From a290470880669630dba46ebe0c94b44f36f34f00 Mon Sep 17 00:00:00 2001 From: Tom Sepez Date: Mon, 1 May 2017 16:51:21 -0700 Subject: CRYPT_ArcFourSetup: don't use key[0] when length is 0 Bug: 686128 Change-Id: Ie8d71d7c0b76abb3f39ea2ea5ce43c82994a047a Reviewed-on: https://pdfium-review.googlesource.com/4750 Reviewed-by: Lei Zhang Commit-Queue: Tom Sepez --- core/fdrm/crypto/fx_crypt.cpp | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/core/fdrm/crypto/fx_crypt.cpp b/core/fdrm/crypto/fx_crypt.cpp index aac4edb317..f4ead91d33 100644 --- a/core/fdrm/crypto/fx_crypt.cpp +++ b/core/fdrm/crypto/fx_crypt.cpp @@ -6,6 +6,8 @@ #include "core/fdrm/crypto/fx_crypt.h" +#include + #define GET_UINT32(n, b, i) \ { \ (n) = (uint32_t)((uint8_t*)b)[(i)] | \ @@ -139,22 +141,15 @@ void md5_process(CRYPT_md5_context* ctx, const uint8_t data[64]) { void CRYPT_ArcFourSetup(CRYPT_rc4_context* s, const uint8_t* key, uint32_t length) { - int i, j, k, *m, a; s->x = 0; s->y = 0; - m = s->m; - for (i = 0; i < 256; i++) { - m[i] = i; - } - j = k = 0; - for (i = 0; i < 256; i++) { - a = m[i]; - j = (j + a + key[k]) & 0xFF; - m[i] = m[j]; - m[j] = a; - if (++k >= (int)length) { - k = 0; - } + for (int i = 0; i < 256; ++i) + s->m[i] = i; + + int j = 0; + for (int i = 0; i < 256; ++i) { + j = (j + s->m[i] + (length ? key[i % length] : 0)) & 0xFF; + std::swap(s->m[i], s->m[j]); } } -- cgit v1.2.3