Signature Profiles

Signature profiles define the appearance and settings for visible signatures.

Creating a custom signature profile with logo and positioning options

Overview

A signature profile controls:

Visibility: Invisible (cryptographic only) or visible (appears on page)
Position: Where the signature appears (page, coordinates)
Appearance: What the signature box displays (name, date, logo)

Built-in Profiles

Lankir includes two default profiles:

Invisible Signature

ID: 00000000-0000-0000-0000-000000000001
Description: Cryptographic signature with no visual appearance
Use case: Documents where layout shouldn’t change

Visible Signature

ID: 00000000-0000-0000-0000-000000000002
Description: Signature box showing signer name and timestamp
Position: Bottom-right of last page
Size: 200×80 points

Listing Profiles

lankir sign profiles list

# JSON output
lankir sign profiles list --json

Using Profiles

In GUI

Click Sign in the toolbar
Select certificate
Choose profile from Signature Profile dropdown
For visible signatures, optionally adjust position by clicking on the page

In CLI

# Use default profile (invisible)
lankir sign pdf doc.pdf out.pdf --cert ABC123...

# Use visible signature profile
lankir sign pdf doc.pdf out.pdf \
    --cert ABC123... \
    --profile "00000000-0000-0000-0000-000000000002"

# Override position for visible signature
lankir sign pdf doc.pdf out.pdf \
    --cert ABC123... \
    --visible \
    --page 1 \
    --x 400 --y 50

Profile Settings

Visibility Options

Value	Description
`invisible`	No visual appearance on document
`visible`	Signature box appears on specified page

Position Settings

Setting	Type	Description
`page`	int	Page number (1-indexed, 0 = last page)
`x`	float	Horizontal position from left edge (points)
`y`	float	Vertical position from bottom edge (points)
`width`	float	Signature box width (points)
`height`	float	Signature box height (points)

Note

PDF coordinates start from the bottom-left corner. 1 inch = 72 points.

Appearance Settings

Setting	Type	Description
`showSignerName`	bool	Display the certificate holder’s name
`showSigningTime`	bool	Display date and time of signing
`showLocation`	bool	Display geographic location (if available)
`showLogo`	bool	Display a custom logo image
`logoPath`	string	Base64 data URL of logo image
`logoPosition`	string	Logo placement: `"left"` or `"top"`
`customText`	string	Additional text to display
`fontSize`	int	Text size in points

Profile Storage

Profiles are stored as JSON files in:

~/.config/lankir/signature_profiles/

Each profile is a separate file named {uuid}.json.

Profile JSON Structure

{
  "id": "12345678-1234-1234-1234-123456789012",
  "name": "Company Signature",
  "description": "Standard company signature with logo",
  "visibility": "visible",
  "isDefault": false,
  "position": {
    "page": 0,
    "x": 360,
    "y": 50,
    "width": 200,
    "height": 80
  },
  "appearance": {
    "showSignerName": true,
    "showSigningTime": true,
    "showLocation": false,
    "showLogo": true,
    "logoPath": "data:image/png;base64,iVBORw0KGgo...",
    "logoPosition": "left",
    "customText": "Approved for release",
    "fontSize": 10
  }
}

Creating Custom Profiles

Via GUI

Go to Settings → Signature Profiles
Click New Profile
Configure settings:
- Name and description
- Visibility (invisible/visible)
- Position (page, coordinates, size)
- Appearance options
Click Save

Via File

Create a JSON file in ~/.config/lankir/signature_profiles/:

cat > ~/.config/lankir/signature_profiles/my-profile.json << 'EOF'
{
  "id": "$(uuidgen)",
  "name": "My Custom Profile",
  "description": "Signature for internal documents",
  "visibility": "visible",
  "isDefault": false,
  "position": {
    "page": 1,
    "x": 72,
    "y": 72,
    "width": 200,
    "height": 60
  },
  "appearance": {
    "showSignerName": true,
    "showSigningTime": true,
    "showLocation": false,
    "showLogo": false,
    "customText": "",
    "fontSize": 10
  }
}
EOF

Position Examples

Bottom-Right Corner (Last Page)

"position": {
  "page": 0,
  "x": 360,
  "y": 50,
  "width": 200,
  "height": 80
}

Top-Right Corner (First Page)

"position": {
  "page": 1,
  "x": 360,
  "y": 700,
  "width": 200,
  "height": 80
}

Centered (Specific Page)

For a Letter-size page (612×792 points):

"position": {
  "page": 3,
  "x": 206,
  "y": 356,
  "width": 200,
  "height": 80
}

Logo Requirements

Formats: PNG, JPEG, GIF
Recommended size: 100-200 pixels wide
Encoding: Base64 data URL

Converting Logo to Base64

# Convert image to base64 data URL
echo "data:image/png;base64,$(base64 -w0 logo.png)"

Logo Positioning

Position	Description
`left`	Logo on left, text on right
`top`	Logo above text

Best Practices

Consistent Positioning

For multi-page documents signed by the same organization:

Use the same profile for all signatures
Position signatures consistently (same corner, same size)

Readable Signatures

Keep font size at 10+ points for readability
Ensure adequate contrast with document background
Leave margin from page edges

Logo Usage

Use transparent PNG for best results
Keep logos simple and recognizable at small sizes
Ensure logo doesn’t overpower text information

Troubleshooting

Profile Not Appearing

Check profiles directory exists:

ls -la ~/.config/lankir/signature_profiles/

Invalid Profile

Validate JSON syntax:

python3 -m json.tool ~/.config/lankir/signature_profiles/my-profile.json

Required fields:

id: Valid UUID
name: Non-empty string
visibility: "invisible" or "visible"

Signature Cut Off

Position too close to edge. Ensure:

x + width < page_width - margin
y + height < page_height - margin

Next Steps

Signing PDFs - Use profiles when signing
Verification - Verify signed documents