Secure settings refactoring

client/encryption_helper.cpp

@@ -0,0 +1,143 @@
+#include "encryption_helper.h"
+
+#include <QTextStream>
+#include <QVariantMap>
+#include <QDebug>
+
+#include "openssl/evp.h"
+
+int gcm_encrypt(const char *plaintext, int plaintext_len,
+                const char *key, const char *iv, int iv_len,
+                char *ciphertext)
+{
+    return gcm_encrypt((uchar*)plaintext, plaintext_len,
+                       (uchar*)key, (uchar*)iv, iv_len,
+                       (uchar*)ciphertext);
+}
+
+int gcm_decrypt(const char *ciphertext, int ciphertext_len,
+                const char *key,
+                const char *iv, int iv_len,
+                char *plaintext)
+{
+    return gcm_decrypt((uchar*)ciphertext, ciphertext_len,
+                       (uchar*)key, (uchar*)iv, iv_len,
+                       (uchar*)plaintext);
+}
+
+void handleErrors() {
+    qDebug() << "handleErrors";
+}
+
+int generate_key_and_iv(unsigned char *iv, unsigned char *key) {
+//    unsigned char key[32];
+//    unsigned char iv[16];
+//    EVP_BytesToKey(EVP_aes_256_gcm(), EVP_md5(),
+//                   NULL,
+//                   key_file_buf, key_size, 1, // const unsigned char *data, int datal, int count,
+//                   key, iv);
+    return 0;
+}
+
+int gcm_encrypt(const unsigned char *plaintext, int plaintext_len,
+                const unsigned char *key,
+                const unsigned char *iv, int iv_len,
+                unsigned char *ciphertext)
+{
+    EVP_CIPHER_CTX *ctx;
+    int len;
+    int ciphertext_len;
+
+    /* Create and initialise the context */
+    if(!(ctx = EVP_CIPHER_CTX_new()))
+        handleErrors();
+
+    /* Initialise the encryption operation. */
+    if(1 != EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))
+        handleErrors();
+
+    /*
+     * Set IV length if default 12 bytes (96 bits) is not appropriate
+     */
+    if(1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, iv_len, NULL))
+        handleErrors();
+
+    /* Initialise key and IV */
+    if(1 != EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv))
+        handleErrors();
+
+    /*
+     * Provide the message to be encrypted, and obtain the encrypted output.
+     * EVP_EncryptUpdate can be called multiple times if necessary
+     */
+    if(1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len))
+        handleErrors();
+    ciphertext_len = len;
+
+    /*
+     * Finalise the encryption. Normally ciphertext bytes may be written at
+     * this stage, but this does not occur in GCM mode
+     */
+    if(1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len))
+        handleErrors();
+    ciphertext_len += len;
+
+    /* Clean up */
+    EVP_CIPHER_CTX_free(ctx);
+
+    return ciphertext_len;
+}
+
+int gcm_decrypt(const unsigned char *ciphertext, int ciphertext_len,
+                const unsigned char *key,
+                const unsigned char *iv, int iv_len,
+                unsigned char *plaintext)
+{
+    EVP_CIPHER_CTX *ctx;
+    int len;
+    int plaintext_len;
+    int ret;
+
+    /* Create and initialise the context */
+    if(!(ctx = EVP_CIPHER_CTX_new()))
+        handleErrors();
+
+    /* Initialise the decryption operation. */
+    if(!EVP_DecryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))
+        handleErrors();
+
+    /* Set IV length. Not necessary if this is 12 bytes (96 bits) */
+    if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, iv_len, NULL))
+        handleErrors();
+
+    /* Initialise key and IV */
+    if(!EVP_DecryptInit_ex(ctx, NULL, NULL, key, iv))
+        handleErrors();
+
+    /*
+     * Provide the message to be decrypted, and obtain the plaintext output.
+     * EVP_DecryptUpdate can be called multiple times if necessary
+     */
+    if(!EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len))
+        handleErrors();
+    plaintext_len = len;
+
+    /*
+     * Finalise the decryption. A positive return value indicates success,
+     * anything else is a failure - the plaintext is not trustworthy.
+     */
+    ret = EVP_DecryptFinal_ex(ctx, plaintext + len, &len);
+
+    /* Clean up */
+    EVP_CIPHER_CTX_free(ctx);
+
+    if(ret > 0) {
+        /* Success */
+        plaintext_len += len;
+        return plaintext_len;
+    } else {
+        /* Verify failed */
+        return -1;
+    }
+}
+