Initial code.

src/lib/crypto/crypto_aesctr.c

Index: src/lib/crypto/crypto_aesctr.c
diff --git a/src/lib/crypto/crypto_aesctr.c b/src/lib/crypto/crypto_aesctr.c
new file mode 100644
index 0000000000000000000000000000000000000000..00db8f0fbf128027197f577a80e07fec713c99c1
--- /dev/null
+++ b/src/lib/crypto/crypto_aesctr.c
@@ -0,0 +1,124 @@
+/*-
+ * Copyright 2007-2009 Colin Percival
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * This file was originally written by Colin Percival as part of the Tarsnap
+ * online backup system.
+ */
+#include "scrypt_platform.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <openssl/aes.h>
+
+#include "sysendian.h"
+
+#include "crypto_aesctr.h"
+
+struct crypto_aesctr {
+	AES_KEY * key;
+	uint64_t nonce;
+	uint64_t bytectr;
+	uint8_t buf[16];
+};
+
+/**
+ * crypto_aesctr_init(key, nonce):
+ * Prepare to encrypt/decrypt data with AES in CTR mode, using the provided
+ * expanded key and nonce.  The key provided must remain valid for the
+ * lifetime of the stream.
+ */
+struct crypto_aesctr *
+crypto_aesctr_init(AES_KEY * key, uint64_t nonce)
+{
+	struct crypto_aesctr * stream;
+
+	/* Allocate memory. */
+	if ((stream = malloc(sizeof(struct crypto_aesctr))) == NULL)
+		goto err0;
+
+	/* Initialize values. */
+	stream->key = key;
+	stream->nonce = nonce;
+	stream->bytectr = 0;
+
+	/* Success! */
+	return (stream);
+
+err0:
+	/* Failure! */
+	return (NULL);
+}
+
+/**
+ * crypto_aesctr_stream(stream, inbuf, outbuf, buflen):
+ * Generate the next ${buflen} bytes of the AES-CTR stream and xor them with
+ * bytes from ${inbuf}, writing the result into ${outbuf}.  If the buffers
+ * ${inbuf} and ${outbuf} overlap, they must be identical.
+ */
+void
+crypto_aesctr_stream(struct crypto_aesctr * stream, const uint8_t * inbuf,
+    uint8_t * outbuf, size_t buflen)
+{
+	uint8_t pblk[16];
+	size_t pos;
+	int bytemod;
+
+	for (pos = 0; pos < buflen; pos++) {
+		/* How far through the buffer are we? */
+		bytemod = stream->bytectr % 16;
+
+		/* Generate a block of cipherstream if needed. */
+		if (bytemod == 0) {
+			be64enc(pblk, stream->nonce);
+			be64enc(pblk + 8, stream->bytectr / 16);
+			AES_encrypt(pblk, stream->buf, stream->key);
+		}
+
+		/* Encrypt a byte. */
+		outbuf[pos] = inbuf[pos] ^ stream->buf[bytemod];
+
+		/* Move to the next byte of cipherstream. */
+		stream->bytectr += 1;
+	}
+}
+
+/**
+ * crypto_aesctr_free(stream):
+ * Free the provided stream object.
+ */
+void
+crypto_aesctr_free(struct crypto_aesctr * stream)
+{
+	int i;
+
+	/* Zero potentially sensitive information. */
+	for (i = 0; i < 16; i++)
+		stream->buf[i] = 0;
+	stream->bytectr = stream->nonce = 0;
+
+	/* Free the stream. */
+	free(stream);
+}