Add ctaes-based constant time AES implementation

2 files changed, 139 insertions, 0 deletions

diff --git a/src/crypto/aes.cpp b/src/crypto/aes.cpp
new file mode 100644
index 0000000000..035abd75bd
--- /dev/null
+++ b/src/crypto/aes.cpp
@@ -0,0 +1,73 @@
+// Copyright (c) 2016 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "aes.h"
+#include "crypto/common.h"
+
+#include <assert.h>
+#include <string.h>
+
+extern "C" {
+#include "crypto/ctaes/ctaes.c"
+}
+
+AES128Encrypt::AES128Encrypt(const unsigned char key[16])
+{
+    AES128_init(&ctx, key);
+}
+
+AES128Encrypt::~AES128Encrypt()
+{
+    memset(&ctx, 0, sizeof(ctx));
+}
+
+void AES128Encrypt::Encrypt(unsigned char ciphertext[16], const unsigned char plaintext[16]) const
+{
+    AES128_encrypt(&ctx, 1, ciphertext, plaintext);
+}
+
+AES128Decrypt::AES128Decrypt(const unsigned char key[16])
+{
+    AES128_init(&ctx, key);
+}
+
+AES128Decrypt::~AES128Decrypt()
+{
+    memset(&ctx, 0, sizeof(ctx));
+}
+
+void AES128Decrypt::Decrypt(unsigned char plaintext[16], const unsigned char ciphertext[16]) const
+{
+    AES128_decrypt(&ctx, 1, plaintext, ciphertext);
+}
+
+AES256Encrypt::AES256Encrypt(const unsigned char key[32])
+{
+    AES256_init(&ctx, key);
+}
+
+AES256Encrypt::~AES256Encrypt()
+{
+    memset(&ctx, 0, sizeof(ctx));
+}
+
+void AES256Encrypt::Encrypt(unsigned char ciphertext[16], const unsigned char plaintext[16]) const
+{
+    AES256_encrypt(&ctx, 1, ciphertext, plaintext);
+}
+
+AES256Decrypt::AES256Decrypt(const unsigned char key[32])
+{
+    AES256_init(&ctx, key);
+}
+
+AES256Decrypt::~AES256Decrypt()
+{
+    memset(&ctx, 0, sizeof(ctx));
+}
+
+void AES256Decrypt::Decrypt(unsigned char plaintext[16], const unsigned char ciphertext[16]) const
+{
+    AES256_decrypt(&ctx, 1, plaintext, ciphertext);
+}
diff --git a/src/crypto/aes.h b/src/crypto/aes.h
new file mode 100644
index 0000000000..4bf17a33ea
--- /dev/null
+++ b/src/crypto/aes.h
@@ -0,0 +1,66 @@
+// Copyright (c) 2015 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+//
+// C++ wrapper around ctaes, a constant-time AES implementation
+
+#ifndef BITCOIN_CRYPTO_AES_H
+#define BITCOIN_CRYPTO_AES_H
+
+extern "C" {
+#include "crypto/ctaes/ctaes.h"
+}
+
+static const int AES_BLOCKSIZE = 16;
+static const int AES128_KEYSIZE = 16;
+static const int AES256_KEYSIZE = 32;
+
+/** An encryption class for AES-128. */
+class AES128Encrypt
+{
+private:
+    AES128_ctx ctx;
+
+public:
+    AES128Encrypt(const unsigned char key[16]);
+    ~AES128Encrypt();
+    void Encrypt(unsigned char ciphertext[16], const unsigned char plaintext[16]) const;
+};
+
+/** A decryption class for AES-128. */
+class AES128Decrypt
+{
+private:
+    AES128_ctx ctx;
+
+public:
+    AES128Decrypt(const unsigned char key[16]);
+    ~AES128Decrypt();
+    void Decrypt(unsigned char plaintext[16], const unsigned char ciphertext[16]) const;
+};
+
+/** An encryption class for AES-256. */
+class AES256Encrypt
+{
+private:
+    AES256_ctx ctx;
+
+public:
+    AES256Encrypt(const unsigned char key[32]);
+    ~AES256Encrypt();
+    void Encrypt(unsigned char ciphertext[16], const unsigned char plaintext[16]) const;
+};
+
+/** A decryption class for AES-256. */
+class AES256Decrypt
+{
+private:
+    AES256_ctx ctx;
+
+public:
+    AES256Decrypt(const unsigned char key[32]);
+    ~AES256Decrypt();
+    void Decrypt(unsigned char plaintext[16], const unsigned char ciphertext[16]) const;
+};
+
+#endif // BITCOIN_CRYPTO_AES_H