Winzip AES encryption support for writing.

lib/zip_source_winzip_aes_decode.c

diff --git a/lib/zip_source_winzip_aes_decode.c b/lib/zip_source_winzip_aes_decode.c
new file mode 100644
index 0000000..e083f95
--- /dev/null
+++ b/lib/zip_source_winzip_aes_decode.c
@@ -0,0 +1,282 @@
+/*
+  zip_source_winzip_aes.c -- Winzip AES de/encryption routines
+  Copyright (C) 2009-2015 Dieter Baron and Thomas Klausner
+
+  This file is part of libzip, a library to manipulate ZIP archives.
+  The authors can be contacted at <libzip@nih.at>
+
+  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.
+  3. The names of the authors may not be used to endorse or promote
+  products derived from this software without specific prior
+  written permission.
+ 
+  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.
+*/
+
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "zipint.h"
+
+#include "gladman-fcrypt.h"
+
+#define MAX_HEADER_LENGTH (16+PWD_VER_LENGTH)
+#define HMAC_LENGTH 10
+
+static int salt_length[] = { 0, 8, 12, 16 };
+
+struct winzip_aes {
+    char *password;
+    int mode;
+
+    zip_uint64_t data_length;
+    zip_uint64_t current_position;
+
+    fcrypt_ctx fcrypt_ctx;
+    zip_error_t error;
+};
+
+
+static int decrypt_header(zip_source_t *src, struct winzip_aes *ctx);
+static void winzip_aes_free(struct winzip_aes *);
+static zip_int64_t winzip_aes_decrypt(zip_source_t *src, void *ud, void *data, zip_uint64_t len, zip_source_cmd_t cmd);
+static struct winzip_aes * winzip_aes_new(int mode, const char *password);
+
+
+zip_source_t *
+zip_source_winzip_aes_decode(zip_t *za, zip_source_t *src, zip_uint16_t em, int flags, const char *password)
+{
+    zip_source_t *s2;
+    int mode = 0;
+    zip_stat_t st;
+    zip_uint64_t aux_length;
+    struct winzip_aes *ctx;
+
+    switch (em) {
+    case ZIP_EM_AES_128:
+	mode = 1;
+	break;
+    case ZIP_EM_AES_192:
+	mode = 2;
+	break;
+    case ZIP_EM_AES_256:
+	mode = 3;
+	break;
+    }
+	
+    if (password == NULL || src == NULL || mode == 0) {
+	zip_error_set(&za->error, ZIP_ER_INVAL, 0);
+	return NULL;
+    }
+    if (flags & ZIP_CODEC_ENCODE) {
+	zip_error_set(&za->error, ZIP_ER_ENCRNOTSUPP, 0);
+	return NULL;
+    }
+
+    if (zip_source_stat(src, &st) != 0) {
+	_zip_error_set_from_source(&za->error, src);
+	return NULL;
+    }
+
+    aux_length = PWD_VER_LENGTH + salt_length[mode] + HMAC_LENGTH;
+    
+    if ((st.valid & ZIP_STAT_COMP_SIZE) == 0 || st.comp_size < aux_length) {
+	zip_error_set(&za->error, ZIP_ER_OPNOTSUPP, 0);
+	return NULL;
+    }
+
+    if ((ctx = winzip_aes_new(mode, password)) == NULL) {
+	zip_error_set(&za->error, ZIP_ER_MEMORY, 0);
+	return NULL;
+    }
+
+    ctx->data_length = st.comp_size - aux_length;
+
+    if ((s2 = zip_source_layered(za, src, winzip_aes_decrypt, ctx)) == NULL) {
+	winzip_aes_free(ctx);
+	return NULL;
+    }
+
+    return s2;
+}
+
+
+static int
+decrypt_header(zip_source_t *src, struct winzip_aes *ctx)
+{
+    zip_uint8_t header[MAX_HEADER_LENGTH];
+    zip_uint8_t password_verification[PWD_VER_LENGTH];
+    zip_uint8_t headerlen;
+    zip_int64_t n;
+    unsigned char key[16];
+
+    headerlen = PWD_VER_LENGTH + salt_length[ctx->mode];
+    if ((n=zip_source_read(src, header, headerlen)) < 0) {
+	_zip_error_set_from_source(&ctx->error, src);
+	return -1;
