CryptX Library
Industry-Standard Cryptography for the Texas Instruments TI-84+ CE Graphing Calculator
Cryptography is a specialization within the information security field that deals almost exclusively with protecting data from being read or modified by unauthorized parties. Cryptographic standards are vigorously tested for vulnerabilities and subject to constant analysis and improvement.
CryptX is a specialty library designed to provide cryptographic functionality for the TI-84+ CE. It integrates with the CE C toolchain and allows developers to easily implement cryptography into their projects without needing to worry about low-level implementation details. Distribution as a dynamic library also allows for the library to be updated with new functionality, bug fixes, and vulnerability patches usually without even requiring programs be rebuilt. Just install the new library version on your device and it should be forwards-compatible.
CryptX was made possible thanks to the work of a number of individuals from the Cemetech development community. From code contributions to lengthy discussions about ways and means to analysis of hardware behavior, this project would not have evolved into what it became without their support.
Contributor |
Contribution |
|---|---|
Anthony Cagliano |
lead developer, main algorithm implementation/sourcing |
Adam Beckingham |
porting to ez80 assembly and optimizing many algorithms |
John Cesarz |
general code contributions |
jacobly |
general code contributions |
Zeroko |
info and analysis for entropic RNG construction |
calc84maniac |
general code contributions |
MateoConLechuga |
words of encouragement, incl. “That’s not how RSA works, you idiot” |
Most of this library’s modules have been tested for compatibility with several other cryptographic libraries including openssl, cryptodome/pycryptodome, and cryptography, although in some cases where libraries do not expose their primitives, use of their hazardous materials layer may be required. If you do find an incompatibility with another cryptographic library, please open an issue on the CryptX Github.
API Documentation
CryptX has a number of modules that implement various standards for data obfuscation and integrity verification. The library attempts to evidence this by utilizing the following function naming convention:
cryptx_[module]_[method]
Module |
Implements |
|---|---|
public key cryptographic standards #8 |
|
secure hashing: SHA256, SHA1 |
|
hash-based message authentication code: SHA256, SHA1 |
|
cryptographically-secure random number generator |
|
bytearray comparison, string conversion, endianness reversal |
|
advanced encryption standard (AES) |
|
rivest-shamir-adleman (RSA) public key encryption |
|
elliptic curves: Diffie-Helman kex, Digitial Signing Algorithm |
|
DER/ASN.1 codex |
|
PEM/Base64 codex |
|
hazardous materials/compatibility/custom construction layer |
Coming Soon |
Implements |
|---|---|
ecdsa |
implements elliptic curve digital signing algoritm |
tls |
implements TLS protocol |
To avoid text overload, the entire library documentation will not be dumped onto a single page. You may click on the links in the table above if you wish to view more detailed documentation for a particular module.
Security Considerations
Last but not least, this library implements platform-specific considerations for side-channel attacks to the best extent possible on the hardware. This includes:
constant-time implementations where possible
stack frame zeroing after cryptographic transformations
system interrupts disabled during cryptographic transformations
Check out the Analysis & Overview for more technical implementation details including platform-specific security considerations.