--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/pdf/pdf-crypt.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,1513 @@
+// Copyright (C) 2004-2025 Artifex Software, Inc.
+//
+// This file is part of MuPDF.
+//
+// MuPDF is free software: you can redistribute it and/or modify it under the
+// terms of the GNU Affero General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
+//
+// Alternative licensing terms are available from the licensor.
+// For commercial licensing, see <https://www.artifex.com/> or contact
+// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
+// CA 94129, USA, for further information.
+
+#include "mupdf/fitz.h"
+#include "mupdf/pdf.h"
+
+#include <string.h>
+
+enum
+{
+	PDF_CRYPT_NONE,
+	PDF_CRYPT_RC4,
+	PDF_CRYPT_AESV2,
+	PDF_CRYPT_AESV3,
+	PDF_CRYPT_UNKNOWN,
+};
+
+typedef struct
+{
+	int method;
+	int length;
+} pdf_crypt_filter;
+
+struct pdf_crypt
+{
+	pdf_obj *id;
+
+	int v;
+	int length;
+	pdf_obj *cf;
+	pdf_crypt_filter stmf;
+	pdf_crypt_filter strf;
+
+	int r;
+	unsigned char o[48];
+	unsigned char u[48];
+	unsigned char oe[32];
+	unsigned char ue[32];
+	unsigned char perms[16];
+	int p;
+	int encrypt_metadata;
+
+	unsigned char key[32]; /* decryption key generated from password */
+};
+
+static void pdf_parse_crypt_filter(fz_context *ctx, pdf_crypt_filter *cf, pdf_crypt *crypt, pdf_obj *name);
+
+pdf_crypt *
+pdf_new_crypt(fz_context *ctx, pdf_obj *dict, pdf_obj *id)
+{
+	pdf_crypt *crypt;
+	pdf_obj *obj;
+
+	crypt = fz_malloc_struct(ctx, pdf_crypt);
+
+	/* Common to all security handlers (PDF 1.7 table 3.18) */
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Filter));
+	if (!pdf_is_name(ctx, obj))
+	{
+		pdf_drop_crypt(ctx, crypt);
+		fz_throw(ctx, FZ_ERROR_FORMAT, "unspecified encryption handler");
+	}
+	if (!pdf_name_eq(ctx, PDF_NAME(Standard), obj))
+	{
+		pdf_drop_crypt(ctx, crypt);
+		fz_throw(ctx, FZ_ERROR_FORMAT, "unknown encryption handler: '%s'", pdf_to_name(ctx, obj));
+	}
+
+	crypt->v = pdf_dict_get_int_default(ctx, dict, PDF_NAME(V), 0);
+	if (crypt->v != 0 && crypt->v != 1 && crypt->v != 2 && crypt->v != 4 && crypt->v != 5)
+	{
+		pdf_drop_crypt(ctx, crypt);
+		fz_throw(ctx, FZ_ERROR_FORMAT, "unknown encryption version");
+	}
+
+	/* Standard security handler (PDF 1.7 table 3.19) */
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(R));
+	if (pdf_is_int(ctx, obj))
+		crypt->r = pdf_to_int(ctx, obj);
+	else if (crypt->v <= 4)
+	{
+		fz_warn(ctx, "encryption dictionary missing revision value, guessing...");
+		if (crypt->v < 2)
+			crypt->r = 2;
+		else if (crypt->v == 2)
+			crypt->r = 3;
+		else if (crypt->v == 4)
+			crypt->r = 4;
+	}
+	else
+	{
+		pdf_drop_crypt(ctx, crypt);
+		fz_throw(ctx, FZ_ERROR_FORMAT, "encryption dictionary missing version and revision value");
+	}
+	if (crypt->r < 1 || crypt->r > 6)
+	{
+		int r = crypt->r;
+		pdf_drop_crypt(ctx, crypt);
+		fz_throw(ctx, FZ_ERROR_FORMAT, "unknown crypt revision %d", r);
+	}
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(O));
+	if (pdf_is_string(ctx, obj) && pdf_to_str_len(ctx, obj) == 32)
+		memcpy(crypt->o, pdf_to_str_buf(ctx, obj), 32);
+	/* /O and /U are supposed to be 48 bytes long for revision 5 and 6, they're often longer, though */
+	else if (crypt->r >= 5 && pdf_is_string(ctx, obj) && pdf_to_str_len(ctx, obj) >= 48)
+		memcpy(crypt->o, pdf_to_str_buf(ctx, obj), 48);
+	else
+	{
+		pdf_drop_crypt(ctx, crypt);
+		fz_throw(ctx, FZ_ERROR_FORMAT, "encryption dictionary missing owner password");
+	}
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(U));
+	if (pdf_is_string(ctx, obj) && pdf_to_str_len(ctx, obj) == 32)
+		memcpy(crypt->u, pdf_to_str_buf(ctx, obj), 32);
+	/* /O and /U are supposed to be 48 bytes long for revision 5 and 6, they're often longer, though */
+	else if (crypt->r >= 5 && pdf_is_string(ctx, obj) && pdf_to_str_len(ctx, obj) >= 48)
+		memcpy(crypt->u, pdf_to_str_buf(ctx, obj), 48);
+	else if (pdf_is_string(ctx, obj) && pdf_to_str_len(ctx, obj) < 32)
+	{
+		fz_warn(ctx, "encryption password key too short (%zu)", pdf_to_str_len(ctx, obj));
+		memcpy(crypt->u, pdf_to_str_buf(ctx, obj), pdf_to_str_len(ctx, obj));
+	}
+	else
+	{
+		pdf_drop_crypt(ctx, crypt);
+		fz_throw(ctx, FZ_ERROR_FORMAT, "encryption dictionary missing user password");
+	}
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(P));
+	if (pdf_is_int(ctx, obj))
+		crypt->p = pdf_to_int(ctx, obj);
+	else
+	{
+		fz_warn(ctx, "encryption dictionary missing permissions");
+		crypt->p = 0xfffffffc;
+	}
+
+	if (crypt->r == 5 || crypt->r == 6)
+	{
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(OE));
+		if (!pdf_is_string(ctx, obj) || pdf_to_str_len(ctx, obj) != 32)
+		{
+			pdf_drop_crypt(ctx, crypt);
+			fz_throw(ctx, FZ_ERROR_FORMAT, "encryption dictionary missing owner encryption key");
