OpenSSL RAND_byte issue with iOS Simulator

Question

I have downloaded the latest source from OpenSSL Page (released on April 7th, 2014), and created a libcrypto.a library using Tutorial Where i have followed the steps in which i run ./build-openssl.sh script file to generate libcrypto.a file for all environments (armv7s, armv7, i386) on Mac OS X having version 10.9.2.

I am able to encrypt / decrypt the date using EVP_aes_256_cbc encryption but my code gets failed when i try to get RAND_byte. The code gets crashed on RAND_byte call.

Below are the codes, which i am trying to get the RAND_byte seeds:

// Code 1

unsigned char seed[32];
RAND_bytes(seed, 32);

// Code 2

int count = 24;
unsigned char *buffer = (unsigned char *)calloc(count, sizeof(unsigned char));
RAND_bytes(buffer, count);

// Code 3

int count = 24;
unsigned char *buffer = (unsigned char *)malloc(sizeof(int)*count);
RAND_bytes(buffer, count);

// Code 4

int count = 24;
unsigned char *buffer = OPENSSL_malloc(count);
RAND_bytes(buffer, count);

When I run above code on iOS 6.0/6.1 Simulator, It gets crashed on RAND_byte call and I get “_interposition_vtable_unimplemented” on Thread 1 and no message get displayed on console.

When I run the same code on iOS 7.0+ Simulator, It gets crashed on RAND_byte call and I get “__pthread_kill” on Thread 1 and “Detected an attempt to call a symbol in system libraries that is not present on the iPhone: open$UNIX2003 called from function RAND_poll in image CryptographyTest.” on Console.

But WHEN I run the same code on iPad with iOS 7.0.4, All above codes runs perfectly. Where i get the return value from RAND_byte is 1.

I don’t understand the behavior that some of the functions does not work on iOS simulator but everything works with iOS devices.

Any help highly appreciated! Many thanks in advance.

Answer 1

... using Tutorial where i have followed the steps in which i
run ./build-openssl.sh script file to generate libcrypto.a file
for all environments (armv7s, armv7, i386) 
...
I don’t understand the behavior that some of the functions does
not work on iOS simulator but everything works with iOS devices.

The script is wrong for your usage:

Its not building for the simulator. Its building for the desktop. This:

ARCHS=("armv7s" "armv7" "i386")
SDKS=("iphoneos" "iphoneos" "macosx")

Probably needs to be changed to:

ARCHS=("armv7s" "armv7" "i386")
SDKS=("iphoneos" "iphoneos" "iPhoneSimulator")

With iPhoneSimulator, the proper SDK will be used:

$ ls /Applications/Xcode.app/Contents/Developer/Platforms/
MacOSX.platform         iPhoneSimulator.platform
iPhoneOS.platform

Does the project you are using claim its multi-arch and for the iPhone and iPhone Simulator? Or does it claim its multi-arch and for iPhone and OS X?

Answer 2

and created a libcrypto.a library for iOS use using Tutorial.

I don't know about that Tutorial, but OpenSSL has procedures to build the library for iOS. You can find it in the FIPS User Guide 2.0, Appendix E.

You can fetch a prebuilt version of OpenSSL for iOS at Github. It was built using the OpenSSL procedures. Its a fat library, and it has i386, ARMv7, ARMv7s and ARM64 architectures.

---

“__pthread_kill” on Thread 1 and “Detected an attempt to call a symbol in system libraries that is not present on the iPhone: open$UNIX2003 called from function RAND_poll in image CryptographyTest.” on Console.

I believe this indicates the OpenSSL library was not built properly for the simulator or devices.

---

int count = 24;
unsigned char *buffer = OPENSSL_malloc(count);
RAND_bytes(buffer, count);

Just bike shedding here, but you ignored the return value from RAND_bytes. According to the docs on RAND_bytes:

RAND_bytes() returns 1 on success, 0 otherwise. The error code can be obtained by ERR_get_error(3).

Silent failures are a kiss of death to high integrity software.