CyberChef

02Outside layer first

Hex uses pairs of digits 0–9 and a–f to represent bytes. Standard Base64 uses letters, digits, + and /, with = sometimes added as padding. These shapes suggest possible formats; provenance, the record of how the data was made, is stronger evidence. A string can fit more than one alphabet.

For the declared worked input, removing Base64 exposes hex text. The next step interprets those pairs as bytes and the bytes as readable ASCII. From Hex first would apply the wrong interpretation to the outer string. CyberChef’s Magic feature suggests interpretations; record the actual operations and settings rather than treating a suggestion as proof. Auto Bake can run a changed recipe automatically, so keep personal or secret material out of experimental inputs.

03Decode the activity input

The guided input is 6c616e65. Its provenance says one hex layer representing ASCII text. Trace it on paper; opening CyberChef later is optional.

Encoding card. Python's standard library encoded these strings while the card was written.
 Nothing below is an observed CyberChef result.

Alphabets, reused from Stage 04
Hex digits are 0-9 and a-f.
Standard Base64 uses A-Z, a-z, 0-9, +, /, and = for padding.

Worked input
NmU2Zjc0NjU=
Outer layer: Base64 of the hex text 6e6f7465
Those hex digits are the ASCII bytes of: note
Recipe order for this input: From Base64, then From Hex
Predicted output: note

Activity input
6c616e65
The characters are hex digits, and the length is even.
One operation: From Hex
Predicted output: lane
ASCII map for the activity: 6c=l, 61=a, 6e=n, 65=e.
Use the map to check your one-layer prediction.

Field input
NjQ2NTczNmI=
This string is Base64 of hex text.
It contains = and letters outside the hex digits.

Authored recipe note. Not a file saved by CyberChef.
Argument fields were not verified against a CyberChef build.

Name: desk-note-worked
Input: NmU2Zjc0NjU=
Step 1: From Base64
Step 2: From Hex
Predicted output: note
This recipe does not use Magic. A Magic suggestion would be a hypothesis until the steps are written down.

Name: desk-note-activity
Input: 6c616e65
Step 1: From Hex
Predicted output: lane

Independent input: NjQ2NTczNmI=, declared Base64 of hex text.

1. Split the input into pairs: 6c 61 6e 65. Each pair represents one byte.
2. Use the supplied ASCII mapping: 6c means l, 61 means a, 6e means n and 65 means e. Write the operation that interprets these pairs.
3. Compare your prediction with lane. Record input, From Hex and that output in order; a second decoding operation is unnecessary.
4. Stop with the written recipe. In a later optional browser run, use only these strings and the named local transforms; do not add a network-fetch operation.

04Optional challenge

Spend about ten optional minutes explaining why reversing the two worked operations fails. Name the visible outer representation and the representation expected by each operation. Your explanation should describe the mismatch rather than relying on an error message from a particular build.

05Fresh cases for the checks

Use these fictional cases for the checks below. They have different inputs from the worked examples. Read them here or make notes; no installation or external service is needed.

The input is Base64 of hex text.
Input: Nzc2MTc2NjU=
Supplied transformation map: From Base64(Nzc2MTc2NjU=) = 77617665
ASCII byte map: 77=w, 61=a, 76=v, 65=e.
Read these maps as authored predictions, not a CyberChef run.

Provenance: plain ASCII bytes represented once in hex.
Input: 70696e
ASCII map: 70=p, 69=i, 6e=n.
No Base64 layer is present.

06Explain your evidence

Optional written self-check: explain one decision using the supplied case. No tool run is required.

Check your explanation: name the declared outer layer; trace each intermediate representation; record operation order and exact input; explain why readability does not establish origin or confidentiality.