Private Key Extraction from Qualcomm Hardware-backed Keystores
A side-channel attack can extract private keys from certain versions of Qualcomm’s secure keystore. Recent Android devices include a hardware-backed keystore, which developers can use to protect their cryptographic keys with secure hardware. On some devices, Qualcomm’s TrustZone-based keystore leaks sensitive information through the branch predictor and memory caches, enabling recovery of 224 and 256-bit ECDSA keys. We demonstrate this by extracting an ECDSA P-256 private key from the hardware-backed keystore on the Nexus 5X.