decompile rc4 init functions (#999)

lib/crypto/asm/rc4.s

@@ -1,93 +0,0 @@
-	.include "macros/function.inc"
-
-	
-
-	.text
-
-
-	arm_func_start CRYPTO_RC4FastInit
-CRYPTO_RC4FastInit: ; 0x020A490C
-	stmfd sp!, {r4, r5, r6, lr}
-	mov r3, #0
-	str r3, [r0, #0]
-	cmp r2, #0x10
-	str r3, [r0, #4]
-	movhi r2, #0x10
-	add r0, r0, #8
-_020A4928:
-	str r3, [r0, r3, lsl #2]
-	add r3, r3, #1
-	cmp r3, #0x100
-	blt _020A4928
-	mov r5, #0
-	mov r6, r5
-	mov lr, r5
-	mov ip, r5
-_020A4948:
-	ldrb r3, [r1, r6]
-	ldr r4, [r0, lr, lsl #2]
-	add r6, r6, #1
-	add r3, r4, r3
-	add r3, r5, r3
-	and r5, r3, #0xff
-	ldr r3, [r0, r5, lsl #2]
-	cmp r6, r2
-	str r3, [r0, lr, lsl #2]
-	add lr, lr, #1
-	moveq r6, ip
-	str r4, [r0, r5, lsl #2]
-	cmp lr, #0x100
-	blt _020A4948
-	mov r2, #0
-_020A4984:
-	ldr r1, [r0, r2, lsl #2]
-	mov r1, r1, lsl #0x18
-	str r1, [r0, r2, lsl #2]
-	add r2, r2, #1
-	cmp r2, #0x100
-	blt _020A4984
-	ldmia sp!, {r4, r5, r6, lr}
-	bx lr
-	arm_func_end CRYPTO_RC4FastInit
-
-	arm_func_start CRYPTO_RC4Init
-CRYPTO_RC4Init: ; 0x020A49A4
-	stmfd sp!, {r4, r5, r6, r7, lr}
-	sub sp, sp, #4
-	mov r3, #0
-	strb r3, [r0]
-	cmp r2, #0x10
-	strb r3, [r0, #1]
-	movhi r2, #0x10
-	add r0, r0, #4
-_020A49C4:
-	strb r3, [r0, r3]
-	add r3, r3, #1
-	cmp r3, #0x100
-	blt _020A49C4
-	mov r6, #0
-	mov r7, r6
-	mov r4, r6
-	mov r3, r6
-	and ip, r2, #0xff
-_020A49E8:
-	ldrb r5, [r0, r4]
-	ldrb lr, [r1, r7]
-	add r2, r7, #1
-	and r7, r2, #0xff
-	add r2, r5, lr
-	add r2, r6, r2
-	and r6, r2, #0xff
-	ldrb r2, [r0, r6]
-	add lr, r0, r4
-	add r4, r4, #1
-	strb r2, [lr]
-	cmp r7, ip
-	moveq r7, r3
-	cmp r4, #0x100
-	strb r5, [r0, r6]
-	blt _020A49E8
-	add sp, sp, #4
-	ldmia sp!, {r4, r5, r6, r7, lr}
-	bx lr
-	arm_func_end CRYPTO_RC4Init

lib/crypto/include/crypto/rc4.h

@@ -7,20 +7,22 @@ extern "C" {
 
 #include <nitro/types.h>
 
-typedef struct CRYPTORC4Context_t {
+#define RC4_S_SIZE 256
+
+typedef struct CRYPTORC4Context {
     u8 i, j;
     u8 padd[2];
-    u8 s[256];
+    u8 s[RC4_S_SIZE];
 } CRYPTORC4Context;
 
-typedef struct CRYPTORC4FastContext_t {
+typedef struct CRYPTORC4FastContext {
     u32 i, j;
-    u32 s[256];
+    u32 s[RC4_S_SIZE];
 } CRYPTORC4FastContext;
 
-void CRYPTO_RC4Init(CRYPTORC4Context *, const void *, u32);
+void CRYPTO_RC4Init(CRYPTORC4Context *ctx, const void *key, u32 keyLength);
 void CRYPTO_RC4Encrypt(CRYPTORC4Context *, const void *, u32, void *);
-void CRYPTO_RC4FastInit(CRYPTORC4FastContext *, const void *, u32);
+void CRYPTO_RC4FastInit(CRYPTORC4FastContext *ctx, const void *key, u32 keyLength);
 void CRYPTO_RC4FastEncrypt(CRYPTORC4FastContext *, const void *, u32, void *);
 
 static inline void CRYPTO_RC4Decrypt(CRYPTORC4Context *param0, const void *param1, u32 param2, void *param3)

lib/crypto/meson.build

@@ -13,7 +13,7 @@ libcrypto_c_args = [
 libcrypto_public_includes = include_directories('include')
 
 libcrypto_static_srcs = files(
-    'asm/rc4.s',
+    'src/rc4.c',
     'asm/rc4-arm4cw.s'
 )
 
@@ -25,8 +25,11 @@ libcrypto_ov97_srcs = files(
 
 libcrypto_static = static_library('crypto_static',
     sources: libcrypto_static_srcs,
+    c_args: libcrypto_c_args,
     nasm_args: asm_args,
-    pic: false
+    pic: false,
+    include_directories: libcrypto_public_includes,
+    dependencies: nitrosdk_dep
 )
 
 libcrypto_ov97 = static_library('crypto_ov97',

lib/crypto/src/rc4.c

@@ -0,0 +1,69 @@
+#include "crypto/rc4.h"
+
+#include <nitro/types.h>
+
+void CRYPTO_RC4Init(CRYPTORC4Context *ctx, const void *key, u32 keyLength)
+{
+    u8 *s;
+    u8 id1, id2;
+    int i;
+
+    if (keyLength > 16) {
+        keyLength = 16;
+    }
+
+    ctx->i = 0;
+    ctx->j = 0;
+
+    s = ctx->s;
+
+    for (i = 0; i < RC4_S_SIZE; i++) {
+        s[i] = i;
+    }
+
+    id1 = id2 = 0;
+    for (i = 0; i < RC4_S_SIZE; i++) {
+        u8 tmp = s[i];
+        id2 = (((u8 *)key)[id1] + tmp + id2);
+        if (++id1 == (u8)keyLength) {
+            id1 = 0;
+        }
+        s[i] = s[id2];
+        s[id2] = tmp;
+    }
+}
+
+void CRYPTO_RC4FastInit(CRYPTORC4FastContext *ctx, const void *key, u32 keyLength)
+{
+    u32 *s;
+    u32 id1, id2;
+    int i;
+
+    if (keyLength > 16) {
+        keyLength = 16;
+    }
+    
+    ctx->i = 0;
+    ctx->j = 0;
+
+    s = ctx->s;
+
+    for (i = 0; i < RC4_S_SIZE; i++) {
+        s[i] = i;
+    }
+
+    id1 = id2 = 0;
+    for (i = 0; i < RC4_S_SIZE; i++) {
+        u32 tmp = s[i];
+        id2 = (((u8 *)key)[id1] + tmp + id2) % RC4_S_SIZE;
+        if (++id1 == keyLength) {
+            id1 = 0;
+        }
+        s[i] = s[id2];
+        s[id2] = tmp;
+    }
+
+    for (i = 0; i < RC4_S_SIZE; i++) {
+        s[i] <<= 24;
+    }
+}