+		}
+		memcpy(crypt->oe, pdf_to_str_buf(ctx, obj), 32);
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(UE));
+		if (!pdf_is_string(ctx, obj) || pdf_to_str_len(ctx, obj) != 32)
+		{
+			pdf_drop_crypt(ctx, crypt);
+			fz_throw(ctx, FZ_ERROR_FORMAT, "encryption dictionary missing user encryption key");
+		}
+		memcpy(crypt->ue, pdf_to_str_buf(ctx, obj), 32);
+	}
+
+	crypt->encrypt_metadata = pdf_dict_get_bool_default(ctx, dict, PDF_NAME(EncryptMetadata), 1);
+
+	/* Extract file identifier string */
+
+	if (pdf_is_array(ctx, id) && pdf_array_len(ctx, id) == 2)
+	{
+		obj = pdf_array_get(ctx, id, 0);
+		if (pdf_is_string(ctx, obj))
+			crypt->id = pdf_keep_obj(ctx, obj);
+	}
+	else
+		fz_warn(ctx, "missing file identifier, may not be able to do decryption");
+
+	/* Determine encryption key length */
+
+	crypt->length = 40;
+	if (crypt->v == 2 || crypt->v == 4)
+	{
+		crypt->length = pdf_dict_get_int_default(ctx, dict, PDF_NAME(Length), crypt->length);
+
+		/* work-around for pdf generators that assume length is in bytes */
+		if (crypt->length < 40)
+			crypt->length = crypt->length * 8;
+
+		if (crypt->length % 8 != 0)
+		{
+			pdf_drop_crypt(ctx, crypt);
+			fz_throw(ctx, FZ_ERROR_FORMAT, "invalid encryption key length");
+		}
+		if (crypt->length < 40 || crypt->length > 128)
+		{
+			pdf_drop_crypt(ctx, crypt);
+			fz_throw(ctx, FZ_ERROR_FORMAT, "invalid encryption key length");
+		}
+	}
+
+	if (crypt->v == 5)
+		crypt->length = 256;
+
+	if (crypt->v == 0 || crypt->v == 1 || crypt->v == 2)
+	{
+		crypt->stmf.method = PDF_CRYPT_RC4;
+		crypt->stmf.length = crypt->length;
+
+		crypt->strf.method = PDF_CRYPT_RC4;
+		crypt->strf.length = crypt->length;
+	}
+
+	if (crypt->v == 4 || crypt->v == 5)
+	{
+		crypt->stmf.method = PDF_CRYPT_NONE;
+		crypt->stmf.length = crypt->length;
+
+		crypt->strf.method = PDF_CRYPT_NONE;
+		crypt->strf.length = crypt->length;
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(CF));
+		if (pdf_is_dict(ctx, obj))
+		{
+			crypt->cf = pdf_keep_obj(ctx, obj);
+		}
+		else
+		{
+			crypt->cf = NULL;
+		}
+
+		fz_try(ctx)
+		{
+			obj = pdf_dict_get(ctx, dict, PDF_NAME(StmF));
+			if (pdf_is_name(ctx, obj))
+				pdf_parse_crypt_filter(ctx, &crypt->stmf, crypt, obj);
+
+			obj = pdf_dict_get(ctx, dict, PDF_NAME(StrF));
+			if (pdf_is_name(ctx, obj))
+				pdf_parse_crypt_filter(ctx, &crypt->strf, crypt, obj);
+		}
+		fz_catch(ctx)
+		{
+			pdf_drop_crypt(ctx, crypt);
+			fz_rethrow(ctx);
+		}
+
+		/* in crypt revision 4, the crypt filter determines the key length */
+		if (crypt->strf.method != PDF_CRYPT_NONE)
+			crypt->length = crypt->stmf.length;
+	}
+
+	return crypt;
+}
+
+void
+pdf_drop_crypt(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (!crypt)
+		return;
+
+	pdf_drop_obj(ctx, crypt->id);
+	pdf_drop_obj(ctx, crypt->cf);
+	fz_free(ctx, crypt);
+}
+
+/*
+ * Parse a CF dictionary entry (PDF 1.7 table 3.22)
+ */
+
+static void
+pdf_parse_crypt_filter(fz_context *ctx, pdf_crypt_filter *cf, pdf_crypt *crypt, pdf_obj *name)
+{
+	pdf_obj *obj;
+	pdf_obj *dict;
+	int is_identity = (pdf_name_eq(ctx, name, PDF_NAME(Identity)));
+	int is_stdcf = (!is_identity && pdf_name_eq(ctx, name, PDF_NAME(StdCF)));
+
+	if (!is_identity && !is_stdcf)
+		fz_throw(ctx, FZ_ERROR_FORMAT, "Crypt Filter not Identity or StdCF (%d 0 R)", pdf_to_num(ctx, crypt->cf));
+
+	cf->method = PDF_CRYPT_NONE;
+	cf->length = crypt->length;
+
+	if (!crypt->cf)
+	{
+		cf->method = (is_identity ? PDF_CRYPT_NONE : PDF_CRYPT_RC4);
+		return;
+	}
+
+	dict = pdf_dict_get(ctx, crypt->cf, name);
+	if (pdf_is_dict(ctx, dict))
+	{
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(CFM));
+		if (pdf_is_name(ctx, obj))
+		{
+			if (pdf_name_eq(ctx, PDF_NAME(None), obj))
+				cf->method = PDF_CRYPT_NONE;
+			else if (pdf_name_eq(ctx, PDF_NAME(V2), obj))
+				cf->method = PDF_CRYPT_RC4;
+			else if (pdf_name_eq(ctx, PDF_NAME(AESV2), obj))
+			{
+				cf->method = PDF_CRYPT_AESV2;
+				cf->length = 128;
+			}
+			else if (pdf_name_eq(ctx, PDF_NAME(AESV3), obj))
+			{
+				cf->method = PDF_CRYPT_AESV3;
+				cf->length = 256;
+			}
+			else
+				fz_warn(ctx, "unknown encryption method: %s", pdf_to_name(ctx, obj));
+		}
+
+		cf->length = pdf_dict_get_int_default(ctx, dict, PDF_NAME(Length), cf->length);
+	}
+	else if (!is_identity)
+		fz_throw(ctx, FZ_ERROR_FORMAT, "cannot parse crypt filter (%d 0 R)", pdf_to_num(ctx, crypt->cf));
+
+	if (cf->method != PDF_CRYPT_NONE)
+	{
+		if (crypt->r == 4 && cf->method != PDF_CRYPT_RC4 && cf->method != PDF_CRYPT_AESV2)
+			fz_warn(ctx, "unexpected encryption method for revision 4 crypto: %s", pdf_crypt_method(ctx, crypt));
+		else if (crypt->r >= 5 && cf->method != PDF_CRYPT_AESV3)
+		{
+			fz_warn(ctx, "illegal encryption method for revision 5/6, assuming AESV3");
+			cf->method = PDF_CRYPT_AESV3;
+		}
+	}
+
+	/* the length for crypt filters is supposed to be in bytes not bits */
+	if (cf->length < 40)
+		cf->length = cf->length * 8;
+
+	if ((cf->length % 8) != 0)
+		fz_throw(ctx, FZ_ERROR_FORMAT, "invalid key length: %d", cf->length);
+
+	if ((crypt->r == 1 || crypt->r == 2 || crypt->r == 3 || crypt->r == 4) &&
+		(cf->length < 40 || cf->length > 128))
+		fz_throw(ctx, FZ_ERROR_FORMAT, "invalid key length: %d", cf->length);
+	if ((crypt->r == 5 || crypt->r == 6) && cf->length != 256)
+	{
+		fz_warn(ctx, "illegal key length for revision 5/6, assuming 256 bits");
+		cf->length = 256;
+	}
+}
+
+/*
+ * Compute an encryption key (PDF 1.7 algorithm 3.2)
+ */
+
+static const unsigned char padding[32] =
+{
+	0x28, 0xbf, 0x4e, 0x5e, 0x4e, 0x75, 0x8a, 0x41,
+	0x64, 0x00, 0x4e, 0x56, 0xff, 0xfa, 0x01, 0x08,
+	0x2e, 0x2e, 0x00, 0xb6, 0xd0, 0x68, 0x3e, 0x80,
+	0x2f, 0x0c, 0xa9, 0xfe, 0x64, 0x53, 0x69, 0x7a
+};
+
+static void
+pdf_compute_encryption_key(fz_context *ctx, pdf_crypt *crypt, unsigned char *password, size_t pwlen, unsigned char *key)
+{
+	unsigned char buf[32];
+	unsigned int p;
+	int i, n;
+	fz_md5 md5;
+
+	n = fz_clampi(crypt->length / 8, 0, 16);
+
+	/* Step 1 - copy and pad password string */
+	if (pwlen > 32)
+		pwlen = 32;
+	memcpy(buf, password, pwlen);
+	if (pwlen < 32)
+		memcpy(buf + pwlen, padding, 32 - pwlen);
+
+	/* Step 2 - init md5 and pass value of step 1 */
+	fz_md5_init(&md5);
+	fz_md5_update(&md5, buf, 32);
+
+	/* Step 3 - pass O value */
+	fz_md5_update(&md5, crypt->o, 32);
+
+	/* Step 4 - pass P value as unsigned int, low-order byte first */
+	p = (unsigned int) crypt->p;
+	buf[0] = (p) & 0xFF;
+	buf[1] = (p >> 8) & 0xFF;
+	buf[2] = (p >> 16) & 0xFF;
+	buf[3] = (p >> 24) & 0xFF;
+	fz_md5_update(&md5, buf, 4);
+
+	/* Step 5 - pass first element of ID array */
+	fz_md5_update(&md5, (unsigned char *)pdf_to_str_buf(ctx, crypt->id), pdf_to_str_len(ctx, crypt->id));
+
+	/* Step 6 (revision 4 or greater) - if metadata is not encrypted pass 0xFFFFFFFF */
+	if (crypt->r >= 4)
+	{
+		if (!crypt->encrypt_metadata)
+		{
+			buf[0] = 0xFF;
+			buf[1] = 0xFF;
+			buf[2] = 0xFF;
+			buf[3] = 0xFF;
+			fz_md5_update(&md5, buf, 4);
+		}
+	}
+
+	/* Step 7 - finish the hash */
+	fz_md5_final(&md5, buf);
+
+	/* Step 8 (revision 3 or greater) - do some voodoo 50 times */
+	if (crypt->r >= 3)
+	{
+		for (i = 0; i < 50; i++)
+		{
+			fz_md5_init(&md5);
+			fz_md5_update(&md5, buf, n);
+			fz_md5_final(&md5, buf);
+		}
+	}
+
+	/* Step 9 - the key is the first 'n' bytes of the result */
+	memcpy(key, buf, n);
+}
+
+/*
+ * Compute an encryption key (PDF 1.7 ExtensionLevel 3 algorithm 3.2a)
+ */
+
+static void
+pdf_compute_encryption_key_r5(fz_context *ctx, pdf_crypt *crypt, unsigned char *password, size_t pwlen, int ownerkey, unsigned char *validationkey)
+{
+	unsigned char buffer[128 + 8 + 48];
+	fz_sha256 sha256;
+	fz_aes aes;
+
+	/* Step 2 - truncate UTF-8 password to 127 characters */
+
+	if (pwlen > 127)
+		pwlen = 127;
+
+	/* Step 3/4 - test password against owner/user key and compute encryption key */
+
+	memcpy(buffer, password, pwlen);
+	if (ownerkey)
+	{
+		memcpy(buffer + pwlen, crypt->o + 32, 8);
+		memcpy(buffer + pwlen + 8, crypt->u, 48);
+	}
+	else
+		memcpy(buffer + pwlen, crypt->u + 32, 8);
+
+	fz_sha256_init(&sha256);
+	fz_sha256_update(&sha256, buffer, pwlen + 8 + (ownerkey ? 48 : 0));
+	fz_sha256_final(&sha256, validationkey);
+
+	/* Step 3.5/4.5 - compute file encryption key from OE/UE */
+
+	if (ownerkey)
+	{
+		memcpy(buffer + pwlen, crypt->o + 40, 8);
+		memcpy(buffer + pwlen + 8, crypt->u, 48);
+	}
+	else
+		memcpy(buffer + pwlen, crypt->u + 40, 8);
+
+	fz_sha256_init(&sha256);
+	fz_sha256_update(&sha256, buffer, pwlen + 8 + (ownerkey ? 48 : 0));
+	fz_sha256_final(&sha256, buffer);
+
+	/* clear password buffer and use it as iv */
+	memset(buffer + 32, 0, sizeof(buffer) - 32);
+	if (fz_aes_setkey_dec(&aes, buffer, crypt->length))
+		fz_throw(ctx, FZ_ERROR_FORMAT, "aes invalid key size (%d)", crypt->length);
+	fz_aes_crypt_cbc(&aes, FZ_AES_DECRYPT, 32, buffer + 32, ownerkey ? crypt->oe : crypt->ue, crypt->key);
+}
+
+/*
+ * Compute an encryption key (PDF 1.7 ExtensionLevel 8 algorithm)
+ *
+ * Adobe has not yet released the details, so the algorithm reference is:
+ * http://esec-lab.sogeti.com/post/The-undocumented-password-validation-algorithm-of-Adobe-Reader-X
+ */
+
+static void
+pdf_compute_hardened_hash_r6(fz_context *ctx, unsigned char *password, size_t pwlen, unsigned char salt[8], unsigned char *ownerkey, unsigned char hash[32])
+{
+	unsigned char data[(128 + 64 + 48) * 64];
+	unsigned char block[64];
+	int block_size = 32;
+	size_t data_len = 0;
+	int i, j, sum;
+
+	fz_sha256 sha256;
+	fz_sha384 sha384;
+	fz_sha512 sha512;
+	fz_aes aes;
+
+	/* Step 1: calculate initial data block */
+	fz_sha256_init(&sha256);
+	fz_sha256_update(&sha256, password, pwlen);
+	fz_sha256_update(&sha256, salt, 8);
+	if (ownerkey)
+		fz_sha256_update(&sha256, ownerkey, 48);
+	fz_sha256_final(&sha256, block);
+
+	for (i = 0; i < 64 || i < data[data_len * 64 - 1] + 32; i++)
+	{
+		/* Step 2: repeat password and data block 64 times */
+		memcpy(data, password, pwlen);
+		memcpy(data + pwlen, block, block_size);
+		if (ownerkey)
+			memcpy(data + pwlen + block_size, ownerkey, 48);
+		data_len = pwlen + block_size + (ownerkey ? 48 : 0);
+		for (j = 1; j < 64; j++)
+			memcpy(data + j * data_len, data, data_len);
+
+		/* Step 3: encrypt data using data block as key and iv */
+		(void)fz_aes_setkey_enc(&aes, block, 128);
+		fz_aes_crypt_cbc(&aes, FZ_AES_ENCRYPT, data_len * 64, block + 16, data, data);
+
+		/* Step 4: determine SHA-2 hash size for this round */
+		for (j = 0, sum = 0; j < 16; j++)
+			sum += data[j];
+
+		/* Step 5: calculate data block for next round */
+		block_size = 32 + (sum % 3) * 16;
+		switch (block_size)
+		{
+		case 32:
+			fz_sha256_init(&sha256);
+			fz_sha256_update(&sha256, data, data_len * 64);
+			fz_sha256_final(&sha256, block);
+			break;
+		case 48:
+			fz_sha384_init(&sha384);
+			fz_sha384_update(&sha384, data, data_len * 64);
+			fz_sha384_final(&sha384, block);
+			break;
+		case 64:
+			fz_sha512_init(&sha512);
+			fz_sha512_update(&sha512, data, data_len * 64);
+			fz_sha512_final(&sha512, block);
+			break;
+		}
+	}
+
+	memset(data, 0, sizeof(data));
+	memcpy(hash, block, 32);
+}
+
+static void
+pdf_compute_encryption_key_r6(fz_context *ctx, pdf_crypt *crypt, unsigned char *password, size_t pwlen, int ownerkey, unsigned char *validationkey)
+{
+	unsigned char hash[32];
+	unsigned char iv[16];
+	fz_aes aes;
+
+	if (pwlen > 127)
+		pwlen = 127;
+
+	pdf_compute_hardened_hash_r6(ctx, password, pwlen,
+		(ownerkey ? crypt->o : crypt->u) + 32,
+		ownerkey ? crypt->u : NULL, validationkey);
+	pdf_compute_hardened_hash_r6(ctx, password, pwlen,
+		(ownerkey ? crypt->o : crypt->u) + 40,
+		(ownerkey ? crypt->u : NULL),
+		hash);
+
+	memset(iv, 0, sizeof(iv));
+	(void)fz_aes_setkey_dec(&aes, hash, 256);
+	fz_aes_crypt_cbc(&aes, FZ_AES_DECRYPT, 32, iv, ownerkey ? crypt->oe : crypt->ue, crypt->key);
+}
+
+/*
+ * Computing the user password (PDF 1.7 algorithm 3.4 and 3.5)
+ * Also save the generated key for decrypting objects and streams in crypt->key.
+ */
+
+static void
+pdf_compute_user_password(fz_context *ctx, pdf_crypt *crypt, unsigned char *password, size_t pwlen, unsigned char *output)
+{
+	int n = fz_clampi(crypt->length / 8, 0, 16);
+
+	if (crypt->r == 2)
+	{
+		fz_arc4 arc4;
+
+		pdf_compute_encryption_key(ctx, crypt, password, pwlen, crypt->key);
+		fz_arc4_init(&arc4, crypt->key, n);
+		fz_arc4_encrypt(&arc4, output, padding, 32);
+	}
+
+	if (crypt->r == 3 || crypt->r == 4)
+	{
+		unsigned char xor[32];
+		unsigned char digest[16];
+		fz_md5 md5;
+		fz_arc4 arc4;
+		int i, x;
+
+		pdf_compute_encryption_key(ctx, crypt, password, pwlen, crypt->key);
+
+		fz_md5_init(&md5);
+		fz_md5_update(&md5, padding, 32);
+		fz_md5_update(&md5, (unsigned char*)pdf_to_str_buf(ctx, crypt->id), pdf_to_str_len(ctx, crypt->id));
+		fz_md5_final(&md5, digest);
+
+		fz_arc4_init(&arc4, crypt->key, n);
+		fz_arc4_encrypt(&arc4, output, digest, 16);
+
+		for (x = 1; x <= 19; x++)
+		{
+			for (i = 0; i < n; i++)
+				xor[i] = crypt->key[i] ^ x;
+			fz_arc4_init(&arc4, xor, n);
+			fz_arc4_encrypt(&arc4, output, output, 16);
+		}
+
+		memcpy(output + 16, padding, 16);
+	}
+
+	if (crypt->r == 5)
+	{
+		pdf_compute_encryption_key_r5(ctx, crypt, password, pwlen, 0, output);
+	}
+
+	if (crypt->r == 6)
+	{
+		pdf_compute_encryption_key_r6(ctx, crypt, password, pwlen, 0, output);
+	}
+}
+
+/*
+ * Authenticating the user password (PDF 1.7 algorithm 3.6
+ * and ExtensionLevel 3 algorithm 3.11)
+ * This also has the side effect of saving a key generated
+ * from the password for decrypting objects and streams.
+ */
+
+static int
+pdf_authenticate_user_password(fz_context *ctx, pdf_crypt *crypt, unsigned char *password, size_t pwlen)
+{
+	unsigned char output[32];
+	pdf_compute_user_password(ctx, crypt, password, pwlen, output);
+	if (crypt->r == 2 || crypt->r == 5 || crypt->r == 6)
+		return memcmp(output, crypt->u, 32) == 0;
+	if (crypt->r == 3 || crypt->r == 4)
+		return memcmp(output, crypt->u, 16) == 0;
+	return 0;
+}
+
+/*
+ * Authenticating the owner password (PDF 1.7 algorithm 3.7,
+ * ExtensionLevel 3 algorithm 3.12, ExtensionLevel 8 algorithm)
+ * Generates the user password from the owner password
+ * and calls pdf_authenticate_user_password.
+ */
+
+static int
+pdf_authenticate_owner_password(fz_context *ctx, pdf_crypt *crypt, unsigned char *ownerpass, size_t pwlen)
+{
+	int n = fz_clampi(crypt->length / 8, 0, 16);
+
+	if (crypt->r == 2)
+	{
+		unsigned char pwbuf[32];
+		unsigned char key[16];
+		unsigned char userpass[32];
+		fz_md5 md5;
+		fz_arc4 arc4;
+
+		if (pwlen > 32)
+			pwlen = 32;
+		memcpy(pwbuf, ownerpass, pwlen);
+		if (pwlen < 32)
+			memcpy(pwbuf + pwlen, padding, 32 - pwlen);
+
+		fz_md5_init(&md5);
+		fz_md5_update(&md5, pwbuf, 32);
+		fz_md5_final(&md5, key);
+
+		fz_arc4_init(&arc4, key, n);
+		fz_arc4_encrypt(&arc4, userpass, crypt->o, 32);
+
+		return pdf_authenticate_user_password(ctx, crypt, userpass, 32);
+	}
+
+	if (crypt->r == 3 || crypt->r == 4)
+	{
+		unsigned char pwbuf[32];
+		unsigned char key[16];
+		unsigned char xor[32];
+		unsigned char userpass[32];
+		int i, x;
+		fz_md5 md5;
+		fz_arc4 arc4;
+
+		if (pwlen > 32)
+			pwlen = 32;
+		memcpy(pwbuf, ownerpass, pwlen);
+		if (pwlen < 32)
+			memcpy(pwbuf + pwlen, padding, 32 - pwlen);
+
+		fz_md5_init(&md5);
+		fz_md5_update(&md5, pwbuf, 32);
+		fz_md5_final(&md5, key);
+
+		for (i = 0; i < 50; i++)
+		{
+			fz_md5_init(&md5);
+			fz_md5_update(&md5, key, n);
+			fz_md5_final(&md5, key);
+		}
+
+		memcpy(userpass, crypt->o, 32);
+		for (x = 0; x < 20; x++)
+		{
+			for (i = 0; i < n; i++)
+				xor[i] = key[i] ^ (19 - x);
+			fz_arc4_init(&arc4, xor, n);
+			fz_arc4_encrypt(&arc4, userpass, userpass, 32);
+		}
+
+		return pdf_authenticate_user_password(ctx, crypt, userpass, 32);
+	}
+
+	if (crypt->r == 5)
+	{
+		unsigned char key[32];
+		pdf_compute_encryption_key_r5(ctx, crypt, ownerpass, pwlen, 1, key);
+		return !memcmp(key, crypt->o, 32);
+	}
+
+	if (crypt->r == 6)
+	{
+		unsigned char key[32];
+		pdf_compute_encryption_key_r6(ctx, crypt, ownerpass, pwlen, 1, key);
+		return !memcmp(key, crypt->o, 32);
+	}
+
+	return 0;
+}
+
+static void pdf_docenc_from_utf8(char *password, const char *utf8, int n)
+{
+	int i = 0, k, c;
+	while (*utf8 && i + 1 < n)
+	{
+		utf8 += fz_chartorune(&c, utf8);
+		for (k = 0; k < 256; k++)
+		{
+			if (c == fz_unicode_from_pdf_doc_encoding[k])
+			{
+				password[i++] = k;
+				break;
+			}
+		}
+		/* FIXME: drop characters that can't be encoded or return an error? */
+	}
+	password[i] = 0;
+}
+
+static void pdf_saslprep_from_utf8(char *password, const char *utf8, int n)
+{
+	/* TODO: stringprep with SALSprep profile */
+	fz_strlcpy(password, utf8, n);
+}
+
+int
+pdf_authenticate_password(fz_context *ctx, pdf_document *doc, const char *pwd_utf8)
+{
+	char password[2048];
+	int auth;
+
+	if (!doc->crypt)
+		return 1; /* No password required */
+
+	password[0] = 0;
+	if (pwd_utf8)
+	{
+		if (doc->crypt->r <= 4)
+			pdf_docenc_from_utf8(password, pwd_utf8, sizeof password);
+		else
+			pdf_saslprep_from_utf8(password, pwd_utf8, sizeof password);
+	}
+
+	auth = 0;
+	if (pdf_authenticate_user_password(ctx, doc->crypt, (unsigned char *)password, strlen(password)))
+		auth = 2;
+	if (pdf_authenticate_owner_password(ctx, doc->crypt, (unsigned char *)password, strlen(password)))
+		auth |= 4;
+	else if (auth & 2)
+	{
+		/* We need to reauthenticate the user password,
+		 * because the failed attempt to authenticate
+		 * the owner password will have invalidated the
+		 * stored keys. */
+		(void)pdf_authenticate_user_password(ctx, doc->crypt, (unsigned char *)password, strlen(password));
+	}
+
+	/* To match Acrobat, we choose not to allow an empty owner
+	 * password, unless the user password is also the empty one. */
+	if (*password == 0 && auth == 4)
+		return 0;
+
+	return auth;
+}
+
+int
+pdf_needs_password(fz_context *ctx, pdf_document *doc)
+{
+	if (!doc->crypt)
+		return 0;
+	if (pdf_authenticate_password(ctx, doc, ""))
+		return 0;
+	return 1;
+}
+
+int
+pdf_has_permission(fz_context *ctx, pdf_document *doc, fz_permission p)
+{
+	if (!doc->crypt)
+		return 1;
+	switch (p)
+	{
+	case FZ_PERMISSION_PRINT: return doc->crypt->p & PDF_PERM_PRINT;
+	case FZ_PERMISSION_EDIT: return doc->crypt->p & PDF_PERM_MODIFY;
+	case FZ_PERMISSION_COPY: return doc->crypt->p & PDF_PERM_COPY;
+	case FZ_PERMISSION_ANNOTATE: return doc->crypt->p & PDF_PERM_ANNOTATE;
+	case FZ_PERMISSION_FORM: return doc->crypt->p & PDF_PERM_FORM;
+	case FZ_PERMISSION_ACCESSIBILITY: return doc->crypt->p & PDF_PERM_ACCESSIBILITY;
+	case FZ_PERMISSION_ASSEMBLE: return doc->crypt->p & PDF_PERM_ASSEMBLE;
+	case FZ_PERMISSION_PRINT_HQ: return doc->crypt->p & PDF_PERM_PRINT_HQ;
+	}
+	return 1;
+}
+
+int
+pdf_document_permissions(fz_context *ctx, pdf_document *doc)
+{
+	if (doc->crypt)
+		return doc->crypt->p;
+	/* all permissions granted, reserved bits set appropriately */
+	return (int)0xFFFFFFFC;
+}
+
+/*
+ * Compute the owner password (PDF 1.7 algorithm 3.3)
+ */
+
+static void
+pdf_compute_owner_password(fz_context *ctx, pdf_crypt *crypt, unsigned char *opassword, size_t opwlen, unsigned char *upassword, size_t upwlen, unsigned char *output)
+{
+	unsigned char obuf[32];
+	unsigned char ubuf[32];
+	unsigned char digest[32];
+	int i, n;
+	fz_md5 md5;
+	fz_arc4 arc4;
+
+	n = fz_clampi(crypt->length / 8, 0, 16);
+
+	/* Step 1 - copy and pad owner password string */
+	if (opwlen > 32)
+		opwlen = 32;
+	memcpy(obuf, opassword, opwlen);
+	if (opwlen < 32)
+		memcpy(obuf + opwlen, padding, 32 - opwlen);
+
+	/* Step 2 - init md5 and pass value of step 1 */
+	fz_md5_init(&md5);
+	fz_md5_update(&md5, obuf, 32);
+	fz_md5_final(&md5, obuf);
+
+	/* Step 3 (revision 3 or greater) - do some voodoo 50 times */
+	if (crypt->r >= 3)
+	{
+		for (i = 0; i < 50; i++)
+		{
+			fz_md5_init(&md5);
+			fz_md5_update(&md5, obuf, n);
+			fz_md5_final(&md5, obuf);
+		}
+	}
+
+	/* Step 4 - encrypt owner password md5 hash */
+	fz_arc4_init(&arc4, obuf, n);
+
+	/* Step 5 - copy and pad user password string */
+	if (upwlen > 32)
+		upwlen = 32;
+	memcpy(ubuf, upassword, upwlen);
+	if (upwlen < 32)
+		memcpy(ubuf + upwlen, padding, 32 - upwlen);
+
+	/* Step 6 - encrypt user password md5 hash */
+	fz_arc4_encrypt(&arc4, digest, ubuf, 32);
+
+	/* Step 7 - */
+	if (crypt->r >= 3)
+	{
+		unsigned char xor[32];
+		int x;
+
+		for (x = 1; x <= 19; x++)
+		{
+			for (i = 0; i < n; i++)
+				xor[i] = obuf[i] ^ x;
+			fz_arc4_init(&arc4, xor, n);
+			fz_arc4_encrypt(&arc4, digest, digest, 32);
+		}
+	}
+
+	/* Step 8 - the owner password is the first 16 bytes of the result */
+	memcpy(output, digest, 32);
+}
+
+unsigned char *
+pdf_crypt_key(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->key;
+	return NULL;
+}
+
+int
+pdf_crypt_version(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->v;
+	return 0;
+}
+
+int pdf_crypt_revision(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->r;
+	return 0;
+}
+
+static char *
+crypt_method(fz_context *ctx, int method)
+{
+	switch (method)
+	{
+	default:
+	case PDF_CRYPT_UNKNOWN: return "Unknown";
+	case PDF_CRYPT_NONE: return "None";
+	case PDF_CRYPT_RC4: return "RC4";
+	case PDF_CRYPT_AESV2: return "AES";
+	case PDF_CRYPT_AESV3: return "AES";
+	}
+}
+
+const char *
+pdf_crypt_string_method(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt_method(ctx, crypt->strf.method);
+	return "None";
+}
+
+const char *
+pdf_crypt_stream_method(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt_method(ctx, crypt->stmf.method);
+	return "None";
+}
+
+const char *
+pdf_crypt_method(fz_context *ctx, pdf_crypt *crypt)
+{
+	return pdf_crypt_string_method(ctx, crypt);
+}
+
+int
+pdf_crypt_length(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->length;
+	return 0;
+}
+
+int
+pdf_crypt_permissions(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->p;
+	return 0;
+}
+
+int
+pdf_crypt_encrypt_metadata(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->encrypt_metadata;
+	return 0;
+}
+
+unsigned char *
+pdf_crypt_owner_password(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->o;
+	return NULL;
+}
+
+unsigned char *
+pdf_crypt_user_password(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->u;
+	return NULL;
+}
+
+unsigned char *
+pdf_crypt_owner_encryption(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->oe;
+	return NULL;
+}
+
+unsigned char *
+pdf_crypt_user_encryption(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->ue;
+	return NULL;
+}
+
+unsigned char *
+pdf_crypt_permissions_encryption(fz_context *ctx, pdf_crypt *crypt)
+{
+	if (crypt)
+		return crypt->perms;
+	return 0;
+}
+
+/*
+ * PDF 1.7 algorithm 3.1 and ExtensionLevel 3 algorithm 3.1a
+ *
+ * Using the global encryption key that was generated from the
+ * password, create a new key that is used to decrypt individual
+ * objects and streams. This key is based on the object and
+ * generation numbers.
+ */
+
+static int
+pdf_compute_object_key(pdf_crypt *crypt, pdf_crypt_filter *cf, int num, int gen, unsigned char *key, int max_len)
+{
+	fz_md5 md5;
+	unsigned char message[5];
+	int key_len = crypt->length / 8;
+
+	if (key_len > max_len)
+		key_len = max_len;
+
+	/* Encryption method version 0 is undocumented, but a lucky
+	   guess revealed that all streams/strings in those PDFs are
+	   encrypted using the same 40 bit file encryption key using RC4. */
+	if (crypt->v == 0 || cf->method == PDF_CRYPT_AESV3)
+	{
+		memcpy(key, crypt->key, key_len);
+		return key_len;
+	}
+
+	fz_md5_init(&md5);
+	fz_md5_update(&md5, crypt->key, key_len);
+	message[0] = (num) & 0xFF;
+	message[1] = (num >> 8) & 0xFF;
+	message[2] = (num >> 16) & 0xFF;
+	message[3] = (gen) & 0xFF;
+	message[4] = (gen >> 8) & 0xFF;
+	fz_md5_update(&md5, message, 5);
+
+	if (cf->method == PDF_CRYPT_AESV2)
+		fz_md5_update(&md5, (unsigned char *)"sAlT", 4);
+
+	fz_md5_final(&md5, key);
+
+	if (key_len + 5 > 16)
+		return 16;
+	return key_len + 5;
+}
+
+/*
+ * PDF 1.7 algorithm 3.1 and ExtensionLevel 3 algorithm 3.1a
+ *
+ * Decrypt all strings in obj modifying the data in-place.
+ * Recurse through arrays and dictionaries, but do not follow
+ * indirect references.
+ */
+
+static int is_signature(fz_context *ctx, pdf_obj *obj)
+{
+	if (pdf_dict_get(ctx, obj, PDF_NAME(Type)) == PDF_NAME(Sig))
+		if (pdf_dict_get(ctx, obj, PDF_NAME(Contents)) && pdf_dict_get(ctx, obj, PDF_NAME(ByteRange)) && pdf_dict_get(ctx, obj, PDF_NAME(Filter)))
+			return 1;
+	return 0;
+}
+
+static void
+pdf_crypt_obj_imp(fz_context *ctx, pdf_crypt *crypt, pdf_obj *obj, unsigned char *key, int keylen)
+{
+	unsigned char *s;
+	int i;
+
+	if (pdf_is_indirect(ctx, obj))
+		return;
+
+	if (pdf_is_string(ctx, obj))
+	{
+		size_t n = pdf_to_str_len(ctx, obj);
+		s = (unsigned char *)pdf_to_str_buf(ctx, obj);
+
+		if (crypt->strf.method == PDF_CRYPT_RC4)
+		{
+			fz_arc4 arc4;
+			fz_arc4_init(&arc4, key, keylen);
+			fz_arc4_encrypt(&arc4, s, s, n);
+		}
+
+		if (crypt->strf.method == PDF_CRYPT_AESV2 || crypt->strf.method == PDF_CRYPT_AESV3)
+		{
+			if (n == 0)
+			{
+				/* Empty strings are permissible */
+			}
+			else if (n & 15 || n < 32)
+				fz_warn(ctx, "invalid string length for aes encryption");
+			else
+			{
+				unsigned char iv[16];
+				fz_aes aes;
+				memcpy(iv, s, 16);
+				if (fz_aes_setkey_dec(&aes, key, keylen * 8))
+					fz_throw(ctx, FZ_ERROR_FORMAT, "AES key init failed (keylen=%d)", keylen * 8);
+				fz_aes_crypt_cbc(&aes, FZ_AES_DECRYPT, n - 16, iv, s + 16, s);
+				/* delete space used for iv and padding bytes at end */
+				if (s[n - 17] < 1 || s[n - 17] > 16)
+					fz_warn(ctx, "aes padding out of range");
+				else
+					pdf_set_str_len(ctx, obj, n - 16 - s[n - 17]);
+			}
+		}
+	}
+
+	else if (pdf_is_array(ctx, obj))
+	{
+		int n = pdf_array_len(ctx, obj);
+		for (i = 0; i < n; i++)
+		{
+			pdf_crypt_obj_imp(ctx, crypt, pdf_array_get(ctx, obj, i), key, keylen);
+		}
+	}
+
+	else if (pdf_is_dict(ctx, obj))
+	{
+		int n = pdf_dict_len(ctx, obj);
+		for (i = 0; i < n; i++)
+		{
+			if (pdf_dict_get_key(ctx, obj, i) == PDF_NAME(Contents) && is_signature(ctx, obj))
+				continue;
+
+			pdf_crypt_obj_imp(ctx, crypt, pdf_dict_get_val(ctx, obj, i), key, keylen);
+		}
+	}
+}
+
+void
+pdf_crypt_obj(fz_context *ctx, pdf_crypt *crypt, pdf_obj *obj, int num, int gen)
+{
+	unsigned char key[32];
+	int len;
+
+	len = pdf_compute_object_key(crypt, &crypt->strf, num, gen, key, 32);
+
+	pdf_crypt_obj_imp(ctx, crypt, obj, key, len);
+}
+
+/*
+ * PDF 1.7 algorithm 3.1 and ExtensionLevel 3 algorithm 3.1a
+ *
+ * Create filter suitable for de/encrypting a stream.
+ */
+static fz_stream *
+pdf_open_crypt_imp(fz_context *ctx, fz_stream *chain, pdf_crypt *crypt, pdf_crypt_filter *stmf, int num, int gen)
+{
+	unsigned char key[32];
+	int len;
+
+	len = pdf_compute_object_key(crypt, stmf, num, gen, key, 32);
+
+	if (stmf->method == PDF_CRYPT_RC4)
+		return fz_open_arc4(ctx, chain, key, len);
+
+	if (stmf->method == PDF_CRYPT_AESV2 || stmf->method == PDF_CRYPT_AESV3)
+		return fz_open_aesd(ctx, chain, key, len);
+
+	return fz_keep_stream(ctx, chain);
+}
+
+fz_stream *
+pdf_open_crypt(fz_context *ctx, fz_stream *chain, pdf_crypt *crypt, int num, int gen)
+{
+	return pdf_open_crypt_imp(ctx, chain, crypt, &crypt->stmf, num, gen);
+}
+
+fz_stream *
+pdf_open_crypt_with_filter(fz_context *ctx, fz_stream *chain, pdf_crypt *crypt, pdf_obj *name, int num, int gen)
+{
+	if (!pdf_name_eq(ctx, name, PDF_NAME(Identity)))
+	{
+		pdf_crypt_filter cf;
+		pdf_parse_crypt_filter(ctx, &cf, crypt, name);
+		return pdf_open_crypt_imp(ctx, chain, crypt, &cf, num, gen);
+	}
+	return fz_keep_stream(ctx, chain);
+}
+
+void
+pdf_print_crypt(fz_context *ctx, fz_output *out, pdf_crypt *crypt)
+{
+	int i;
+
+	fz_write_printf(ctx, out, "crypt {\n");
+
+	fz_write_printf(ctx, out, "\tv=%d length=%d\n", crypt->v, crypt->length);
+	fz_write_printf(ctx, out, "\tstmf method=%d length=%d\n", crypt->stmf.method, crypt->stmf.length);
+	fz_write_printf(ctx, out, "\tstrf method=%d length=%d\n", crypt->strf.method, crypt->strf.length);
+	fz_write_printf(ctx, out, "\tr=%d\n", crypt->r);
+
+	fz_write_printf(ctx, out, "\to=<");
+	for (i = 0; i < 32; i++)
+		fz_write_printf(ctx, out, "%02X", crypt->o[i]);
+	fz_write_printf(ctx, out, ">\n");
+
+	fz_write_printf(ctx, out, "\tu=<");
+	for (i = 0; i < 32; i++)
+		fz_write_printf(ctx, out, "%02X", crypt->u[i]);
+	fz_write_printf(ctx, out, ">\n");
+
+	fz_write_printf(ctx, out, "}\n");
+}
+
+void pdf_encrypt_data(fz_context *ctx, pdf_crypt *crypt, int num, int gen, void (*write_data)(fz_context *ctx, void *, const unsigned char *, size_t), void *arg, const unsigned char *s, size_t n)
+{
+	unsigned char buffer[256];
+	unsigned char key[32];
+	int keylen;
+
+	if (crypt == NULL)
+	{
+		write_data(ctx, arg, s, n);
+		return;
+	}
+
+	keylen = pdf_compute_object_key(crypt, &crypt->strf, num, gen, key, 32);
+
+	if (crypt->strf.method == PDF_CRYPT_RC4)
+	{
+		fz_arc4 arc4;
+		fz_arc4_init(&arc4, key, keylen);
+		while (n > 0)
+		{
+			size_t len = n;
+			if (len > (int)sizeof(buffer))
+				len = sizeof(buffer);
+			fz_arc4_encrypt(&arc4, buffer, s, len);
+			write_data(ctx, arg, buffer, len);
+			s += len;
+			n -= len;
+		}
+		return;
+	}
+
+	if (crypt->strf.method == PDF_CRYPT_AESV2 || crypt->strf.method == PDF_CRYPT_AESV3)
+	{
+		size_t len = 0;
+		fz_aes aes;
+		unsigned char iv[16];
+
+		/* Empty strings can be represented by empty strings */
+		if (n == 0)
+			return;
+
+		if (fz_aes_setkey_enc(&aes, key, keylen * 8))
+			fz_throw(ctx, FZ_ERROR_FORMAT, "AES key init failed (keylen=%d)", keylen * 8);
+
+		fz_memrnd(ctx, iv, 16);
+		write_data(ctx, arg, iv, 16);
+
+		while (n > 0)
+		{
+			len = n;
+			if (len > 16)
+				len = 16;
+			memcpy(buffer, s, len);
+			if (len != 16)
+				memset(&buffer[len], 16-(int)len, 16-len);
+			fz_aes_crypt_cbc(&aes, FZ_AES_ENCRYPT, 16, iv, buffer, buffer+16);
+			write_data(ctx, arg, buffer+16, 16);
+			s += len;
+			n -= len;
+		}
+		if (len == 16) {
+			memset(buffer, 16, 16);
+			fz_aes_crypt_cbc(&aes, FZ_AES_ENCRYPT, 16, iv, buffer, buffer+16);
+			write_data(ctx, arg, buffer+16, 16);
+		}
+		return;
+	}
+
+	/* Should never happen, but... */
+	write_data(ctx, arg, s, n);
+}
+
+size_t pdf_encrypted_len(fz_context *ctx, pdf_crypt *crypt, int num, int gen, size_t len)
+{
+	if (crypt == NULL)
+		return len;
+
+	if (crypt->strf.method == PDF_CRYPT_AESV2 || crypt->strf.method == PDF_CRYPT_AESV3)
+	{
+		len += 16; /* 16 for IV */
+		if ((len & 15) == 0)
+			len += 16; /* Another 16 if our last block is full anyway */
+		len = (len + 15) & ~15; /* And pad to the block */
+	}
+
+	return len;
+}
+
+/* PDF 2.0 algorithm 8 */
+static void
+pdf_compute_user_password_r6(fz_context *ctx, pdf_crypt *crypt, unsigned char *password, size_t pwlen, unsigned char *outputpw, unsigned char *outputencryption)
+{
+	unsigned char validationsalt[8];
+	unsigned char keysalt[8];
+	unsigned char hash[32];
+	unsigned char iv[16];
+	fz_aes aes;
+
+	/* Step a) - Generate random salts. */
+	fz_memrnd(ctx, validationsalt, nelem(validationsalt));
+	fz_memrnd(ctx, keysalt, nelem(keysalt));
+
+	/* Step a) - Compute 32 byte hash given password and validation salt. */
+	pdf_compute_hardened_hash_r6(ctx, password, pwlen, validationsalt, NULL, outputpw);
+	memcpy(outputpw + 32, validationsalt, nelem(validationsalt));
+	memcpy(outputpw + 40, keysalt, nelem(keysalt));
+
+	/* Step b) - Compute 32 byte hash given password and user salt. */
+	pdf_compute_hardened_hash_r6(ctx, password, pwlen, keysalt, NULL, hash);
+
+	/* Step b) - Use hash as AES-key when encrypting the file encryption key. */
+	memset(iv, 0, sizeof(iv));
+	(void)fz_aes_setkey_enc(&aes, hash, 256);
+	fz_aes_crypt_cbc(&aes, FZ_AES_ENCRYPT, 32, iv, crypt->key, outputencryption);
+}
+
+/* PDF 2.0 algorithm 9 */
+static void
+pdf_compute_owner_password_r6(fz_context *ctx, pdf_crypt *crypt, unsigned char *password, size_t pwlen, unsigned char *outputpw, unsigned char *outputencryption)
+{
+	unsigned char validationsalt[8];
+	unsigned char keysalt[8];
+	unsigned char hash[32];
+	unsigned char iv[16];
+	fz_aes aes;
+
+	/* Step a) - Generate random salts. */
+	fz_memrnd(ctx, validationsalt, nelem(validationsalt));
+	fz_memrnd(ctx, keysalt, nelem(keysalt));
+
+	/* Step a) - Compute 32 byte hash given owner password, validation salt and user password. */
+	pdf_compute_hardened_hash_r6(ctx, password, pwlen, validationsalt, crypt->u, outputpw);
+	memcpy(outputpw + 32, validationsalt, nelem(validationsalt));
+	memcpy(outputpw + 40, keysalt, nelem(keysalt));
+
+	/* Step b) - Compute 32 byte hash given owner password, user salt and user password. */
+	pdf_compute_hardened_hash_r6(ctx, password, pwlen, keysalt, crypt->u, hash);
+
+	/* Step b) - Use hash as AES-key when encrypting the file encryption key. */
+	memset(iv, 0, sizeof(iv));
+	(void)fz_aes_setkey_enc(&aes, hash, 256);
+	fz_aes_crypt_cbc(&aes, FZ_AES_ENCRYPT, 32, iv, crypt->key, outputencryption);
+}
+
+/* PDF 2.0 algorithm 10 */
+static void
+pdf_compute_permissions_r6(fz_context *ctx, pdf_crypt *crypt, unsigned char *output)
+{
+	unsigned char buf[16];
+	unsigned char iv[16];
+	fz_aes aes;
+
+	/* Steps a) and b) - Extend permissions field and put into lower order bytes. */
+	memcpy(buf, (unsigned char *) &crypt->p, 4);
+	memset(&buf[4], 0xff, 4);
+
+	/* Step c) - Encode EncryptMetadata as T/F. */
+	buf[8] = crypt->encrypt_metadata ? 'T' : 'F';
+
+	/* Step d) - Encode ASCII characters "adb". */
+	buf[9] = 'a';
+	buf[10] = 'd';
+	buf[11] = 'b';
+
+	/* Step e) - Encode 4 random bytes. */
+	fz_memrnd(ctx, &buf[12], 4);
+
+	/* Step f) - Use file encryption key as AES-key when encrypting buffer. */
+	memset(iv, 0, sizeof(iv));
+	(void)fz_aes_setkey_enc(&aes, crypt->key, 256);
+	fz_aes_crypt_cbc(&aes, FZ_AES_ENCRYPT, 16, iv, buf, output);
+}
+
+pdf_crypt *
+pdf_new_encrypt(fz_context *ctx, const char *opwd_utf8, const char *upwd_utf8, pdf_obj *id, int permissions, int algorithm)
+{
+	pdf_crypt *crypt;
+	int v, r, method, length;
+	unsigned char opwd[2048];
+	unsigned char upwd[2048];
+	size_t opwdlen, upwdlen;
+
+	crypt = fz_malloc_struct(ctx, pdf_crypt);
+
+	/* Extract file identifier string */
+
+	if (pdf_is_string(ctx, id))
+		crypt->id = pdf_keep_obj(ctx, id);
+	else
+		fz_warn(ctx, "missing file identifier, may not be able to do decryption");
+
+	switch (algorithm)
+	{
+	case PDF_ENCRYPT_RC4_40:
+		v = 1; r = 2; method = PDF_CRYPT_RC4; length = 40; break;
+	case PDF_ENCRYPT_RC4_128:
+		v = 2; r = 3; method = PDF_CRYPT_RC4; length = 128; break;
+	case PDF_ENCRYPT_AES_128:
+		v = 4; r = 4; method = PDF_CRYPT_AESV2; length = 128; break;
+	case PDF_ENCRYPT_AES_256:
+		v = 5; r = 6; method = PDF_CRYPT_AESV3; length = 256; break;
+	default:
+		fz_throw(ctx, FZ_ERROR_FORMAT, "invalid encryption method");
+	}
+
+	crypt->v = v;
+	crypt->r = r;
+	crypt->length = length;
+	crypt->cf = NULL;
+	crypt->stmf.method = method;
+	crypt->stmf.length = length;
+	crypt->strf.method = method;
+	crypt->strf.length = length;
+	crypt->encrypt_metadata = 1;
+	crypt->p = (permissions & 0xf3c) | 0xfffff0c0;
+	memset(crypt->o, 0, sizeof (crypt->o));
+	memset(crypt->u, 0, sizeof (crypt->u));
+	memset(crypt->oe, 0, sizeof (crypt->oe));
+	memset(crypt->ue, 0, sizeof (crypt->ue));
+
+	if (crypt->r <= 4)
+	{
+		pdf_docenc_from_utf8((char *) opwd, opwd_utf8, sizeof opwd);
+		pdf_docenc_from_utf8((char *) upwd, upwd_utf8, sizeof upwd);
+	}
+	else
+	{
+		pdf_saslprep_from_utf8((char *) opwd, opwd_utf8, sizeof opwd);
+		pdf_saslprep_from_utf8((char *) upwd, upwd_utf8, sizeof upwd);
+	}
+
+	opwdlen = strlen((char *) opwd);
+	upwdlen = strlen((char *) upwd);
+
+	if (crypt->r <= 4)
+	{
+		pdf_compute_owner_password(ctx, crypt, opwd, opwdlen, upwd, upwdlen, crypt->o);
+		pdf_compute_user_password(ctx, crypt, upwd, upwdlen, crypt->u);
+	}
+	else if (crypt->r == 6)
+	{
+		/* 7.6.4.4.1 states that the file encryption key are 256 random bits. */
+		fz_memrnd(ctx, crypt->key, nelem(crypt->key));
+
+		pdf_compute_user_password_r6(ctx, crypt, upwd, upwdlen, crypt->u, crypt->ue);
+		pdf_compute_owner_password_r6(ctx, crypt, opwd, opwdlen, crypt->o, crypt->oe);
+		pdf_compute_permissions_r6(ctx, crypt, crypt->perms);
+	}
+
+	return crypt;
+}