1 files changed, 99 insertions, 0 deletions
diff --git a/src/core/aes/aes_ssl_cbc.cpp b/src/core/aes/aes_ssl_cbc.cpp
new file mode 100644
index 00000000..95ae0ce2
--- /dev/null
+++ b/src/core/aes/aes_ssl_cbc.cpp
@@ -0,0 +1,99 @@
+/**
+ * AES encryption/decryption demo program using OpenSSL EVP apis
+ * gcc -Wall openssl_aes.c -lcrypto
+ * this is public domain code.
+ * Saju Pillai ([email protected])
+ **/
+
+#include "aes_ssl.h"
+
+namespace GpgFrontend::RawAPI {
+
+/**
+ * @brief Create a 256 bit key and IV using the supplied key_data. salt can be
+ * added for taste. Fills in the encryption and decryption ctx objects and
+ * returns 0 on success
+ *
+ * @param key_data
+ * @param key_data_len
+ * @param salt
+ * @param e_ctx
+ * @param d_ctx
+ * @return int
+ */
+int aes_256_cbc_init(uint8_t *key_data, int key_data_len, uint8_t *salt,
+                     EVP_CIPHER_CTX *e_ctx, EVP_CIPHER_CTX *d_ctx) {
+  int i, nrounds = 5;
+  uint8_t key[32], iv[32];
+
+  /*
+   * Gen key & IV for AES 256 CBC mode. A SHA1 digest is used to hash the
+   * supplied key material. nrounds is the number of times the we hash the
+   * material. More rounds are more secure but slower.
+   */
+  i = EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha1(), salt, key_data,
+                     key_data_len, nrounds, key, iv);
+  if (i != 32) {
+    printf("Key size is %d bits - should be 256 bits\n", i);
+    return -1;
+  }
+
+  EVP_CIPHER_CTX_init(e_ctx);
+  EVP_EncryptInit_ex(e_ctx, EVP_aes_256_cbc(), NULL, key, iv);
+  EVP_CIPHER_CTX_init(d_ctx);
+  EVP_DecryptInit_ex(d_ctx, EVP_aes_256_cbc(), NULL, key, iv);
+
+  return 0;
+}
+
+/**
+ * @brief  Encrypt *len bytes of data All data going in & out is considered
+ * binary (uint8_t[])
+ *
+ * @param e
+ * @param plaintext
+ * @param len
+ * @return uint8_t*
+ */
+uint8_t *aes_256_cbc_encrypt(EVP_CIPHER_CTX *e, uint8_t *plaintext, int *len) {
+  /* max ciphertext len for a n bytes of plaintext is n + AES_BLOCK_SIZE -1
+   * bytes */
+  int c_len = *len + AES_BLOCK_SIZE, f_len = 0;
+  auto *ciphertext = (uint8_t *)malloc(c_len);
+
+  /* allows reusing of 'e' for multiple encryption cycles */
+  EVP_EncryptInit_ex(e, nullptr, nullptr, nullptr, nullptr);
+
+  /* update ciphertext, c_len is filled with the length of ciphertext generated,
+   *len is the size of plaintext in bytes */
+  EVP_EncryptUpdate(e, ciphertext, &c_len, plaintext, *len);
+
+  /* update ciphertext with the final remaining bytes */
+  EVP_EncryptFinal_ex(e, ciphertext + c_len, &f_len);
+
+  *len = c_len + f_len;
+  return ciphertext;
+}
+
+/**
+ * @brief Decrypt *len bytes of ciphertext
+ *
+ * @param e
+ * @param ciphertext
+ * @param len
+ * @return uint8_t*
+ */
+uint8_t *aes_256_cbc_decrypt(EVP_CIPHER_CTX *e, uint8_t *ciphertext, int *len) {
+  /* plaintext will always be equal to or lesser than length of ciphertext*/
+  int p_len = *len, f_len = 0;
+  auto *plaintext = (uint8_t *)malloc(p_len);
+
+  EVP_DecryptInit_ex(e, nullptr, nullptr, nullptr, nullptr);
+  EVP_DecryptUpdate(e, plaintext, &p_len, ciphertext, *len);
+  EVP_DecryptFinal_ex(e, plaintext + p_len, &f_len);
+
+  *len = p_len + f_len;
+  return plaintext;
+}
+
+} // namespace GpgFrontend::RawAPI
+\ No newline at end of file