- HOW TO CHECK FILE HASH ALGORITH HOW TO
- HOW TO CHECK FILE HASH ALGORITH SOFTWARE
- HOW TO CHECK FILE HASH ALGORITH CODE
Using the Debug Interface Access SDK ( bit.ly/2gBqKDo), it’s easy to create a simple tool such as the Debugging Information Dumper, cvdump.exe (which, along with its source code, is now available at bit.ly/2hAUhyy). Effectively, the set of SHA-256 hash values stored in the PDB file of the binary executable file collectively becomes the identifiers in the “birth certificate” of the binary executable file, as these identifiers are registered by the compiler that “gives birth” to the binary executable file.
HOW TO CHECK FILE HASH ALGORITH CODE
If an SHA-256 hash for a source code file matches an SHA-256 hash stored in the PDB file of a binary executable, it’s certain that the same source code file was compiled into the executable, allowing any stakeholder to have confidence in the binary executable file. With the new switch, the compiler implements the SHA-256 option, which is cryptographically stronger than MD5. The default is MD5, which is known to be more collision-prone but remains the default because its hash values are computationally cheaper to generate.
Native Code Compiler The Visual Studio 2015 native C/C++ compiler, cl.exe, comes with a new switch for choosing a different hash algorithm for the compiler to hash source code files: /ZH. Microsoft recently updated its various compiler file-hashing operations (such as source hashes embedded in PDB files) to use strong cryptographic algorithms. Generating Strong Hashes During CompilationĪ program database (PDB) file is a separate data file that stores the information used to debug a binary executable file.
HOW TO CHECK FILE HASH ALGORITH HOW TO
This article describes the new Visual Studio switch for choosing a hashing algorithm, scenarios where such hashes might prove useful and how to use Visual Studio to generate source code hashes. Clearly, this is good for users (who would, in fact, benefit further if vendors of other compilers also followed a similar approach).
Matching hash values from the compiler to hash values generated from examined source code files verifies that the executable code did indeed result from the particular source code files. To address this issue, it’s helpful to use a Visual Studio compiler to hash source code files during compilation. In either case, the problem is one of certainty-knowing for sure that the file you have is the one you want. On the other hand, it’s also possible that a single set of source code files could result in different executable files from different compilation processes. Having more or fewer whitespaces or text comments inside the source code files shouldn’t affect the binary code emitted by the compiler. It’s possible that two different sets of source code files could result in two bitwise-identical executable files.
But this transformation may not be deterministic.
HOW TO CHECK FILE HASH ALGORITH SOFTWARE
A critical part of software assurance is trusting that the reviewed source code files are the same source code files that were built into executable files.ĭuring the compilation and linking processes, a set of source code files written in a specific programming language (C#, C++, Objective C, Java and so forth) is transformed into a binary executable file for running on a computer of a specific architecture (x86, 圆4, ARM, for example). The transformation of human-readable code to machine-readable code introduces a challenge to software assurance for all compiled software languages: How does a user have confidence that a software program running on his computer was built from the same source code file created by the developer? That’s not necessarily a certainty-even if the source code files are reviewed by subject-matter experts, as they may be in the case of open source software. Volume 32 Number 3 Hashing Source Code Files with Visual Studio to Assure File Integrity