Notes and Calculator

Notes and Calculator

Two small ChipWhisperer Studio tools for everyday lab work. Notes is a text pad for keys you recovered, glitch settings that worked and to-dos, saved automatically. Calc is a calculator with side-channel helpers, plus statistics (count, sum, mean, median, min, max, peak to peak, standard deviation, RMS) of whatever you select: part of the waveform, one sample across all traces, or numbers anywhere in Studio.

Notes

The Notes tab. Selecting numbers in a note shows their statistics in the log bar at the bottom.

Open the Notes tab in the left navigation (near the bottom).

Control	What it does
Note list	Switch between notes. The first time, Studio creates a note called Notes.
New	Creates a note named after the current date and time (for example Note 2026-09-30 14.05) and selects its name so you can type a better one.
Delete	Deletes the current note after confirmation.
Name	Rename the note: type a new name and press Enter or click elsewhere. Names must be unique.
Insert selection stats	Inserts a line with the statistics of your current selection (see below), for example Selected text: count 4, sum 172, mean (average) 43, ....
Insert CPA key	Inserts the latest CPA result, for example CPA (sbox_hw, 400 traces): key 2b7e1516....
Preview	Toggles between editing and a formatted view of the note.
Status	Editing... while you type, Saved once written to disk.

Notes are saved automatically 0.7 seconds after you stop typing, and before you switch notes. Text is inserted at the cursor position.

Notes are plain text files written in Markdown, so # Heading, - list item, **bold**, `code` and tables show up formatted in Preview. They are stored as .md files in <data dir>/notes/ (by default ~/ChipWhispererStudio/notes/); you can open them with any editor, and .txt files you put there appear in the list too.

Calculator

The Calc tab: calculator history at the top, statistics of the waveform between cursors A and B below.

Type an expression and press Enter (or =). Results appear in a history list, newest first. Integer results also show their hexadecimal and binary form. Click a result to put it back into the input (in hex if your expression used hex). Press the Up and Down arrow keys to recall earlier expressions.

Numbers and operators

Kind	Syntax
Numbers	42, 3.3, 1e-6, hexadecimal 0x2b, binary 0b1011, octal 0o17
Arithmetic	+ - * /, integer division //, remainder %, power **
Bitwise	^ is XOR (as in C and Python, not power), & AND, | OR, ~ NOT, << and >> shifts
Comparisons	==, !=, <, <=, >, >= give 1 (true) or 0 (false)
Lists	[1, 2, 3], for functions that take several values
Constants	pi, e, tau, inf

Functions

Function	What it returns
hw(x), popcount(x)	Hamming weight: the number of 1 bits in x.
hd(a, b)	Hamming distance: the number of bits that differ between a and b.
sbox(x)	The AES S-box value of the byte x, for example sbox(0x53) is 0xed.
db(ratio), undb(dB)	Amplitude ratio to decibels (20 * log10(ratio)) and back.
mean(...), avg(...)	Average of the values (as separate arguments or one list).
median(...)	Median.
std(...), var(...)	Population standard deviation and variance (divide by n).
rms(...)	Root mean square.
sum(...), min(...), max(...)	Sum, smallest and largest value.
abs, round, int, float	As in Python.
hex, bin, oct, chr, ord	Conversions, as in Python.
sqrt, exp, log (natural), log2, log10	Roots and logarithms.
sin, cos, tan, asin, acos, atan, atan2, sinh, cosh, tanh, degrees, radians	Trigonometry (radians).
floor, ceil, factorial, gcd, hypot, isqrt, comb, perm	Other maths functions from Python's math module.

Variables

• ans is always the last result: ans * 2.
• name = expression stores a variable: vref = 3.3, then vref / 4096.
• Variables live in Studio (not in the browser), so they are shared by every open Studio window and by AI agents, and they reset when Studio restarts.

Examples

Expression	Result
0x2b ^ 0x7e	85 (0x55): XOR of two key bytes
hw(sbox(0x00 ^ 0x2b))	Hamming weight of the first-round S-box output, the leakage the sbox_hw CPA model uses
hd(0x3c, 0xc3)	8: all bits differ
3.3 / 4096 * 1000	0.8056640625: millivolts per step of a 12-bit ADC at 3.3 V
1 / 7.37e6 * 1e9	about 135.7: nanoseconds per clock cycle at 7.37 MHz
mean(1, 2, 3, 10)	4

The calculator is deliberately limited to maths: it cannot run Python code, access files or call arbitrary functions, and very large powers and shifts are refused.

Selection statistics

The Selection statistics card in the Calc tab computes statistics of a set of numbers you pick. Choose the source at the top of the card:

Source	What is measured
Selected text (anywhere in Studio)	The numbers in the text you have selected: in a note, a notebook output, the log, the serial console, a settings value, anywhere. Updates as you select.
Waveform: between cursors A and B	The samples of the displayed trace between the two cursors (click the plot for cursor A, Shift+click for cursor B).
Waveform: visible (zoomed) range	The samples currently visible in the waveform view.
Waveform: whole displayed trace	Every sample of the trace shown in the waveform view (the live trace, or the one you are browsing).
Stored traces: value at cursor A across traces	The value of one sample (the one under cursor A) in every stored trace: how that point varies from trace to trace.
Numbers I type or paste	Numbers you type or paste into the box, separated by spaces, commas or new lines.

Selecting numbers anywhere shows their count, sum, mean, min and max in the log bar.

The statistics

Statistic	Meaning
Count	How many numbers.
Sum	Their total.
Mean (average)	Sum divided by count.
Median	The middle value when sorted (the average of the two middle values for an even count).
Min, Max	The smallest and largest value.
Peak to peak	Max minus min.
Std deviation	Sample standard deviation (divides by count minus 1).
Variance	The square of the standard deviation.
RMS	Root mean square: the square root of the average of the squares.
Index of min, Index of max	Position of the smallest and largest value, counted from 0 within the selection.

For the waveform sources the card also shows the sample range and, when the scope's sample rate is known, the Duration of the range in microseconds and 1 / duration in kHz, handy for measuring the length of an operation or the period of a repeating pattern.

Note: The calculator's std() and var() functions use the population formula (divide by n), while the Selection statistics card uses the sample formula (divide by n minus 1). For large selections the difference is negligible.

Copy puts a one-line summary on the clipboard; Add to notes inserts it into the current note. Refresh recalculates (the card also refreshes when you open the tab, when the selection changes, and after each capture for the waveform sources).

The selection badge in the log bar

Whenever you select text that contains numbers, anywhere in Studio, a small badge appears in the log bar at the bottom: n 4 · Σ 172 · mean 43 · min 3 · max 126, like the status bar of a spreadsheet. With a single number it shows Selected: 42. Click the badge to open the Calc tab.

Numbers are recognised in decimal (42, -3.5, .5), scientific (1e-6, 2.5E3) and hexadecimal with a 0x prefix (0x2b). Other hexadecimal text, such as a key written as 2b7e1516, is not recognised as one number: parts of it are read as separate decimal (or scientific) numbers, so select plain numbers, or 0x prefixed ones, for meaningful results. Numbers inside words (for example the 2 in SS_VER_2_1) are counted too. Selections longer than 500,000 characters are ignored.

From the API and MCP

Action	HTTP API	MCP tool
List notes	GET /api/notes	notes_list
Create a note	POST /api/notes with {"name": "..."}	note_write creates missing notes
Read a note	GET /api/notes/{name}	note_read
Write or rename a note	PUT /api/notes/{name} with {"text": "...", "rename": "new name.md"}	note_write (append by default)
Delete a note	DELETE /api/notes/{name}
Evaluate an expression	POST /api/calc with {"expr": "0x2b ^ 0x7e"}	calculate
Calculator variables	GET /api/calc/variables
Statistics	POST /api/calc/stats with {"values": [...]}, {"source": "trace", "index": -1, "start": 0, "end": 100} or {"source": "sample", "sample": 1500}	selection_stats

See HTTP API and MCP Server.