  Although cryptographic algorithms may be mathematically secure, it is often
possible to leak secret information from the implementation of the algorithms.
Timing and power side-channel vulnerabilities are some of the most widely
considered threats to cryptographic algorithm implementations. Timing
vulnerabilities may be easier to detect and exploit, and all high-quality
cryptographic code today should be written in constant-time style. However,
this does not prevent power side-channels from existing. With constant time
code, potential attackers can resort to power side-channel attacks to try
leaking secrets. Detecting potential power side-channel vulnerabilities is a
tedious task, as it requires analyzing code at the assembly level and needs
reasoning about which instructions could be leaking information based on their
operands and their values. To help make the process of detecting potential
power side-channel vulnerabilities easier for cryptographers, this work
presents Pascal: Power Analysis Side Channel Attack Locator, a tool that
introduces novel symbolic register analysis techniques for binary analysis of
constant-time cryptographic algorithms, and verifies locations of potential
power side-channel vulnerabilities with high precision. Pascal is evaluated on
a number of implementations of post-quantum cryptographic algorithms, and it is
able to find dozens of previously reported single-trace power side-channel
vulnerabilities in these algorithms, all in an automated manner.
