1 files changed, 103 insertions, 0 deletions
diff --git a/crypto.c b/crypto.c
new file mode 100644
index 0000000..86da70a
--- /dev/null
+++ b/crypto.c
@@ -0,0 +1,103 @@
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/random.h>
+#include <libscrypt.h>
+
+#include "checksum.h"
+#include "crypto.h"
+
+char *read_passphrase(const char *prompt)
+{
+	char *buf = NULL;
+	size_t buflen = 0;
+	ssize_t len;
+
+	if (isatty(STDIN_FILENO)) {
+		struct termios old, new;
+
+		fprintf(stderr, "%s", prompt);
+		fflush(stderr);
+
+		if (tcgetattr(STDIN_FILENO, &old))
+			die("error getting terminal attrs");
+
+		new = old;
+		new.c_lflag &= ~ECHO;
+		if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &new))
+			die("error setting terminal attrs");
+
+		len = getline(&buf, &buflen, stdin);
+
+		tcsetattr(STDIN_FILENO, TCSAFLUSH, &old);
+		fprintf(stderr, "\n");
+	} else {
+		len = getline(&buf, &buflen, stdin);
+	}
+
+	if (len < 0)
+		die("error reading passphrase");
+	if (len && buf[len - 1] == '\n')
+		buf[len - 1] = '\0';
+
+	return buf;
+}
+
+void derive_passphrase(struct bch_sb_field_crypt *crypt,
+		       struct bch_key *key,
+		       const char *passphrase)
+{
+	const unsigned char salt[] = "bcache";
+	int ret;
+
+	switch (BCH_CRYPT_KDF_TYPE(crypt)) {
+	case BCH_KDF_SCRYPT:
+		ret = libscrypt_scrypt((void *) passphrase, strlen(passphrase),
+				       salt, sizeof(salt),
+				       1ULL << BCH_KDF_SCRYPT_N(crypt),
+				       1ULL << BCH_KDF_SCRYPT_R(crypt),
+				       1ULL << BCH_KDF_SCRYPT_P(crypt),
+				       (void *) key, sizeof(*key));
+		if (ret)
+			die("scrypt error: %i", ret);
+		break;
+	default:
+		die("unknown kdf type %llu", BCH_CRYPT_KDF_TYPE(crypt));
+	}
+}
+
+void bch_sb_crypt_init(struct bch_sb *sb,
+		       struct bch_sb_field_crypt *crypt,
+		       const char *passphrase)
+{
+	struct bch_key passphrase_key;
+
+	SET_BCH_CRYPT_KDF_TYPE(crypt, BCH_KDF_SCRYPT);
+	SET_BCH_KDF_SCRYPT_N(crypt, ilog2(SCRYPT_N));
+	SET_BCH_KDF_SCRYPT_R(crypt, ilog2(SCRYPT_r));
+	SET_BCH_KDF_SCRYPT_P(crypt, ilog2(SCRYPT_p));
+
+	derive_passphrase(crypt, &passphrase_key, passphrase);
+
+	crypt->key.magic = BCH_KEY_MAGIC;
+	get_random_bytes(&crypt->key.key, sizeof(crypt->key.key));
+
+	assert(!bch_key_is_encrypted(&crypt->key));
+
+	if (bch_chacha_encrypt_key(&passphrase_key, __bch_sb_key_nonce(sb),
+				   &crypt->key, sizeof(crypt->key)))
+		die("error encrypting key");
+
+	assert(bch_key_is_encrypted(&crypt->key));
+
+	memzero_explicit(&passphrase_key, sizeof(passphrase_key));
+}