StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
text
Body
copied!<p>Here is an example to encrypt and decrypt 128 bytes every call to update for example:</p> <pre><code> int howmany, dec_success, len; const EVP_CIPHER *cipher; switch(key_len) { case 128: cipher = EVP_aes_128_gcm ();break; case 192: cipher = EVP_aes_192_gcm ();break; case 256: cipher = EVP_aes_256_gcm ();break; default:break; } // Encrypt EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new(); EVP_EncryptInit (ctx, cipher, KEY, IV); EVP_EncryptUpdate (ctx, NULL, &howmany, AAD, aad_len); len = 0; while(len <= in_len-128) { EVP_EncryptUpdate (ctx, CIPHERTEXT+len, &howmany, PLAINTEXT+len, 128); len+=128; } EVP_EncryptUpdate (ctx, CIPHERTEXT+len, &howmany, PLAINTEXT+len, in_len - len); EVP_EncryptFinal (ctx, TAG, &howmany); EVP_CIPHER_CTX_ctrl (ctx, EVP_CTRL_GCM_GET_TAG, 16, TAG); EVP_CIPHER_CTX_free(ctx); // Decrypt ctx = EVP_CIPHER_CTX_new(); EVP_DecryptInit (ctx, cipher, KEY, IV); EVP_CIPHER_CTX_ctrl (ctx, EVP_CTRL_GCM_SET_TAG, 16, ref_TAG); EVP_DecryptInit (ctx, NULL, KEY, IV); EVP_DecryptUpdate (ctx, NULL, &howmany, AAD, aad_len); len = 0; while(len <= in_len-128) { EVP_DecryptUpdate (ctx, decrypted_CT+len, &howmany, CIPHERTEXT+len, 128); len+=128; } EVP_DecryptUpdate (ctx, decrypted_CT+len, &howmany, CIPHERTEXT+len, in_len-len); dec_success = EVP_DecryptFinal (ctx, dec_TAG, &howmany); EVP_CIPHER_CTX_free(ctx); </code></pre> <p>In the end you should check that the value of dec_success is 1. If you modify the CIPHERTEXT, before you decrypt it, you should get value of 0.</p>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload