Add support for AESv3 encryption from SumatraPDF.

2 files changed, 200 insertions, 0 deletions

diff --git a/fitz/crypt_sha2.c b/fitz/crypt_sha2.c
new file mode 100644
index 00000000..6796c5ab
--- /dev/null
+++ b/fitz/crypt_sha2.c
@@ -0,0 +1,182 @@
+/*
+This code is based on the code found from 7-Zip, which has a modified
+version of the SHA-256 found from Crypto++ <http://www.cryptopp.com/>.
+The code was modified a little to fit into liblzma and fitz.
+
+This file has been put into the public domain.
+You can do whatever you want with this file.
+*/
+
+#include "fitz.h"
+
+static inline int isbigendian(void)
+{
+	static const int one = 1;
+	return *(char*)&one == 0;
+}
+
+static inline unsigned int bswap32(unsigned int num)
+{
+	if (!isbigendian())
+	{
+		return	( (((num) << 24))
+			| (((num) << 8) & 0x00FF0000)
+			| (((num) >> 8) & 0x0000FF00)
+			| (((num) >> 24)) );
+	}
+	return num;
+}
+
+/* At least on x86, GCC is able to optimize this to a rotate instruction. */
+#define rotr_32(num, amount) ((num) >> (amount) | (num) << (32 - (amount)))
+
+#define blk0(i) (W[i] = data[i])
+#define blk2(i) (W[i & 15] += s1(W[(i - 2) & 15]) + W[(i - 7) & 15] \
+		+ s0(W[(i - 15) & 15]))
+
+#define Ch(x, y, z) (z ^ (x & (y ^ z)))
+#define Maj(x, y, z) ((x & y) | (z & (x | y)))
+
+#define a(i) T[(0 - i) & 7]
+#define b(i) T[(1 - i) & 7]
+#define c(i) T[(2 - i) & 7]
+#define d(i) T[(3 - i) & 7]
+#define e(i) T[(4 - i) & 7]
+#define f(i) T[(5 - i) & 7]
+#define g(i) T[(6 - i) & 7]
+#define h(i) T[(7 - i) & 7]
+
+#define R(i) \
+	h(i) += S1(e(i)) + Ch(e(i), f(i), g(i)) + SHA256_K[i + j] \
+		+ (j ? blk2(i) : blk0(i)); \
+	d(i) += h(i); \
+	h(i) += S0(a(i)) + Maj(a(i), b(i), c(i))
+
+#define S0(x) (rotr_32(x, 2) ^ rotr_32(x, 13) ^ rotr_32(x, 22))
+#define S1(x) (rotr_32(x, 6) ^ rotr_32(x, 11) ^ rotr_32(x, 25))
+#define s0(x) (rotr_32(x, 7) ^ rotr_32(x, 18) ^ (x >> 3))
+#define s1(x) (rotr_32(x, 17) ^ rotr_32(x, 19) ^ (x >> 10))
+
+static const unsigned int SHA256_K[64] = {
+	0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5,
+	0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5,
+	0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3,
+	0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174,
+	0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC,
+	0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA,
+	0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7,
+	0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967,
+	0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13,
+	0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85,
+	0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3,
+	0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070,
+	0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5,
+	0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3,
+	0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208,
+	0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2,
+};
+
+static void
+transform(unsigned int state[8], const unsigned int data_xe[16])
+{
+	unsigned int data[16];
+	unsigned int W[16];
+	unsigned int T[8];
+	unsigned int j;
+
+	/* ensure big-endian integers */
+	for (j = 0; j < 16; j++)
+		data[j] = bswap32(data_xe[j]);
+
+	/* Copy state[] to working vars. */
+	memcpy(T, state, sizeof(T));
+
+	/* 64 operations, partially loop unrolled */
