1 files changed, 76 insertions, 0 deletions
diff --git a/src/crypt_sha256.c b/src/crypt_sha256.c
new file mode 100644
index 0000000..c480637
--- /dev/null
+++ b/src/crypt_sha256.c
@@ -0,0 +1,76 @@
+#include <string.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <fcntl.h>
+#include <openssl/sha.h>
+#include <openssl/evp.h>
+
+#define RAND_FILE		"/dev/random"
+#define SHA_STR			"{SHA256}"
+
+/* string length */
+#define LEN_PASSWD_MIN		8
+#define LEN_PASSWD_MAX		64
+#define LEN_RAND_STR            16
+#define LEN_BUFFER		LEN_PASSWD_MAX + LEN_RAND_STR + \
+						SHA256_DIGEST_LENGTH
+#define LEN_ENC64		64
+#define	LEN_SHA_STR		8
+#define LEN_FINAL_PASSWD	LEN_ENC64 + LEN_SHA_STR + 1
+
+
+uint8_t check_passwd(const char *p, size_t len)
+{
+	return ((len > LEN_PASSWD_MIN) || (len < LEN_PASSWD_MAX)) ? 1 : 0;
+}
+
+char* get_crypt_sha256(const char *p)
+{
+	int rand_fd;
+	ssize_t size;
+	size_t len = strlen(p);
+	char rand_str[LEN_RAND_STR];
+	char passwd_buff[LEN_BUFFER];
+	char sha_pwd[SHA256_DIGEST_LENGTH];
+	char enc64_pwd[LEN_ENC64];
+	char *final_pwd;
+
+	if (!check_passwd(p, len)) {
+		fprintf(stderr,
+			"the password has to be between 8 and 64 chars\n");
+		exit(EXIT_FAILURE);
+	}
+
+	rand_fd = open(RAND_FILE, O_RDONLY);
+	if (rand_fd < 0) {
+		fprintf(stderr, "impossible to open " RAND_FILE "\n");
+		exit(EXIT_FAILURE);
+	}
+
+	size = read(rand_fd, rand_str, LEN_RAND_STR);
+	close(rand_fd);
+	if (size != LEN_RAND_STR) {
+		fprintf(stderr, "failed to read from " RAND_FILE "\n");
+		exit(EXIT_FAILURE);
+	}
+
+	memcpy(passwd_buff + SHA256_DIGEST_LENGTH, p, len);
+	memcpy(passwd_buff + SHA256_DIGEST_LENGTH + len,
+						rand_str, LEN_RAND_STR);
+
+	SHA256((unsigned char*) passwd_buff + SHA256_DIGEST_LENGTH,
+			len + LEN_RAND_STR, (unsigned char*) sha_pwd);
+
+	memcpy(passwd_buff, sha_pwd, SHA256_DIGEST_LENGTH);
+
+	EVP_EncodeBlock((unsigned char*) enc64_pwd, (unsigned char*) sha_pwd,
+				SHA256_DIGEST_LENGTH + len + LEN_RAND_STR);
+
+
+	final_pwd = (char*) malloc (LEN_FINAL_PASSWD);
+	memcpy(final_pwd, SHA_STR, LEN_SHA_STR);
+	memcpy(final_pwd+8, enc64_pwd, LEN_ENC64);
+	final_pwd[LEN_SHA_STR + LEN_FINAL_PASSWD] = '\0';
+
+	return final_pwd;
+}