+    }
+    
+    if (n != headerlen) {
+	zip_error_set(&ctx->error, ZIP_ER_EOF, 0);
+	return -1;
+    }
+
+    if (_zip_fcrypt_init(ctx->mode, ctx->password, strlen(ctx->password), header, password_verification, &ctx->fcrypt_ctx) != 0) {
+	zip_error_set(&ctx->error, ZIP_ER_MEMORY, 0);
+	return -1;
+    }
+    if (memcmp(password_verification, header + salt_length[ctx->mode], PWD_VER_LENGTH) != 0) {
+	zip_error_set(&ctx->error, ZIP_ER_WRONGPASSWD, 0);
+	return -1;
+    }
+    return 0;
+}
+
+
+static bool
+verify_hmac(zip_source_t *src, struct winzip_aes *ctx)
+{
+    unsigned char computed[HMAC_LENGTH], from_file[HMAC_LENGTH];
+    if (zip_source_read(src, from_file, HMAC_LENGTH) < HMAC_LENGTH) {
+	_zip_error_set_from_source(&ctx->error, src);
+	return false;
+    }
+
+    _zip_fcrypt_end(computed, &ctx->fcrypt_ctx);
+    
+    if (memcmp(from_file, computed, HMAC_LENGTH) != 0) {
+	zip_error_set(&ctx->error, ZIP_ER_CRC, 0);
+	return false;
+    }
+
+    return true;
+}
+
+
+static zip_int64_t
+winzip_aes_decrypt(zip_source_t *src, void *ud, void *data, zip_uint64_t len, zip_source_cmd_t cmd)
+{
+    struct winzip_aes *ctx;
+    zip_int64_t n;
+
+    ctx = (struct winzip_aes *)ud;
+
+    switch (cmd) {
+    case ZIP_SOURCE_OPEN:
+	if (decrypt_header(src, ctx) < 0) {
+	    return -1;
+	}
+	ctx->current_position = 0;
+	return 0;
+
+    case ZIP_SOURCE_READ:
+	if (len > ctx->data_length - ctx->current_position) {
+	    len = ctx->data_length - ctx->current_position;
+	}
+
+	if (len == 0) {
+	    if (!verify_hmac(src, ctx)) {
+		return -1;
+	    }
+	    return 0;
+	}
+	
+	if ((n=zip_source_read(src, data, len)) < 0) {
+	    _zip_error_set_from_source(&ctx->error, src);
+	    return -1;
+	}
+	ctx->current_position += n;
+
+	/* TODO: loop if len > UINT_MAX */
+	_zip_fcrypt_decrypt(data, n, &ctx->fcrypt_ctx);
+
+	return n;
+
+    case ZIP_SOURCE_CLOSE:
+	return 0;
+
+    case ZIP_SOURCE_STAT:
+    {
+	zip_stat_t *st;
+
+	st = (zip_stat_t *)data;
+
+	st->encryption_method = ZIP_EM_NONE;
+	st->valid |= ZIP_STAT_ENCRYPTION_METHOD;
+	if (st->valid & ZIP_STAT_COMP_SIZE) {
+	    st->comp_size -= 12 + salt_length[ctx->mode];
+	}
+	
+	return 0;
+    }
+            
+    case ZIP_SOURCE_SUPPORTS:
+	return zip_source_make_command_bitmap(ZIP_SOURCE_OPEN, ZIP_SOURCE_READ, ZIP_SOURCE_CLOSE, ZIP_SOURCE_STAT, ZIP_SOURCE_ERROR, ZIP_SOURCE_FREE, -1);
+
+    case ZIP_SOURCE_ERROR:
+	return zip_error_to_data(&ctx->error, data, len);
+
+    case ZIP_SOURCE_FREE:
+	winzip_aes_free(ctx);
+	return 0;
+
+    default:
+	zip_error_set(&ctx->error, ZIP_ER_INVAL, 0);
+	return -1;
+    }
+}
+
+
+static void
+winzip_aes_free(struct winzip_aes *ctx)
+{
+    if (ctx == NULL) {
+	return;
+    }
+
+    _zip_crypto_clear(&ctx->fcrypt_ctx, sizeof(ctx->fcrypt_ctx));
+    _zip_crypto_clear(ctx->password, strlen(ctx->password));
+    free(ctx->password);
+    zip_error_fini(&ctx->error);
+    free(ctx);
+}
+
+
+static struct winzip_aes *
+winzip_aes_new(int mode, const char *password) {
+    struct winzip_aes *ctx;
+    
+    if ((ctx = (struct winzip_aes *)malloc(sizeof(*ctx))) == NULL) {
+	return NULL;
+    }
+    
+    if ((ctx->password = strdup(password)) == NULL) {
+	free(ctx);
+	return NULL;
+    }
+
+    ctx->mode = mode;
+
+    zip_error_init(&ctx->error);
+
+    return ctx;
+}