSSL_free(ciphertext_buffer);
+
+    /* total buffer */
+    OPENSSL_free(total_buffer);
+
+    length_data_payload = 0;
+    length_padding = 0;
+
+    EVP_CIPHER_CTX_free(ctx);
+    EVP_MD_CTX_destroy(mdctx);
+
+    return rc;
+
+}
+
+
+gint decrypt_data(gchar **decrypted,
+                  const gchar *data,
+                  const gchar *passphrase,
+                  gint length_data) {
+
+    gint rc; /* return code */
+    gint decrypt_buffer_cnt, length_ciphertext, length_decrypted;
+    guint key_size, length_hash, length_cleartext;
+    gsize length_total;
+    guchar salt[SALT_SIZE];
+    guchar *ciphertext_buffer, *total_buffer;
+    /* sensitive buffers and counters */
+    gint data_size;
+    guint length_data_payload;
+    gchar str_data_size[3];
+    guchar *data_payload_buffer, *hash_buffer, *key;
+    guchar *cleartext_buffer;
+
+    EVP_CIPHER_CTX *ctx;
+    EVP_MD_CTX *mdctx;
+
+    rc = -1;
+
+    if (length_data < 1) {
+        return -1;
+    }
+
+    total_buffer = g_base64_decode(data, &length_total);
+    length_ciphertext = length_total - SALT_SIZE;
+    ciphertext_buffer = OPENSSL_malloc(length_ciphertext);
+    OPENSSL_cleanse(ciphertext_buffer, length_ciphertext);
+
+    memcpy(salt, total_buffer, SALT_SIZE);
+    memcpy(ciphertext_buffer, total_buffer + SALT_SIZE, length_ciphertext);
+
+    key_size = EVP_CIPHER_key_length(CIPHER);
+
+    /* decryption */
+    if(!(ctx = EVP_CIPHER_CTX_new())) {
+        debug_print("New ctx failed\n");
+        goto cleanup;
+    }
+
+    key = OPENSSL_malloc(key_size);
+    OPENSSL_cleanse(key, key_size);
+    if (secure_derive_key(key,
+                          key_size,
+                          passphrase,
+                          salt) != 0) {
+        OPENSSL_cleanse(key, key_size);
+        debug_print("Could not generate secure key\n");
+        goto cleanup;
+    }
+
+    if (EVP_DecryptInit_ex(ctx, CIPHER, NULL, key, salt) != 1) {
+        debug_print("EVP_DecryptInit_ex failed\n");
+        goto cleanup;
+    }
+    OPENSSL_cleanse(key, key_size); /* highly sensitive */
+    cleartext_buffer = OPENSSL_malloc(length_ciphertext);
+    OPENSSL_cleanse(cleartext_buffer, length_ciphertext);
+
+    length_cleartext = 0;
+    decrypt_buffer_cnt = 0;
+
+    while(1) {
+        if (EVP_DecryptUpdate(ctx,
+                              cleartext_buffer + length_cleartext,
+                              &decrypt_buffer_cnt,
+                              ciphertext_buffer + length_cleartext,
+                              1) != 1) { /* one byte at a time */
+            debug_print("EVP_EncryptUpdate failed\n");
+            goto cleanup;
+        }
+
+        if (decrypt_buffer_cnt != 1) { /* paranoia */
+            debug_print("The sizes of enc and dec text do not correspond");
+            goto cleanup;
+        }
+
+        ++length_cleartext;
+
+        if (length_cleartext >= length_ciphertext) {
+            break;
+        }
+    }
+
+
+    length_hash = EVP_MD_size(DIGEST_HASH);
+    hash_buffer = OPENSSL_malloc(length_hash);
+    length_data_payload = length_cleartext - length_hash;
+    data_payload_buffer = OPENSSL_malloc(length_data_payload);
+    OPENSSL_cleanse(data_payload_buffer, length_data_payload);
+
+    memcpy(data_payload_buffer,
+           cleartext_buffer + length_hash,
+           length_data_payload);
+
+    mdctx = EVP_MD_CTX_create();
+    EVP_DigestInit_ex(mdctx, DIGEST_HASH, NULL);
+    EVP_DigestUpdate(mdctx, data_payload_buffer, length_data_payload);
+    EVP_DigestFinal_ex(mdctx, hash_buffer, &length_hash);
+
+    if (strncmp((const gchar*) hash_buffer,
+                (const gchar*) cleartext_buffer,
+                length_hash) != 0) {
+        debug_print("Invalid hash\n");
+        rc = RC_WRONG_HASH_OR_KEY;
+        goto cleanup;
+    }
+
+    memcpy(str_data_size, cleartext_buffer + length_hash, 2);
+    data_size = atoi(str_data_size);
+
+    if (data_size < 0) {
+        length_decrypted = length_data_payload - 2;
+    } else {
+        length_decrypted = data_size;
+    }
+    *decrypted = OPENSSL_malloc(length_decrypted);
+    memcpy(*decrypted, data_payload_buffer + 2, length_decrypted);
+
+    rc = RC_OK;
+
+cleanup:
+
+    /* key */
+    OPENSSL_cleanse(key, key_size);
+    OPENSSL_free(key);
+    /* payload buffer */
+    OPENSSL_cleanse(data_payload_buffer, length_data_payload);
+    OPENSSL_free(data_payload_buffer);
+    /* hash */
+    OPENSSL_cleanse(hash_buffer, length_hash);
+    OPENSSL_free(hash_buffer);
+    /* ciphertext */
+    OPENSSL_free(ciphertext_buffer);
+    OPENSSL_free(total_buffer);
+
+    EVP_CIPHER_CTX_free(ctx);
+    EVP_MD_CTX_destroy(mdctx);
+
+    return rc;
+
+}
+
 #endif /* USE_SSL */