+	for (j = 0; j < 64; j += 16) {
+		R( 0); R( 1); R( 2); R( 3);
+		R( 4); R( 5); R( 6); R( 7);
+		R( 8); R( 9); R(10); R(11);
+		R(12); R(13); R(14); R(15);
+	}
+
+	/* Add the working vars back into state[]. */
+	state[0] += a(0);
+	state[1] += b(0);
+	state[2] += c(0);
+	state[3] += d(0);
+	state[4] += e(0);
+	state[5] += f(0);
+	state[6] += g(0);
+	state[7] += h(0);
+}
+
+void fz_sha256init(fz_sha256 *context)
+{
+	context->count[0] = context->count[1] = 0;
+
+	context->state[0] = 0x6A09E667;
+	context->state[1] = 0xBB67AE85;
+	context->state[2] = 0x3C6EF372;
+	context->state[3] = 0xA54FF53A;
+	context->state[4] = 0x510E527F;
+	context->state[5] = 0x9B05688C;
+	context->state[6] = 0x1F83D9AB;
+	context->state[7] = 0x5BE0CD19;
+}
+
+void fz_sha256update(fz_sha256 *context, const unsigned char *input, unsigned int inlen)
+{
+	/* Copy the input data into a properly aligned temporary buffer.
+	 * This way we can be called with arbitrarily sized buffers
+	 * (no need to be multiple of 64 bytes), and the code works also
+	 * on architectures that don't allow unaligned memory access. */
+	while (inlen > 0)
+	{
+		const unsigned int copy_start = context->count[0] & 0x3F;
+		unsigned int copy_size = 64 - copy_start;
+		if (copy_size > inlen)
+			copy_size = inlen;
+
+		memcpy(context->buffer.u8 + copy_start, input, copy_size);
+
+		input += copy_size;
+		inlen -= copy_size;
+		context->count[0] += copy_size;
+		/* carry overflow from low to high */
+		if (context->count[0] < copy_size)
+			context->count[1]++;
+
+		if ((context->count[0] & 0x3F) == 0)
+			transform(context->state, context->buffer.u32);
+	}
+}
+
+void fz_sha256final(fz_sha256 *context, unsigned char digest[32])
+{
+	/* Add padding as described in RFC 3174 (it describes SHA-1 but
+	 * the same padding style is used for SHA-256 too). */
+	unsigned int j = context->count[0] & 0x3F;
+	context->buffer.u8[j++] = 0x80;
+
+	while (j != 56)
+	{
+		if (j == 64)
+		{
+			transform(context->state, context->buffer.u32);
+			j = 0;
+		}
+		context->buffer.u8[j++] = 0x00;
+	}
+
+	/* Convert the message size from bytes to bits. */
+	context->count[1] = (context->count[1] << 3) + (context->count[0] >> 29);
+	context->count[0] = context->count[0] << 3;
+
+	context->buffer.u32[14] = bswap32(context->count[1]);
+	context->buffer.u32[15] = bswap32(context->count[0]);
+	transform(context->state, context->buffer.u32);
+
+	for (j = 0; j < 8; j++)
+		((unsigned int *)digest)[j] = bswap32(context->state[j]);
+	memset(context, 0, sizeof(fz_sha256));
+}
diff --git a/fitz/fitz.h b/fitz/fitz.h
index 8f756895..6a339303 100644
--- a/fitz/fitz.h
+++ b/fitz/fitz.h
@@ -285,6 +285,24 @@ void fz_md5init(fz_md5 *state);
 void fz_md5update(fz_md5 *state, const unsigned char *input, const unsigned inlen);
 void fz_md5final(fz_md5 *state, unsigned char digest[16]);
 
+/* sha-256 digests */
+
+typedef struct fz_sha256_s fz_sha256;
+
+struct fz_sha256_s
+{
+	unsigned int state[8];
+	unsigned int count[2];
+	union {
+		unsigned char u8[64];
+		unsigned int u32[16];
+	} buffer;
+};
+
+void fz_sha256init(fz_sha256 *state);
+void fz_sha256update(fz_sha256 *state, const unsigned char *input, unsigned int inlen);
+void fz_sha256final(fz_sha256 *state, unsigned char digest[32]);
+
 /* arc4 crypto */
 
 typedef struct fz_arc4_s fz_arc4;